11 replies to this topic

[mniguy_nz]

Hi Guys,

Seeing as Minispares is engaged and I want to go to bed thought I'd put up a quick post. I'm after a cross pin diff and just wondered whats involved.
I assume I'll use my pinion/crown wheel off my original diff and pot joints. I read somewhere about shims. Is this for the pot joints or somewhere else?
I've never fiddled with diffs before so any help would be much appreciated.


Cheers

Tim

Edited by mniguy_nz, 22 October 2010 - 07:35 AM.

[Cooperman]

You fit your existing crownwheel to the new diff casing which comes as a kit of parts. Assembly is quite straightforward. It's a good idea to get a new set of lock tabs, 3 off required' for the crownwheel to diff case bolts which should also be 'Loctited' in.
The shims are to set the pre-load on where the register on the diff end covers locat the entire diff assembly. It's all in the workshop manual, but it is so difficult to get absolutely correct. You need a set of genuine output cover gaskets too as these are a set thickness. The diff bearings are so over-strength that, IMHO, so long as the pre-load is near enough correct it's never been a problem. Measure across the diff bearing faces to get the total width with a vernier before and after and adjust the original shim thickness to take out the difference and it should be fine.
I must be the only person who has managed to snap a pin in the cross-pin diff, but that's another story!

[Ethel]

But was it as spectacular as breaking a standard diff?

[Guess-Works.com]

or look here http://www.guess-wor...m/Tech/Xpin.htm

ps, don't bother with locktabs, they are made of soft metal which crushes and can allow the crownwheel to move, loctite the bolts in with something like 201.

[Cooperman]

Oh yes. I came down to a hairpin left junction on the Epynt army ranges in Wales. As I went around the hairpin, the surface went loose and there was a big drop off the outside. The car started to slide towards the outside and the big drop and I had to give it max in 1st to keep it from sliding off backwards. I reckon I was at 7500 rpm in 1st with the inside tyre smoking. This must have friction-welded a planet wheel to a pin, which then sheared. However, so strong is the cross-pin diff that we did the rest of the rally (the National Welsh Retro Rally), another 280 miles, with the broken pin and we achieved an outright win. The problem then was that to get the valuable 'S' output shafts out I had to put the diff casing in a lathe and use a parting-off tool to split the casing in two.

Edited by Cooperman, 22 October 2010 - 01:06 PM.

[mniguy_nz]

Excellent thanks for the answers and and nice story cooperman, sounds like something that'd only happen in a Mini

[Dan]

The problem then was that to get the valuable 'S' output shafts out I had to put the diff casing in a lathe and use a parting-off tool to split the casing in two.

I can imagine the tears mixed with the lathe suds quite well.

Was it a short pin that snapped? There must have been a whole heap of swarf swilling around in there.

[Cooperman]

Yes, it was a short pin. there was virtually no swarf as it was a very clean shear and the rest of the pin just rotated in the housing. Thank goodness for Valvoline Racing oil.
Cost me a complete new cross pin diff, though. The main thing was that we won the event. The funny thing was that after the planet wheel welded itself to the pin, it was like a fully locked diff and I did 1/2 a mile thinking that we would just retire at the end of that test. Then, at the next tight hairpin it all freed off as the pin sheared, so we just carried on.

[LondonDry]

Hi Folks:
I'm new to the forum, and working on my first Mini, a 95 SPI, with a blown diff. I bought the Mini Spares cross pin diff, and while everything rotated well with the first drive shaft in place, after I dropped in the 2nd drive shaft and torqued down the crown wheel to Mini Spares' recommended setting (60ft/lbs) I couldn't move the shafts. Wondering if removing the mica thrust washers would allow enough play to allow freedom of movement?

Any help/wisdom would be appreciated.

[mniguy_nz]

Hi Folks:
I'm new to the forum, and working on my first Mini, a 95 SPI, with a blown diff. I bought the Mini Spares cross pin diff, and while everything rotated well with the first drive shaft in place, after I dropped in the 2nd drive shaft and torqued down the crown wheel to Mini Spares' recommended setting (60ft/lbs) I couldn't move the shafts. Wondering if removing the mica thrust washers would allow enough play to allow freedom of movement?

Any help/wisdom would be appreciated.

Try putting your old mica thrust washers back in a see how it feels. You can't run the diff without them

[Dan]

Absolutley, you must not do without them but worn ones work well here.

[LondonDry]

Thanks Dan. The previous mica washers are at 35 thousandths, same as the new ones that came in the kit. No wear at all. Thinking about putting the shafts on the lathe and taking the faces that rest on the washers down a few thousandths to create some room to move.

Could there be a mismatch between the teeth on the new planet gears the ones on the ends of the shafts?