Losi Constant Velocity Drive (LCD) vs MIP CVD
02-03-2006, 10:09 PM
#136
Spektrum Antenna Mod
When I first saw the spektrum transmitter I looked at the antenna and said to myself, that flimsy thing is going to break off in the pit bag (in its own separate end compartment). Well today I picked up the bag and heard the snap. I did not even bump into anything. Time for the mod I saw in a magazine. Here are the my instructions.
Take the spectrum transmitter apart. 4 screws; it's easy. There is no sticky stuff. The antenna lead is plugged into the board with a tiny plug, unplug it. Take the back off the M8. Two screws hold the M8 circuit board down. Undo these, but leave all the plugs alone. Now you have enough room to stab the Spektrum antenna into the stock location by going under the M8's circuit board. Pull the antenna up untill it jams (it's tapered). Put the M8 circuit board back down and replace the 2 screws. Now lower the antenna into the stock antenna chrome big clip. Put the back on while threading the antenna lead throught the hole in the back of the M8 near the pins. Enlarge a hole in the back of the Spektrum in the middle of the pin slot, outboard of the pin slot or make a new hole. Take the circuit board out to do this. The circuit board just falls out. Thread the antenna lead through your hole, plug it into the Spektrum board, reassemble the Spektrum and plug it in to the M8. Took 20-30 minutes. This antenna location is a lot more rugged a setup than stock location. I'll test the range at Mikes later. When finished pull the antenna up until it jams. Put a rubber plug in the hole. The automotive vacuum hose plug makes a nice bumper. Worked fine at home.
You do similar work on a radio changing from left to right hand, so don't be afraid of this mod.
When I first saw the spektrum transmitter I looked at the antenna and said to myself, that flimsy thing is going to break off in the pit bag (in its own separate end compartment). Well today I picked up the bag and heard the snap. I did not even bump into anything. Time for the mod I saw in a magazine. Here are the my instructions.
Take the spectrum transmitter apart. 4 screws; it's easy. There is no sticky stuff. The antenna lead is plugged into the board with a tiny plug, unplug it. Take the back off the M8. Two screws hold the M8 circuit board down. Undo these, but leave all the plugs alone. Now you have enough room to stab the Spektrum antenna into the stock location by going under the M8's circuit board. Pull the antenna up untill it jams (it's tapered). Put the M8 circuit board back down and replace the 2 screws. Now lower the antenna into the stock antenna chrome big clip. Put the back on while threading the antenna lead throught the hole in the back of the M8 near the pins. Enlarge a hole in the back of the Spektrum in the middle of the pin slot, outboard of the pin slot or make a new hole. Take the circuit board out to do this. The circuit board just falls out. Thread the antenna lead through your hole, plug it into the Spektrum board, reassemble the Spektrum and plug it in to the M8. Took 20-30 minutes. This antenna location is a lot more rugged a setup than stock location. I'll test the range at Mikes later. When finished pull the antenna up until it jams. Put a rubber plug in the hole. The automotive vacuum hose plug makes a nice bumper. Worked fine at home.
You do similar work on a radio changing from left to right hand, so don't be afraid of this mod.
Last edited by John Stranahan; 02-05-2006 at 08:24 AM.
02-05-2006, 03:58 PM
#137
Originally Posted by John Stranahan
So here is the suggested change. Up about .025 inches on the rear inner A-arm hinge pivots with the 2.42 inch tires.
CALCULATED VALUES
ROLL CENTER 0.25 inch
Roll Moment Arm 0.64 inch
Roll Moment @1.5 g 3.23 pound-inch
This gives you near identical roll moment as with the short tire. I suspect it will then drive in a similar manner, but I have not gotten results yet. It is quite a bit easier to change the camber link inner pivot on this TC3 which has FTTC4 aluminum camber link blocks than to shim the lower pivots. For this reason it might be better to use a thicker shim under the pivots to make sure you have plenty of adjustability at the camber link inner pivot. Then small chages can be made as the tire wears. On this car the outer camber link pivot is already all the way up.
Also it is not neccesary to use the same chassis height with the tall tires. It may work better a little higher of the ground, or maybe not. My XXXS used to work better at 6 mm than 5 mm.
Any carpet racers with foam tires please make a post on what works for you in this situation.
CALCULATED VALUES
ROLL CENTER 0.25 inch
Roll Moment Arm 0.64 inch
Roll Moment @1.5 g 3.23 pound-inch
This gives you near identical roll moment as with the short tire. I suspect it will then drive in a similar manner, but I have not gotten results yet. It is quite a bit easier to change the camber link inner pivot on this TC3 which has FTTC4 aluminum camber link blocks than to shim the lower pivots. For this reason it might be better to use a thicker shim under the pivots to make sure you have plenty of adjustability at the camber link inner pivot. Then small chages can be made as the tire wears. On this car the outer camber link pivot is already all the way up.
