I have a 76 2.0 which recently had the rear bearings replaced. The mechanic, who is very reputable with 30 years experience in germany as a porsche mechanic, said that the rubber bushings have become hardened. He stated that the bushings actually loosend the nuts on the posts on which the trailing arms pivot. After replacing my rear bearings the mechanic tightened the bolts to spec. and now the bushing squeek so badly that I'm embarrased to drive the car. The mechanic has never had to remeedy this situation before and is not sure if you can refurbish these bushings or if parts are available. Has anyone out there had to deal with this issue? Are these bushing still available, can the arm be refurbished or does it need to be replaced, are there any lubricants to soften them up etc...????

You can buy new ones (which is probably a good idea)
Also, some of the members here have methods for keeping the bushings from squeaking once they are greased and installed
As for buying them, try Dave at GPR
I bought a set of bushings (all suspesion bushings) from him recently

Usually that nut that loosened is a entirely seperate thing.
In my opinion (others have differing theories) those nuts become loose due to trailing arm and chassis flex.

let me ask you, have you recently done an drivers ed events or more spirited driving than normal.

I know on my car that once I braced those mounts they quite coming loose.

often if they have been loose a while, the mounting point will "oval" so it might be worth you checking for that if they continue to come loose.

regarding the bushings.
the stock rubber bushings are not available seperately from the factory.
you may be able to buy replacement suspension arms with the bushing made permanently into them. I'm guessing 400 a side roughly, but they may be NLA too....

the bushings that are available are usually called poly bushings because they are made from various hardnesses of plastic or urethane. The problem with all replacements versus stock is that the original design of the rubber was that it NOT be a bushing that turns inside the arm, but rather is adhered to both the ID and OD and only twist without rotating.

All of the replacement styles rotate.
so your NON PORSCHE options are
1) plastic
2)metal bearings
3) bronze

the plastics are notorious for squeeking
this can be helped by installing zerk grease fittings and using special care to make the fitment perfect.

all of them have different costs, benefits, and applications.
assume that you will need an alignment after installing any of the options.

brant

Dave's "Good News/Bad News" joke on this--

The stock rubber bushings are vulcanized to the trailing arm. You cannot replace them (with new stock bushings!) without buying a new trailing arm.

There are aftermarket bushings.

They squeak.

There are some things that can be done to keep them from squeaking.

They only work for a while.

You can re-do them periodically.

It's a pain in the butt...

...OK, you can have grease channels cut into the aftermarket bushings and a Zerk fitting put on them, so you can re-grease them periodically. That's less of a PITA than disassembly and reassembly every year or two. They still need to be fitted carefully.

You could, on the other hand, go to a roller-bearing setup. More $$ to buy, more work to install, but they don't make noise and they let your suspension move the way it's supposed to. They may transmit a bit more NVH (Noise, Vibration, Harshness) into the cabin than the soft rubber bushings do.

There are options, but they all have bad points as well as good ones.

--DD

All those parts are available and there are upgrades such as roller bearings,

polybronze and others. Alot of these are posted here, try a search. Oh and

We just put Poly-Bronze bushings in Linda's car and it is quiet. Worth every cent.
:PERMAGRIN: Joe

First, your mechanic must have removed the rubber bushings and replaced them with poly ones.

We have had reasonable luck with squeek free poly bushings. PP sells a lube that you generously apply to the inside of the bushing and to the shaft before pressing the pieces together (not to the outer diameter of the bushing. As stated above the poly bushing becomes a bearing, whereas the rubber was a flexable insert that absorbed the rotation of the arm by twisting internally.

So, now the bushing is rotating around the shaft as the arm moves. (The shaft has splines, or when new had them so that when it was tightened up properly the shaft could not rotate. If the nuts are coming loose, I suspect that the shaft is turning with the trailing arm, something you do not want. To prevent this, make sure that the shaft surface stands proud a little (1/32) past the side of the bushing. This will allow the splines on the shaft end to bite into the mounting ears, and keep it stationery. Now wit all that said the system should work.

