John Stranahan

iTrader: (27)

I did add small washer top an bottom. I wondered if there was an extra red post that goes there in the kit to stiffen the longish pod.

Rick-I will order that part. All the wear parts will be back like new. I put them in a bag to replace later. I am happy with pinks. No need to send tires.

Today I ran GRP pink front and pink Rear on both sides. I would have run BSR pinks front and rear but I am saving the fronts for the race. The shop got some more BSR tires now so I will probably run them front and back next time I practice. I found lower lap times with my other car using two GRP pink fronts instead of a pink left and purple right front. My other car had too much traction with BSR tires in pink all around.

At the moment I am using Kingsford Charcoal lighter fluid in a Corally plastic bottle applicator. What's cool is there is a big picture of a Nascar COT on the label. These two items work and smell very similar to each other.

On the big track on road, I favored The Corally Jack The gripper that came in a metal can. This worked the best of all that I had tried on foams. It worked better than paragon or paragon plus suntan lotion.

So here is the deal on the suntan lotion. You use Paragon for about 15 minutes then you slather on Suntan lotion for 15 more minutes and it is supposed to make the paragon last longer. It does have some oils that may help. I noticed no improvement, and then my bag and car stinks like suntan lotion forever more. I know that some 1/12 guys swear by it, but I found it innefective on high powered 1/10th on road compared to Jack the Gripper.

I found the paragon traction action to be superior to Corally Jack the Gripper on rubber tires on road.
We noticed jack the gripper in the new plastic bottle is a little less effective and smells different than the old Jack the gripper in the metal can.

There is a new yellow expensive traction product that contains banana esters (smells like bananas) that worked well on the foam. The odor did not seem to harm me but it was strong. Much More Racing. It is actually recommended for rubber.

I like to do the whole tire. Fix the car so you can do so. Use this as a very expedient measure when setup time is limited. The tire wears funny if you do half. The dry side wears more. On our oval the extra traction is not really needed but the tires wear less for me if I use full traction compound. Since we are outdoors I use traction compound on all four tires for 15 minutes. It is so damn hot now it is completely dry after this. Normally it is still wet and you either run a couple practice laps or use a paper towel that you can throw away to wipe the tires off.

The new servo is a titanium gear servo from Hitec (HSC 5996TG). It is only 10% faster than that small one but has 3 times the torque and a metal output shaft with titanium gears. It is not going to strip on you and leave you with a did not finish (DNF) in a race. If you like to run the Aluminum Body posts then you have to trade some weight somewhere to stay light. The small servo might be an option. I basically consider a plastic gear servo with plastic output shaft a liability when racing.

Thanks for the post guys.

John

John Stranahan

iTrader: (27)

Track test 93 F Track Temp 140 F ouch!
I put 40 minutes of run time on the car today. No setup changes. I was happy with the way it handled. I thought I would post the current driving technique and then the current setup.

Driving Technique
Oval
The car is handling very much like a full size car now with the exception that no brakes are being used. I go to 1/4 throttle for corner entry. This sets the car up for cornering without losing too much speed. hold 1/2 throttle until the apex or mid corner, There I can start a gradual throttle roll on and reach full throttle before corner exit. This seemed to be the fastests. Motor temps were at 170 F geared 3.20 inch/revolution after about a 10 minute run. I am getting good power to the ground. Scrub is less than yesterday from the Ackerman Change and careful setting of 0 toe. Full throttle until the next corner entry. I am using a little wider line than with my old car.

On Road
On the road cars it's a bit different. Enter on neutral (with some drag brake) Hold throttle constant part throttle until corner exit. Slight pause while you straighten wheels. (probably considerably less than .1 seconds). Start throttle roll on. Roll on means gradual increase of throttle keeping the back tires within their limits of traction. Gradual throttle roll on is the secret with powerful motors.

Current Setup June 13, 2008 (reedit), Oval, Asphalt, Battle Axe
Many of these setting can probably be used on the road car.

Left side weight preload (front and back tires on a beam on each side). 12.1 ounces. Batterys back, transponder and receiver left.
Left Rear Down Tweak 10.4 ounces (car on corner weight scales body on) with copper right rear spring and red left rear spring.
Center spring silver all the way up in front.
Ride height 6mm front back and center (low side). 2-3 mm rear droop.
Center shock 50# and sides 40# oil. As delivered

1/4 inch spacer inside of left rear to help with corner exit hooking. Works great. There is no more corner exit hooking.