Also it is not neccesary to use the same chassis height with the tall tires. It may work better a little higher of the ground, or maybe not. My XXXS used to work better at 6 mm than 5 mm.
Any carpet racers with foam tires please make a post on what works for you in this situation.
02-06-2006, 04:23 PM
#138
LJay- Thanks for the report. I got a report on a tire truer that suggested it trued a slight angle into the foam to make the contact higher on the inner part of the contact patch. I imagine that the purpose of that is to reduce traction with roll. I wonder if you need to (or are able to) tinker with this angle on the new tire. Maybe a little more angle to compensate for a more flexible (gripier) tires. Anyway be sure and tell us what you find out.
Chassis Flex Tuning Report on the JRXS
I started out on 17 pound (Blue) TC3 springs today. This was an increase from the 14.5 pound TC3 Silver Springs. I lost a little cornering traction at all four corners, but the chassis was well behaved now on the high speed corner coming off the very high speed straight onto the infield. I thought this would be a good time to try increasing the flex in the chassis. I have measured the chassis stiffness on the JRXS and it is 4 times more stiff in torsion than the XXXS. The XXXS (graphite) always seemed ideal for Mod Touring.
By removing the 4 posts, the JRXS becomes more flexible by a factor of 4, now equal to the XXXS. This increased flex had a couple of effects.
First it detuned the car. I moved the rear shock over one hole to retune it.
It did give me some more cornering traction with the 17 pound springs.
It did not give me more traction than with the 14 pound spring.
So the big benefit for me was to be able to run the heavier springs which gave me good steering precision coming off the straight, but still keep good cornering traction for the infield. The heavier springs also limited chassis roll and rubbing on the track. This was becoming pretty essential.
I find that these longer TC3 springs, although very close in spring rate to the Losi short springs make the car more supple. This seems to help me to keep it planted over the bumps. I did have to space the front shocks farther forward with the blue springs. Two washer under the lower pivots, thick rather than thin plastic spacer on the shock tower, slight bevel to caster blocks with the Dremmel.
GTB 6.5 Thermal Shutdown
I had some thermal shutdowns to the GTB 6.5 today. I am missing two fan blades though. When my new fan arrives this problem may go away. The car is faster with the 12 gauge wiring. I had to move my braking point off the straight back about 1-2 feet as a result. I geared just a bit lower until my new fan comes. If the fan does not cure the problem then maybe the speedcontrol needs the tiny 14 gauge wires to keep cool. It had worked fine a previous evening with the 12 gauge when it was cooler. GTB case temp was only 100 F today. I tried running previously without the fan and it would shut down at 3 minutes like a clock. Similar action today.
Rerouted Spektrum Antenna
Worked Great. No stress on it in the pit bag anymore.
Chassis Flex Tuning Report on the JRXS
I started out on 17 pound (Blue) TC3 springs today. This was an increase from the 14.5 pound TC3 Silver Springs. I lost a little cornering traction at all four corners, but the chassis was well behaved now on the high speed corner coming off the very high speed straight onto the infield. I thought this would be a good time to try increasing the flex in the chassis. I have measured the chassis stiffness on the JRXS and it is 4 times more stiff in torsion than the XXXS. The XXXS (graphite) always seemed ideal for Mod Touring.
By removing the 4 posts, the JRXS becomes more flexible by a factor of 4, now equal to the XXXS. This increased flex had a couple of effects.
First it detuned the car. I moved the rear shock over one hole to retune it.
It did give me some more cornering traction with the 17 pound springs.
It did not give me more traction than with the 14 pound spring.
So the big benefit for me was to be able to run the heavier springs which gave me good steering precision coming off the straight, but still keep good cornering traction for the infield. The heavier springs also limited chassis roll and rubbing on the track. This was becoming pretty essential.
I find that these longer TC3 springs, although very close in spring rate to the Losi short springs make the car more supple. This seems to help me to keep it planted over the bumps. I did have to space the front shocks farther forward with the blue springs. Two washer under the lower pivots, thick rather than thin plastic spacer on the shock tower, slight bevel to caster blocks with the Dremmel.
