Suspension bushing, the right way

[Chuck Moreland]

If you don't have time to do it right, be sure to make time to do it again.

Several months ago I put new bushings in my front control arms. I opted for the "street hardness" poly bushings.

Here is the link to that thread:
http://www.pelicanparts.com/cgi-bin/vb/showthread.php?s=&threadid=9861&highlight=bushings

They where tight, very tight. But I thought they would wear in with some miles and loosen up. How wrong I was.

So I pulled the front end off again to do it right.

The bushings are actually a bit oversize. They need to be machined down for a custom fit.

Material can be removed from the inside or outside radius, depending on where they are tight. In my case the outside radius was tight.

This was a great opportunity to break out my new lathe.

I turned a piece of wood so that it fit snuggly inside the bushing. I used the wood as a shaft to turn the bushing.

Here are a couple of pictures:





Be careful not to remove too much material. Take a little off, test fit, take more off if you need to. The goal is snug fit that moves freely. You are striving for a friction free connection with no slop!

The street hardness bushings are somewhat elastic. Much harder than stock rubber, but some stretch. Because of this you can take material off the outside to loosen both the outside and the inside fit.

Edit - bad advice, see the "Edit and update 2003" at the end of this post.


With the full race plastic bushings this is not the case. To loosen the inside diameter you need to remove material from the inside.

To remove material from the inside turn a similar piece of wood on the lath. Then affix very fine sandpaper to the wood. Slide the bushing over the wood/sandpaper and turn. Sorry, no pictures.

Next I put in zirk fittings. Great chance to break out my new drill press.

I used 6 mm straight zirks.



Note that I drilled right through the bushing.

Pull the bushing out and get rid of all the drill residue that accumulates between the metal and bushing.

Then tap the hole.


Use a saw blade to create a channel for the grease to be distributed over the bushing surface.



Here is the finished front bushing with the bracket. Notice the groove lines up the the zirk fitting. The zirk protrudes into the bushing and helps to keep in from rotating. Only the inside diameter is greased and that is where the movement occurs.

Notice that I put the zirk over to the side. This way it is not the lowest point on the bracket and is less prone to damage from scraping. I would recommend putting it further to the side then I have shown in the picture.



Here is the finished rear bracket.



Sand any paint off the metal surface of the control arm. It slides better with bare metal. You would be surprised at how much it loosens the fit just by removing the paint.



Here is the finished front. Note the zirk could have been further to the side for better protection.



Here is the finished rear



The results are outstanding!

Absolutely no squeaks and the suspension moves freely. And if it ever does squeak, I'll just give it a squirt of grease.






EDIT and Update 2003 ********************************

Since a lot of people use this thread as a reference, I thought I'd add what I've learned over the past couple years.

The technique shown above for resizing the bushing by turning the OD is wrong. That approach can get the bushing to be sized to fit, as I demostrated. However it will never get the ID of the bushing truly round.

The bushings mouints are not precision machined parts, they are rough sheet metal stampings. They are not perfectly round, and that is especially true of the fronts that are formed by welding two halves. They may also have minor surface irregularities.

Polyurethane bushings are not rigid. When pressed into the outer mounts, they will distort. This distortion is transfered to the ID, which is the friction surface the control arm must ride on. Thus the friction surface becomes out of round and irregular. Not good.

The proper way to custom fit polyurethane bushings is to first press them into the outer mounts. This way they deform to assume the shape of mounts before custom cutting. Now, with the bushings still in the mounts, turn the ID on a metal lathe. The goal is to true up the ID and open it up to be about .005 larger than your specific control arms. Careful not to remove too much or you will have a sloppy fit.

[turbo dave]

Wow, Chuck/Clark/Chuck (oh boy, I'm beginning to sound like my mother...) great post! I'm in the middle of this, will do it just as you suggest. Thanks for all the technical articles, glad to have you back-

[89Cabman]

Chuck is the MAN! Great info. & pics!

[Jim Smolka]

Be sure to send that info to Wayne so he can add the it to the tech article section of Pelican's site!

Good job!

[911nut]

Chuck, how do you rate the "street" bushings your using vs the factory bushings? I've seen a PCA tech article which uses '68 factory rubber bushings in the rehab. This will be a fall project for me and I'm still undecided on which bushing to use.

[APKhaos]

My wrench dissassembled the suspension on a track car two weeks ago - I was doing some rebuild work on my engine in his shop. The poly bushings had not been installed by Clark.........

The bushings had been press-fitted without reducing their outside diameter as Chuck describes - the rear brackets had actually cracked along their length as a result. Nasty!

[makaio]

Bravo Chuck! I'll be sure to add the zerk fittings when I do mine.

[chrisp]

Also keep in mind that with the way the Weltmeister bushings are molded they have a "draft" meaning that the walls of the mold are narrower at one side versus the other. This is done so the part can be pulled from the part. Becuase of this I noticed that the bushing surface for the front control arm is not parallel to the bushings (remember the bushing inner diameter has a taper to it). So I machined my own bushings from Delrin. Sure having a machine shop quality lathe is not common place but machined bushings are the right way to go. If you have this option please utilize it. my susp is much more supple now. In fact I went from stock t-bars up to 22F/28R and 22 F/22R sway bars and my susp ride smoother with less bump chatter than before. I would have expected a harsher ride. Those tight bushings we really screwing things up.