Front suspension
Purple Wintunnel Racing large cylindrical springs. Thin blue spring buckets on the bottom only.
Camber Right +3 degree camber, left -3 degree.
Steering links straight out servo in upper holes. Inner steering links on bottom outside holes of medium servo saver.
Bump steer: short ballstud on right steering arm, long ball stud on left steering arm. 0 Toe in.
Caster left 2 degree and right 2 degree. (I use 4 degree on road)

Wheelbase and width in middle holes.

Pink GRP foams all around. Kingsford charcoal lighter fluid with a full coat on each tire for 10-15 minutes.

Novak 4 cell GTB with short 12 gauge wires. Novak SS 13.5 motor with the large rotor option. 3.2 inch/revolution rollout.
Picture shows what I meant by filling that hole with some hardware. I would do this even if no delamination has occured yet. The repair worked fine. This will make a suitable spare top plate.


John

John Stranahan

iTrader: (27)

I noticed that the setup I posted did not have caster settings. I also noted the caster setting on the car were not what I expect. Kind of the reverse. This is an easy mistake for me make. I have seen others do it as well. Upper arms forward gives you zero caster. You adjust it in 2 degree increments by moving backward the white shims one at a time. See the photo. I have made the addition to the above setup.

Caster
So what does caster do for you. Well three things actually. Firstly as a wide flat bottomed tire rotates around the angled kingpin it will start to ride on the edges a little. If you watch the front of the car with 4 degrees caster on both sides and use the radio to turn the wheels left you can see the left front of the chassis lift. You are adding load to the left front and right rear. This is increasing wedge. It is giving you more steering the more you turn the wheel from increased wedge (you also of course are using more slip angle, but this by itself is somtimes ineffective like when you crank the wheel more and the car stays on its present course or pushes). I believe this is the primary and strongest benefit of caster. This lets you crank in more steering by just turning the dual rate wheel on the radio to give more steering throw even when you are not using full throw. You don't get much of this benefit if your left front wheel is at 0 caster.

Secondly Caster improves the camber of the outside front wheel as you turn and the car rolls more. It gives you negative camber gain. It improves midcorner steering at the expense of corner entry steering or turn in. The negative camber gain is only helpful after the car has rolled a little in the turn.

Thirdly, and of little benefit to us, caster actually lifts the front end of cars with wide flat bottomed tires. The natural tendency is for the car to settle back down and drive straight. Our servo steered cars are little affected by this tendency.

Caster Experiments
I have been told that caster causes scrub on the oval so I try to use low settings.
I ran the car with several caster setting today.
2 right and 6 left. Now this was opposite of what I inteded. I intended 4 right and 0 left. The car steered great but there was some possible scrub mid corner.
0 right and 0 left. I lost some late corner steering. The car now stumbled on itself on corner entry. You could hear it and see the car slow. It was helpful to steer extremely gently into the turn. I just did not like this at all.

2 right and 0 left. This reduced turn in so that it was very smooth. I still lacked just a little late corner steering. I was out very close to the bumpers a lot.

2 right and 2 left. I like this a lot. I got my late corner steering back. I had smooth turn in. I had little scrub. Jeff saw the car and said it looked good. He had complained of scrub the day before. I use the same setting on-rioad.

Inner Hinge Pin spacer
The picture shows the little device CRC sells (as do many other oval companies) to raise that inner upper A-arm hinge pin. The CRC device is just a spare top cap with longer screws. It fit well. So what is it supposed to do. Most of the oval writing I see concentrates on its effect on negative camber gain. Upper arms more parallel to the ground gives you less negative camber gain. I put it on the car on the left side. I took it off today. The effect on the flat oval was small. I could not tell the difference. It is important to reset toe in after you take it off as this changes a little and gives the appearance of more steering if you just take it off. You get some toe in. Camber has an effect on tuning but it is not a large one. We mostly adjust camber to wear the tires flat. (I do sometimes remove camber to get some better straight line stability on fast road cars). So what does less negative camber gain do to the left front tire. Well I think that it moves the tire the wrong way as the car rolls to the right. Negative camber gain on the left side when rolling left means positive camber gain when rolling right if there is a little left droop available. I would think you would want to keep this positive camber gain when rolling right on the left front.