GTB 6.5 Thermal Shutdown
I had some thermal shutdowns to the GTB 6.5 today. I am missing two fan blades though. When my new fan arrives this problem may go away. The car is faster with the 12 gauge wiring. I had to move my braking point off the straight back about 1-2 feet as a result. I geared just a bit lower until my new fan comes. If the fan does not cure the problem then maybe the speedcontrol needs the tiny 14 gauge wires to keep cool. It had worked fine a previous evening with the 12 gauge when it was cooler. GTB case temp was only 100 F today. I tried running previously without the fan and it would shut down at 3 minutes like a clock. Similar action today.
Rerouted Spektrum Antenna
Worked Great. No stress on it in the pit bag anymore.
Last edited by John Stranahan; 02-06-2006 at 06:23 PM.
02-07-2006, 11:57 AM
#139
GTB 6.5, Speed control Centered, Thermal shutdown solved, Ballast Removed
They say the third time is a charm. This is the third position for my GTB 6.5 in the Losi JRXS. This solved my thermal shutdown. I think there must be cooler air higher up in the body or the transistors cool better with things upright. Anyway, the 12 gauge stays. I was able to push the original gear ratio (faster).
This position completely eliminated my need for extra ballast (3 ounces). Corner weights are perfect.
I tried some new tires for the first time with this car and this setup. The car was dialed. Ready to race. No apparent harm from raising the center of gravity a little.
They say the third time is a charm. This is the third position for my GTB 6.5 in the Losi JRXS. This solved my thermal shutdown. I think there must be cooler air higher up in the body or the transistors cool better with things upright. Anyway, the 12 gauge stays. I was able to push the original gear ratio (faster).
This position completely eliminated my need for extra ballast (3 ounces). Corner weights are perfect.
I tried some new tires for the first time with this car and this setup. The car was dialed. Ready to race. No apparent harm from raising the center of gravity a little.
02-10-2006, 07:22 PM
#140
Precision Racing Pinions and Spurs
I received my Precision Racing Products Pinion and Spurs courtesy of Tony (Tornado Racing who posted above). Photo one shows a 130 tooth 64 pitch spur and a 32 tooth matching pinion. Very nice looking pieces. I did a couple of preliminary measurements. I used both the supplied button head screws and the purple flathead aluminum screws in the photo. The gear holes are beveled to fit the flathead screws well. No need to overtighten these screws. (Note that it may not be possible to use a 130. It sticks out the bottom of the chassis a few thousandths inch. 128 might be the maximum)
First the adaptor is a nicely machined aluminum piece. It was a light drag fit on the shaft, just as I would have wanted it. No effort was required to install it. I checked the lateral runout of the spur adaptors flange and it was less than .0001 inch (1 tenthousandth). Excellent. This also means my shaft and bearings are in good shape. I checked the axial runout (movement side to side of the gear rim as the gear is rotated) of a 128 tooth spur and it was about .005 inch. This is just barely noticable runout. Radial runout (movement in and out as the gear is rotated) of the gear teeth points was .003 inch. Now the gears don't mesh on the points but this is the best measure I could make radialy. A second 130 tooth spur had .005 inch axial runout and .0003 (3 ten thousanths radial runout). I deburred the threaded holes in the adaptor by cutting the edge with an X=acto knife point in between two measures, so this was not a problem. The adaptor has nice clearance cuts where the pilot meets the flange of the adaptor, so this was not a problem either. These are very acceptable specs and is probably due to properties of the material as it ages absorbs moisture and is shipped as they are machine cut to tighter specs. Totally acceptable here.
I measured a new Losi 128 spur and it had .0075 inch lateral runout. Now after you take these on and off a few times this can go up to about .020 as it requires TOO MUCH FORCE to install them.
Weights. The Losi spur is 5.98 grams. The Precision Racing System 128 spur and adaptor are 7.73 grams. This is just a little more, but the spur is lightened around a large radius. This means the rotational inertia or the power robbing effect of the two are probably pretty close. In other words the Losi spur is heavier on the part of the spur that robs the most power, farther out.
Free Gear Chart Maker Spreadsheet
I have been using 48 pitch spur and pinion. The gears I need are in the 7.20 t0 7.56 Region with the GTB 6.5 on a large oudoor track. I will enjoy the extra flexibility of the 64 pitch gears and the ability to move the motor forward and back by using large or small spurs. Later I will need gears in the 7.5 range for a 10 x 1 and then maybe lower turn mods.
To give you some idea of th size of Mikeshobbyshop.com's Gulf Coast Track, I paced off my braking distance off the straight onto the infield turn. 60 feet back with the GTB 6.5, 30 feet back with a Trinity Cobalt 10 x 1. The cars get going really fast.
