1G Squatting Solution (AWD Spring Options)

[danl]

Sorry. I didn't mean to suggest that I'd put drag-racing stuff on my Evo. I shouldn't have even mentioned that part. The key question was whether drag-racers use highly progressive springs in the rear to be both soft and stay off the bump-stops.

In general, no. Smart drag racers use good suspension geometry and good shocks (and sometimes shock computers). The springs simply hold the car up and you let the shock and suspension geometry work together (on a rwd car). Look at a pro stock car leave, that is ideal. You want the shock and geometry to hit the tire just enough to get the weight out back when the clutch or transbrake lets off, front end lifts but doesen't wheelie (nose in the air = wasted energy). /drunkxmasevepost

 

[jtmcinder]

Aren't most RWD drag cars live axle? Not a whole lot of math to do with regard to the geometry on those, is there? tee hee

 

[Tyeler18]

Aren't most RWD drag cars live axle? Not a whole lot of math to do with regard to the geometry on those, is there? tee hee

Not sure if sarcasm?

Have you seen the adjustment points on a true 4 link solid rear? The one I built on a ford 9" had some like 2000 assortments of adjustments to induce anti-squat, not an easy setup by any means.

 

[jtmcinder]

Yeah, OK, but the math is nothing compared to IRS.

 

[Tyeler18]

I agree completely, but there is still quite a bit of setup on a real drag car. Not the half-assed suspension setup most of these guys run on here.

 

[doesitonall4rs]

My car is on 100% stock suspension (not sure of age) QTPs and a welded center diff. I think the welded diff is the real trick here to keep front wheels from spinning.

At the shootout I was launching only on the 2step building about 10-13psi, with no antilag, now I have the antilag turned on and build about 26psi. Car does not spin no matter what road its on.

Here is a picture of it at the shootout on just the 2step.

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Here is a video of how it launches currently set up with the antilag building about 25-26psi.
https://www.youtube.com/watch?v=0fph9z0LazE

I been thinking about going with coil overs but everyone tells me not to, since the car already works good how it is.

 

[daplatano91]

Why not try running limiting straps on the front suspension Like this

 

[Mischif]

Why not try running limiting straps on the front suspension Like this

^This. Another name for them is droop straps. With 10 bucks and a trip down to home depot you can grab everything you need to make your own set.

 

[BoostedBeaver]

Thank you for all of the replies. I have picked up a set of Pro-Kits to see how they will help. If all else fails, I may try the limit straps as an alternative.

I think the welded center diff may be the way to go but I still have some reading to do before making an informed decision. Thanks for all the input and that lauch at the shootout looks crazy.

Robert

 

[RWD4G63]

Let me try and clear up some of the concepts that are floating around this thread, hopefully this will make sense and people won't leave the thread feeling so confused.

Weight transfer is not really the enemy. Weight transfer will happen whether the car squats or stays perfectly flat, there really isn't much you can do to stop weight transfer outside of some extreme modifications. This is the same with lateral weight transfer in a corner. When you run stiffer springs and anti-roll bars, you aren't actually affecting weight transfer, you're just making the car more predictable and easier to drive through less geometry change and faster weight transfer.

This being said, limiting squat helps because you're not bouncing up and down the track due to improper shock valving, and in a manual car the 1st-2nd shift can be rough as well. We also want to move the car forward as fast as possible, not waste time and force moving the front end up.

I would definitely weld the center diff. Coilovers/a stiffer spring and shock combo all the way around will generally help you, but they will need to be adjusted as well. I'd stay away from K-sports and the like, they damping adjustment knob usually does very little.

Beyond that, I would look more into anti-squat geometry in the rear.

I'll set some time aside to write a longer reply, but, for now, yes, my suggestion is a new center diff. My near-stock Evo pitches like mad on a hard launch (because the springs are pretty soft, there's no anti-lift geometry in the front, and the rear anti-squat geometry isn't very good), but the center diff is so good that none of this matters.

Double the power and tire traction and I'm betting it'll become an issue .

 

[jtmcinder]

The rules I run under limit me to about 350 torque and 225 tires, so I don't think it will ever be an issue.

Thanks for the good post on how squat doesn't mean squat WRT weight transfer (tee hee). One point to add: by limiting squat, you are actually increasing total weight transfer, because the CG stays up. On the other hand, front droop straps reduce weight transfer by either keeping the nose down or causing the weight transfer to happen sooner, lowering the tail.