HWH vs Rear Spindle Busings

I've heard that the Poly rear spindle bushings will kill HWH.

Here's the theory: The forward / backward wheel hop is caused by the rear spindle rocking back & forth, which swings the axle back & forth.

Power applied, axle rotates forward, Pushes spindle rearward, tires grip

Tires looses grip (do to massive TQ), spindle bushings rebound, pushing the axle forward.

Repeat, Repeat, Repeat.

If this theory is correct, stabilizing the rear spindle, will kill HWH.

This actually makes MORE sense than my idea of a 150 lb. subframe dancing around.

What thinks You Guys?

68COUGAR

I think that there's a bit more to it...Example:

On my '89 [AUTO] the upper control arm to subframe bushing was completely shot. Still there, but deformed and dry rotted enough. I had SEVERE wheel hop with that as an auto. And that was on a primarily stock SC. So I think that you have to take the upper and lower control arm bushings into account too. Do they need to be poly? I don't think so. I just think that new bushings there, combined with the poly spindle bushings will eliminate a lot of the wheel hop until you get to the extreme level of performance.

I think that you're on to it though...That's where the wheel hop starts at. Eliminate that source and that will help in curing the overall problem. My '92 doesn't have any trouble with wheel hop at all. It does have more power than the '89 did too. I'm still going to be replacing ALL of the bushings on the back 1/2 of the car in the future. Subframe, and all suspension bushings. Wheel hop could be a problem in the future...so I want to fix it before I get there...

Poly vs HWH

I bought my '89 5-spd new. No HWH then. Now the car has some pretty good mods. Best numbers so far are: 14.250 & 97.6 mph. Pass. side hops so bad, I'm afraid it's gonna break something. Drivers side doesn't hop "to bad".

The car has 3.27 gears, Auburn Cone diff., IRS Pinion Brace, RAXLES, 1 3/8" sway bars & 255/50/16 Comp T/A's. Also have (not yet installed) air bags for the coils (which I believe will do NOTHING for HWH).

Nobody makes poly bushings for the Control Arms, so I might just go poly on the spindle bushings & OEM rubber on the Control Arms. I don't like using OEM parts, but if they are the only game in town, what ya gonna do?

My theory is: Why use a part that you ALREADY know you can break?

68COUGAR

68COUGAR said:

My theory is: Why use a part that you ALREADY know you can break?
68COUGAR

Click to expand...

I have the same theory...unfortunately though there is no one else in the game at this point. In fact, the inner suspension bushings (after much debate) should remain OEM, whereas the spindle bushings I will replace with poly. The subframe will be replaced with OEM unless there is another alternative when I actually replace the subframe. I'm also going to weld up the subframe as outlined on the MN12 Performance web site. I'm not sure if a larger sway bar might actually help reduce WH as well. It is tied into the rear spindle, so I have to think that it may have an effect as well.

Re: Big Sway Bars

007_SuperCoupe said:

the inner suspension bushings (after much debate) should remain OEM, whereas the spindle bushings I will replace with poly. The subframe will be replaced with OEM unless there is another alternative when I actually replace the subframe. I'm also going to weld up the subframe as outlined on the MN12 Performance web site. I'm not sure if a larger sway bar might actually help reduce WH as well. It is tied into the rear spindle, so I have to think that it may have an effect as well.

Click to expand...

The sway bar only comes into play IF the hopping is vertical AND both sides are hopping out of sync. with each other. My experience is that big sway bars do nothing for HWH.

I'm convinced that the movement is fore / aft, not vertical.

Those Big Squishy sub-frame connectors could be a source of HWH, if they were letting the entire sub-frame dance around. I've been trying for years to get somebody to make poly sub-frame bushings. Wynn (Tbird88) could do solid alum. bushings, but he has so much work, he doesn't have time to do the R&D.

Where can I find the "much debate" on the control arm bushings? That sounds like some good reading!!!

68COUGAR

68COUGAR said:

Where can I find the "much debate" on the control arm bushings? That sounds like some good reading!!!

68COUGAR

Click to expand...

I'll have to dig that up later. I think there were a few emails along with some threads. It might take a little time to find it all, but I'll get it to you.