Question for those of you running poly bushings on your cars... (JWG, Mance, and others)
 

what kinda grease do you use on your poly bushings on your car?

I picked up a set of delrin control arm bushings for my 4000 and they have channels in them for grease... but I am not sure what kind of grease to use on them to prevent squeaking. They have a zerk fitting that you put in the CAs so you can grease them, but I had a friend warn me that certain grease will eat the Delrin... this true?

thanks guys!

A little workshop then the answer you seek....
 

<center><img src="http://pictureposter.audiworld.com/711/solidbushing5.jpg"></center><p>
Delrin is not a typical "poly" material as the name relates to suspension components. Acetal is the common name for a family of thermoplastics with the chemical name "PolyOxy-Methylene". Acetal is available in a general purpose copolymer grade, a homopolymer version (Delrin). Acetal provides high strength and stiffness, enhanced dimensional stability, and is easy to machine. As a semi-crystalline material, acetal is characterized by a low coefficient of friction and good wear properties.

However the most desireable and latest high-tech acetal product to come down the pike is Acetron. Acetron KILLS delrin on suspension parts for many reasons.

AcetronGP/NS is a patented Acetal-based compound containing special solid lubricants which help provide superior performance in bearing and wear applications. These lubricants are uniformly dispersed in the base Acetal, providing a premium, internally-lubricated compound with high Pressure Velocity (PV) capabilities, a low coefficient of friction, and an extremely good "k" factor.

The additive system which delivers the lubrication is a patented composite. With it, the solid lubricants-firmly locked in the Acetal matrix are always exposed to the bearing surface. It's this constant source of lubrication which enables AcetronGP/NS Acetal to outperform other bearing materials like Delrin in high load/stress applications. It also provides lubrication during break-in of bearings and for greatly enhanced wear resistance.

Because the Acetal and solid lubricants do not absorb significant quantities of moisture like Delrin, AcetronGP/NS Acetal is very stable in both wet and dry environments. It is highly recommended for precision, close/ultra-close tolerance parts.

The presence of the lubricant system in the Acetal matrix also allows very free machining. The result is a very competitively priced product which will outperform other filled Acetals like Delrin in all high load bearing and wear applications, and give it a noticeable advantage over more expensive, premium priced, internally-lubricated Acetal compositions.

Above pic is AcetronGP solid bushings for B4 front lower control arms.

Best lubricant for either Delrin/Acetron is and always will be Permatex Anti-Seize lubricant. The reason I listed the above info is that "poly" bushings are urethane/polyurethane bushings which are far better suited to silicone paste lubricants. However these two lubricants should NEVER be shared between the 2 materials. They are NOWHERE close to being suitable for each other! Anti-seize for Acetyl and silicone for "poly" or urethane bushings.

Hope this helps...

Thanks for the lesson, Mance. Good read!
 

So basically I'll use my NAPA Anti-seize I haev sitting in the A4. Only problem is that I won't be able to "squirt" it into the Delrin bushing if I were to get any squeaking... unless somehow I could put it in a tube that I could use in a grease gun... hmmmm.

BTW, you don't by chance have, oh say, an 8" long chunk (they sell them as a cylinder, correct?) of that AcetronGP/NS laying around that you might wanna get rid of... do ya? :) How much does that stuff cost to buy anyway?

I saw your postings when you made those on the 90 forum... real slick man, beautiful work as always...

The Acetron bushings have been flawless and absolutely noise-free for over 4000+ miles...
 

of winter driving in the NY tri-state area. Anti-seize was generously used on the installation as instructed. The car is kept in a climate contolled(68*) garage when not driven and so far I have not noticed any expand/contract issues either from heat/cold.

Great lesson on the properties of both, thanks Mance.

The problem with delrin is its "hygroscopic" and WILL absorb water...
 

once its done that it will always squeak. Re-lubrication offers minimal/short term relief. However I've enjoyed great success with anti-seize which is a great "sealer/lubricant." If you can prevent water from getting into the delrin matrix with anti-seize then you'll likely never hear a peep/squeek out of them. I've never had a delrin squeak since using anti-seize on "new installations" but I was never able to quiet down a squeaky pair with anti-seize once the squeak started.

And bear in mind upon assembly you simply CANNOT use too much anti-seize upon installation. You can however use too little. And its icky/messy when it starts squishing out everywhere when you install them. But its the best you can do then wipe off with rags once installation is complete.

Done right you'll likely never need to re-pack the bushings tho you might consider it when doing near-by items like tie-rod ends or wheel bearings. But if they ever start squeaking it wont do any good to re-lube as at that point in time they'll ALWAYS be singers!

ah, didn't realize that...
 

good thing I have a nice new bottle of anti-seize to use :) haha.

BTW, can I buy the Acetron stuff over the counter or is that something you need to buy in bulk?

I'm tempted to see if I use that to make some subframe bushings for when I do an entire rebuild of the suspension (which will be after the motor swap)

you can buy it in sheet/rod stock in most any major metro area...
 

check the YP's under "plastic" and make a few calls. Most places will sell rod by the foot and sheet-stock by the sq ft tho they "may" have minimums. Black/white Acetron GP Rod runs $17-$20 linear foot for 2.25" diameter. Figure a percentage increase/decrease for larger/smaller diameters.

Hope this helps

that's perfect, thank you Mance!
 

And you used normal SS tube for the inserts, correct? Then you center drilled it and trued them, right? BTW, how did you do the spiral on the SS insert on yours? Is that done on a lathe?

I'm going to look into this stuff, then find a friendly machine shop and see what they can do for me :) Or I can wait till I'm home and see if my uncle can help me out with his lathe (though I'm not sure if he has the necessary metal machining bits)... we shall see. It's times like this that I miss the machine shop at school...

if you're gonna have this done on a "one-up" basis to these tolerances...
 

you're looking at thousands of dollars for the first piece. Mine are precision ground T-304 stainless tubing that started life as .750" O.D. then was ground to within 50 millionths tolerances along the full 12 foot lengths. Spiral helix was done on my CNC lathe and inside were "precision bored" (not drilled) to the proper fit on the thru-bolts. The Acetron GP bushings also had the helix done on the smaller O.D. that goes into the CA bushing to retain lubricant. In essence an "inside/outside" helix on "all" wear surfaces.

I seriously doubt you're gonna want to step up to these tolerances and especially the precision grinding and the spiral helix. Any spiral helix "must" be done on CNC equipment and those guys want a grand to roll outta bed. Of course if you're having ten made they'll go down to about a hundred bucks each... and so on and so on.

Having "one" of anything custom CNC'd is totally cost prohibitive.

ah, didn't realize that was a CNC only kinda move...
 

if I were to do these myself, I wasn't going to do that tight of a tolerance. Hell, the Delrin ones I have I don't think were done that tight of a tolerance.

hearing that though makes it even more relevant why you aren't making any more of these things ;) lol... what a PITA!

we'll see what I end up doing. This is all me thinking out loud here, but thanks for the warning. I wouldn't mind trying to get this stuff done myself on a regular machinist's lathe (obviously not as tight toleranced as yours... but good enough for gubment work). This wouldn't be something I sold either, just something I make for myself. I think we have the necessary lathes at home in our old factory, but I could be mistaken.... we shall see!

on the spiral, is there a special bit you used? I'm assuming you basically controlled the speed it was spinning and the pace of the bit so it was all done perfectly even... right?