R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Reply
 
Thread Tools Search this Thread
Old 02-28-2010, 09:47 PM   #256
Tech Addict
 
paraletic's Avatar
 
Join Date: Apr 2009
Location: ADELAIDE
Posts: 553
Trader Rating: 13 (100%+)
Default

Almost 6 months since I've had the chance too run my xxxs
hadn't touched it in that time either

was impressed it ran sweet was a tad undergeared due too fact was so hot last I drove it so after a couple of runs I had the gearing pretty close
car speed was pretty good aswell as acceleration

biggest issue I had was the rear o the car would become very loose an tend too break out when braking from max high speeds into our hairpin (this is also made trickier due too the fact it goes from uphill on camber too down hill off camber)
I wasn't game too make changes too the car as it felt pretty good elsewhere and I was runnin some pretty old rubber on the car
the main aim of racing it was jus too get feel of driving again etc
next time out I mite throw some new rubber on an think about gooping the tyres an using warmers too then I'll see if I need any more adjustments too suspension - don't want do too many changes at once
__________________
Losi XXX-S G+..................Tamiya M03.......................TOP Photon
Losi XXX-4 G+.................HoBao ST Pro electric........Losi Micro SCT
Losi XXX-CR....................Losi Mini Baja.....................Losi XX-4 W/E
ASSociated RC12L4
T.O.P PHOTON EX & Tamiya M05 - currently undergoing rigorous crash testing!
paraletic is offline   Reply With Quote
Old 03-07-2010, 10:51 AM   #257
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

Droop
By PM. You have the right idea of what droop is. Measure ride height. Measure ride height with car lifted just to the point where tires lift. Subtract. That is the actual droop.
I use droop to make fine adjustments to roll stiffness when cornering indoors. Reducing droop makes that end a little stiffer in roll. Outdoors my droop is usually set to maximum. That is the wheel extends until the spring is just shy of getting loose. That would be my maximum setting.
Increasing rear droop will increase weight transfer to the front only in that the center of gravity is slightly raised on brakes. The amount of pitch does not affect weight transfer.


Losing the rear on brakes
Setup the speed control and radio at 100% brakes. On medium traction you will need to reduce this to 55-65% on the radio. What you want is a good slowing, what you don't want is any wheel skidding.

Another thing to look at is weight distribution. This has to be right on for good high speed braking. Left must weight the same as right. The front locked diff if installed must not slip. Front corners must have equal weight. Hope this helps.
John
__________________
JohnStranahan@aol.com
TeamCRC.com Mikes-HobbyShop.com
John Stranahan is offline   Reply With Quote
Old 03-08-2010, 10:09 AM   #258
Tech Elite
 
Boomer's Avatar
R/C Tech Charter Subscriber
 
Join Date: Feb 2002
Location: Southern Cal - Claremont
Posts: 3,337
Send a message via ICQ to Boomer Send a message via AIM to Boomer
Default

Quote:
Droop
By PM. You have the right idea of what droop is. Measure ride height. Measure ride height with car lifted just to the point where tires lift. Subtract. That is the actual droop.
I use droop to make fine adjustments to roll stiffness when cornering indoors. Reducing droop makes that end a little stiffer in roll. Outdoors my droop is usually set to maximum. That is the wheel extends until the spring is just shy of getting loose. That would be my maximum setting.
Increasing rear droop will increase weight transfer to the front only in that the center of gravity is slightly raised on brakes. The amount of pitch does not affect weight transfer.
One little note on Droop - different people like different amounts, but I think one thing we can all agree on is that Droop needs to be the same Left to Right (at least to start) - so start with even L-R droop.
__________________
-
RC10L2.5W - RC12.4 - RCNTC3(bmi) - TC4 (modded) - B44.2 - plus rent-a-rides! :D
Boomer is offline   Reply With Quote
Old 03-21-2010, 09:54 PM   #259
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

Common Sense RC 6 mm Battery Plug Test
I put four good runs on the XXXS today. On the first run I had a Deans Half Plug connector melt down and loose contact. I have been using this very fine connector for years. Gains in battery, motor, and speed controls have put it on the very ragged edge. Occassionaly after some use they will desolder or melt down. It is not easy changing connectors once you count that you you have three cars, four batterries and four chargers. Well the time had come. I pop into the shop, and, lo and behold the 6 mm wedge type cylindrical connector I had in mind. These had been highly recommended previously by the aircraft guys pulling the big amps. Well the touring car averages 47 amps with good traction but it pulls 200 plus amps at full throttle. I have put a photo of a series of plugs with the better plugs toward the bottom. For me better means: They don't catch fire, don't melt down, don't unplug in a small crash. Pretty simple requirements.