Note the roll center is also changed a little by this part, but not very much. The roll center stays kind of high. I wish for a lower one. Experiment to come. I plan to bend a left side axle up at 5 degrees and remachine it round on the lathe. I hope it bends 5 degrees before it cracks (T6 temper is not know for flexibility). (Rick I have spares already). This will give me a inward incined kingpin angle and low roll center along with positive camber on the left side.

The car was hooked up. 170 F motor temp after 10 minutes 85/36 2.320 inch rear tire.

I welcome comments on caster. Personal observations are prefered.

John

John Stranahan

iTrader: (27)

4 cell NiMH Use and Care

I was asked recently by PM about NiMH charging and care. On first purchase, you need to discharge each cell individually down to .9 volts. I use a turbo thirty. You can use a tray and remove the battery as soon as all the lights are out. This will let the matched pack charge evenly the first time. If the cell is already discharged to zero by storage expect some major loss in capacity.

Delta Peak
This is how much voltage reversal the charger requires before it shuts off a charge. I have the best luck with .030 mV on the turbo thirty. The pack reaches about 130 F. I also use an old Tekin charger. The pack comes off at 140F (in 90 + ambient temperature). The Delta peak is probably .040 mV on the Tekin. Now this Temperature looks like a high number but then I purchased an EnerG pack from SMC by lefthander and the instructions say to make it come off at 140F. This is fine for stock and superstock. If you use a battery this hot in mod 6 cell it is going to vent and be short lived.

Cycles in a day
Run the pack in practice. Then race it twice. It will be faster on the second and third cycle. (I race them four times and try to own only a couple packs). After 15-20 cycles they will be way down on capacity and you will be running on lower voltage in a 4-5 minute race. Time for a new one.

Charge Rate
I charge at 6 amps which has been recommended by several matchers. I am not interested in the absolute highest zip on the track and resulting danger of explosion while charging. If you want that ultra zip charge at 8-10 amps; explosions are seriously loud and energetic and will find you eventually.

Capacity When New
I have had bad luck on first testing new 4 cell packs from a variety of matchers and of a variety of brands. Some meet the label and an equal to greater number are way depleted already before I even use it. When you do this first test, if you have the equipment, you have to make sure the charge is full. In other words charge until it gets hot rather than until the charger shuts off. I have sent four packs back to manufacturers. I have not received a return yet on any of them. It's been several weeks to a month.

After the Race
The EnerG instructions also say to discharge the pack after racing. I know they deteriorate if charge gets to zero. For this reason I like some backup up charge in them so they don't self discharge to zero if you miss a week or somenthing like that. I race the main then store the pack as is.

Voltage at 300 seconds
One of the numbers that Josh and I look at on a home discharge test is what is the voltage at 5:00 minutes @ 20A or in his case 330 seconds, 5 minutes plus some practice laps. Generally the higher the capacity on the pack the higher this number will be and the more working voltage you will have in a race. This number is more important than average voltage now because we run batteries with excess capacity.

John

John Stranahan

iTrader: (27)

Race Report
93F track temp 140 F
The car performed well in its first outing for me. I qualified second 1 lap back (4 seconds). I improved the performance of the car up to heat three which was my fastest. I broke that top plate in the main (right at the extra hole). I got a nudge in the right rear quarter panel on corner exit which drove us both head on into a bumper. The gear stripped as well.

Best lap for me was a 4.28 which is .06 slower than my record. Best qualifyer is 2 laps less than my record. I still have plenty of room to improve. I was 1 lap faster than the last race.

Tires seemed to be the secret as it is with touring cars. I had four BSR pinks in the first race. I felt too hooked up. I went to GRP pinks and was .2 seconds faster. The race leader had gone to 3 BSR pinks and one purple on the right front. I'll try that next time in a similar situation. I added 2 degree of left caster to improve a corner exit push as well in the second heat.

In the main I was out of tricks (except tire tricks). I moved the left wheel forward increasing wheel base. I thought this would improve steering. I added one more thin washer inside the left rear wheel to get the car to exit towards the boards. The car was slower as a result, but the leader was slower as well. The main had all cars within the same lap at the time of my accident.

