I'm at the stage of my restore of putting the suspension parts back on the car. 1972 coupe, Front A-arm poly bushing to be installed. My mechanic who will press the bushings in for me tells me the bushings are loose on the shafts, You need to buy new shafts. So I called where I purchased the suspension parts. I was told the bushing should fit loose on the shafts. After they are pushed on the Arm and bolts tightened up they will be right.
When back at home I checked using a few of the old bushings that I still had. There is some with play, some too tight to go on the shaft, they would have to be forced on. The shafts do have some rust pitting and some with groves. I emery sanded them to clean them up before this install.
So my mechanic tells me to buy new shafts but the supplier believes the shafts and POLY bushings will be fine.
Help?

 

The sleeves (bushings) on the shafts (when installed) should be snug without the bolts tightened.

That being said, the poly bushings all seem to be looser than the rubber bushings. (I believe they must be allowed to slip slightly on the shaft since the poly won't give as much as the rubber bushings and allow for full suspension travel.)


M

 

Those shafts look pretty pitted. From the look of the painted parts I'm guessing they were pretty rusty before refinishing? You may have taken off enough material during cleaning to cause the loose fitting bushings. It might be pricing new shafts. Play in the bushings will result in handling quirks and you will hate driving around with a suspension that isn't tight.



Rick B.

 

On the other hand......if the bushing inner metal sleeve will NOT rotate on the shaft when test-fitted.....the rubber part of the bushing will fail and twist apart much sooner because of the up/down motion of the A-arm.

 

Thought for you; take a micrometer and measure the shafts in a number of places.

I do not have a new control arm shaft, but someone will know what the od is supposed to be. Then you can compare and see how much wear you have.

 

We just did the left side on my '74. The shaft is a pretty beefy piece and it's hard to imagine that you can take off, that much material cleaning it up. It's the A-arm itself, that provides the holding tension and we purchased an A-Arm bushing tool kit. It was an easy job, that took all of five minutes. Personally, I like the rubber bushings and I went with the Moog brand. Finally, if you did need a new shaft (doubt it), you're not going to find one new. You'd end up buying used A-arms and having to remove.the shaft yourself, because I doubt the Corvette junkyard guy will do that. I paid $70 for a used A-arm, complete, with that shaft, but I still doubt you need it, IMHO.

 

With respect, I'd have to disagree on that one (I think)

On the rubber bushings, the inner sleeve is serrated at the ends and designed to bite into the shaft shoulder and the large washer when tightened.
This is why the bolts need to be tightened with the suspension in the loaded position. If they are tightened with the arms hanging, then the problem of twisting them apart could occur but they are meant to stretch through the movement of the suspension, not slide.

The poly bushings don't stretch anywhere near as far and that's the reason they use non-serrated sleeves, to allow them to slip at the maximum suspension travel (if needed) while taking out the "slop" associated with the rubber bushings twisting.

My .02.

M

 

New shafts are available through MOOG direct.
Be sure to check the shafts well. My old lowers were bent. May be the pic, but that lower pictured looks a little iffy.
The new MOOG shafts are nice, and not pricey.

Carter

 

I mistakenly, after rebuilding the arms, tightened the retaining bolts/washers while the arms were in the down position....as I lowered the car and the arms settled I could see the rubber in the bushings twisting A LOT.....which this rookie knew wasn't a good thing....I immediately raised the front end before the bushings were ruined----then I remembered the rule of putting the car on the pavement/THEN torqueing the retaining bolts, which I did. As for the serrations on the rubber bushings, that will be a GM mystery to me, considering the "new" poly bushings don't have them.....LOL.

 

Good to know! Thanks!

 

I had the EXACT same feeling when I installed my poly bushings. I thought the machine shop had messed them up. I talked to a Corvette specialist that I trust and he said not to worry about them, just torque them to specs and they will be fine. I hope you are aware that you can torque them on the bench when using poly bushings. Mine is working well with no squeaks or any other issues.

John

 

Absolutely correct.
Perhaps the OP's mechanic is concerned that there is excessive play between the bushing ID and the shaft OD. I'd think if the bushing is flopping around on the shaft then you have an issue but it's not supposed to be a interference fit if that's what he's thinking.

 

Great answers, Thank you for the replies.
The shaft ends were not sandblasted or wire wheeled. They were taped before blasting and painting. I only lightly sanded to take away the rust and some paint that ran under the tape. Only rust and new paint was removed, definitely no steel was removed.
I just checked the old bushings on the shafts. The top ones will not go back onto the shafts. They will need to be pressed or hammered to go back on. Where the new top poly bushings go on freely and have some play.
The old bottom bushings go on and do have some play but not as much play as the new poly ones. The more I try and compare them they are not too different, just a bit looser. Maybe this is normal play?
My mechanic was afraid that we will hear clicking, Shaft and inner sleeve clicking/banging when going over bumps?. This was his feeling and recommended me to change the shafts for new ones.
So do I try new rubber bushings? Hoping they will fit a bit tighter on the shaft? I’m wondering if the rubber bushings inner sleeves are a smaller id than the poly?
Thanks again for all the great info in the replies.
I'm enjoying this restore, close the garage door and dream of the one day driving a vette. The car is in pieces so that day is a ways away, but we are still enjoying.

 

I do like the idea of doing most work myself. I thought a press is the only way to put these on? What tool did you buy and where did you get it?
Thanks,
Derrick

 

After reading all the replies I'm beginning to think some play is ok, and that the poly do have more play than the rubber. Maybe I don't have anything to worry about. Only just worry about paying the bills,
thanks, Derrick

 

I think your mechanic is trying to cover "all the bases"...which is a good idea on his part. But I made sure my Moog rubber bushings were a slip fit on well-greased shafts and could be rotated on the shafts with my fingers before pressing everything together...they've been installed for a month with no clicking/squeeking/etc.....just as smooth as can be (and I even went with the softer-riding Monroe Sensa-Trac shocks to make long trips more relaxing).

 

Technically; they're not pressed onto the shafts; they're pressed into the A-Arm holes. Once the assembly is pressed together you'll find that the shaft turns somewhat freely within the bushings. As stated previously, when the end bolts are tightened they will pull the teeth of the rubber bushing sleeve against the shaft & retaining cup locking the inner bushing in place. Poly bushings don't require pressing into the A-arm or so the story goes. The rubber bushing can be difficult to press into the A-arms without something to support the A-arm and prevent it from bending. GM had a special support tool for this - I use a custom cut piece of angle iron from Lowe's. You should read up on this process before taking it on yourself if you go rubber.

 

Rubber and poly bushings operate on completely different principles. Rubber bushings are meant to be secured firmly on both their inner and outer surfaces. This means that the rubber core flexes in torsion as the suspension deflects. This torsion also causes the rubber to stiffen and pretty much eliminate any suspension deflection under heavy load. To minor degree, the resistance to movement also increases the spring rate slightly.

All of these desirable properties are lost when converting to poly bushings.

This is without going into all the other disadvantages of poly in locations where 3D movement is required.