The four banana plug type connectors near the top suffer from a design defect. Fine for audio, but not for 200 amp squirts of power. The fingers that make the contact unfortunately supply the spring tension. Because they are of a brass like material for good conduction, they make terrible springs. They quickly fatigue. I have seen this type jump out of the battery when the car just encounters a bump in the track. the will run at higher resisitance once the fingers fatique. There are three types shown. The one at the top swivels with play in the swivel. This has got to be the worst. The second swivels but at least there is tension. Better. The third is solid better still. The black plastic plug is from Traxxas: The offroad guys like this in their 1/8 scales. It is a little oversize and relies on plastic for spring tension. This latter part, I don't like. Next the red deans are very good. I have become accustomed to cutting them in half so I can cover the whole plug with thick shrink. It also cools better this way.

Now the CommonsenseRC.com 6 mm plugs. Note there are NO SPRING FINGERS like a banana plug. There are tapered slots so that when you plug it in the Male end wedges into the female plug. Very nice indeed. There is a beefy amount of metal to conduct. Soldering cavities are walled off from the plug. Nice. I had a smooth install. They come with thick shrink. It installs after soldering. Very nice. I covered it with yellow for my old eyes and the fact that eventually the shrink blackens a bit from dirty fingers.

They performed great for 3 heats. I bought the shop out. I need a few more. The plugs require very firm pressure to plug and unplug. That means they are going to be secure in the bumps and crashes. No heat was noticed after a run.


Sweep Racing Tires
We are in the midst of Pine tree Pollen Season. I treated the track but the air is filled with pollen the cars come back yellowed with dust. I had good results with Sweep 36 EXP tires, but I had the best luck when I treated them with traction compound. I used Kingsford Charcoal lighter fluid. The benefit lasted for about 10 laps.
Attached Thumbnails
LOSI XXX-S, Tips and Tricks, Open Mod, etc-battle-axe-js-pro-10-020.jpg   LOSI XXX-S, Tips and Tricks, Open Mod, etc-battle-axe-js-pro-10-018.jpg   LOSI XXX-S, Tips and Tricks, Open Mod, etc-common-sense-rc-6-mm-plugs-001.jpg  
__________________
JohnStranahan@aol.com
TeamCRC.com Mikes-HobbyShop.com

Last edited by John Stranahan; 03-21-2010 at 10:21 PM.
John Stranahan is offline   Reply With Quote
Old 03-27-2010, 07:22 PM   #260
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

LRP SPX8
105F track temp track test
I had a good long practice Friday in preparation for a 2 day race. I had good traction as a result of 10 or so guys practicing for the next day. Mostly Nitros. I ran my best practice time ever with the XXXS. Because of the higher temp and good traction I had two thermal shutdowns of the LRP spx8 so it is not invunerable to this. The Tekin RX8 is probably a little more stout although I did not try it on this day. I had to reduce my pinion by 2 teeth and use the bigger spur (about 2.5 teeth lower then). This are big 48 pitch teeth Final gea r is 8.20 which is still relatively high. I could hear that armature screaming on the straight though. Too many revs on this track causes armature explosions. In spite of this I achieved my best time with the lower gear. This brought motor temperatures back to the 180 range and kept the speed control from thermalling.

Sweep Racing EXP 36R
I had planned to use an almost new set of EXP 36R tires for this race. I put them on first for a trial run. On the second lap a factory glued almost new tire with only two runs and no damage on it, completely blew up and sent the car about 2 feet into the air mid straight. Several guys came to look at the remains. Here is what happened based on close inspection of the tire. If you look at the photo I am holding a section of bead away from the wheel. It is apparent that the bead has only 1/32 inch or so of glue right in the gap. There is no penetration onto the side of the tire groove in the rim. Certaninly no penetration onto the bottom of the tire groove. Little evidence of scuffing in either area. So a bead let go and at about 50mph started to flap onto the frame. Tread breakage and explosion were a quick event thereafter. There is no way for a customer to improve the glue bead, after the fact, as the small area of glue effectively seals the wheel from more glue penetration.