My Weltmeister were very, very tight. I needed a vice to disassemble. Previous owner installed them.

[Jdub]

First-class: thanks very much for this contribution!

Nut: On the rubber (not poly) bushing idea: I have not gotten to my rebuild of the F/R suspension, but do have a set of four "OEM" rubber bushes for the front end. They are not actually factory bushings, which I understand are not available anyway. They are rubber bushings available from a popular speed shop for Pcars.

My understanding is that rubber bushings may be a big mistake. If I remember correctly, the factory basically adhered (vulcanized, though I think I use the term incorrectly here...) the inner and outer sides of the factory rubber bushings to their respective metal and used the give inherent in the rubber itself to govern the A-arm movement. You might remember how Automaticon/Performance said they'd come out with Neatrix front A-arm bushings, but found that this was not solid enough. You can imagine that, if Neatrix bushings won't do the job, then rubber bushings will be somewhere down in stiffness from these. So I am ruminating on how to proceed. If I go with these rubber bushes, then I risk a "rubbery" front end. But God hates a coward...

Again, thanks for the excellent pics and writeup Chuck!

John

[GIBSON]

Chuck, nice job. I think I'm going to quit my job so I can buy a new lathe and drill press! Must be nice. My shop is just too small for a lathe but they sure are nice. I've done that bushing reduction by hand and it's a pain, not to mention not as accurate.Thanks for taking the time to snap all the photos, nothing like a good picture to help describe a job. Good work.

[Porsche_monkey]

I would suggest a radial rather than a longitudinal grease groove. You will not get grease on the side opposite your grease fitting. Perhaps an X pattern.

As an alternative to machining the bushing I pressed a plug (2" diamter I think) into the arm and stretched it slightly. Same result, maybe less work.

[Chuck Moreland]

The grease finds its way around as the bushing rotates. An X or spiral is fine idea but would certainly be more difficult to make a clean cut.

It occurs to me that a lot of people lack the equipment or inclination to do this right. And I now know from experience that this is a case of do it right or don't do it at all.

So I'm looking for a virtual show of hands:

If my company, www.elephantracing.com, offered a bushing service for control arms and spring plates would you buy it?

I can see having a couple of options -

1 - Elephant Racing ships you bushings that have been machined, you install
2 - You send in your control arms / spring plates and Elephant Racing does the whole job; dissassemble, machine, install bushings and zirks.
3 - Third option with stripping and powder coating/plating

Price TBD.

Would this be of interest?

[skinnerd]

Chuck:
Incredible pictures... very easy to follow and see what's up. I like others, do not have some of these nifty tools (but would like to), so would need some help from time to time with this type of project. The shop that did my work a while back, took it upon themself to do this very upgrade. I could use help in the future, if this type of project comes up on another car. -Doug

[304065]

The PO said I have steel roller bearings in the front, instead of bushings. Does this make sense?

[turbo dave]

Okay, here are the tweeks to Chuck's process that I did (finished a couple hours ago).

When sanding down to size, I allowed the bushings to still be a press fit into the brackets. I don't want any movement between the two, so I allowed the fit to be very tight- but still sanded the exterior down so it wasn't too tight. The brackets aren't completely round (even after sanding the interior surfaces), so after pressing the bushings in, the interior of the bushings were no longer round, plus they were too tight. I sanded the interiors with 100 grit, leaving the dust, and test fit by hand. The high spots get polished back to black, so off again and sanding just the high spots. About a half dozen fittings per bushing, and I got a great fit- easy to put on and rotate by hand, very little friction, but absolutely no play.

I left the 100 grit finish, thinking some texture will give someplace for the grease to go (if it was smooth, I can imagine it starting to squeek within a dozen miles). Added zirk fittings per your excellent instructions, and back on they went. It'll be a month or so before I get the rest of the car buttoned up to get an alignment, but it felt good going in.

One question for everyone: when I ordered the bushings from Pelican, I ordered the street hardness. But, they are hard as solid plastic. Did I get the race hardness bushings by mistake? They are black, marked 'Weltmeister 012'.

[turbo dave]

Oh yeah, I also cut radial grooves with a dremel, along with the lengthwise sawblade cut like Chuck's. Very easy to do-

[GIBSON]

Chuck, I think option 2 or 3 would be your best bet, the small
differences in these front suspensions might make it hard to produce a bushing that would be an ideal fit in every suspension.
Just offer the fitting service or both fitting and powder-coating and I think you'd have something...

[Silver Surfer]

Boy, Chuck, I'd sign up for that service! I'd go for option 3.

[alfizzo]

Hi chuck,

Can you use a zirk fitting on the rear bananna arm bushing?

[Lucky]

I'm interested in option 2 of you proposed service, Chuck! I'm not too concerned with how my car looks from the bottom, so I'd skip the powder coating unless it was a reasonably priced option.

Cool idea to offer the service. Now you've got me thinking about quiting my day job and applying to be your East Coast rep!!