Powerflex vs Nylatron NSM.

[RollingCamel]

We are planning to use bushes for control arms mounts. I have read a thread before discussing bushes, but I'd like to know what do you think about polyurethane bushes.

My thoughts is that due to time constraints is that we could go with ready made polyurethane bushes from Powerflex. Its disadvantage that it should have more compliance than Nylon bushes.

[RollingCamel]

We are planning to use bushes for control arms mounts. I have read a thread before discussing bushes, but I'd like to know what do you think about polyurethane bushes.

My thoughts is that due to time constraints is that we could go with ready made polyurethane bushes from Powerflex. Its disadvantage that it should have more compliance than Nylon bushes.

[Zac]

I would advise against using bushings of any type in your suspension.

Compliance can be a powerful tool for suspension tuning when packaging constraints limit what you can do with your kinematics, but I think you'll have an easier time of it if you use sphericals.

[exFSAE]

He's not using bushings. He's using bushes. Personally my recommendation is to use a shrubbery.

Bring me...

[Adambomb]

Hmm, all I see on their site are full size car applications. Those would be gi-normous and heavy. I'm picturing like 25-30 lbs for the whole shebang by the time you make retainers. Compliance probably wouldn't be an issue since they would be so horribly oversized.

Our Baja team uses Igus bushings, we also use them for various bits like steering column and shifter axles, gas pedal, etc. Barring that it's really not hard to machine some nylon down to make your own. Get a bar of Delrin and they could be cranked out in a couple hours, and would probably outlive many of the components on the car.

[RollingCamel]

They have a "Universal Range" of other sizes. There is one size of 21mm OD and with top hat of 31.5mm OD.

[Kirk Feldkamp]

If for some reason you feel compelled to use bushings instead of spherical bearings, use delrin instead of polyurethane. At my last job I was asked to make a kit to replace the poly bushings on a Radical with delrin bushings. The drivers that used them were head over heels in favor of the delrin over the poly. The only reason we didn't do sphericals in that case was it would require every A-arm and suspension mount to be redone, which was certainly not a viable commercial solution. While the delrin was better from a deflection and friction standpoint, it's still tricky to get the preload on the joint just right because of the manufacturing tolerances involved. An overzealous mechanic can really throw the setup of the car off if he cranks down the bolts too much!

-Kirk

[RollingCamel]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kirk Feldkamp:
If for some reason you feel compelled to use bushings instead of spherical bearings, use delrin instead of polyurethane. At my last job I was asked to make a kit to replace the poly bushings on a Radical with delrin bushings. The drivers that used them were head over heels in favor of the delrin over the poly. The only reason we didn't do sphericals in that case was it would require every A-arm and suspension mount to be redone, which was certainly not a viable commercial solution. While the delrin was better from a deflection and friction standpoint, it's still tricky to get the preload on the joint just right because of the manufacturing tolerances involved. An overzealous mechanic can really throw the setup of the car off if he cranks down the bolts too much!

-Kirk </div></BLOCKQUOTE>

Ehem.....I didn't leave enough clearance for the mounts for spherical ball joints' housing to move... I'm also considering rod ends for mountings. I was going to manufacture the outer wishbone housings from mild steel and i think that I'll do simple adapters too.

[Adambomb]

Rod ends on the inboard joints aren't a bad idea, IMO. Still loaded axially so strength isn't a problem, probably the easiest to manufacture (just crank out some threaded inserts to stick axially in the a-arm tube). Then for the outboards a super quick and dirty solution would be ball joints for an ATV (our baja team has been doing that for years)

As far as making a bushing setup "mechanic-proof," take note that most OEM bushings have a steel insert on the inside to limit axial deflection of the bushing when tightening the bolt. Another solution (more expensive) would be to use shoulder bolts.

[fixitmattman]

UHMW Polyethelyne is cheap, plentify, and easily machined. Nylon6 is also pretty good. Delrin is a decent choice, but I find it a bit on the hard side, seen more delrin bushings shatter than anything else.

[Adambomb]

I currently have UHMW motor mounts in my daily driver. Works pretty well, cheap, and very easy to machine.