So what to do. Firstly, I have used the method where you apply glue to the sides of the wheel at the gap hundreds of times. I use the fastest superglue available for the best penetration. It alway works the best inside at moderate temperatures so the glue doe not instantly harden. I have also cut dozens of tires off of broken wheels to save the tires. I always found a complete cut axial to the wheel axle or parallel to the wheel axle in the gap of a short depth necessary and then stretching the tire to the other side I used the X-Acto to cut the tire off the side of the tire bead groove or inside lip. A full depth cut was required, now also on 5 or six spots around the wheel the glue even penetrated to the bottom of the groove. So some more cutting was needed. So if you use this method, just cut down the center of a practice tire. Pull the tire out. Inspect the contact. If you are not getting glue all the way to the bottom of the groove on the sies, something needs to be improved.

Second method.
I will call this the "Matt Franciss Method" as while he was at the peak of off-road winning, I watched him glue a tire on. This method requires a medium setting speed glue. You put the tire on. You pull the bead out of the groove, you put a drop or two in the groove, you rock the wheel back and forth and have that drop completely coat the bottom of the groove. You do that every third or every fourth of the wheel revolution or in other words two or three spots around the rim. Then make sure everything is seated well and true after you snap the tire back in place. You can only do this with a slower setting glue than you need with the method above, obviously, or things will stick while out of true. It requires some practice to keep from making a mess, but your tires are more secure. They are glued up along the wide bottom of the bead groove.

In each case wheel oils that seep out of plastic can be removed with rubbing alcohol from the pharmacy or a detergent wash like we do our LEXAN bodies before painting. I never needed to scuff the wheels but then I mostly used a little harder plastic type of wheel.

I offer these fixes in order to improve the breed of a tire with good grip and performance. It is not a criticism. You may never experience this on a slower track. This is the second total blowup, but the first tire had a cut and I had glued it myself.
Attached Thumbnails
LOSI XXX-S, Tips and Tricks, Open Mod, etc-sweep-blowup-001.jpg  
__________________
JohnStranahan@aol.com
TeamCRC.com Mikes-HobbyShop.com
John Stranahan is offline   Reply With Quote
Old 03-27-2010, 09:40 PM   #261
Tech Adept
 
TXstreetracer's Avatar
 
Join Date: Jul 2005
Location: New Waverly,TX.
Posts: 107
Trader Rating: 4 (100%+)
Send a message via MSN to TXstreetracer
Default

Ok, I'd like to get some advice from you XXX-S folks.....

I just bought a Hobbywing 5.5T 6000KV EZ-run brushless combo and I want to drop this into my XXX-S.

I'll be using my XXX-S for mainly straightline racing against friends....and parking lot bashing. In particular, what gearing should I go with to run the fastest in say 132'? (A scale 1l4 mile dragstrip)

I've already ordered a heatsink with a small built in electric fan to help keep the motor cooler (if possible).....

I'll eventually be running 2S Lipos.


Thanks for any and all advice ahead of time
TXstreetracer is offline   Reply With Quote
Old 03-28-2010, 04:28 AM   #262
Tech Addict
 
paraletic's Avatar
 
Join Date: Apr 2009
Location: ADELAIDE
Posts: 553
Trader Rating: 13 (100%+)
Default

Hey John

Just wondering Have you thought of running a Mamba Max set up?
I know that they're originally designed with bashing in mind so there built to handle the heat etc ( so it says in the manual)
they don't hav a fan on the speedy but I wouldn't think fitting one would be overly hard

I've also heard of people running these speedys on 1/8th scale buggies

not sure if it would be suitable for you but I just thought I'd mention it
__________________
Losi XXX-S G+..................Tamiya M03.......................TOP Photon
Losi XXX-4 G+.................HoBao ST Pro electric........Losi Micro SCT
Losi XXX-CR....................Losi Mini Baja.....................Losi XX-4 W/E
ASSociated RC12L4
T.O.P PHOTON EX & Tamiya M05 - currently undergoing rigorous crash testing!
paraletic is offline   Reply With Quote
Old 03-28-2010, 10:34 AM   #263
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

Gearing- the 5.5-I have run a 6.5 at about 7.5/1 overall. I suspect the 5.5 would be in the neighborhood of 7.0 to one. On a dragstrip you are really just going to have to have a set of gears and tinker with the ratio using teh time clock.

