How to fix pinion angle?

[hurt]

I just replaced the U/L control arm bushings with poly and now have a vibration when I accelerate. I put the arms back in their original spot. How could replacing the bushings mess up the pinion angle and what should I do about it now?

Dan

 

[94-302-vert]

are you sure it is the angle?

It could jsut be that the poly bushings transfer a lot more vibration and forces than the worn out stock rubber ones. I know that was the case on my car.

 

[hurt]

It only vibrates under acceleration and from what I've read that's caused by a positive pinion angle (nose up).

 

[GRGT1994]

I thought I read that poly bushings in the rear suspension = really bad.

 

[TMC]

I thought I read that poly bushings in the rear suspension = really bad.

It's a mixed boat. Poly bushings work well in some application but have drawbacks in others. I use them in my car but I don't really car about handling or how it rides right now which are the downfalls to them.

 

[hurt]

The car grips alot better just around town. The rubber bushings were split, cracked and just plain wore out so I opted for what I thought would be a cheap upgrade. Keep the stock arms but switch to poly bushings. What I can't figure out is why the difference in pinion angle. Same arms, same positions. I'm not talking a little bit of vibration, this feels like you're driving over washboards on a dirt road. Rattles your teeth. Oh well, who the hell knows?

 

[94-302-vert]

all you changed were teh bushings? I bet you are jsut feeling something more.

Try rotating your tires front to rear, or removing the dogbone... Either something changed (and it is possible) or you are just feeling somethign that was there before a lot more. I know I feel everythign a lot more since upgrading to the poly's but nothing like you are saying.

have you tried to measure the pinion angle?

 

[GRGT1994]

It's a mixed boat. Poly bushings work well in some application but have drawbacks in others. I use them in my car but I don't really car about handling or how it rides right now which are the downfalls to them.

Actually, I think what I have read is that poly bushings are REALLY bad in the rear suspension. I'll just parrot back what I have read, and you can do the searches to find more knowledgeable comments along these lines.

The stock rear suspension is designed with the plyable rubber bushings in mind. And poly bushings (which have relatively no give) will cause excessive binding in the rear suspension. This can lead to highly erratic and dangerous suspension behavior in typical road conditions. And might explain the poster's "vibration" issues.

That said, I think the issue is most problematic with poly bushings on one set of arms in the back (upper or lower?) or maybe it's one of the end's. I don't remember, and I don't know enought about the rear suspension to understand anyway.

Here's a good discussion of the Mustang suspension: link