The gear chart is an Microsof Excel Spreadsheet. Scanner just died, so I took a photo of it. You put in your available spurs and then your pinions. You measure the rollout of your tire. The rest of the chart then self generates. If you want a copy send me an e-mail request to [email protected]
Gear Durabilty and track test to come.
I received my Precision Racing Products Pinion and Spurs courtesy of Tony (Tornado Racing who posted above). Photo one shows a 130 tooth 64 pitch spur and a 32 tooth matching pinion. Very nice looking pieces. I did a couple of preliminary measurements. I used both the supplied button head screws and the purple flathead aluminum screws in the photo. The gear holes are beveled to fit the flathead screws well. No need to overtighten these screws. (Note that it may not be possible to use a 130. It sticks out the bottom of the chassis a few thousandths inch. 128 might be the maximum)
First the adaptor is a nicely machined aluminum piece. It was a light drag fit on the shaft, just as I would have wanted it. No effort was required to install it. I checked the lateral runout of the spur adaptors flange and it was less than .0001 inch (1 tenthousandth). Excellent. This also means my shaft and bearings are in good shape. I checked the axial runout (movement side to side of the gear rim as the gear is rotated) of a 128 tooth spur and it was about .005 inch. This is just barely noticable runout. Radial runout (movement in and out as the gear is rotated) of the gear teeth points was .003 inch. Now the gears don't mesh on the points but this is the best measure I could make radialy. A second 130 tooth spur had .005 inch axial runout and .0003 (3 ten thousanths radial runout). I deburred the threaded holes in the adaptor by cutting the edge with an X=acto knife point in between two measures, so this was not a problem. The adaptor has nice clearance cuts where the pilot meets the flange of the adaptor, so this was not a problem either. These are very acceptable specs and is probably due to properties of the material as it ages absorbs moisture and is shipped as they are machine cut to tighter specs. Totally acceptable here.
I measured a new Losi 128 spur and it had .0075 inch lateral runout. Now after you take these on and off a few times this can go up to about .020 as it requires TOO MUCH FORCE to install them.
Weights. The Losi spur is 5.98 grams. The Precision Racing System 128 spur and adaptor are 7.73 grams. This is just a little more, but the spur is lightened around a large radius. This means the rotational inertia or the power robbing effect of the two are probably pretty close. In other words the Losi spur is heavier on the part of the spur that robs the most power, farther out.
Free Gear Chart Maker Spreadsheet
I have been using 48 pitch spur and pinion. The gears I need are in the 7.20 t0 7.56 Region with the GTB 6.5 on a large oudoor track. I will enjoy the extra flexibility of the 64 pitch gears and the ability to move the motor forward and back by using large or small spurs. Later I will need gears in the 7.5 range for a 10 x 1 and then maybe lower turn mods.
To give you some idea of th size of Mikeshobbyshop.com's Gulf Coast Track, I paced off my braking distance off the straight onto the infield turn. 60 feet back with the GTB 6.5, 30 feet back with a Trinity Cobalt 10 x 1. The cars get going really fast.
The gear chart is an Microsof Excel Spreadsheet. Scanner just died, so I took a photo of it. You put in your available spurs and then your pinions. You measure the rollout of your tire. The rest of the chart then self generates. If you want a copy send me an e-mail request to [email protected]
Gear Durabilty and track test to come.
Last edited by John Stranahan; 02-11-2006 at 08:56 PM.
02-14-2006, 03:27 PM
#141
Gear Durability, Ratios Available, and Ease of Use Test
I have put about 24 packs on the Precision Racing Gears. They are very silent in the car. This is an indication of the proper meshing of the gears. There is no noticeable wear yet.
Although the Losi spur gear is held on with only one snap ring, I much prefer removing and replacing the spur with the three small screws, so no bending forces are put on the spur. In spite of the lightening holes, this Precision Racing Spur seems to be adequately stiff laterally as the runout has not increased.
I gained a useful ratio over using 48 pitch gears. I am running 7.44. ((126/31)*1.83) The car looked and felt really fast today. You can duplicate this ratio with Losi 64 pitch spurs. I found that even though the Precision Racing Spurs repeat every two teeth, that this is not an advantage on this car with this motor on this track, because the pinion spur ratio is about 4 which is an even number. 3 useful ratios were exactly repeated for three spurs to the hundreth place, the 128, 126,and 124. My dream gears would have an odd numbered spur like a 127 thrown into the mix then I would have
7.26
7.32
7.44
7.50
7.56
7.69
Some of the even numbered gears could be dropped from the lineup.
This is how fine I like to split the gears. I gained .1 - .2 seconds improvement on the lap time in going from 7.5 to 7.44 on this long outdoor track, so these fine splits are worth while in my view. Now I am using up the pack in 5 minutes. Time for some fresh packs.