More complete results on our new club website.

http://www.gulfcoastovalrc.com/Home_Page.html

John

John Stranahan

iTrader: (27)

Left Down Tweak
In the last race I ran a pretty safe very easy to drive setup. Mike D drove the car an noticed that he can apply more throttle mid corner. He is running about 12.5 ounce of left down tweak. I made a new temporary top plate from .125 inch G10. I have two spares on order. Note that my homemade part has a slightly beefier shape and thickness. Looks like a snake now. I set my left down tweak to 12.5. from about 15 ounces. I should get more steering.

Low Roll Center
An experiment I did on my 3-link oval car with standard associated front suspension was to drill a custom left steering block so that the axle pointed down at a 5 degree angle. This lets you put in 2 degrees of positive camber and then also allows 3 degrees of inward tilted kingpin angle (as you go up) to lower the roll center back down like it is on road cars. The roll center is unfortunately tied to the kingpin angle on a strut type of suspension. I made the prototype part here for the Battle axe. I bent the part up at a 5 degree angle and then turned the inside portion of the distorted axle on the lathe until a bearing would slide onto it. This should do fine for a test. It is upside down in the photo. I will have to use it as a trailing axle. I want the hooked up feeling that a low roll center gives you without going to softer front springs.

There are other ways to make small adjustments to the roll center but none that make it really low or at ground level with this strut type of suspension. I'll discuss roll center more If the part shows any promise. It seemed to on the other car.

Side Shock Setup
Barry took a look at my car before the last race and noticed that the left rear shock had inadequate travel. This contributes to stressing that top plate as the pod twists. I decided to correct the problem later as I would have to reset the left down tweak on scales. I did so by cutting 1/16 -1/8 inch off each of the ball cups on the ends of the shocks and then screwing them all the way down. He noted previously to have the shocks at the middle of their travel when the car is on the tires. You can see a little more shock shaft in photo one than before.

Loctite
All of the flat head Aluminum screws on the bottom of the chassis are tending to come out. Especially those on the pod. Here is what I do to secure them but still maintain serviceability. Unscrew them only 1/16 inch. Put blue Loctite liquid or paste under the head. Screw them back down. The Loctite hardens and just holds the head of the screw. This way you don't break threaded shafts off trying to get the screw out, but they don't back out by themselves.
John

John Stranahan

iTrader: (27)

Track Test
Air Temp 95F, Track Dusty

I had several items I wanted to test. Jeff graciosly turned on the track audible lap timer for me. I have made several changes since the last race to add late corner steering traction. I removed the spacer between the motor and the pod plate. I reduced left downtweak from 15 to about 12 ounces. I put on trailing axles because just by chance I made my +5 degree bent axle roll center experiment on a trailing axle.

Trailing Axles
These seem to trail a little more than Associated The length of the car is noticeably reduced and required trimming of the rear of the front wheel cutouts. I got my baseline tiime here for the dusty conditions. I was using 3 BSR pinks and one New right front purple. The car drove well. I could still use a little more steering.

+5 degree homemade axle
I put this axle on the left front so that I could have a positive camber of about 2 degrees and an inward tilted pin angle of about 3 degrees to give me a low roll center. I saw no improvement in lap times. The car felt like the hard purple tire was on its edge (or the left pink tire) and still needed to be scrubbed into the track. I did not wait for this to happen. (too damned hot). I took it back off and went to standard inline axles. There was an improvement in my times. I went back to four pinks because of the dust. I will test the 5 degree axle again later.

Ackerman Change
The picture shows an extra little hole that I made in the steering arm. This let me slide the arm toward the wheel by one hole and reduce the ackerman. My times were not improved. I noticed no extra steering. I went back to standard ackerman here. CRC has done their homework and given us a good ackerman value. I think it is a little more ackerman than an associated steering arm just from looking at the angle of the arm. No further tests needed. I had changed it previously by sliding the servo forward.

Wing Change
You may have noticed I have been running a road sedan type of rear wing. Well I finally ordered a KSG wing mount and some Darkforce wing buttons to put on the oval type of wing with the large side dams. My wing is a BRP model. I took off the second level. I set the flat part even with the roof line. Toward the end of the session I was talking to Jeff about how to reduce pan car flying on our long straight. One technique especially useful on a GT body is to move that wing to the axle or forward of it if possible. I did the same to my oval wing. I moved the kicker 1/2 forward of the back edge of the body. There was an improvement. I was now running .1 second faster most of the time. Not at race speed because of the lower traction mind you but .1 faster than any other combination this day.

