Ok...so I've been doing some research on setting my suspension up and I've been reading alot about Drive Line Angle, Instant Center, and Center Of Gravity. Currently my driveline angle is 2.5* with my pinion angle currently at 0*. Now as far as IC, with a torque arm car how do I go about finding and adjusting my instant center? I know I'm supposed to find the instersection of the torque arm and lca's but besides getting a straight edge and piece of graph paper is their an easy way to do this? A formula perhaps? I have found a few IC Calculators (http://home.earthlink.net/~whshope/id28.html) but I'm lost as to what measurements they are asking for. Also how do I calculate my Center of Gravity? What measurements do I take and what is the best method the figure it out? Also while I'm at it what is a good baseline to set my adjustable front and rear coilovers to? Currently 2 front and 7 rear. All input would be greatly appreciated.



-Dave

 

Can't help you much on the torque arm settings as I don't have one but as far as your PA I can give you a little insight. Your PA is +2.5. Depending if you have poly bushings or solids, I'd set your rear between -2.5 and -4. That way under load your PA would be at 0 or -1.5.

Billy Shopes site is a great site for suspension tuning.

-Mark

 

But isn't it the driveline angle you want to be at 0* under accel? Meaning don't you want the driveshaft and pinion to be completely straight?

 

Correct. Under load right now you're atleast at 2.5+. So lets say you that you lowered your rear down to -2.5. So now under load is would be at zero (2.5-2.5).

EDIT: **** my bad. I re-read your post. I thought your rear was at zero, and not your PA. I usually see people give the DS angle then the rear angle. The way you had it threw me off.

So your at zero right now. What kind of bushings do you have. Cause poly's will shift more than a solid. For solids you should still have -1 to -1.5. For poly's you go -2 to -3*.

-Mark

 

For now all my ends are poly...but this brings me back to my main issue of IC and CG....cause I've pretty much got driveline angle understood for poly ends. But thanks alot Mark for the input.

-Dave

 

any more input on this topic?

 

Still looking for some insight on the subject....

 

Set your pinion angle off the rear end only. Put an angle finder on the flat of the yoke, and set it to -2*. What kind of torque arm do you have? do you have adj. lca's? make sure the rear end is squared in the car.

 

So your saying go off the pinion to ground angle? And it's Spohn adjustable with adjustable LCA's and the rear is squared....is there any other methods to squaring a rear than the ones mentioned in the stickies?

 

set the pinion angle at ride height w/ the car on a level surface.

I square the rear end side to side with a 48" level. Butt the level up against the fender of the car, make sure it's level, then measure from the center of the axle to the edge of the level. Do the same on the other side, and use your panhard to move the rear end side to side until your measurements are equal.

To square the rear end front to back, measure from the door jam (along the seam between the kicker panel and the rear quarter panel) to the front of the tire. measure in the same place on both sides, and use the adj. lca's to make the measurements equal.

that's the easiest way i know of to square the rear end.

One last thing, make sure that every time you make an adjustment on the torque arm, check your pinion angle, and reset it back to -2* if necessary.

 

does drive line angle effect our cars at all? Or is it all pinion angle?

 

Pinion angle only. I know alot of people think otherwise, but the boss and I have been working primarily with f-bodies for the past 10+ years. We have thousands of recorded passes with our set-up, and driveline angle hasn't ever effected us in a negative way.

 

Ok thats alot Steve....how about some insight on the other parts of my OP....

 

Well, a good set of double adjustable shocks (strange or afco) would be my next step. afco being the better of the two, but also the more expensive.
If you're having any kind of wheel hop issues, lower control arm relocates would solve that problem.
One other part i'd recommend investing in, would be a good rear anti-sway bar. Either the BMR Xtreme rear sway bar or the Wolfe single anti-roll. Both are excellent products. BMR's is a little heavier, and a little more expensive, but just as good as Wolfe's.

If you want to order any of these parts we've talked about, please give me a call at the shop. 225-673-3533. I'll be out for the rest of today, after 1 o'clock, but will resume normal business hours tomorrow.

Thanks
Steve

 

Well currently I have the QA1 Coilovers on my car and the location brackets on my 9"....and still it seems my LCA's are almost parrallel with my TA....

-Dave

 

Call me at the shop whenever you get a chance. 225-673-3533