Fabricating bushings

As anyone on here fabricated there own bushings? I have done it before for a project I was a member of but that was on a human powered vehicle and the bushings were oil-impregnated bronze. I was thinking of using Delrin for the Spitfire project. I just want a sanity check before I begin fabrication. I have access to a full shop.

I do it all the time. If you have a lathe it is laughably simple

Those were rabbit front control arm bushings I made offset to add caster.

If you search over on corner-carvers.com there is a lot of debate regarding materials and how UHMW is preferrable to delrin. I found UHMW deforms too easily and I hate machining it.

With access to a lathe, it would be bit dumb to not fabricate your own bushings. You can pick the material and control the quality.

What about using oil-impregnated bronze? I mean it is going on a track rat and the bronze will not deform. I am not using urethane.

You generally want bushings to deform. It is possible for a suspension design to lock itself up if there isn't some compliance in the bushing. That's why the OEM's use rubber.

Dr. Hess wrote: You generally want bushings to deform. It is possible for a suspension design to lock itself up if there isn't some compliance in the bushing. That's why the OEM's use rubber.

It seems like that would depend on the location of bushings.

the oems use rubber to allow their compromised multi link geomtery to work without binding up and to cut down on vibration..

also, cost..

i've got a few large chunks of Delrin that i saved from the dumpster at work. they were what was left over after machining some parts out for some machine we were building, and i didn't want to just throw away about 100 square inches of 1" thick Delrin.. don't know what i'll use it for, but it's cool to have..

93EXCivic wrote: What about using oil-impregnated bronze?

If you are going that far I would just use spherical bearings.

Mmmmm..... sphericals. I has.

92CelicaHalfTrac wrote: Mmmmm..... sphericals. I has.

Are those spot welded? It makes sense except the part where the plastic cages in the bearing might melt/deform or the grease might run out and cause early failure.

Yeah they're spot welded, but there's no plastic in these things.

Where they're going, there's very little movement and i probably didn't even need the pliability that these offer. That picture is from the seller in my case, i'm only using two, one for each of the rear mounting points of the front LCAs. The rest of my arms are all rod-ended.

I made Delrin bushings for my Challenge car (the Abomination, my rotary Spitfire). The stuff is super easy to machine, but the stuff I used did not last. That is, all was tight when I put it together (I made them a tap fit in the arms) but after maybe a year's use I noticed some twitchiness in the rear when accel/decel. I discovered that the bushings had deformed to the point where the outside end of the C/A's could be wiggled 3/4". Not good. I sourced poly bushings from, IIRC, Victoria British to replace them, they are 3 1/2 years old and are holding up well.

How about Nylon as a material? Is round stock available?

Delrin is stronger than Nylon I think. Check Mcmaster for material and costs. I can't stand oil impregnanted bronze, it's really quite weak and will wear out rather quickly in other applications.

In reply to Giant Purple Snorklewacker:

McMaster-Carr has various types of all kinds of plastics including Nylon, UHMW, VHMW, Phenolics, etc. in round stock form.

There are varying durometers for Polyurathane, I assume poly bushings are molded? I know I've "whittled" on poly bushings in the past, but never actually tried machining it. I don't know where you'd get hard poly stock either.

• Lee

If you think the polyurethane material is the direction you wan to go, you can get casting urethane thru mcmaster and pour you own. The two-part mix is the consistency of water to start and comes in several durometers. There is also silicone casting material.

I have used the casting urethane for production car engine mounts (heat resistant) and noticably reduced the amount of engine movement. Check the specs depending on where the bushing need to go for heat and chemical resistance. Metal inner sleeves and reduced bushing thickness will increase stiffness, but limit rotation.

I have used sintered bronze for lower control arm bushings on the Spit/GT6 racecar (Front and rear)

No problems, with the qualifier that the car has never been driven on the street.

I made all these parts on the machines at work.

Rog

Sorry, wood lathe or metal lathe? Or does it matter? I've never used a wood lathe.

There was a great thread a few years back in which someone fabbed bushings for a challenge car using the material used for bathroom stall divider walls.

I have made bushings from oilite, but they were a custom pilot bushing and then a custom shifter bushing. Both have lasted very well but neither is under ginormous stresses. I'm of the opinion that by the time you go to the trouble of fabricating oilite bushings for suspension it's time to step up to rod ends (if your class allows it). They allow float in more than one direction so the mounting bolts etc do not have to be in perfect alignment.

I used a metal lathe for the parts I made.

I was looking at using Rod ends for the lower control arms, then happened to be at a regional SCCA race. The Lola formula ford cars used solid bearings for the (front) lower control arms and Rod ends for the uppers.

Not sure that this is the best rationale, but I have had zero problems using this concept.

Rog

Lots of circle track guys run solid steel, greasable LCA bushings in 2nd-gen F-body cars with no trouble.

I have them in my T/A and I've had no issues.

Heavy equipment uses steel-on-steel bushings with grease and they see far more stress than a lower control arm bushing.

Shawn

I have a lathe and have made many bushings! I have also made parts to install sperical bearings when the application allowed it.