Question about rear end and traction.

[Tight Lines]

First off i am learning as i go, so keep that in mind if terminology isn't correct. I have upgraded my suspension and have it dialed in. BMR, panhard, adjustable upper, adjustable lower CA's and relocation brackets. Everything is installed correctly and torqued to proper specs. I did this upgrade to help with planting the current power and future power to the ground and eliminating wheel hop. I was hoping it would also be a little safer if the tires did break loose (keeping them in a straight line), instead of kicking the ass end out to the right. I went out and and tested all the upgrades. It seems as though traction is better, however if the tires break loose the rear kicks to the right quicker and more then before. I am concerned with this because there isn't room in the staging lanes for this to happen. It is also happening while breaking loose while rolling. So now I'm wondering WTF? Is this something to do with the differential and the carbon clutch plates? Maybe one tire getting better traction then the other? Any ideas or direction you guys can point me in. I am running MPSS out back as well. Hope this makes sense. Thanks!

 

[19COBRA93]

How about just run a set of slicks?

Otherwise I'd suggest hitting up a performance driving school. Don't take that the wrong way though. Sometimes a little car control can go a long way.

 

[Butter pants]

Cut your losses now, buy a Camaro.oke:

 

[PRP]

First off i am learning as i go, so keep that in mind if terminology isn't correct. I have upgraded my suspension and have it dialed in. BMR, panhard, adjustable upper, adjustable lower CA's and relocation brackets. Everything is installed correctly and torqued to proper specs. I did this upgrade to help with planting the current power and future power to the ground and eliminating wheel hop. I was hoping it would also be a little safer if the tires did break loose (keeping them in a straight line), instead of kicking the ass end out to the right. I went out and and tested all the upgrades. It seems as though traction is better, however if the tires break loose the rear kicks to the right quicker and more then before. I am concerned with this because there isn't room in the staging lanes for this to happen. It is also happening while breaking loose while rolling. So now I'm wondering WTF? Is this something to do with the differential and the carbon clutch plates? Maybe one tire getting better traction then the other? Any ideas or direction you guys can point me in. I am running MPSS out back as well. Hope this makes sense. Thanks!

Have you tried playing with tire pressures?

When we first started racing a '29 Bantam Altered in the WCTA Nostalgia drags we had a NASTY right turn on launch. Not too terrible bad if we were in the left lane but if in the right lane, the wall was in the way.

We measured both of the tire circumferences and the difference was SLIGHT. We switched the tires from side-to-side and never had another problem with it after that.


Live and learn,
Phill

 

[jaiasmit]

Anybody with a serious answer. I'd also like a little info here. I know I've read of others that have done suspension upgrades that keep things going straight even when the wheels break loose.

 

[DepWraith]

Serious answer? Ok...get some real tires, those are not meant for the strip. When you get some dr's or slicks, let us know what it's doing because with your current tires it isn't worth trying to figure out honestly.

 

[dirtyo2000]

I have a wave loc and my car spins straight if pointed straight before it breaks loose. You can invest in some type of positive unit to improve handling for drag racing. Over the years of racing very seldom do you get a clutch pack to constantly spin straight.

Since you have adjustable lowers you may want to recheck your distances on the LCA. If they are off that will definitely cause the car to pull to one side under load. Watch videos with clutch packs leaving and you will always see the car step off to the side on launch. Normally to the right. Learning to better handle the car helps but find someone to scale it and set up pinch will also help straighten it up

 

[NELCO]

Hi Tight Lines, I have a 13 gt 500 and i just installed the BMR rear mods like you have and ford's lowering springs.. This car goes straight as nails , The rear does not kick out at all and traction is so much better.. I had my pinion angle set at zero. All parts came from [email protected] is the man and he told me do these mods. Good Luck!!
Nelco

 

[Crushinator]

I recently switched to 305 Nitto 555's and the difference is remarkable. My suspension is 100% stock and now the car grabs really nice on a second gear roll-on and grabs hard on a full blast 3rd gear punch. Best thing about them is they stay straight as an arrow when they do spin. But the acceleration now is crazy.

 

[Tight Lines]

First off, thanks for the serious responses. I understand that slicks or other tires will be used for the track. Unfortunately, I'm not at the track and wanted to test out my upgrades. I will try switching the back tires from side to side to see what happens. As Jaiasmit said, others have done these mods and are tracking straight. Again, new to this so I figured I would ask I was hoping I was missing something. My pinion is set at -2 and wheel base to 107". I measured many other areas under the car to the axle as well and all were equal.

 

[APMECH]

I agree with what dirtyo2000 said. I run drag radials and mine still moves around quite a bit. It's due to the lsd allowing the power to go to the wheel with the least amount of traction, it can't keep up.

 

[PistolWhip]

You're looking for an answer that doesn't necessarily exist in the way you want it to be put. There are just way too many variables. It's not primarily the suspension (unless it's not set up properly) that's causing the car to track to the right when the tires break loose, it's either the driver or the differential. A standard clutch posi differential will always apply more torque in the direction of the turning drive train in front of it. It's part of load transfer, static friction (spinning tire vs. non spinning tire or tire spinning less) and vehicle dynamics.
You have options; you can swap out the dif with a torsion or locker which reduce the movement by applying equal torque to both wheels and keeping one from spinning faster than the other, but will not eliminate it because load transfer will still exist in the direction of torque. Or you can learn to control the car better with practice. I'm not breaking your balls, I am being 100% serious. The best way to stop the car from kicking out to the right is to get tires that don't spin as much.

