echoechoecho New Reader
1/28/15 9:36 p.m.

The old bushing are shot on my Tercel, The car is going to be autox often, 2015 challenge and its going to be my DD. whats better polyurethane or delrin for front LCA bushing? I can custom make the bushings in either material

DeadSkunk SuperDork
1/28/15 9:40 p.m.

I'd vote poly, just because I believe it is more compliant for a DD. It should last longer than Delrin. There will be other opinions, I'm sure.

SkinnyG Dork
1/28/15 9:41 p.m.

Poly might be more forgiving of bushing axis misalignment. That's all I got. I have UHMW in the front of my Locost, and have run poly in my last three daily drivers over the past 12 years.

GameboyRMH MegaDork
1/29/15 7:44 a.m.

Yeah I've also heard delrin doesn't last nearly as long as poly, while being much harsher and noisier.

Graefin10 SuperDork
1/29/15 8:37 a.m.

I used poly bushings in an MGB and then the car sat for several years. It has not been driven since. I knew from past experience that MGBs will make a noise during normal driving if some grease isn't put on the inside of the bushing. I don't recall for sure what type of grease was used. The bushings totally disintegrated just sitting there. It must have been caused by using an incompatible grease. I've never had poly bushings do that before.

"echo . . ." didn't mean to hijack your thread but I thought I might learn something and others also. Any thoughts on the subject or advise would be appreciated.

Advan046 SuperDork
1/29/15 8:55 a.m.

In reply to echoechoecho:

The Delrin can work very well. However, they will flow over time and use. So eventually they will be oblong. Even if you use metal sleeves the Delrin will eventually move. When I had them it just was a matter of checking them regularly and having replacements handy.

High fiber or microhook content can hold the Delrin together longer but you can reach a point where the elasticity is insufficient for shock loads and thus you get cracking.

Another method is to insert mold a spherical(or standard) bearing depending on the joint, into the Poly.

GameboyRMH MegaDork
1/29/15 9:11 a.m.

Yeah the wrong grease can degreade polyurethane (I think Lithium grease will do it?)

When in doubt, use silicone, it's chemically safe with everything.

Also a good way to keep the squeaks at bay is to use teflon tape, similar to MotoIQ's famous sway bar bushing trick.

echoechoecho New Reader
1/29/15 11:22 a.m.

thanks for your help, what I have read on the internet is the that delrin out last poly and that poly is the noisier one. Since I can make the bushing myself Ill just do the poly its easier to install/remove. Gameboy thats a really a good idea about the teflon tape

Graefin10 SuperDork
1/29/15 11:30 a.m.

In reply to GameboyRMH:

Thanks! I'll have to try Teflon tape next time.

mr2peak HalfDork
1/29/15 4:53 p.m.

AKG has an awesome materials guide on their website, here

I'd definitely go poly for a DD. Delrin is harsh stuff. Your next question should be what durometer for the Polyurethane bushings.

echoechoecho New Reader
1/29/15 6:20 p.m.

In reply to mr2peak:

I have some 65A red round stock and some black stuff which I have no idea what the hardness is.

Is it worth to put in some zerk fittings also?

Kenny_McCormic PowerDork
1/29/15 6:57 p.m.

Poly, you want some give, both for comfort and to accommodate for any inherent bind in the system.

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