Ultima Diff Slipping - What Is Wrong

[DennisM]

You can mount the spur now - then put the white spacer in the spur, then the bearing, next the washer and finally the o-ring.

The best would be two flanged bearings - then there´s no need for the spacer.

[Kyoshojoe]

go to competitionx.com and download the manual to start. the ultima series used a plastic final pinion with a pin and hole set up. you have an optima style metal final pinion that would normally mate up to a top shaft that had notch in the shaft. you can either get the correct final pinion or file a flat in the shaft.

[Snaab9-2]

go to competitionx.com and download the manual to start. the ultima series used a plastic final pinion with a pin and hole set up. you have an optima style metal final pinion that would normally mate up to a top shaft that had notch in the shaft. you can either get the correct final pinion or file a flat in the shaft.

Thanks as soon as I get some time I will check that out.

yes, it has a notch in the shaft. I will get a better picture but from what I can tell, the hole that the set screw goes into isn't aligned perfectly and is off by enough the set screw cannot go deep enough to lock the flat part of the shaft. Is there any advantage to the Optima setup in the Ultima?

[Snaab9-2]

You can mount the spur now - then put the white spacer in the spur, then the bearing, next the washer and finally the o-ring.

The best would be two flanged bearings - then there´s no need for the spacer.

Thanks!

[Snaab9-2]

Ok guys, I think I may have found what is wrong.

When I was running the car sometimes the gearbox would slip and other times it wouldn't. It never seemed to make sense as the set screw seemed to have no control over it.

Well, when I was looking at it now the shaft was locked in place again which was really strange as the other day when I was fooling with it, the shaft would only spin no matter how tight the set screw was. Well it looked like a little piece of something was stuck in it. I got it to come out and now the shaft spins freely no matter how tight the set screw.

Does it look like something is broken off the set screw? Is it supposed to be longer?

The picture of the hole for the set screw is hard to see but you can see how the hole isn't perfectly round all that way down as part of it is blocked by the end of the shaft. I assume this is why my set screw cannot get down in there far enough to lock it in place. If it had a smaller diameter piece that is supposed to be on the end that is broken off, it could lock in there. I am onto something or am I off in the weeds?

Thanks

[Snaab9-2]

Any thoughts?

[Coelacanth]

Wish I could give a better answer, but the set screw doesn't need to be long, as long as it's screwed in properly and up against the flat on the shaft, with some threadlock. How much it protrudes on the hex end doesn't really matter. The "inside" end of the set screw should be flat, and should be screwed right down to press against the flat spot on the shaft. That's how it works for securing the final pinion and all 4 diff outdrives on the Optima series of cars, anyway. That said, the inside end of the set screw shown in your picture doesn't look too flat. Maybe file it a bit to make it more flat, so it'll mate up against the flat of the shaft better.

[Snaab9-2]

Thanks for the reply. I see what you are saying.

I guess I need to first see if I can pull the shaft out of the way a little or if it is fixed in place. As u can see from the pic, it is blocking the set screw slightly. If it can't move..... i will Dremel the set screw if it looks like that will help or dremel the blockage it just enough so the set screw will go in properly.

[Coelacanth]

Doesn't the shaft that appears through that set screw hole have a flat machined on it?

[Snaab9-2]

Doesn't the shaft that appears through that set screw hole have a flat machined on it?

Yes it does but the set screw doesn't seem to reach it as the part without the hole is partially blocking it. I think u can make out what I am saying in the pic.... the top part of where the hole is.

The gear seems stuck on the shaft.... the shaft is a bit marred up from it spinning with the set screw loose

[Snaab9-2]

Fixed it!

Thanks again everyone.... just had to shave it slightly to get set screw back in

[Coelacanth]

Doesn't the shaft that appears through that set screw hole have a flat machined on it?

Yes it does but the set screw doesn't seem to reach it as the part without the hole is partially blocking it. I think u can make out what I am saying in the pic.... the top part of where the hole is.

The gear seems stuck on the shaft.... the shaft is a bit marred up from it spinning with the set screw loose

I see what you're describing, now, with the partial blockage. Good job resolving it.