I have an advanced set-up question.

[Nitroaddict]

On my NTC3, I think the tweak is off. When I accelerate, it pulls to the left, when i brake, it pulls to the right. Not alot, but enough that it requires me to adjust. By doing the tweak test - ie checking shock levels, droop settings, and balance, i find that they are all okay.

I am assuming this is being caused by the only other option - the chassis. A while back, I bent my chassis, and had to straighten it. Is it possible to adjust tweak by changing shock spring, or ride height on the corners that are faulty? Or is there no other way but to buy a new chassis?

Please advise.

 

[RandyT]

Have you put it on a tweak board~?

 

[Nitroaddict]

i dont have a tweak board - but i took the wheels off and laid it on a concrete slab that is level. it rocks back and forth, so i know the chassis is bent.

 

[RandyT]

With your tires on, when you lift the front from the center of the bumper, do your tires lift at the same time, and when you put it back down, to they hit at the same time. Do this for the rear also.

If your lucky you'll get a chassis that is perfectly flat, your going to have to try to compensate for the bend.

 

[robriguez]

Yeah....My chassis is slightly twisted about 2-3mm counter clockwise from the front. How would you compensate for something like that? I keep going through right front tires like their made out of cotton candy.

I dont mean to hijack this thread Nitro but I'm having the EXACT same issue.

 

[RandyT]

You've done all the remeasuring and droop, etc~? Then you would have to either shorten the shock on the tire that touches first or lenghten the opposite. Also have you guys checked to see if your suspension is binding anywhere. If you crashed sometimes the pins are bent and will bind the suspension.

 

[Çh®i§tiªñ]

Raise the ride height on the front right and it should correct it. Just go a little at a time and test it.

 

[Nitroaddict]

sorry i havnt been around - i had to goto conneticut for a 3 day weekend. Randy - as i said before - i already checked the droop, by raising the wheels like u say, it was correct. i have concluded that the chassis is what is tweaked. christian - u say i can just twist the shocks so one is higher than the other and that will compensate for the tweak?

 

[Çh®i§tiªñ]

Absolutely. Even a perfectly flat chassis suffers the same results and requires tuning. Sometimes you may have to adjust ride height on one corner or the other too.

Some HIGHLY suggested reading would be the XXX-Main on-road suspension tuning guide. PHENOMINAL book and while pricey, to me it was worth it.

 

[Nitroaddict]

Originally posted by Çh®i§tiªñ
Some HIGHLY suggested reading would be the XXX-Main on-road suspension tuning guide. PHENOMINAL book and while pricey, to me it was worth it.

I've read it cover to cover - learned alot. That is where i saw the mention about adjusting shocks to counter shassis tweak. To adjust it this way i would - remove wheels, find out which sides of chassis are higher, and stiffen/raise the shocks on those sides?

 

[Çh®i§tiªñ]

I do it with the wheels on. The only thing I have ever set with the wheels off is the ride height. This is done with the set screws located in the a-arm itself.

The shocks will compensate for the issue you are having. At least they should. The concept is basically this:

Whatever front wheel is having more contact with the ground at any given point in time, will become the more steering tire. The goal is to equal this out as much as possible.

On take-off, the front wheels will understeer or have less control that during braking. Simply because of the shift in weight transferring. When braking, the front wheels are much more sensitive to drift and input. So, if when you brake, the car pulls to the right, then the front right tire has more contact with the surface. This can be offset with the shock. Tighten it up. You should see an immediate result.

This will only work right if your toe-in and camber/caster settings are the same. If not, you can have a whole different issue.

For general bashing, I run the rear tires at 0/0 and the fronts at 0/1. 1 being the degree of toe-in.

 

[RandyT]

A tweak board is helpful, I know that Serpent says that their Set-Up boards are suppose to eliminate the need for them, but not having one, I found a tweak board beneficial in having the car running straight, and they're not that expensive. I probably get a Serpent Set-Up board when I finish my 835 and see if what Serpent says is true.

 

[Nitroaddict]

thanks guys for all your help - i ran the NTC3 last night, and was able to adjust the shocks to compensate for the tweaked chassis. Tracks nice n straight now.

 

[RandyT]

Great~!