drew, didn't see your last reply...

I'm going with delrin, which looks like it will solve the problem. I'm also going with original 944 control arms, I'm buying used, I will strengthen them. (as long as they're rust free, I should be OK). It seems that when VW shifted manufacturing to Brazil, from Germany, the control arms were not built to the same standards as the old one. Tolerences are lower, and welds aren't the same quality. And as suspected, the bushing contact area is smaller with the newer brazil made control arms.

Anyway, what's the deal with UHMWP?
At Tstar.com, how do I know which one to go with?

PS: The weltmeisters that I messed up are discontinued, I wonder why!!! Maybe I should try a refund, I paid lots more than $100, as I used more than 3 full sets of this stuff, not to mention the alignments!

Thanks for the help so far, I need your opinions the most now though, as I need to come to a conclusion soon, as the new subframe is going in friday night! (I'm getting custom Delrin, but wanna go with the ultimate bushing there is).
Ahmet

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It's all the driver...

Ahmet,

UHMWP is ultra high molecular weight polyethelyne. It is used in wear & impact parts in textiles, agriculture, mining, etc. Delrin & Acetron are trade names for an acetate polymer. With Delrin close machining tolerances are easier to hold, since it's modulus of elasticity is higher. The drawbacks as compared to uhmwp are moisture absorsion (don't think it's enough to hurt), impact resistance (uhmwp is what you would call unbreakable from about 20 to 200 degrees F), it's not as wear resistant, wears mating parts more. The higher modulus of elasticity or less give may mean holding your alignment better.

At tstar.com, I found it during a yahoo search to compare properties. Check out the mechanical properties for bearing plastics.

I'm not a polymer chemist scientist, but what I say is based on my experience and published properties.

Got to go, in the middle of helping wife do research for grad school paper.

drew1

Drew, thanks for staying with me on this one.

I'm specifically wondering, how do I go from no bushing to bushing in my 944 control arms, in less than 8-9 days max. I'm not going through all this work, to have my new subframe messed up too. Subframe should be in, along with new con-rod bearings, and oil pan gasket by saturday morning (that's when I return the engine hoist). Control arm bushings can wait, but not much longer, as I would still need to get an alignment. Lets say my deadline is April 9th or 10th, 11th at the very latest.

I like the tstar, but don't know how to go along picking up the right dimention? and right material? in the right shape???

Lacking the practical thinking here...
Ahmet

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It's all the driver...

Hey Ahmet, send me the dimensions of the bushing you need and Ill turn them out for you. Have had these thoughts myself, about taking the squish out of the bushings. Grab some dial calipers and just measure the a-arm for what you need. I've got just what you need to use (nylatron). Used it on a guys dirt track car, works great!

that's an interesting idea, i don't know why the thought of making my own bushings never crossed my mind. Mine need replacement soon, and i certainly have the equipment, and know-how. After all, i used to work for a bearing company that made plain sleeve bushings.

It looks like i've got a new project on my hands! I guess i'll have to order some UHMW

If you think we have a good shot at doing these bushings, I'll be glad to take measurements and send them to you.

I'll keep in touch, and as I'm sure you know by now, my e-mail is "over1g@hotmail.com".

As long as you've got the right tools, and material I don't see why one wouldn't make his own tools...
Ahmet

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It's all the driver...

Ahmet,

If the rules say "... no more metal than stock", I suggest a steel sleeve inside the same diameter as the stock bushing's sleeve.
One of the rubber flanges can be forced through on the stock bushing but you'll need a two peice plastic bushing because the flange won't go.

I would make the back bushings too. The rubber in the flange giving on them puts more stress on the flanges of the front during braking.

If I had known a week or two ago, I could have got some material a week or two ago & took it to work and fixed you some. Now it's really a short notice unless KC can't fix you up.

drew1

They'd be illegal in stock classes, per the rules. They WOULD however be permitted in street prepared classes, whereas straight out bearings would go in the modified class. I may set up the car for street prepared, which is still this side of having to tow the car to the track for EVERY race (but only barely, if you take racing seriously).

Anyway, I still don't know how to go along with this???

Let's say I'm using UHMW, and got the dimentions, how would I order this part? And machine (trim?) it to shape? There's no problem with a two piece bushing, most aftermarkets are like this anyway.

PS: Haven't heard from KC!

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It's all the driver...

Ahmet,

I would use round stock material & cut to size on a lathe. If using 'as extruded' plastic, getting one size bigger than the flange diameter is best because of material out of roundness.

For your flange diameter, go as big as you can can without rubbing the frame. The OD of the bushing should be a press fit in the control arm. I'm remembering about 1 1/4" on the bushing part. With UHMWP, this should be .001" + .005" or .006". Since UHMWP is a real ductile material, for the ID "running fit" use .002" + .006" (squeeze of press).

I'll tell the steps I would use if you're doing it yourself.
1. Put stock in chuck of lathe, leaving enough sticking out the part & cutting off.
2. Face the stock or cut the end flat & true.
3. Center drill the stock.
4. Drill the stock (under ID size).
5. Bore to ID.
6. turn bushing OD.
7. I wound cut a small pilot (same diameter as arm hole ID) about 1/4" back to help in starting bushing installation.
8. Turn flange OD.
9. Cut off with parting tool.

For deburring, a leather working tool works good.

The Carolinas are a big textile machine area, so you may be able to find a local machine shop with material and equipment to fab these if you can give them a sketch of what you need.

drew1

edit: to order stock, order by OD then get enough to make bushings & chuck up on in making then. 1 ft may be enough but if 5 ft is standard lgt, you may come out about same by not having to pay a sawing charge.

[This message has been edited by drew1 (edited 04-04-2001).]