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Refrigerator Raider Hater
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Are you talking where the IRS butts up to the unibody (just in front of the wheel wells on the rear)? I think this idea has been brought up before but I don't think there was decision made about NVH on the issue.
 

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the four subframe to Body mounts i can see playing a key role in the wheelhop but MAN the the 6 big *** rubber bushing on the control arms i think will play even a bigger role in the cuase of the wheelhop..

but people have replaced the subframe mounts and say the wheel hop had disapeared so..
 

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GreenBird said:
I've got a pair of these that where made for my SHO, but I think I could make them work on the bird to stop wheel hop. a poly bushing would go between the aluminum pieces.

http://members.tccoa.com/greenbird/Thunderbird/bottom.jpg
http://members.tccoa.com/greenbird/Thunderbird/top.jpg
I'd buy some alum. rear subframe bushings in a second. The problem is gonna be finding somebody who can make the poly bushing!!!!!

I've been saying for Years that HWH is caused by the large squishy subframe bushings.

I already have: Poly front diff. bushings, Poly rear diff mount, the IRS Pinion Brace, 1 3/8" sway bar & air bags. I still dribble the tires in 1st. & 2nd.

As far as NVH goes, I don't think it will be any worse than it is right now. I'd gladdly give up some NVH to cure my HWH!!!!!!!!!!

68COUGAR
 

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The subframe bolts are a real pain in the *** to get out. Mine were locked in there real good and my car isn't even rusty at all. Just a warning to anyone wanting to drop the whole subframe.

I looked into other bushing materials when I had my subframe out. No one makes anything. I was extremely disappointed. I put new rubber ones in. Right now I have zero wheel hop, its nice. I imagine when those bushings get worn though that it will show back up. I did so much at once though that I really can't put a finger on what the biggest wheel hop eliminating thing I did was.
 

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4 Cam Bird said:
I put new rubber ones in. Right now I have zero wheel hop
I bought my '89 5-spd XR-7 new. It did not have any wheel hop, for several years. Now I hop 3rd. gear when I race. I think you've proved that when the rear subframe bushings get old, they cause HWH.

Now all we have to do, is find somebody who can machine some poly or alum. replacements!!!!!!!!!!!!

68COUGAR
 

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At Carlisle this year, George and Duffy from SCCoA arranged for two retired Ford engineers to speak to us after dinner on Saturday evening. They both had worked on the MN-12 program, one was a driveline NVH guy, the other a suspension ride & handling specialist. Chuck Weiss, the susp. guy, was of the opinion that a probable cause for the wheel hop could be the fact that the rear upper control arms only have a single mounting point, allowing for movement back and forth ... which is the direction of the hopping when observed on MN-12 cars. The only way to fix that would be to design a new upper control arm and attachment to the subframe.

cheers,
Ed N.
 

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fast Ed N said:
... which is the direction of the hopping when observed on MN-12 cars. The only way to fix that would be to design a new upper control arm and attachment to the subframe.
And was thinking a Nice new A-arm setup with the Camber adjusting ability reloated on the outboard point.. is wouldn't be THAT hard to make something up... alittle welding here, some Custom bushings there... a spacer here and there.....
 

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It's got to be a combination of all the damn bushings down there, whatever is worn is going to let the wheel hop happen easier. I say do the quadshocks and all new bushings, at least that's what I'm going to do.

-J
 

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jturmel said:
It's got to be a combination of all the damn bushings down there, whatever is worn is going to let the wheel hop happen easier.
Forget the notion that the changing pinion angle is what's causing HWH. That's for solid axle cars, and doesn't apply to IRS cars. I have Poly front diff. mount, Poly rear diff mount, & IRS Pinion brace. My diff isn't moving at all, and I still have HWH.

The knuckle bushings are a possible source of HWH as are the large squishy rear subframe mounts.

68COUGAR
 

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68COUGAR said:

Forget the notion that the changing pinion angle is what's causing HWH. That's for solid axle cars, and doesn't apply to IRS cars. I have Poly front diff. mount, Poly rear diff mount, & IRS Pinion brace. My diff isn't moving at all, and I still have HWH.

The knuckle bushings are a possible source of HWH as are the large squishy rear subframe mounts.

68COUGAR
:confused:

I never said anything about pinion angle...

I'm going to do all new bushings (on the spindle) and the quad shocks. Thanks for the assumption though. :)

-J
 

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I have been looing into the possibility of fabbing up a triangular upper control arm as well. There is not much room back there. You cannot do a 60-60-60 degree upper control arm (like our front upper control arm) b/c one leg of the control arm will be going right thru the spring. I have looked into a 30-60-90 dgree triangular set up with the control arm, basicly having a tubular section where the existing upper control arm is and adding another tubular section hooking in to the front side of the control arm.
I started this project last winter and work ended up taking all my time. I am hoping to get back started on it here in the next three weeks or so.
Needless to say, I totally agree with the statement that our rear upper control arms are the main contributing factor to the HWH.
 
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