Rear tires are unloading under light throttle

[BuickMike]

So let me just start out with my suspension setup:

SPC springs (car is at least 1.5" lower)
Bilstein HD shocks
Energy Suspension body mounts
UB Machine front UCA's
Stock rear UCA's and LCA's that are boxed and have HR Parts N Stuff greasable poly bushings
S10 Blazer 4X4 2dr rear sway bar. It bolts to the rear axle and the endlinks mount to the frame. (Poor man's HR bar)
Rear tires are 255/50/16 Kumho Ecstas (hard compound)

Obviously I set my suspension up with handling in mind, and it handles fantastic and rides sooo nice. The only problem is that when I give it throttle and it hits 2nd gear the rear tires break loose in a bad way. That's only 1/4 throttle and 10psi of boost. Of course the tires may be the main issue and some DR's would help, but I'd like to optimize my rear geometry and see where it gets me.

As it sits now my current pinion angle (in relation to the driveshaft) is about 0 to +1/4 degree. I don't have any airbags installed at this time.

Other than getting my rear pinion angle to -2 to -2.5, what else can I do? Are there any control arm relocation kits that will help?

Keep in mind that I like my suspension setup, so drag shocks or lighter springs are not in my plan. I don't care about getting an insane 60ft out of it. I just want to get the rear to plant a bit better so my car is not a total death trap.

Thanks!

 

[Amelio]

unfortunately that is a trade off when going for a car that handles......I would deffinitely get some Dr's and a set of bags back there and see how it does. It will help but at your 10psi level but the the problem will most likely come right back with more boost.

 

[Chuck Leeper]

Pinion angle is not a tuning tool.

After you lowered it, did you check the instant center?

 

[jlat]

hello; I would ch. the TV cable for adjustment. Mine use to shift very hard going into second with a mild churp but nothing as hard as you say. And checking for instant center I know nothing about but I'd like to here more.
IBBY

 

[ZNix]

Mine likes to do this in the rain.. Small bark in second on normal days. BFGoodrich on the back.. Street tires.

 

[BuickMike]

I have not checked instant center. I will need to research and figure out how to do that.

 

[DailyDrifter]

How old are the tires? I would put a 275 on the rear personally. I've had Hankook tires that work pretty good, only problem with them was they wore out kind of fast (I think they were 280 tread rated??). Remember that the only thing actually touch's the road is the tires!

 

[Fast4Ward]

The only problem is that when I give it throttle and it hits 2nd gear the rear tires break loose in a bad way. That's only 1/4 throttle and 10psi of boost. Of course the tires may be the main issue and some DR's would help, but I'd like to optimize my rear geometry and see where it gets me.
Thanks!

is there a car that does not do this on street tires. with the different street surfaces, the dr's will behave the same way most of the time.

 

[BuickMike]

Having a full tank of gas helps out a bit LOL. The tires are a couple years old and have a hard compound. I will eventually mount the DR's and see how it behaves.

Ok, someone help me out of setting up the correct instant center. I did a couple brief Google searches and didn't find anything I could really understand.

 

[charlief1]

Enjoy the reading.

http://www.baselinesuspensions.com/

 

[BuickMike]

Wow! Good reading!!! Thank you. The only thing that is not lear to me is how to determine projected control arm length on the calculator. Also, what anti squat value am I supposed to shoot for and do I just change the front bolt height for the LCA's on the calculator in order to figure out where I need to relocate them to in order to achieve the best value? Thanks.

 

[charlief1]

Not a problem. The owner of the website is a mamber and his name is Kevins. You might want to conact him and I'm sure he can help you out.