I have put about 24 packs on the Precision Racing Gears. They are very silent in the car. This is an indication of the proper meshing of the gears. There is no noticeable wear yet.
Although the Losi spur gear is held on with only one snap ring, I much prefer removing and replacing the spur with the three small screws, so no bending forces are put on the spur. In spite of the lightening holes, this Precision Racing Spur seems to be adequately stiff laterally as the runout has not increased.
I gained a useful ratio over using 48 pitch gears. I am running 7.44. ((126/31)*1.83) The car looked and felt really fast today. You can duplicate this ratio with Losi 64 pitch spurs. I found that even though the Precision Racing Spurs repeat every two teeth, that this is not an advantage on this car with this motor on this track, because the pinion spur ratio is about 4 which is an even number. 3 useful ratios were exactly repeated for three spurs to the hundreth place, the 128, 126,and 124. My dream gears would have an odd numbered spur like a 127 thrown into the mix then I would have
7.26
7.32
7.44
7.50
7.56
7.69
Some of the even numbered gears could be dropped from the lineup.
This is how fine I like to split the gears. I gained .1 - .2 seconds improvement on the lap time in going from 7.5 to 7.44 on this long outdoor track, so these fine splits are worth while in my view. Now I am using up the pack in 5 minutes. Time for some fresh packs.
Last edited by John Stranahan; 02-14-2006 at 05:32 PM.
02-14-2006, 03:39 PM
#142
Servo Saver Mod for the JRXS
About the time you break your second steering linkage bit or servo arm (or worse your servo), or the first time it happens in a race, it's time to add a servo saver which did not come with my JRXS. Now there are a couple of reasons that Losi may have for not including one. Primarily there is no room for it on the servo, Second maybe you are supposed to be good enough not to crash before you buy this car. You can't place if you don't finish.
A servo saver should be transparent in use. You don't want the steering to get mushy as a result. The TC3 servo saver tends to get loose with use. The Losi XXXS servo saver just keeps on ticking, so this is the one I chose. Use all three springs. It will fit on any servo. Now to squeek out some more room.
Measure your clearance from the front of the installed servo to the chassis parts and from the wire harness to the pulley. You need 1/8 inch additional clearance with a little room to spare. If you have clearanace, which I did with a Hitec high speed high torque servo, cut or sand 1/8 inch off the mounting surface of the servo mounts so that the servo will move forward 1/8 inch. Sand away just into the locating pin a bit. Drill the servo mounting holes a little deeper with a #43 drill. This drill is the one that comes with a 4-40 tap. Remount the servo. Install the Losi XXXS servo saver. I used a Losi JRXS sway bar link to connect the servo to the steering linkage this gave me additional clearance on full left lock on the steering. I also beveled the edge of the servo just a little where the link would touch at full left lock (normally you don't steer quite this far as you turn the dual rate wheel down to prevent oversteer. Here is a photo. I can put part numbers if anybody is interested in doing this mod.
This also helped my front to back balance. I had a bit too much weight in the back.
Note that I have room between the saver and the motor. The photo does not show it. I can use the 128 spur which is max for this car.
About the time you break your second steering linkage bit or servo arm (or worse your servo), or the first time it happens in a race, it's time to add a servo saver which did not come with my JRXS. Now there are a couple of reasons that Losi may have for not including one. Primarily there is no room for it on the servo, Second maybe you are supposed to be good enough not to crash before you buy this car. You can't place if you don't finish.
A servo saver should be transparent in use. You don't want the steering to get mushy as a result. The TC3 servo saver tends to get loose with use. The Losi XXXS servo saver just keeps on ticking, so this is the one I chose. Use all three springs. It will fit on any servo. Now to squeek out some more room.
Measure your clearance from the front of the installed servo to the chassis parts and from the wire harness to the pulley. You need 1/8 inch additional clearance with a little room to spare. If you have clearanace, which I did with a Hitec high speed high torque servo, cut or sand 1/8 inch off the mounting surface of the servo mounts so that the servo will move forward 1/8 inch. Sand away just into the locating pin a bit. Drill the servo mounting holes a little deeper with a #43 drill. This drill is the one that comes with a 4-40 tap. Remount the servo. Install the Losi XXXS servo saver. I used a Losi JRXS sway bar link to connect the servo to the steering linkage this gave me additional clearance on full left lock on the steering. I also beveled the edge of the servo just a little where the link would touch at full left lock (normally you don't steer quite this far as you turn the dual rate wheel down to prevent oversteer. Here is a photo. I can put part numbers if anybody is interested in doing this mod.