Final left down tweak 10 ounces.

John

John Stranahan

iTrader: (27)

CRC GenXPro 10
Jeff has one of these on backorder from Horizon. I thought I would start discussing this car as I may be able to get hold of it to photograph, examine, and drive.

First off this is a narrow Pan car that will fit a lot of 200 mm bodies. The front end will have some adjustability in length and width to fit the bodies a little better than previous narrow pan cars which tended to be narrow in the front leaving a gap in the wheel well. Suitable bodies that tend to go along with suggestions on RCtech include GT1 bodies that run at Lemans or the US Lemans series. These include corvettes, Vipers, Porsches etc. (a widening kit will become available)

The GenXPro 10 was designed to be very versatile as far as motor and batteries go. I discussed this with Jeff based on my recent experience running road cars at Mikes-HobbyShop.com. The track is a large 1/8 scale track. I was happiest when my pan had a Novak 3.5 R motor and a LiPo battery on the long track. The reason was that the power band of the motor was well matched to the traction of the pan car. The speed on the straight matched the other cars running on the track. The motor was soft on the bottom end where pan car rear traction is low. As a pan car develops some speed the wing aids rear traction immensely. The 3.5 comes on strong then. Gearing is 12/90. The 3.5 is easy to modulate in the corners. I had no trouble running it on the oval. You just use part throttle more. Now you might think this is too much power for a beginner and I will tell you that beginners at our track usually start out with two speed Nitro cars of about the same speed. It is not much trouble when the lanes are wide and long.
We may be getting an indoor carpet track soon. Suitable power would then include. A 17.5 or (21.5) LiPo for a beginner class and a 13.5 Lipo for the more experienced racers. The bigger the track the more motor you might need for adequate performance.
One problem you might have if there are bumps on the straight of a long track is that pan cars have a tendency to go airborne when they exceed 45 mph or so. This is not much of a safety issue on a 1/8 th scale track. They slow extremely quickly in the air. It is not an issue on smooth tracks. You can limit the motor to stay below this threshold. Probably LiPo 13.5 would do fine.

Batteries
Why LiPo
I have been using LiPo's for a couple of years now. Every pack I have bought met the label specs when new. Most packs went 50 cycles before I thought performance was off enough to replace them. Safety has been improved with Roar Legal packs that can tolerate a little overcharge. I can't believe that I am struggling with these antique 4 cell packs at the moment. Just trying to find one that meets the label specs is difficult. They deteriorate quickly. They cost the same for one pack of NiMH vs 1 LiPo and last about 1/3 the time. If that is what your track wants the GenX Pro 10 is happy to accomodate with a separate NiMH battery tray.

I am hoping delivery of the car will be soon. Oval talk will also continue.

Pic is of an HPI Porsche GT1 body.

John

John Stranahan

iTrader: (27)

Here is a pic of the Darkforce 6 inch wing. It is glued so there are no little rivets. Darkforce wing buttons hold it to a KSG wing mount. Benefit is adjustability and possibly reduced drag.

Left end point adjustment (EPA). This warrants a discussion. I have noted in the past that some touring car drivers drive on the radio stop on each corner. That is they turn the radio wheel until it stops. Adjustments are made before a race with the dual rate so that adequate steering is possible. My school of thought has always been to have extra steering, still adjusted by the dual rate.
On the oval you can do a similar thing with your left EPA and ajust your steering throw down until you cannot make the mistake of too much steering throw which scrubs a lot of speed. You can keep your right steering EPA with considerably more throw to get you out of jams with right steering. Any thoughts pro or con please. I am going to experiment with this on the oval.

John

C5Vette

Maybe it's covered here and I missed it but I'm looking for a good starting tire size for a CRC GenX Pro10 car. I guessed with 2.20" rear and 2.165" front.

What do you guys recommend?

espresso1967

iTrader: (18)

I am also new to this pan car class but I went with these

http://www.jacoracing.net/panz_1_10.html

two sets of pink for rear, one set pink for the front and a second front set purple to try out at a 1/10 1/8 asphalt track that I will be playing at.

