RC10Talk - The Net's Largest Vintage R/C Community

I have too much play in the metal cup (what is the name?) where my dogbone comes out of the diff as shown below.
I don't want to buy a new part and throw away what I have. I wonder if there is a creative fix for this problem.

I tried to be MacGyver, and heated up shrink tubing so as to reduce the play where the dogbone enters. I think my solution is not a good one lol. What can I do, that is cost-effective to fix this issue? Thank you for any suggestions!

You mean the gap for the drive pin is worn so the pin is a sloppy fit?
I have several cars with the same problem and I just live with it. I used to believe that the pin was made from a softer material than the drive cups so it became a sacrificial part but now I don't think that's always true in every case.
If it's any consolation, I have some that are much worse than yours and they still function.

You might want to adjust the ride height so the bone is level leaving the drive cup - this will reduce wear.

I also swap drive cups left to right during routine maintenance for my gear diff cars. Probably some things you've already considered.

So if you're the earlier B4, that should be 7667 and 7668 replacement outdrives. If you're the later B4 with the metric outdrive bearings, it should be the 9852 outdrive set... if you change your mind and are willing to get replacement parts.

Thank you for the suggestion. It's half satisfying but appreciated nonetheless! But you did diagnose my problem or rather the wear problem on the drive cup. I'm not sure why having all that wear gap irritates me, I even tried to sauder the dog bone pins, but that doesn't work, or my iron isn't good enough lol.

My T3 gearbox had blue aluminum outdrives that were worn and sloppy. The CVD dogbones had plastic sleeved steel pins. I replaced the outdrives with OEM steel parts and the worn plastic sleeves with brass pins. Eventually I ended up with new condition, all steel parts. The brass pins also didn't hold up. There's no shame in replacing worn out parts. It's more satisfying to have proper fitting, smooth operating parts. Also, using worn parts can lead to accelerated wear to other parts.

Measure the OD of the drive and get a small length of brass or aluminum pipe you can tightly fit over the outdrive. Use a dremel to slot it just enough to allow for free movement of the dogbone. That might help out.

As a side note, MIP makes a "Puck" system that uses replaceable (orange) plastic inserts as the sacrificial part of the bone.
However, the system also requires purpose made drive cups.

Thank you for all the creative tips and suggestions ya'll.

In the end, for now, I decided to just change my mind on the play in the pins and drive cups as you recommended. Change of mind, means I have no problem .
The plastic shrink wrap was not effective and small changes created other issues (resistance) in the drivetrain.

Drive them until they get about twice as bad, then replace them. That is about all you can do. They are a wear item unfortunately.

Frankentruck wrote: ↑Tue Mar 08, 2022 9:00 pm So if you're the earlier B4, that should be 7667 and 7668 replacement outdrives. If you're the later B4 with the metric outdrive bearings, it should be the 9852 outdrive set... if you change your mind and are willing to get replacement parts.

Given that the parts are still available at list prices it's likely best to pick up a set of outdrives.

To resurrect this older thread I have some 2.25 out drives that I’d like to salvage.

Has anyone tried jbweld epoxy on the out drives?
I was thinking of putting something to prevent the epoxy from getting to the internals then filling the slots.

From there I was not sure what path to take.
I could grind though the jbweld or I could cut new slots in the steel, basically reslotting the drives

Nope don't bother.

Hardened steel doesn't hold up so there isn't much that will

About the best option is not a great one and that is to weld it up and grind back to shape. It won't be hardened but you could change the bone pin to use pin cushions.

jwscab wrote: ↑Fri May 27, 2022 1:53 pm Nope don't bother.

Hardened steel doesn't hold up so there isn't much that will

About the best option is not a great one and that is to weld it up and grind back to shape. It won't be hardened but you could change the bone pin to use pin cushions.

What about sealing up the sides and slotting into the previously uncut steel? I've seen some pretty aggressive material removal for lightening outdrives for 17.5 seems like there would be enough there for a mild runner.

That would be an interesting idea to try. Not sure if the outdrive would have enough strength or if the ends would' 'fan out' and spread like fingers under load. A ring sleeve over the outdrive could help with preventing that spreading out.

If you were to grind out two new grooves 90 degrees from the original ones, then fitted outdrive sleeves, that would probably work well. Those things are HARD, just so you know. Dremel cutoff wheels would work.