This also helped my front to back balance. I had a bit too much weight in the back.
Note that I have room between the saver and the motor. The photo does not show it. I can use the 128 spur which is max for this car.
Last edited by John Stranahan; 02-14-2006 at 05:54 PM.
02-14-2006, 04:43 PM
#143
John, you might as well list the parts for the servo saver as some guys will want to try it. Too bad you have to cut the servo mounts since I use a Dynamite aluminum one.
02-14-2006, 05:27 PM
#144
Mill those Aluminum Puppies down.
LOS 1540 XXXS Servo Saver/ Servo Mount Plastics 4.95
LOS 1542 XXXS Steering and Servo saver Hardware 4.95
Drill the servo mounting holes a little deeper after they are shortened. I added details of this to the post above.
Additional Rub Points on the JRXS
When evalutating this servo saver job, I noticed the front belt had rubbed a shiny spot on the lower right servo mount screw's washer. I installed a narrow washer and there was still some contact. I used the cutoff wheel and then a sanding wheel on the Dremel to remove some material from this area. Some of this contact is caused by the front pulley getting squeezed thinner by locking it with sandpaper and removing the diff balls. I think the big washer would have rubbed a bit anyway without a locked diff. Check your car and fix this. All these tiny little rubs, rob your motor power. Also my front bumper was hitting the tire at near steering lock, which I use sometime when I'm in trouble. That's not what you want, when you are getting out of the trouble, to have a bumper brake on one tire. I trimmed it at a sharper angle to parallel the tread when the wheel is at steering lock. I have always thought that this "bumper brake" is really what stops our driveline dead in its tracks when we hit a pipe and causes the locked diff to bust up the driveline. Don't know for sure. My new trim should avoid this.
LOS 1540 XXXS Servo Saver/ Servo Mount Plastics 4.95
LOS 1542 XXXS Steering and Servo saver Hardware 4.95
Drill the servo mounting holes a little deeper after they are shortened. I added details of this to the post above.
Additional Rub Points on the JRXS
When evalutating this servo saver job, I noticed the front belt had rubbed a shiny spot on the lower right servo mount screw's washer. I installed a narrow washer and there was still some contact. I used the cutoff wheel and then a sanding wheel on the Dremel to remove some material from this area. Some of this contact is caused by the front pulley getting squeezed thinner by locking it with sandpaper and removing the diff balls. I think the big washer would have rubbed a bit anyway without a locked diff. Check your car and fix this. All these tiny little rubs, rob your motor power. Also my front bumper was hitting the tire at near steering lock, which I use sometime when I'm in trouble. That's not what you want, when you are getting out of the trouble, to have a bumper brake on one tire. I trimmed it at a sharper angle to parallel the tread when the wheel is at steering lock. I have always thought that this "bumper brake" is really what stops our driveline dead in its tracks when we hit a pipe and causes the locked diff to bust up the driveline. Don't know for sure. My new trim should avoid this.
Last edited by John Stranahan; 02-14-2006 at 05:55 PM.
02-15-2006, 08:42 AM
#145
John JGPM
02-15-2006, 03:10 PM
#146
John...
Firstly let me say i really enjoy reading your posts! I have to admit, there's a lot of stuff there i'd like to try with my car but i don't have the time. Very interesting reading nonetheless!!
I just wanted to ask a quick Q in regards to the GTB setup.
I'm running a GTB 5.5R with the stock wiring. Of course, whenever i build up a new batttery pack, on goes the 12gauge.
How hard was it to fit the 12G wires onto the esc PCB? The holes don't look all that big. And secondly, what kind of speed difference was there?
This is exactly the kind of thing that irks me.. 12G on the batts but 14G on the esc? Why would i even bother with a battery then? LOL!
Cheers!
Firstly let me say i really enjoy reading your posts! I have to admit, there's a lot of stuff there i'd like to try with my car but i don't have the time. Very interesting reading nonetheless!!
I just wanted to ask a quick Q in regards to the GTB setup.
I'm running a GTB 5.5R with the stock wiring. Of course, whenever i build up a new batttery pack, on goes the 12gauge.
How hard was it to fit the 12G wires onto the esc PCB? The holes don't look all that big. And secondly, what kind of speed difference was there?
This is exactly the kind of thing that irks me.. 12G on the batts but 14G on the esc? Why would i even bother with a battery then? LOL!
Cheers!