Paraletic-I have used a Mamba max in a touring car (or wide pan car) because some guys were using it for 1/8th scale early on. It was a little tougher heat wise than an LRP TC edition but would still easily thermal. I ran a high voltage test to see if less amp draw at higher voltage might have an edge. I used 4s. It thermalled in 30 seconds with a 6.5 motor. I went back to 2 cell. The Mamba max pro is looking like a good speed control now. It has sensors. The lack of sensors used to give me grief.
__________________
JohnStranahan@aol.com
TeamCRC.com Mikes-HobbyShop.com
John Stranahan is offline   Reply With Quote
Old 03-28-2010, 09:13 PM   #264
Tech Adept
 
TXstreetracer's Avatar
 
Join Date: Jul 2005
Location: New Waverly,TX.
Posts: 107
Trader Rating: 4 (100%+)
Send a message via MSN to TXstreetracer
Default

Quote:
Originally Posted by John Stranahan View Post
Gearing- the 5.5-I have run a 6.5 at about 7.5/1 overall. I suspect the 5.5 would be in the neighborhood of 7.0 to one. On a dragstrip you are really just going to have to have a set of gears and tinker with the ratio using teh time clock.
Hey John, probably a stupid question----but what pitch are the gears in the XXX-S???

So if I'm correct the higher the final ratio I go up the faster the car will be in a shorter distance?

How many different sizes of spur gears are there for the XXX-S???
TXstreetracer is offline   Reply With Quote
Old 03-28-2010, 09:25 PM   #265
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

Quote:
Originally Posted by TXstreetracer View Post
Hey John, probably a stupid question----but what pitch are the gears in the XXX-S???

So if I'm correct the higher the final ratio I go up the faster the car will be in a shorter distance?

How many different sizes of spur gears are there for the XXX-S???
I like to use 48 pitch outside. Even though the drivetrain is sealed little rocks still get in there to mess up the 64 pitch gears. I find that brushless motors can withstand a range of gearing. The fine changes available by 64 pitch may not be needed. I have 88 and 90 tooth 48 pitchs plastic spurs. Plastic spurs are lighter than spurs with an Aluminum gear adaptor and will do well on the dragstrip. There are also 64 pitch Losi spurs available. 128, 118, and 108 64 pitch are available.

Motors put out peak power in the middle of their amp range. For a 5.5 that might be at about 75 amps. For dragstrip you gear it for max power at mid track or so. The short length of the strip should prevent overheating. You will be gearing lower than on a road course, I suspect. Get some nice connectors like those I pictured above. Use a high capacity battery able to deliver good average power say a 40C or 50C. You demands are much like my touring car with just a less powerful motor run at its ragged edge for a shorter time. When it catches fire back off a little!
__________________
JohnStranahan@aol.com
TeamCRC.com Mikes-HobbyShop.com

Last edited by John Stranahan; 03-29-2010 at 11:11 PM.
John Stranahan is offline   Reply With Quote
Old 03-28-2010, 10:17 PM   #266
Tech Addict
 
paraletic's Avatar
 
Join Date: Apr 2009
Location: ADELAIDE
Posts: 553
Trader Rating: 13 (100%+)
Default

Also 86 and 87 tooth spurs avail in 48 pitch
I don't hav part numbers tho as they came with cars I bought
__________________
Losi XXX-S G+..................Tamiya M03.......................TOP Photon
Losi XXX-4 G+.................HoBao ST Pro electric........Losi Micro SCT
Losi XXX-CR....................Losi Mini Baja.....................Losi XX-4 W/E
ASSociated RC12L4
T.O.P PHOTON EX & Tamiya M05 - currently undergoing rigorous crash testing!
paraletic is offline   Reply With Quote
Old 03-28-2010, 10:24 PM   #267
Tech Adept
 
TXstreetracer's Avatar
 
Join Date: Jul 2005
Location: New Waverly,TX.
Posts: 107
Trader Rating: 4 (100%+)
Send a message via MSN to TXstreetracer
Default

Quote:
Originally Posted by John Stranahan View Post
I like to use 48 pitch outside. Even though the drivetrain is sealed little rocks still get in there to mess up the 64 pitch gears. I find that brushless motors can withstand a range of gearing. The fine changes available by 54 pitch may not be needed. I have 88 and 90 tooth 48 pitchs plastic spurs. Plastic spurs are lighter than spurs with an Aluminum gear adaptor and will do well on the dragstrip. There are also 64 pitch Losi spurs available. 128, 118, and 108 64 pitch are available.

