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.

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?

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.

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.

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).

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.

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.:nod::nod::nod:

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.

Use regular stick on lead:D

I've seen pic where people sand the bumps off.

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

get a 21.5, get a lipo, put it to 4.2:1 or as close as you can. and forget bout it

R

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.

That's odd... I never saw temps over 110° on the 21.5 in testing geared down to 3.8 FDR.

robk...thanks for any help. Here's my baseline/older setup I was running outdoors on decent/med grip asphalt link below. TC4 tub chassis. Worked well for me as long as I had med./decent grip. Ran on some sealed asphalt and fresh/green layout at ThunderRc/carpert w/ linked setup below same loose results on these lower grip tracks.

*not noted on setup sheet.... I also had to add ~150grams (due to using the light/200gram orion 3200 lipos)of lead to make our 1531gram min. I balanced it left to right pretty well and stuffed most of what I could in the rear and some in the middle, a touch in the front..I'm guessing a 40/60 or 35/65 front to rear balance on the 'hand scales'. This maybe part of my problem?...too much weight in the rear for soft rear setup? Should I redo the lead more in the middle of the chassis and get closer to 50/50 front to rear balance? Also just realized I'm using the shortest rear wheelbase setting..meant to try longer but didn't have time.

Here's what I have changed/tried to the setup below and where the setup is currently at from the posted/linked setup:
Longer front camber link which took out some steering. helped some.
More droop; front 2mm above ride hight, rear 3-4mm above ride hight
Rear shock oil from 40 to 30wt.
Moved upper rear shock mounts out one hole & outter hole on arm. helped some.
Rear toe in 1* to 2*, thought I had 3* but the setup board measured 2*
1* to 2* rear camber
Tried a sliver/med swaybar, not much changed, removed it.
Dropped rear ride hight; was 5.5mm all corners, tried 5.3 & 5mm in rear. minimal difference noticed.

Thanks for any suggestions/tips..track time is limited and helpful/time saving suggestions are greatly appreciated!

http://www.nashrcracer.com/coppermin..._TC4_VTA-1.zip

Speedster- Try moving the front shock out on the arm, get 3* rear toe, and go out on the rear hub camber position. If you car gets stable again, lean the front shock in on the tower. If you can, you may want to find some springs softer than the AE green (Tamiya??). I am starting to think the cars need to be very soft. Sort wheelbase--this is actually good, stcik with it.

Also, I am not familiar with the TC4 spacers for the hinge pins. How high are they off the chassis? It looks like you have a little kick up in the front, and some pro squat in the rear?? Just try running everything flat for now. Your car will do different things in different corners because of throttle variation when you put kick or squat into your car. Add it back if you need it once you get a handle on things. Also, if the rear hinge pins are higher than the front, that can cause the car to break away if you are in a low traction situation.

You must run on a fairly open track, or you're not pushing it hard enough around the turns :) . Even at the Gate, my motor was always 115, and on smaller tracks, it's 130-140.

Nope, and nope. In all of the pre-21.5 rules testing that was done, those temps were never seen by any of the testers. That's 6 different talented drivers in 6 different chassis at 3 different tracks.

Maybe you're pushing it TOO hard in the turns. ;) Definitely not the fast way around in a spec car.

What is weird is that my motor was up to 150* at the gate, but I had the motor sound setup attached to my car. I was thinking that did something to my motor's performance/temp., but the guy who I had first seen with the same setup on his car said he ran one on a 17.5 with no problems!??! Maybe I have a bad motor. Stealth, maybe you got a funky motor too?? Though yours is really fast:weird:

Crazy. Maybe it's The Gate. :deathstar

In case anyone is running a losi, here is the setup i ran at the Halloween race....it seemed to be really good, tons of corner speed, but it liked to 2 wheel in the corners if ya toss it in too hard.

The warmest my motor ever temped was 97*.

Thanks Rob. Those shims/spacers are 1mm, So they are close to flat...rear pins up 1mm over fronts. I'll try your suggestions.

Is the front to rear weight balance ok..35/65ish frt to rear? I was trying to weigh down the rear to help it stick and why I was using the short WB...something I do in off-road 2wd. Thanks again! :cool:

Try to get your car at 50/50, just to make sure the weight bias isn't part of the problem. Sometimes too much weight at the back can have a pendulum effect.

Hello all, I was wondering if I could use a Associated rc12 1/12 roller for TA racing.Thanks for your help

Nope. The class is for 1/10 AWD touring car chassis.

TC3 VTA Setup needed.

OK, I got inspired, converted my TC3 to a VTA car too. Now I have an extra just in case.

What is a good base setup for a TC3? This car handled well as a 27T stocker. Motor, electronics and gearing will stay pretty much the same. I have golds in front and silvers on the back, 40 wt oil. Second shock hole all the way around (the last race setup I used). This car predates the "droop" adjustable control arms. I'm going to give it a run tonight just to see it go, but wouldn't mind seeing it be competitive. The 21.5 and LiPo are on order for it.