02-15-2006, 04:11 PM
#147
GTB 6.5 Thermal shutdowns with 12 gauge
AngryAsian-Thanks. Now about the 12 gauge. The initial install gave me some thermal shutdowns. This was much improved when I repositioned the speed control up on the chassis. Now, though, the weather has warmed here in Houston, I am having some trouble with thermal shutdowns again. At this point, I suggest you try increasing the wire size from the battery to the speed control only. Wait on the other wires untill after a good testing period. The thermal shutdowns are much dependent on traction (and gearing) as well as ambient temp. Really good traction will let the speed control draw more current. My tires were hooked up really well today and I had warmer ambient temperatures. The speed control never measures hot (less than 100 F usually) by the time I get to it, but I know it's a thermal shutdown, because it goes into a crawl home mode. The 12 gauge is slightly larger than the hole. The procedure is to tin the wire. use the small drum sander on the Dremmel to shape the wire to just go in the hole. This is easy after it is tinned. Then resolder with a good hot tip. 900 F mininimum. If you don't have a good iron it is likely to take too much time to complete the solder and unsolder.
Unsolder then reheat the hole and blow through it strongly. This will jet the molten solder out of the hole. The splatter usually does not stick or do damage except maybe to your eyes so wear safety glasses.
The speed difference was noticed by the competition and by myself. I could run the spectrum without a capacitor without the tiny wires. My lap times are rapidly improving as I get back into things.
I am experimenting with the cooling now.
AngryAsian-Thanks. Now about the 12 gauge. The initial install gave me some thermal shutdowns. This was much improved when I repositioned the speed control up on the chassis. Now, though, the weather has warmed here in Houston, I am having some trouble with thermal shutdowns again. At this point, I suggest you try increasing the wire size from the battery to the speed control only. Wait on the other wires untill after a good testing period. The thermal shutdowns are much dependent on traction (and gearing) as well as ambient temp. Really good traction will let the speed control draw more current. My tires were hooked up really well today and I had warmer ambient temperatures. The speed control never measures hot (less than 100 F usually) by the time I get to it, but I know it's a thermal shutdown, because it goes into a crawl home mode. The 12 gauge is slightly larger than the hole. The procedure is to tin the wire. use the small drum sander on the Dremmel to shape the wire to just go in the hole. This is easy after it is tinned. Then resolder with a good hot tip. 900 F mininimum. If you don't have a good iron it is likely to take too much time to complete the solder and unsolder.
Unsolder then reheat the hole and blow through it strongly. This will jet the molten solder out of the hole. The splatter usually does not stick or do damage except maybe to your eyes so wear safety glasses.
The speed difference was noticed by the competition and by myself. I could run the spectrum without a capacitor without the tiny wires. My lap times are rapidly improving as I get back into things.
I am experimenting with the cooling now.
02-20-2006, 04:58 PM
#148
Novak GTX, Trinity Flat Wire vs Round Wire
I installed a Novak GTX in the Losi JRXS in preparation to test the flat wire vs round wire that Trinity offers in their mod motors. Since I posted previously on this topic, I have a few more details. Most of the flat wire arms are wound on a D1 armature blank which is a bit lighter than the D4 arms that the round wire is put on. This partly explains the faster spool up and quicker saturation time that the Trinity instruction book explains (In theory the flat wire by itself should saturate the arm, with magnetism, slower than the round wire as it has more induction, because it's packed tighter on the arm poles. Then, the total magnetism and efficiency should be higher, and maybe power too, than the round wire.).
Trinity Custom Wound Armatures
To determine the differences between the wires only, I have asked Trinity to wind me two arms as identical as possible except for wire. They have graciously done this and are shipping two 10 turn singles with 17 gauge wire on both, one with flat wire and one with round wire. I may post some results later. If I am lucky Cristian will offer to swap motors for every heat of one of our races. We'll draw lots on the starting motor, as it will be the opposite of the one run in the main. Gearing on a similar 10 x1 round wire today was very good at 7.56 with the Precision Racing Systems gears. Lap times, and driver experience will be able to tell the difference between the wires.
Novak GTX in the Losi JRXS
Anyway here is a picture of the install in the Losi JRXS I put the speedo on top since it weighs almost nothing and the car did not mind having the heavy Novak GTB speedo up high. This allowed me to use very short runs of 12 gauge. About as short as if you were to thread the wires through all the rotating gear on the left back side of the car. I don't particularly like doing that. Profile 1 for maximum punch. Corner Weights are perfect. Quite a few Aluminum screws now. Only .4 ounces overweight. No Ballast, 2 ounces heavier in back; Ideal weights.
Brakes and Setup
The JRXS was dialed today. I am running TC3 Silver Springs now on the JRXS.