Motors put out peak power in the middle of their amp range. For a 5.5 that might be at about 75 amps. For dragstrip you gear it for max power at mid track or so. The short length of the strip should prevent overheating. You will be gearing lower than on a road course, I suspect. Get some nice connectors like those I pictured above. Use a high capacity battery able to deliver good average power say a 40C or 50C. You demands are much like my touring car with just a less powerful motor run at its ragged edge for a shorter time. When it catches fire back off a little!

John, THANKS for the advice.....

Is it possible for me to have too small of a pinion on that 5.5 brushless motor? I found an old chart I had in my race box and I'm trying to figure out how to gear this setup....and I'm looking on Ebay at pinions/gears.

I found a 12 tooth 48 pitch pinion.....is that waay to small----small enough to cause overheating issues?


On a side note, I stopped by Mike's today with my wife and we watched the last two races....man that action was awesome! I wish there had been some electric cars racing also.....but just getting more exposure to rc racing at a track was cool.
TXstreetracer is offline   Reply With Quote
Old 03-28-2010, 11:33 PM   #268
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

We were one short to make an electric heat at the Soutwest Series race. I showed on Saturday.

Put a 3.5 in that puppy and come join us. We race again next Sunday at 12:00 Noon. The lanes are huge.

I had posted overall ratios previously. Sorry if this was misunderstood.

Car ratio = spur/pinion x internal ratio
a 12 pinion gives you 88/12 x 1.83
or 13.42 too low. No speed.

You are lookiing for gears in the 7.0 range.

7.0 = 88/x (1.83)
7.0/1.83=88/x
x = 88 x 1.83/7

or rearanged pinion = spur/car ratio
x=23
__________________
JohnStranahan@aol.com
TeamCRC.com Mikes-HobbyShop.com

Last edited by John Stranahan; 03-29-2010 at 11:11 PM. Reason: messed up the math. The corrected version is here.
John Stranahan is offline   Reply With Quote
Old 03-29-2010, 03:50 AM   #269
Tech Addict
 
paraletic's Avatar
 
Join Date: Apr 2009
Location: ADELAIDE
Posts: 553
Trader Rating: 13 (100%+)
Default

Internal ratio is 1.83:1

another way of gaining ratio if you can't do so with pinions an spurs is to swap out your diff pullies

stock is 42 tooth front and back
Losi give the option of a 41 tooth pulley aswell
so grab two 41 tooth pullies an fit them in and you get an internal ratio of 1.78:1

so - 88spur with say a 35 pinion

1.83 (42pullies) - 4.6 fdr
1.78 (41 pullies) - 4.4 fdr

just another idea

ps this also wil allow u run the belt looser and it won't drag on the belt cover underneath
__________________
Losi XXX-S G+..................Tamiya M03.......................TOP Photon
Losi XXX-4 G+.................HoBao ST Pro electric........Losi Micro SCT
Losi XXX-CR....................Losi Mini Baja.....................Losi XX-4 W/E
ASSociated RC12L4
T.O.P PHOTON EX & Tamiya M05 - currently undergoing rigorous crash testing!
paraletic is offline   Reply With Quote
Old 03-29-2010, 05:33 AM   #270
Tech Adept
 
TXstreetracer's Avatar
 
Join Date: Jul 2005
Location: New Waverly,TX.
Posts: 107
Trader Rating: 4 (100%+)
Send a message via MSN to TXstreetracer
Default

THANKS for the help guys.....for some reason I've always sucked at trying to comprehend gear ratios/gearing setup

I'll crunch some numbers tonight and order some gears.


John, while I'd love to come race on the track (and I'm sure that I will at some point have a car on that track) I just don't have the time or funds to try and compete on a regular basis.

RC is only one of a few hobbies that I have....1:1 cars are my main hobby.....and building something to race in 1:1 scale isn't cheap....so that's where I try and put most of my time and interest. I'm mainly building this XXX-S to beat a few of my friends who have brushless off road trucks or the occasional parking lot thrash
TXstreetracer is offline   Reply With Quote
Reply



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 11:45 PM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net

SEO by vBSEO 3.5.0