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Old 11-02-2008, 08:49 PM   #1
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Lightbulb VTA tuning Q&A

I know a lot of this has been covered in the VTA thread. This thread is an attempt to help close the perceived gap in motors, batteries and learning to get the car handling right. As this class is very hot with a ton of people converting used chassis and RTR Touring cars into Vintage Trans AM cars, I thought this would be a good place to start. A n00b such as myself, might just learn something.

I'd like to see tips on:

How to adjust the suspension: Oil weight, spring weight, shock angle, droop, etc.

How to gear the the motor: spurs, pinions, Final Drive Ratio, Rollout, etc.

How to acheive good weight distribution.

What caster, camber and toe in can and have done for your setup.

What batterys and why.

What motors and why.
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Old 11-02-2008, 08:53 PM   #2
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What FDR is a good starting point for a 17.5 motor running 4 Cell 4600s?

My car seemed slow and sluggish in the 3.8 range, do I want to go to 4.0 or an even higher FDR?
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Old 11-03-2008, 07:30 AM   #3
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http://www.teamxray.com/teamxray/sho...p?file_id=2525

download that manual and read it and you will have a better idea of setup then 90% of the people out there.
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Old 11-03-2008, 08:45 AM   #4
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http://www.teamxray.com/teamxray/sho...p?file_id=2525

download that manual and read it and you will have a better idea of setup then 90% of the people out there.
That is a beautiful thing. I'm printing a copy for my workbench. That wraps up all the tribal knowledge I've ever learned and dismisses a bunch of myths. One guide that works for most any chassis. The stiffening stuff is pretty specific to that car, but I bet I can find similar locations.

I really appreciate this one as should anyone else who reads it.
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Old 11-03-2008, 03:01 PM   #5
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At your track last Sat. I found some very specific stuff to help you.

1. Spring the car softly. I ran 12lb (AE Green) in the front and about 10lb (blue mystery spring from an old Eagle Racing set) in the rear. I did this because I realized that if the car slid the tires at all they began to overheat, and would pick up the fiber from the carpet. Once I softened the car, it had enough mechanical traction to bite without heating up the tires.

2. I also ran a light swaybar, as my car was rolling across the nose too much. THe front to rear weight transfer was right, but having things that soft was bad for side to side transfer. I probably should have run a rear bar as well. I may raise the front hinge pins to get some of the roll out of the front.

3. Rear Camber at -1. This was also part of keeping the tires from going off. Too much camber just gets the tires too hot.

This also netted about .4 second improvement in hot lap for me as well over the course of the day. I think that I may have been able to get to the 4.2 FDR if I had my car working a bit better. If you try to gear up and your car is not ready, you will actually go slower. I noticed that practicing at my home track.
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Old 11-04-2008, 06:37 AM   #6
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Thanks Rob,

I did some more experimenting yesterday with no one else but the RCP staff in the building. First thing I did was clean up my racing line and run some consistent laps. The carpet is pretty tacky now and the car looks and feels predictable and stable. I let everything cool down and I loaded up brand new 4600 4 cells. I thought I'd monkey around with the FDR and see what the motor told me. I'm currently stuck with the Novak ss17.5. I thought I'd try to take the FDR up just to see if I could shave some time off. I went from an FDR of 3.6 to 3.8 and then to 4.0. It seems like the motor is still pulling at the end of the straight. No matter what I did, my lap times didn't improve. The motor and ESC weren't too hot after a run. I checked the time sheets from Saturday before I left and I'm now able to run average laps at my fastest lap time. I have more pinions coming, and will try an even lower pinion for a higher FDR, but I'm not sure when the motor will start to cave in on me. I have not done anything with timing. I was saving that for last (if there is anything to do).
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Old 11-04-2008, 08:46 AM   #7
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Great thread, I was just wondering where to find TA setup help!

Rob, curious what kinda caster you running & antisquat...and how much droop your running frt/rear? I having a hard time getting the rear to not be super loose in the sweepers and slow 180s. more rear-toe (up to 3degrees now) helped but it still aint right! I got plenty of steering/front grip..taking some out helped but still a hard to drive.