Brakes are much improved with the GTX and 10 x 1, I am giving a light stab of the brakes coming off the straight at about the 10 foot mark from the sharp turn onto the infield (more like Cristian now). For a nice view of the track see the 3 photos on our new
Gulf Coast RC Race Track Web page.
Note that we (electric guys) take the shortcut off the straight onto the infield. This is best seen on the third photo of the Web page.
I installed a Novak GTX in the Losi JRXS in preparation to test the flat wire vs round wire that Trinity offers in their mod motors. Since I posted previously on this topic, I have a few more details. Most of the flat wire arms are wound on a D1 armature blank which is a bit lighter than the D4 arms that the round wire is put on. This partly explains the faster spool up and quicker saturation time that the Trinity instruction book explains (In theory the flat wire by itself should saturate the arm, with magnetism, slower than the round wire as it has more induction, because it's packed tighter on the arm poles. Then, the total magnetism and efficiency should be higher, and maybe power too, than the round wire.).
Trinity Custom Wound Armatures
To determine the differences between the wires only, I have asked Trinity to wind me two arms as identical as possible except for wire. They have graciously done this and are shipping two 10 turn singles with 17 gauge wire on both, one with flat wire and one with round wire. I may post some results later. If I am lucky Cristian will offer to swap motors for every heat of one of our races. We'll draw lots on the starting motor, as it will be the opposite of the one run in the main. Gearing on a similar 10 x1 round wire today was very good at 7.56 with the Precision Racing Systems gears. Lap times, and driver experience will be able to tell the difference between the wires.
Novak GTX in the Losi JRXS
Anyway here is a picture of the install in the Losi JRXS I put the speedo on top since it weighs almost nothing and the car did not mind having the heavy Novak GTB speedo up high. This allowed me to use very short runs of 12 gauge. About as short as if you were to thread the wires through all the rotating gear on the left back side of the car. I don't particularly like doing that. Profile 1 for maximum punch. Corner Weights are perfect. Quite a few Aluminum screws now. Only .4 ounces overweight. No Ballast, 2 ounces heavier in back; Ideal weights.
Brakes and Setup
The JRXS was dialed today. I am running TC3 Silver Springs now on the JRXS.
Brakes are much improved with the GTX and 10 x 1, I am giving a light stab of the brakes coming off the straight at about the 10 foot mark from the sharp turn onto the infield (more like Cristian now). For a nice view of the track see the 3 photos on our new
Gulf Coast RC Race Track Web page.
Note that we (electric guys) take the shortcut off the straight onto the infield. This is best seen on the third photo of the Web page.
Last edited by John Stranahan; 02-20-2006 at 07:51 PM.
02-20-2006, 05:34 PM
#149
Updated the setup on the TC4. Car is much faster around the track now. Biggest difference was using Paragon. Car is Locking to the track tremendously. I still could use a tad bit more steering for the 2 hairpins in the middle of the track.
I'm going to try playing with bumpsteer and weight distribution.
I'm going to try playing with bumpsteer and weight distribution.
02-20-2006, 08:28 PM
#150
John, I wasn't able to race for the last two week so i tried to use the time wisely and obtain as accurate measurments as I could to input onto the spreadsheet. After following your advise, I made to adjustment to the car and hit the track this past weekend. I'm please to say that it was worth all the time time I spent into getting the measurments. The TC4's performance is alot closed to the TC3's even with the taller tires. I got a chance to truly test the spreadsheet when a follow racer with a FTTC4 broke his front rims during practice and purchased four new foam tires. I asked if he wouldn't mind if I used the new tires to get measurments on my car and see what adjustment would be needed. He gave me the okay. After readjusting my car to get small tire numbers with new tire, I asked if he wouldn't me taking a few laps with his new tires. He gave me the okay and away I went. The car handled 100% better than before (no more traction rolling with new tires). After watch me practice, the owner of the tires asked to see what adjustments he needed to made so that he would not have to true down the tires for his FTTC4. After entering his info into the spreadsheet and making the adjustments, he experienced simular results. So he will no longer true down his tires. Now I just have to figure out how to better tune the car using the spreadsheet to predict handling changes for different adjustments. Then, I could really use track time more efficently. I ran theTC4 for the first 2 qualifiers and did really good with it but it felt tight in the corners. So for the last qualifier I ran the TC3 and easily dropped .2-.3 sec per lap off my TC4 times. After rechecking the measurments of the TC3, I found that the my inital reading were off due to using the wrong size tires in that setup process. I now have a good set of numbers and will make the adjustment to the TC4 to match the good TC3 numbers. I'll just have to wait until the weekend to see if both car handle the same.