The Stovebolt Site Forums The Shop Area Driveline AD axle pivot rebuild

So I'm trying to rebuild my rear axle pivots. When I disassembled one, I discovered some rust at the end of the sleeves where the rubber washers are. I figure for the cost of a rebuild by Steele at ~$125 per side, and another $50 for the rubber washers, I can do a better job by casting urethane to form the rubber and the washers in one piece. I just finished building a form for the washers out of a 1-1/2 inch PVC coupling. The Inside diameter is just about the exact diameter of the washers (1.9 inches vs 1.875 inches for the washers). I sliced the coupling into a short section so the body is held the proper distance from the end of the sleeve (3/16"), and another for the other end. I'm using RTV to hold the rings in place and will use some silicone grease on the ID of the rings for release agent. The urethane cast around the ends of the sleeve should eliminate the potential for rust on the end of the sleeve. The urethane is the same stuff I used to rebuild the transmission rear mount. The center bolt hole was hogged out on the body, so I welded that up. Here's some pics. I'll follow up when I get further along.

Looking good! That setup is similar to the aluminum molds used for pouring new Babbit bearings, where the "release agent" is soot from an acetyline torch flame without the oxygen added.
Jerry

During my career in the Nuclear field, I rebuilt many cast iron pump casings and heat exchangers with a type of epoxy metal called Belzona. Very expensive, as it was approved for use in some “Safety Related” equipment, and it worked really well. Belzona had a special release agent ($$$), that I used on the dams to help form the degraded sections. It looked and smelled just like Johnson’s Butcher wax. After running out of that special release agent, I used some Butchers Wax and found it worked exactly the same.

When I'm using Brownell's "Acra-Glass" epoxy bedding compound to fit a rifle action to a gunstock, I use a generic brand of spray cooking oil like PAM as a release agent. Several coats of Johnson's paste wax also works well
Jerry

Can't use a spray release product as it would get places where I want the urethane to stick. I used silicone grease on the mold for the transmission mount I fixed. Just about anything would work as a release agent, even motor oil for this project. The urethane may not even stick to the plastic rings, but I don't want to take that chance, because I need to reuse them for the other side. I know it will peel right off the plastic mixing cups I've used for the urethane. I'll probably use a plastic sheet on the bottom.

Mixed up some urethane and poured it in the assembly today. I put some black tint in it and may have used too much, because it's taking much longer than normal to set up. Still sticky. I may have to start over. Had a little leakage around the bottom ring, but shouldn't be a problem. I'll give it overnight to set up and see how it goes.

Update: That batch was messed up. I guess full 10ml vial of tint vs 8 drops made the difference. The first batch never did set up, but it was BLACK. I was able to push the sleeve out with my thumbs, which was definitely not something I was going to use under my rear axle.

Poured a second attempt today and it set up within an hour as expected. I guess I'm getting better with practice. Should be able to strip the rings off in a bit and will post a pic of the finished product.

Here's the pics of the second attempt. Came out looking good, I think. The material hardened up as expected and the integral washers should keep the housing centered nicely.

Looking good Kevin! How the you keep the center sleeve centered in the housing?

That looks factory fresh, just shows what a little outside thinking can do. Nice job.

Thanks, guys.

Phil, I just stood the center sleeve up on the bench and eyeballed it in the center. I put some tape on the lower end to keep the urethane from leaking underneath and filling it up, although I could have drilled that out afterward. It was heavy enough that the urethane didn't "float" it as I poured it in around the outside.

Update: Well, it looks like I'll need to pop for the $50 rubber washers, at a minimum. I bolted the rear axle to the springs today and because there was some tension on the springs toward the outside of the axle, the washers I cast on that side squooshed out. Dang. Either that or remove them and recast with stiffer material. What I used was I believe ~40 durometer, and they have similar stuff that's supposed to be about 80 durometer. They say the harder stuff is like a hockey puck, what I used is more gummy bear like. For now, the chassis is rolling, but not road ready yet. So I'll deal with these a bit down the line.

So I got the harder urethane and tried that. Problem was, there was a issue with that batch and it set up to pudding like consistency before I could pour it into the cavity. I contacted the company I bought it from and they sent a replacement batch. It worked much better, and I now have both axle pivots rebuilt.
Here's a couple of pics of the first attempt (that sleeve is supposed to be centered), the pudding attempt, and the final successful attempt.

Kevin, the bushings look great. Have you cast the washers?

You are a pioneer! With so much work involved in changing them, I would have just spent the $50 and be done with it. It’s fortunate we have ‘bolters like you that are willing to pave the way for new ideas.

Please keep us posted on the final results!

Rather than trying to cast those bushings, I think I'd machine them out of a piece of Teflon round stock, two pieces that include the "washer" section, pressed into the housing from each side. Then press the steel sleeve into the middle.
Jerry

Jerry,

The original bushings were rubber, with some "give" to them to soak up some road vibration and allow a bit of movement as the springs flex. I doubt that Teflon would be resilient enough to allow those functions. That and I don't have a lathe available (yet). I tried to find some bushings with integral washers at Energy Suspension, but they didn't have the correct size.

Once I got the material selection right, casting the bushings with integral washers wasn't that hard. I believe this time, they'll work just fine. If not, I can go for the revulcanization from Steele and the $50 rubber washers. But being a cheapskate, I had to try this approach.

You don't need a lathe - you just need a friend with a lathe. I wanted to replace the front spring bushings with something that doesn't need grease. I bought some Delrin rod and asked a friend who owns a lathe if I could make some bushings. He was interested, so it ended up me watching him make the bushings. The fee was a bottle of Bacardi.

I've got some friends who love to watch me turn out a custom-contoured rifle battel from an unturned blank with the rifling already cut into the bore. That involves a series of straight cuts joined by short tapered sections, and then filed into a smooth contour while the blank is spinning slowly in the lathe. It's a pretty good combination of machining and artistry to produce a pleasing shape.
Jerry