I'm guessing similar to a tc4 but I really don't know, no personal experience but race w/ a few. I know they can be competitive in TA. I'd say try (softer) Silver front & green rears would be better for the harder ta tires. Try the setup you got w/ softer springs to start from and go from there.

I have a question about shock rebound. What handling changes would you expect to happen when changing shock rebound from say 25% rebound to 100% rebound, or going the other way?
Thanks John Schoenauer

John, next time your close to the shop, swing on in with your car/s. Im sure i can get them working good for you. The general rules to setup apply to all cars, but I'm sure we can help get you dialed long before the upcoming USVTA series stop.

Thanks

Jim

Hello all need some help on getting a tt-01 setup to race TA. Any suggestions, Thanks in advance.

Your shock rebound is basically firmness of the suspension. Having more rebound is going to be close to having thicker oil in the car, or a thicker spring.

Here is my setup on my tc5

front
0 degree toe
camber 2 deg
4 deg caster
silver spring
#2 piston
35 weight oil
short wheelbase
1mm of shim added to widen front end between bulk head and hinge pin mount
2mm of shim between the wheel hub and wheel
camber link inside lower
shock position 2nd from outside
integy alum steering blocks using ackerman hole towards rear of car
#3 rollcenter

rear
2 degree rear toe
green spring
1 degree of camber
0 degree hub carriers
35 weight #3 piston
arms all the way forward
camberlink inside middle
1 mm of shim on outside link, link in outside hole
2nd from outside on upper shock mount
#3 roll center

I have the new cams installed, belts in the most free position
Running itf top plate and chassis, all soft plastic

Softer is better with these cars. I noticed a big improvement going from gold front springs to blue and then from blue to silver it got even better. My next step is to try green all the way around. also camber is critical, you will see a big difference when the camber is set correctly, kinda seems like a small sweet spot for these tires.

Also the tires take about 10 runs to get good. So if the car feels like ice on new tires that is why. We have been using jack the gripper and the tires get softer and softer. We are doping half the front (inside 3 ribs) and all of the rears. lightly wipe tires after applying to kinda evenly spread the compound. Let them soak for 30min or so until the jack has about dried into the tire. Then wipe as much as you can with a terrycloth towel. It will take a lap or two to get them good.

We have been running the camaro from hpi, good durability and handles good. Also make sure to balance the car, weight is critical especially if you stay close to the weight min. I think the cars handle high speed turns better once you get into the 1530 gram area. But balance is key to having a raceable car.

This basic setup can be applied to any car, very light springs all around, slightly stiffer front, with camber and toe listed above should get you in the ball park.

Hope this helps

Mike

I tried to get in last night, I ended up working until 7:30 again! But, I will take you up on the offer. The Camaro body for the TC 3 turned out real nice. Even my wife like it.

John

If you sand off the bumps on an Orion case, you end up with holes in the case, which defeats the purpose of the hard case to some extent.

A better option for the Orion packs with bumps (3200/3400/3600/3800) is to flip the pack over so the flat side (or side with the "pocket" for the 3200/3400) is down. Using a drill that's a bit smaller than a bullet connector, drill through to the (new) top of the case to give access to each connector, then use an xacto to open up the holes so the bullet connector fits. You can wrap the drill with tape to avoid scratching up the bullet connector sockets as you drill through them.

Now if you are running a 3200 or 3400 you can fill the "pocket" with ballast and it will be down next to the chassis plate where it belongs. If you are running a 3600 or 3800 you can use a weight plate or just fill the battery slots in the chassis with ballast.

I'll try and dig up the picture, the one I saw had the humps sanded off without any holes in the case.

There will be holes if you sand them off. You have to be very careful but even then the plastic thats there is paper thin at best once you are done.

I figured out how to balance my Xray t2 007 ....I used a 10L4 battery plate and mounted it to the chassis which allowed me to move the batt out a little which gave me almost enough ballast to balance had to use about 1.5 oz to finish also if you take the orions apart you can use Tungsten putty in the humps to add weight. Tungsten is 1.5 times heavier than lead and the putty is well like silly putty and can be molded but it doesnt harden....

bigmike thanks for the reply, and setup info. Here is my theory It can act like having a firmer spring because you are adding a hydraulic spring to the steel ciol spring. I think thicker oil slows shock pistion movement down so morw rebound in the shock would act like thinner oil.
I was wondering if having more rebound might be somewhat like running a soft swaybar, as it should make the car want to return to level more quickly. Most of the setups I have seen run 50% or less rebound. My first shock build when I setup the car for the season had 100% rebound and I have since rebuilt and now have about 50% rebound I changed other parts of my setup so I am not sure what this did.
I will compare your setup with what I have in the car.
Thanks again John Schoenauer

What's with the "Nu"? haven't you been doing this for a while? :)

I always run 25% rebound or about there, that keeps that part of my setups the same, I try not to have too many things to try to get the results I am looking for. but let me know if you need anything else I will help you out.