But, I have seen a lot of them installed wrong, and if the bushing stands proud of the shaft ends, you cannot "lock the shaft" to the mounting ears and it will rotate. You do not want the rotating surface to be between the outer diameter of the bushing and the trailing arm metal. The rotation must occur between the surface of the shaft and the inner bore of the bushing, and you can grease the hell out of that point. During assembly the shaft should press easily (with a bearing press) into the bushing, if not you will want to ream out the inner bore of the bushing until it does.

Sorry for all of the words, but we have been down this road and it is easy to understand once the "light bulb" lights and you understand what you are trying to do.....

Call Chuck at Elephant Racing and get the Polybronze bushings. They work great, won't squeek and are easy to install.Click to view attachmentClick to view attachment

The dogbone shape of the pivot shafts in the Elephant Bushing kit bothers me. My preference would be full or nearly full diameter in the center for rigidity.

Hmm, maybe I should make new ones more like factory, but with heavier wall thickness, and a higher strengh alloy.

Are the factory pivot shafts tubes?

I thought they were solid. They are very light though.

On the Elephant ones (shown above), what keeps the shaft from rotating? The factory pivot shafts at least had serrations on the ends to help keep it from rotating and the nuts from loosening.

Chris, most of the load put on the shafts is very close to the threaded area where the bushings are and shaft full size. I don't think the step down in the middle will be a big factor but I can only speculate. It would seem that Elephant would save a machine step by leaving them the same dimension all the way across. The saved weight is only ounces.

John, no serrations. However, the rotating pressure on the shaft is significantly reduced since they are not vulcanized. When I installed the front bushings, I could move my A-Arms with one finger. When I installed the polybronze on my 911, the suspension was so compliant, I couldn't believe the difference. Personally, I think the Polybronze is a great compromise but $$$$$

They are not solid. I X-Ray'd them. As I suspected, they are a tube that is welded to machined segments at each end. The welds then appear to be machined, and the whole assembly is very likely heat treated to some nominal value, and then probably oxide coated.

I have no basis for just how Porsche bonded the rubber to the shaft and trailing arm. Perhaps a "B" staged semi vulcanized bushing is molded, a metal primer applied to the steel parts, everything assembled, then final cured in an oven. Anyone know for sure?

Andys

I agree. I think many don't take the extra step to ensure the bushings are not axially over-compressed. If they are, they will very likely squeak almost regardless of lubrication. Radial over-compression will also produce squeaking. Though silicone grease is very good, the tech guys at Energy Sysetems mentioned that boat trailer wheel bearing grease may be even better. Its heavy body resists displacement; at least that's what they said.

Andys

Wow, I'm truly impressed with the amount and quality of response to my issue. Some really great info. and ideas and all with a positive helpful attitude. I truely appreciate the input. I stumbled onto this site through a Google search and did not know what to expect. Because there are so few of these cars in my region and a very small Porsche club it's hard to connect with people with similar appreciation for the 914s. This is my third car and loved every one of them. Thanks to all for your help. Cheers from the Inland Northwest! Any members from the Spokane area let me know your around.

This thread convinced me to go poly bronze. Is the Zerk fitting for the rear really necessary? Thanks.

Do you want to remove the trailing arm to re-lube the bushings?

on my ex-race car with Poly bushings, I used to have to pull of the front and rear suspension every year or everyother year...

this went on for about 10 years before I got smart and installed the zerks.

zerks are good!

mueller bearings are better!

I have had mine in about 2 weeks now, and I agree, they are night and day difference. even with KONI yellows and 150 pound springs it rides better than the stock equipment.

Martin

Ah, zerks = gud. Thanks.

Martin,

Are you comparing the Poly-Bronze with the stock rupper bushings or with poly/delrin/plastic bushings? If you can describe it, in what way do you think they are better?

Sorry for the
but could somebody post some pictures and perhaps some specs for zerk fitting a set of bushings?
Thanks,
Charles

My comparison is original vs. the Elephant (poly-bronze lubed with synthetic grease).

It made the car feel more modern, totally different feel over bumps, grooves, etc. The turn in now is awesome as well, no waiting for the rest of the car to catch up after you move the wheel, very smooth transition. Looking forward to the first Auto Cross with this suspension set up.

Ah not so grasshopper!
There are many teeners in the NW. Now if your just refering to Spokane, you may be right but on the other side of the mountains they seem to be as plentiful as rabbits