Solid epoxy diff. Do you really need a working diff?

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JosephS
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Solid epoxy diff. Do you really need a working diff?

Post by JosephS »

On one of my recent ebay buys was a t3 that I just started stripping down. For the most part everything looked good. When I got down to the diff I was happy the out drives looked to be in good shape. Then I realized that it wasn't grease leaking out of the diff.

It appears that the diff was filled with epoxy then tightened down to the point it began to ooze from the gap between the gear and the outdrives.

I was going to just dunk this in acetone, but I was worried that the epoxy won't get the the internals.

Does anyone have tips?

It seems fire could be a good way to go. Are diffs overrated?

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Re: Solid epoxy diff. Do you really need a working diff?

Post by juicedcoupe »

I'd soak it in acetone to remove the outdrives, then replace the gear, rings, and balls.
Always looking for new and interesting ways to waste money.

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Re: Solid epoxy diff. Do you really need a working diff?

Post by Dadio »

Without a diff it puts way more load on the driveline , I tried with my yo-clone-oh to have no one ways up front , it just goes through the chain sprocket in no time , it would be the same locking up the diff , ok if the rest of the driveline is up to it but not really a good idea.
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Re: Solid epoxy diff. Do you really need a working diff?

Post by Phin »

Epoxy locked diffs is sometimes done in a car used for dirt oval, or drag racing.

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Re: Solid epoxy diff. Do you really need a working diff?

Post by jwscab »

If the outdrives are good, they are worth saving. I'd probably try heat, maybe like a toaster oven around 350degrees f. The diff gear and everything except the outdrive will likely be trash.

Any higher temp and you will impact the heat treating.

You should be able to heat, take out of the oven and twist apart.

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Re: Solid epoxy diff. Do you really need a working diff?

Post by cobrakai »

Honestly I feel that a locked diff is probably better than a ball diff :) Though I know most here won't agree with me.
I had so many issues with my ball diffs and they can only take so much power before they start slipping since the entire function of it is built on friction of hardened materials sliding against each other.
Gear diff with oil and/or a clutch to set the "locking %" is the way to go.

With a locked diff it will not turn very well. It would really only be suitable for very loose conditions or where you plan to rear-steer a lot.

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Re: Solid epoxy diff. Do you really need a working diff?

Post by JosephS »

jwscab wrote: Fri Jan 20, 2023 1:55 pm If the outdrives are good, they are worth saving. I'd probably try heat, maybe like a toaster oven around 350degrees f. The diff gear and everything except the outdrive will likely be trash.

Any higher temp and you will impact the heat treating.

You should be able to heat, take out of the oven and twist apart.
Thanks for reminding me about the heat treatment. I was considering setting the whole thing on fire.

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Re: Solid epoxy diff. Do you really need a working diff?

Post by JosephS »

Phin wrote: Fri Jan 20, 2023 12:46 pm Epoxy locked diffs is sometimes done in a car used for dirt oval, or drag racing.
The car was in such nice condition otherwise. It would have made sense that this was on purpose.

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Re: Solid epoxy diff. Do you really need a working diff?

Post by JosephS »

Dadio wrote: Fri Jan 20, 2023 9:19 am Without a diff it puts way more load on the driveline , I tried with my yo-clone-oh to have no one ways up front , it just goes through the chain sprocket in no time , it would be the same locking up the diff , ok if the rest of the driveline is up to it but not really a good idea.
Thanks for that information. If the diff doesn't come apart easily I may just have to abandon this as a project. It sounds like it would be basically undrivable the way it is. I'm still awestruck that the design from the factory uses a structural bumper.

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Re: Solid epoxy diff. Do you really need a working diff?

Post by JosephS »

juicedcoupe wrote: Fri Jan 20, 2023 12:42 am I'd soak it in acetone to remove the outdrives, then replace the gear, rings, and balls.
This was my original thought. I wasn't sure if there was something better.

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Re: Solid epoxy diff. Do you really need a working diff?

Post by JosephS »

A soak in acetone did the trick. The jbweld softened right up.
It came apart as normal.
I also got to see why it was like this. It looks like the center of the diff gear melted off the edge and the jb weld was added in place of a new gear.
5BD4E793-225F-472D-9B25-C4BC9FC3668F.jpeg
Looks like the rings may still be good but I am not sure I can salvage the bearings.

Suppose I should build this T3 now.

Thank you to everyone who offered up a solution.

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Re: Solid epoxy diff. Do you really need a working diff?

Post by TokyoProf »

cobrakai wrote: Fri Jan 20, 2023 6:34 pm Honestly I feel that a locked diff is probably better than a ball diff :) Though I know most here won't agree with me.
With a locked diff it will not turn very well. It would really only be suitable for very loose conditions or where you plan to rear-steer a lot.
I agree with you locked diff can be wonderful. Depending on the application if you have a light car with a rudimentary suspension, a locked diff is great fun and with more traction and with controlled slides and rear steering.
Once you go with a locked diff in a Tamiya grasshopper for example (any of the insects) you likely won't go back...on ANY surface. The fun and smiles increase by 75.9 %.
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Re: Solid epoxy diff. Do you really need a working diff?

Post by morrisey0 »

Not to hijack, but were belt driven and direct driven TrackMaters strictly for drag racing? Or only super loose dirt? They seem like they were pretty common to be such niche devices.
I build RCs like people would have done back in the '90s ..................................... if they had 3D printers.

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Re: Solid epoxy diff. Do you really need a working diff?

Post by juicedcoupe »

TokyoProf wrote: Fri Feb 03, 2023 1:19 am Once you go with a locked diff in a Tamiya grasshopper for example (any of the insects) you likely won't go back...on ANY surface. The fun and smiles increase by 75.9 %.
I can see it on a Hopper. It doesn't have any outdrives or dogbones to get worn, and I don't see those 5mm axles getting hurt easily.

And the steering sucks anyway, so the change probably isn't noticeable.
Always looking for new and interesting ways to waste money.

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Re: Solid epoxy diff. Do you really need a working diff?

Post by Phin »

morrisey0 wrote: Fri Feb 10, 2023 6:48 pm Not to hijack, but were belt driven and direct driven TrackMaters strictly for drag racing? Or only super loose dirt? They seem like they were pretty common to be such niche devices.
Trackmaster produced products predominantly for dirt oval racing....which was a popular racing class.

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