You can't compare a street car to a race car. Race cars are set up very differently than street cars and a lot of the engineering that goes into setting up the rear suspension has equal traction and load transfer differentials as a major part of the determination on how to tune it. Using a spool, like most race cars do, makes for a solid connection between the axles and obviously the most equal amount of power to each wheel. At that point, you only have to deal with the load transfer which is much easier to control with spring weights, heights and link geometry. All of that though, does not have to have anything remotely close to a street-able mannerism or comfortable ride. There's no interest put into making the car handle uneven pavement, pot holes or different surfaces or even taking a turn.

 

[Poppacapp]

Anybody with a serious answer. I'd also like a little info here. I know I've read of others that have done suspension upgrades that keep things going straight even when the wheels break loose.

When i first bought my 12', the goodyears when they broke loose the car would want the throw the tail end out pretty easy. I switched to Nitto 555r 305/35-20's on the rear and when they DO spin, the car tracks straight. But I have also learned how to drive the car as well. At first, it was a handful.

I have an in-car cam vid of how my car tracks spinning in 2nd gear if you want me to post it. Not the best vid, as I should have waited for the cars to pass me.. but it is what it is.

Edit: I have 100% bone stock suspension right now.

 

[Tight Lines]

You're looking for an answer that doesn't necessarily exist in the way you want it to be put. There are just way too many variables. It's not primarily the suspension (unless it's not set up properly) that's causing the car to track to the right when the tires break loose, it's either the driver or the differential. A standard clutch posi differential will always apply more torque in the direction of the turning drive train in front of it. It's part of load transfer, static friction (spinning tire vs. non spinning tire or tire spinning less) and vehicle dynamics.
You have options; you can swap out the dif with a torsion or locker which reduce the movement by applying equal torque to both wheels and keeping one from spinning faster than the other, but will not eliminate it because load transfer will still exist in the direction of torque. Or you can learn to control the car better with practice. I'm not breaking your balls, I am being 100% serious. The best way to stop the car from kicking out to the right is to get tires that don't spin as much.

You can't compare a street car to a race car. Race cars are set up very differently than street cars and a lot of the engineering that goes into setting up the rear suspension has equal traction and load transfer differentials as a major part of the determination on how to tune it. Using a spool, like most race cars do, makes for a solid connection between the axles and obviously the most equal amount of power to each wheel. At that point, you only have to deal with the load transfer which is much easier to control with spring weights, heights and link geometry. All of that though, does not have to have anything remotely close to a street-able mannerism or comfortable ride. There's no interest put into making the car handle uneven pavement, pot holes or different surfaces or even taking a turn.

Thanks for a great explanation. I will be up front and honest, every other car I would take to the track was automatic and obviously a wee bit easier to drive. I had a 2011 GT (auto) and had the same issue with kicking out, did suspension work that helped greatly. I guess I was expecting similar results. I take your advice and will continue to learn the car. I did want to do things right, I wanted to tackle suspension first before other power mods. I think those mods will wait as I continue to learn things. Thanks again for the respectful post.

 

[Van@RevanRacing]

You need to get an alignment and adjust your thrust angle to zero. That will help dramatically with the counter oversteer condition.

 

[PistolWhip]

O.P. ^^^^^^ This is the guy you want to talk to and more importantly LISTEN to... Van will set you up with whatever you need parts and service wise and more importantly the knowledge and experience to put it to the pavement.

 

[2nd2none]

I was following this thread about the Truetrac rear differential. Sounds like it will help eliminate your rear end kickout
http://www.svtperformance.com/forums/svt-shelby-gt500-150/938314-truetrac.html

 

[PLATIADO]

First off i am learning as i go, so keep that in mind if terminology isn't correct. I have upgraded my suspension and have it dialed in. BMR, panhard, adjustable upper, adjustable lower CA's and relocation brackets. Everything is installed correctly and torqued to proper specs. I did this upgrade to help with planting the current power and future power to the ground and eliminating wheel hop. I was hoping it would also be a little safer if the tires did break loose (keeping them in a straight line), instead of kicking the ass end out to the right. I went out and and tested all the upgrades. It seems as though traction is better, however if the tires break loose the rear kicks to the right quicker and more then before. I am concerned with this because there isn't room in the staging lanes for this to happen. It is also happening while breaking loose while rolling. So now I'm wondering WTF? Is this something to do with the differential and the carbon clutch plates? Maybe one tire getting better traction then the other? Any ideas or direction you guys can point me in. I am running MPSS out back as well. Hope this makes sense. Thanks!

My car is doing the same thing, I pretty much have what you have as suspension but my loweres are not adjustable, I also have relocation brackets, I had my lowers set in the center hole and it would go hard to the left once it started spinning, I thn put the arms on the top hole and now it goes hard to the right once it starts spinning, I also bought all the suspension to see if I could keep my car going straight but no luck.

Maybe better tires is the ticket, that's my next step.

 

[Wharf Rat]

With the TrueTrac and 555 DRs I have to intentionally try to get the ass end to move around. All suspension is stone stock.

 

[SuperFly03]

I was following this thread about the Truetrac rear differential. Sounds like it will help eliminate your rear end kickout
http://www.svtperformance.com/forums/svt-shelby-gt500-150/938314-truetrac.html

Damn you... now that's been added to my mod list. :bash::bash: