Polygraphite A Arm bushings

[niner11]

I've done a lot of reading about 911 front end rebuilds and frankly I thought that I would have all kinds of problems fitting these cheaper polygraphite A Arm bushings without a press or a specialized tool like Elephant uses. I used a small amount of lithium grease and they went on both sides relatively easy. I'll try to add a pictures but so far the font end rebuild has been straight forward. I burned the bushings off with very little effort.

[Flat Six]

Thanks for sharing your experience; what can you tell us about squeaks, firmness, compliance, ride, etc.?

[drl911]

I have had the polygraphite A bushings for about a year now, and yes, they definitely squeak, but I really only hear it going over slow parking lot or driveway bumps.

[MotoSook]

You can certainly make them go in without some fitting. That ultimately leaks to some squeaks on sum cars. The trick is to sand or machine off enough to allow for minmum drag on the A-arms during fitting. Then you are good to go.

I'll have to update the thread with pictures for which links don't exist anymore...

but the graphite bushings were on my Carrera for several years...no problems.

Front Suspension R&R with polygraphite bushings ala Souk!

[Flat Six]

Thanks, Souk -- some updated/re-linked pics would be much appreciated!

[Brad394]

I have the poly bushings both front and rear in my 86. they have been in for two years - no squeaks but as mentioned you do have to "fit" them. I used a three stone hone (much like a cylinder hone) only smaller. fitted with some drag - greased and assembled. Added zerk fittings - one shot of grease at the beginning of the season and wha la - bobs your uncle. Working well with lots of road miles ( daily driver most days ) and a dozen track days last summer alone.

Brad

[niner11]

Sorry, the car is still in a bunch of pieces right now but I will give some feedback when I finish it up. I've used polygraphite in several other cars without squeaks so I'm hoping for the best. I usually coat everything with a thin layer of lithium grease.

FWIW, I like the Elephant racing stuff but I was over budget with new struts, inner/outer tie rods, ball joints, and brakes. Chuck

[rolls 912]

I find the squeaking drives me nuts! Quite noticeable. I'm going to rip them out.
Just my thoughts

[chris_seven]

I must admit that I have never been a fan of PU bushes due to the relatively high friction of Polyurethane. Once the grease is squeezed out they will start to bind and wear quite quickly.

The idea of introducing 'graphite' which is supposed to release when the bush is 'rubbed' and hence lubricate seems quite good but in practice the benefit is minimal as the release of graphite is not very effective.

The creaking noises reported are clealry due to binding which will affect ride height and produce coulomb damping - neither of which are beneficial to handling and the idea of opening them up and introducing clearance doesn't seem too good.

We have recently tried some PU bushes with 'pockets' moulded in the inner surface so they will hang onto the grease for longer but after a few laps of Spa they still creak and bind and we tried using a waterproof marine grease.



Nylatron GSM has also been used and this is a cast material with a Moly Disulphide lubricant. These are great when new but as with all nylons they can increase in volume by up to 5% when immersed in moisture and will grow by 2% in high humidity -(don't use them in Houston in the summertime.)

The factory used Delrin for some time and this is quite good as it has low friction and is impervious to moisture.

Recently we have been using a more modern plastic bearing material that has 'zero' stiction, needs no lubrication and is also impervious to moisture.

We have made ground finish, interference fit sleevesthat presses onto the control arms. The sleeves have been electroless Nickel Plated to give both corrosion resistance and wear resistance.

They seem to be working well at present and if trials continue to be positive we will start to sell them at the end of the summer.

[ivangene]

Originally Posted by rolls 912

I find the squeaking drives me nuts! Quite noticeable. I'm going to rip them out.
Just my thoughts

+1 million !!

[chris_seven]

Finally taken some photos of our new plastic bushes - High Impact Bearing Grade Material which is impervious to water and has virtually zero sticiton on the Nickel Plated repair sleeve.

The sleeve is 2mm wall thickness T45 Chromoly tube which has been plated in a high Phosphorus Electroless Nickel and heat treated to a surface hardness of around 65RC (900 Hv) so it will be both wear and corrosion resistant.

The sleeve should be a slight interference on the control arm but if the arm s badly corroded may need a small amout of Loctite Retainer.

[rolls 912]

I'm having a rant here but I cannot believe suppliers tolerate the squeaking. I find it unacceptable. Some of these cars have cost ten of thousands to restore, perhaps more and yet they cruise around squeaking like a 500 bomb....

Ahh I feel better now!

[MotoSook]

Which surface do you expect to move during travel?



Really guys, the squeaks. Did you really expect the bushings to work trouble free when you just shove them in there?

Finally taken some photos of our new plastic bushes - High Impact Bearing Grade Material which is impervious to water and has virtually zero sticiton on the Nickel Plated repair sleeve.



The sleeve is 2mm wall thickness T45 Chromoly tube which has been plated in a high Phosphorus Electroless Nickel and heat treated to a surface hardness of around 65RC (900 Hv) so it will be both wear and corrosion resistant.



The sleeve should be a slight interference on the control arm but if the arm s badly corroded may need a small amout of Loctite Retainer.

[chris_seven]

They press into the outer sleeves and are quite tight so I expect the surface in contact with the sleeve to be the one that moves.

We designed the bush to be sure that the rotation would occur wher we planned and that it wasn't left to chance.


I would say that I expect properly designed and manufactured parts to fit in a relatively straightforward manner. One of the problems with PU is that the parts are often have quite poor dimensional control and do need individual 'fitting'

[safe]

I have PolyBronze on my -77, love them.
On the -69 I currently upgrading/restoring I will try to use some sort of plastic bushing, I found some of "white plastic" in the garage.
It will take some time fitting them and I will install grease zirks. Worst case, I will need to replace them with something that costs money....

[MotoSook]

I will try to use some sort of plastic bushing

If not Delrin, do not use.

The hard plastic stuff like Neatrix is terrible and should bot be used.

[MotoSook]

Originally Posted by chris_seven

They press into the outer sleeves and are quite tight so I expect the surface in contact with the sleeve to be the one that moves.

We designed the bush to be sure that the rotation would occur wher we planned and that it wasn't left to chance.


I would say that I expect properly designed and manufactured parts to fit in a relatively straightforward manner. One of the problems with PU is that the parts are often have quite poor dimensional control and do need individual 'fitting'

Providing the sleeve somewhat solves teh ID fitment issue, but you introduce potential corrosion (no matter how you plate it) issues which may cause the sleeve to fuse to the control arm. And with the variability of the carrier (in contact with the bushing OD) you can potentially have too much strain on the bushing which may lead to the squeaking that folks report when they force a bushing.

[Flat Six]

Souk: slightly OT, but could you please post a pic of the attachment you made to turn the OD of your PG bushings? Picture links in your other post aren't working; I'm imagining some kind arbor w/same OD as A-arm.

Thanks in advance!

[safe]

Originally Posted by Soukus

If not Delrin, do not use.

The hard plastic stuff like Neatrix is terrible and should bot be used.

How do you identify different kind och plastics?
What does Delrin usually look like?

[Flat Six]

Originally Posted by safe

How do you identify different kind och plastics?
What does Delrin usually look like?

Everything I ever wanted to know about high-performance plastics:

McMaster-Carr

http://www.mcmaster.com/param/html/AboutPlasticMaterials/default.htm

HTH

Dale