I've read the setup guides but knowing the theory and know what to do to address handling issues is were experience comes in... I'm still working on that part! lol.

Thanks.
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Old 11-04-2008, 02:39 PM   #8
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I have a question and I am pretty sure I am not the only one having this same issue I am running the Xray T2 007 EU w/21.5/lipo(orion 3800) how do you get the car to balance static or otherwise? My setup seems great under left turn conditons but loose on right turns it's like extreme tweak. I cant use any of the weight plates unless I change batt's due to the humps on the orion. If anyone has an xray or an option or idea I would appreciate.
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Old 11-04-2008, 03:05 PM   #9
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Liljohn- we were running around 3.5 before the 17.5 motors started to fall off. Also, adding timing will help.

Speedster, I run 4* caster. That's pretty standard rubber tire stuff. I don't run antisquat. Some things to check: Do you have enough droop? Also, just work the suspension on the car-does it feel too stiff to you? Check to make sure there are no funky issues with your car, like blades sticking in outdrives or a crapped out bearing. This occurs more than people think.

Put your setup on here so we can see what's going on.
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Old 11-04-2008, 03:06 PM   #10
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Originally Posted by NUCRPTRACER View Post
I have a question and I am pretty sure I am not the only one having this same issue I am running the Xray T2 007 EU w/21.5/lipo(orion 3800) how do you get the car to balance static or otherwise? My setup seems great under left turn conditons but loose on right turns it's like extreme tweak. I cant use any of the weight plates unless I change batt's due to the humps on the orion. If anyone has an xray or an option or idea I would appreciate.
Use regular stick on lead
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Old 11-04-2008, 04:17 PM   #11
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Originally Posted by NUCRPTRACER View Post
I have a question and I am pretty sure I am not the only one having this same issue I am running the Xray T2 007 EU w/21.5/lipo(orion 3800) how do you get the car to balance static or otherwise? My setup seems great under left turn conditons but loose on right turns it's like extreme tweak. I cant use any of the weight plates unless I change batt's due to the humps on the orion. If anyone has an xray or an option or idea I would appreciate.
I've seen pic where people sand the bumps off.
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Old 11-04-2008, 04:55 PM   #12
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Quote:
Originally Posted by NUCRPTRACER View Post
I have a question and I am pretty sure I am not the only one having this same issue I am running the Xray T2 007 EU w/21.5/lipo(orion 3800) how do you get the car to balance static or otherwise? My setup seems great under left turn conditons but loose on right turns it's like extreme tweak. I cant use any of the weight plates unless I change batt's due to the humps on the orion. If anyone has an xray or an option or idea I would appreciate.

Their's a lot of work to do in order to balance the car- the 3800 is much lighter than even a 4-cell pack.

Before you start, you'll need to remove any weights from your car. Weigh the car to find how much lead you'll need to make the minimum.

You need 2 digital scales and 12" wooden rulers. set one ruler on each scale, then the left tires on one ruler and the right tires on another. You'll see a huge difference in weight.

My first step would be to place your ESC on the right, Even if it means setting it high above the battery. Balance is more important then CG.

Now check your weight difference again. Add lead to the right until the car is balanced.

Any leftover weight you need should go in the center, under the belt. I start with mine centered Front to Rear.

This worked out great for my car. for more info, check out this thread. http://www.rctech.net/forum/electric...ps-tricks.html
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Old 11-04-2008, 05:06 PM   #13
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get a 21.5, get a lipo, put it to 4.2:1 or as close as you can. and forget bout it

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Old 11-04-2008, 06:59 PM   #14
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4.2 FDR with a 21.5 lipo is probably overgeared, unless you are on a really big outdoor asphalt track. Even at the Gate, which is one of the bigger carpet onroad tracks, we were getting faster lap times geared down around 4.44. Top speed down the straight is not always the best. Max rip out of every corner is more important than giving up a little bit of straightaway speed. On the tight local carpet track I run at, I'm geared around 4.6 FDR. Gearing up to 4.3 almost burned up my 21.5 and made my GTB shut down from overtemp on the motor.
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Old 11-05-2008, 08:25 AM   #15
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That's odd... I never saw temps over 110 on the 21.5 in testing geared down to 3.8 FDR.
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