17 replies to this topic

[babsbrown]

Good morning everyone.

I've recently rebuilt the diff with the minispares uprated (bushes planet wheel) kit and competition pin.

I used new fibre washers and thrusts. I am concerned about the amount of play here.
It looks as though a thicker fibre washer would help take up some play.

My other guess would be the crown wheel and diff need rebushing.

What are peoples thoughts on the play here?


https://youtube.com/...57LhwNYtw7i2RPV

Cheers.

Edited by babsbrown, 24 February 2025 - 01:59 AM.

[Spider]

Yeah, both the bushes - one in the crown wheel and that in the hemisphere - have seen better days.

The Bushes are inexpensive and easy to change, the issue for you might be sizing them after fitting. The shafts are a nominal 1.050", I give the 0.001" on that for clearance. I do these in the lathe. You could ream them using an adjustable reamer, but they may not be perfectly on centre.

[babsbrown]

Yeah, both the bushes - one in the crown wheel and that in the hemisphere - have seen better days.

The Bushes are inexpensive and easy to change, the issue for you might be sizing them after fitting. The shafts are a nominal 1.050", I give the 0.001" on that for clearance. I do these in the lathe. You could ream them using an adjustable reamer, but they may not be perfectly on centre.

Thanks spider,,


Removed the bushes this morning,
I presume I will need to press them in? Or would a suitable sized drift be OK?

Cheers,

Edited by babsbrown, 24 February 2025 - 09:35 AM.

[Spider]

I press them, but I can't see why you can't carefully drift them in.

[OzOAP]

I press them, but I can't see why you can't carefully drift them in.

If you don't have a press, a vice is good for the job.

[babsbrown]

Cheers guys,

Just ordered some bushes. Bit frustrating, as this engine build has been 2 steps forward, 1 steps back. Really hope I can get this sorted in the next week.

[ACDodd]

A common misconception is that people think rebuilding is replacing parts, the reality is it usually means machine work, and the diff is a classic example, the crownwheel and cage bushes must be replaced at the same time, and the diff side plate bushes should also be changed and machined for
Match your output shafts accordingly. Reaming is pointless as they are unlikely to be centred properly. This is lathe work to do it correctly.

Ac

Edited by ACDodd, 24 February 2025 - 01:44 PM.

[babsbrown]

A common misconception is that people think rebuilding is replacing parts, the reality is it usually means machine work, and the diff is a classic example, the crownwheel and cage bushes must be replaced at the same time, and the diff side plate bushes should also be changed and machined for
Match your output shafts accordingly. Reaming is pointless as they are unlikely to be centred properly. This is lathe work to do it correctly.

Ac

Thanks AC,

I'll have a scout around and see if there's anyone nearby who can do it. In an ideal world if space and money was no object I'd buy a metal working lathe and mill. There's been so many times I've needed such equipment but ultimately have had to lean on machinists for help.

Although saying that, once the engines built, Id like to think I wouldn't be needing this sort of work for a long time.

[babsbrown]

A common misconception is that people think rebuilding is replacing parts, the reality is it usually means machine work, and the diff is a classic example, the crownwheel and cage bushes must be replaced at the same time, and the diff side plate bushes should also be changed and machined for
Match your output shafts accordingly. Reaming is pointless as they are unlikely to be centred properly. This is lathe work to do it correctly.

Ac

Just thinking out loud...


What if hypothetically, once rebushed the thickness of the new bush allows the output shafts to run fine with the correct 1 thou clearance.
Given the shafts will have some wear?


Cheers

[ACDodd]

Unlikely the bushes are quite a bit smaller than the shafts.

Ac

[babsbrown]

Thanks,

Hope to get it done this week

[Spider]

 

A common misconception is that people think rebuilding is replacing parts, the reality is it usually means machine work, and the diff is a classic example, the crownwheel and cage bushes must be replaced at the same time, and the diff side plate bushes should also be changed and machined for
Match your output shafts accordingly. Reaming is pointless as they are unlikely to be centred properly. This is lathe work to do it correctly.

Ac

Thanks AC,

I'll have a scout around and see if there's anyone nearby who can do it. In an ideal world if space and money was no object I'd buy a metal working lathe and mill. There's been so many times I've needed such equipment but ultimately have had to lean on machinists for help.

Although saying that, once the engines built, Id like to think I wouldn't be needing this sort of work for a long time.

 

 

Doing them in a Lathe or Mill is ideal, but the factory routinely reamed them. Yes, they as best centred (and that's why I do them in the Lathe), but with these, it's not the end of the world if they aren't. The Side Covers aren't a neat spigot in the the gearbox case, so any additional 'nth' effort is almost pointless.

[babsbrown]

A common misconception is that people think rebuilding is replacing parts, the reality is it usually means machine work, and the diff is a classic example, the crownwheel and cage bushes must be replaced at the same time, and the diff side plate bushes should also be changed and machined for
Match your output shafts accordingly. Reaming is pointless as they are unlikely to be centred properly. This is lathe work to do it correctly.

Ac

Thanks AC,

I'll have a scout around and see if there's anyone nearby who can do it. In an ideal world if space and money was no object I'd buy a metal working lathe and mill. There's been so many times I've needed such equipment but ultimately have had to lean on machinists for help.

Although saying that, once the engines built, Id like to think I wouldn't be needing this sort of work for a long time.

Doing them in a Lathe or Mill is ideal, but the factory routinely reamed them. Yes, they as best centred (and that's why I do them in the Lathe), but with these, it's not the end of the world if they aren't. The Side Covers aren't a neat spigot in the the gearbox case, so any additional 'nth' effort is almost pointless.

Thanks Spider,

That's reassuring, on the topic of machining, idler gear thrust washers are anything thing a lathe would be handy for!! I can't understand how they cost so much.

[Spider]

Thanks Spider,

That's reassuring, on the topic of machining, idler gear thrust washers are anything thing a lathe would be handy for!! I can't understand how they cost so much.

 

I have made them, mostly on the lathe ! So yes, but the thrusts I've made were customs ones. They need to be hardened after machining, then the stumbling block for the guy with just a lathe is that they then need to be ground to end up parallel, flat and to the right thickness. I have a Surface Grinder for doing that. You could grind them in the lathe using a tool post grinder, but it's not a tool I'm crazy about, a lathe really isn't an ideal tool for that kind of grinding, and you've gotta be so careful that none of the dust ends up in the ways, slides and gears of the lathe or you can kiss any accuracy it had goodbye.

They are dear, yes, but I'd say that's because of low volume.

Make a set and you'll see why they do cost
 

[ACDodd]

A small cut off the transfer case helps to bring the idler gear tolerances back into check, that’s easier to do than make washers.

Ac