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-   -   Cougar SV pulling to left (http://www.oople.com/forums/showthread.php?t=61826)

musicman 26-01-2011 01:31 PM

Cougar SV pulling to left
 
Hi everyone

Has anyone got any advice as to curing a Cougar rear end from pulling to the left under braking and accelerating. I thought it was a loose Diff causing it, but I bought a built one to eliminate the issue, but still does it. Baring in mind it is fine on Astro, it's only an issue on low grip surfaces.

thanks

Paul

ian h 26-01-2011 01:44 PM

Have you checked weight balance left to right?

Cruise 26-01-2011 01:47 PM

Check your shocks for equal Rebound and droop.
Also check for equal springs.Can happen that they are different on one axle.
Check for bent hingepins in/ outboard

Cruise

musicman 26-01-2011 02:10 PM

Thanks for getting back so quickly. The Weight balance has been the same since I first got it, and for the first 5 months of running it, my cougar was great everywhere. All of the hinge pins are fine too, I check the car over after every meeting. I'm not too sure about the shocks, but when I rebuild them (every 2 meetings, I check they match each other. I might look into that a bit more.

It's the braking thing that baffles me, as I can understand the drive getting to one wheel more than the other when accelerating, as that's just the diff action with varying traction on either side, but I can't see why there would be more brake bias to one side to the other.

Rich D 26-01-2011 02:19 PM

I come from a TC background so am happy to be told otherwise, however, the first thing I noticed when driving 2wd on a slippery surface was the unbalanced braking. All the 2wd cars I have driven have tended to pivot at the back when braking in a straight line. I guess the diff will work much the same way as it does under acceleration, when braking. One side is always going to have a slightly different level of grip to the other under braking therefore turning the back end as one wheel will be turning faster than the other. On high grip surfaces there's enough bite to stop the rear end from pivoting. That's my understanding of it anyway.

musicman 26-01-2011 02:24 PM

that sounds exactly like the problem I am having. It just seems strange that it's only in recent meetings that it's become an issue, and in terms of prepping the car, I haven't done anything different to usual...very odd :eh?:

Rich D 26-01-2011 02:36 PM

As I said, I've had three 2wd buggies and they all pivot at the back under braking on slippery surfaces. I think that the secret to being quick with one is having the reactions to manage the pivoting and using it to your advantage on certain corners too. I haven't got the reactions to do it so try to avoid using the brake too often lol. Watching the a final guys at Worksop on it's slippery surface, all their cars look to slide at the back under braking. They are just able to balance it with the steering and throttle to get around the track quickly!

Adam F 26-01-2011 03:19 PM

Had this issue with my SV.

Have rebuilt the diff and the shocks, balanced it up etc etc but nothing cured it.

In the end I have turned the initial braking strength down about 20% and its pretty much disappeared.:)

Northy 26-01-2011 03:31 PM

Un-equal flex? :confused::confused:

Chrislong 26-01-2011 03:31 PM

Try driving a FWD real car, yank the handbrake right up so it locks the rear wheels while driving at a constant speed in a straight line. The rear of the car wants to spin. It will still want to decelerating, handbraking to a stop from speed.

The only way to prevent the car turning under hard braking, is set your brakes to be just enough for the corners & the track - not necessarily stopping fast! So, your maximum brakes are likely to be set a lot less on low grip than they would be for high grip.

Doing this, your lap times are likely to be better too..

Oh just don't forget when your pit-biatch steps out to turn your car off, and knock him off his feet unable to lock the wheels.

musicman 26-01-2011 03:31 PM

cool, I might give that a go and see what it's like. I might change the throttle Exponential aswell to calm down the acceleration a tad.

Thanks

Chrislong 26-01-2011 03:38 PM

Its better to move left thumb slower, and drive to the conditions, than use throttle curve (in my opinion). Throttle and brakes I always liked linear personally.

bigred5765 26-01-2011 06:37 PM

try it with your slipper backed off more and turn your brakes down your probably running them too high and locking the car up under brakes and the slipper too tight which is making it wheel spin under power

Northy 26-01-2011 07:05 PM

But why does it always go the same way? :confused:

TKG26 26-01-2011 08:37 PM

have you checked chassis tweek. lift the back end of the car from the center of the chassis and see that both wheels lift off the ground at the same time?

bigred5765 26-01-2011 09:48 PM

only thing it could probably be is left side is not balanced weight to the right maybe but matty had the same thing under brakes he just turned them down and the problem just doesnt happen anymore

MikePimlott 26-01-2011 10:06 PM

Dodgy bearings ??? possibly not just another thing to check.

bigred5765 26-01-2011 10:37 PM

Quote:

Originally Posted by Northy (Post 456653)
But why does it always go the same way? :confused:

some go left some go right its just the way it is lol :p

musicman 26-01-2011 11:20 PM

Thanks for the advice. I'll check it all over to check for binding parts etc. but it does seem to be a general concensus that it's an intial brake amount causing the problem. I'll give that a go, hopefully it should do the trick.

Chrislong 27-01-2011 07:53 AM

It could be because front left preload is slightly less, or front left spring slightly soft, rear droop inbalance, weight inbalance, trim slightly out, camber slightly out or the way he dresses... :lol:


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