C5Vette

I've done plenty of 1/12 racing and I know how important tire size is....that is why I'm looking for some numbers.......

Anyone?

John Stranahan

iTrader: (27)

Truing Tires Reparing Chunks
C5vette-On oudoor asphalt you may find that full size tires give you better traction than cut down tires. If the track is treated and traction is very good try 2.12 or so for all out competitive racing. Don't worry about it too much for club racing. The smaller tires will work better the higher the traction. You will find the 1/10 pan car less sensitive to tire size than 1/12. There are plenty of us that don't true at all. Practice on the big tire, rotate the fronts side to side every two heats. Keep in mind that with stock or superstock motors the rollout is critical to maintain. You add pinion teeth as the tire wears. With a Novak 3.5 the power band is very wide. You can run a variety of tires sizes at a 90/12 gear.

Another option is to just true worn tires until they are flat and match left and right. This is good for club racing as well. I adjust the camber to do this and rotate side to side to accomplish this.

Saying all that I trued my first purple right front today for the oval. It is hard to wear that one down to match the others in practice. I used a bigger lathe with the Cobra snakeskin cutter in the tool post grinder. Worked well. Went to 2.250 just to match a pink with some wear on it.

Good selection on tire compounds in the post just above. Pinks all around or purple fronts if you have a longer track or more motor on board.

Thanks for the post guys. The thread seemed like it was going to die. lots of views but not much activity. It is not meant to be a monologue.

1/10 cars will also tolerate some chunking. Help prevent this by rounding off the corners with the Dremmels large sand wheel run at an angle to the tire when the tire is 1/2 worn. It does not work real well but does the job eventually leaving you a circle of rubber to pop off the tire.

Glue chunks back in with Fabric glue. Or glue tattered parts of the tire with the glue. Works great dries clear and strong and dries like rubber.
John

Robertw321

iTrader: (1)

First off let me say that I'm a carpet racer and my left front tire is always softer than my right front. I would assume asphalt is the same. With the softer left front tire I actually need less steering to make a right turn. To much right steering tends to make the car dart to the right making small straight-a-way adjustments hard to do. I set up my radio with the dual rate so my normal turn is in my comfort zone. I like to use about 3/4 of the wheel throw. This leaves a little available steering to use if I'm forced in low. The last 1/4 of throw takes a conscious effort on my part so I seldom hit lock. After this I reduce the right EPA to take away the dartiness to the right.

John Stranahan

iTrader: (27)

Bob-RE steering on the stops. Thanks for the post. Nice that you point out a problem with having too much right steering on the oval as well. I welcome other votes on this issue.

Track Test (Oval)
Because of a less than perfect weather forcast we had insufficient number of racers. We ran timed practice and were able to printout our lap times. This helped the tuning session.

Nat helped me tune the Batte axe by watching it carefully in the corners. He noted it was dying in the corner or scrubbing off too much speed. We reduced caster. This helped. I was at 2 degrees left and right so the next stock step is 0 degrees. Instead I replaced one of the white teflon .030 washers with 3 brass .010 inch kingpin shims. This allowed finer tuning. I did not want 0. I ended up with 2 degrees left and 2/3 degrees on the right. This tiny change actually made some difference. The car rolled a little easier through the turn. We took out a little more left downtweak and lowered the center of the car about 1/2 turn on the center shock collar. This helped the car roll more evenly on corner entry.

We had a little too much traction on the BSR pinks with a purple right front. I was trying to tune in this combination, but I still need another .1 or .2 out of the car. I think a little harder tires would have helped.

Gen X 10
I am delighted to have a Gen X 10 car in hand. I don't know at this point if it will be a driver or just for sale. In the meantime I can comment on the assembly and improvement to the previous version of the car the Pantoura.

The first picture shows the lower pod plate assembled to the main chassis. You can see the center pivot and side links which control the motion of the pod. The center football's plastic parts are round and need to be trimmed for clearance on rearward placed batteries or frontward placed motors. Assemble it to this point with the red nuts loose. Push it flat and tighten the red nuts.

Improvements
We now have some beefy large headed steel screws securing the side links where the Pantoura had some smallish philips head screws. I would change that center pivot aluminum screw that holds the post to steel as it helps to support the top plate.