Jump to content


Photo
- - - - -

Diff Housing Swap! Is It Possible?


  • Please log in to reply
8 replies to this topic

#1 kai1380

kai1380

    Starting My Mini Up

  • Noobies
  • Pip
  • 3 posts
  • Location: Colchester

Posted 24 June 2020 - 10:28 AM

Hi there all,

 

looking for some help !

 

I have a cracked diff housing which is leaking oil, and after taking it out it cant be welded due to the position of the crack.

 

I have another diff housing, however i have been told that it is not recommended to fit a housing from a different gear box, onto another one due the housings being made to match up to the one gear box they were originally made on (all be the difference a few thou) 

 

sorry if that makes noooo sense !!!!

 

Im no wizard with engines and in fact this is the first time i have really picked up a spanner - and so far managed to restore most of the mini and now working on the engine and engine bay. so far with out to many dramas, fingers crossed it stays that way.

 

Its probably a really dumb question but thought id ask just to put my mind at rest.

 

I have pinged up a few photos for those that love a pic or 2, hahah

 

 

cheers all

 

kai

Attached Files



#2 Cooperman

Cooperman

    Uncle Cooperman, Voted Mr TMF 2011

  • Mini Docs
  • PipPipPipPipPipPipPipPipPipPipPip
  • 21,867 posts
  • Location: Cambs.
  • Local Club: MCR, HAMOC, Chelmsford M.C.

Posted 24 June 2020 - 11:57 AM

It states in many publications that you can't 'mix & match' a diff housing with a gearbox case.

However, I have done this a couple of times over many, many years and in each case there was no problem.

The diff bearings are huge and any mis-match will not distort the outer bearing races. The potential problem comes with the risk of oil leaks. Use the correct gaskets and use 'Instant Gasket' sealant on all the critical mating faces and you will be fine.

Make sure that during assembly and before tightening everything up you push, or in this case lightly tap, the diff assembly to the right hand side of the case/cover. Then nip up the diff cover nuts and the RH output cover, then fit the LH output caover, measure and fit the necessary shims and then do the final assembly.



#3 KTS

KTS

    One Carb Or Two?

  • TMF+ Member
  • PipPipPipPipPipPipPip
  • 1,030 posts
  • Location: Herts

Posted 24 June 2020 - 12:36 PM

just to add to cooperman's answer - i'd suggest to start by fitting the diff cap to the gearbox without the diff in place and have a look at how well the bores in each part line up against each other

 

if they're obviously misaligned (i.e a significant 'step' where the two halves join, or the bores aren't circular), then it's possible the combination won't provide an effective solution

 

if you post some pictures here of the output bores with the diff cap fitted to the gearbox, we can offer some opinions 

 

edit :  Nice car by the way and welcome to the forum !


Edited by KTS, 24 June 2020 - 12:37 PM.


#4 Cooperman

Cooperman

    Uncle Cooperman, Voted Mr TMF 2011

  • Mini Docs
  • PipPipPipPipPipPipPipPipPipPipPip
  • 21,867 posts
  • Location: Cambs.
  • Local Club: MCR, HAMOC, Chelmsford M.C.

Posted 24 June 2020 - 01:11 PM

The bores themselves are not the problem. If necesary the holes in the casing could be elongated very slightly using a round file, although I have never seen a mis-match on the circular bores of more than a couple of thou or so. The issue is the flat faces having a small step and the 'Instant Gasket' will easily fill that so long as good quality gaskets are also used.

As I said, I have done it on a few rally cars which had damaged or broken diff covers and have never had a problem, even when the cars were used in serious competition afterwards. 

Someone once suggested that the outer races of the two large diff bearings would be distorted, but take a look at the steel outer races and then look at the aluminium housing. You can't imagine those steel outer races being distorted at all. In fact, that area is a bit over-engineered, so no worries. 



#5 kai1380

kai1380

    Starting My Mini Up

  • Noobies
  • Pip
  • 3 posts
  • Location: Colchester

Posted 24 June 2020 - 01:19 PM

First off thanks for the replies.

 

Sorry I didn't go over to the Introduce myself page, ( only saw that after!!).

 

I will do just as you have suggested thanks you very much.

 

I have a full diff gasket set so will replace every seal and gasket.

 

will post some pictures tonight.

 

cheers



#6 KTS

KTS

    One Carb Or Two?

  • TMF+ Member
  • PipPipPipPipPipPipPip
  • 1,030 posts
  • Location: Herts

Posted 24 June 2020 - 01:25 PM

The bores themselves are not the problem. If necesary the holes in the casing could be elongated very slightly using a round file, although I have never seen a mis-match on the circular bores of more than a couple of thou or so. The issue is the flat faces having a small step and the 'Instant Gasket' will easily fill that so long as good quality gaskets are also used.

As I said, I have done it on a few rally cars which had damaged or broken diff covers and have never had a problem, even when the cars were used in serious competition afterwards. 

Someone once suggested that the outer races of the two large diff bearings would be distorted, but take a look at the steel outer races and then look at the aluminium housing. You can't imagine those steel outer races being distorted at all. In fact, that area is a bit over-engineered, so no worries. 

 

my experience is limited to a single instance of putting the 'wrong' diff cap on and it cracking when tightened down over the bearing races - can't vouch for how likely it is for the bores to misaligned sufficiently for this to happen, but it's certainly possible



#7 kai1380

kai1380

    Starting My Mini Up

  • Noobies
  • Pip
  • 3 posts
  • Location: Colchester

Posted 24 June 2020 - 06:54 PM

Right so had a little look.
Need some more precise measuring tools but it looks dead on ( this is with out using a gasket)

Should I defiantly be using gaskets??

Pictures paint a 1000 words so have a peek..

Cheers

Kai

Attached Files



#8 Moke Spider

Moke Spider

    Moved Into The Garage

  • TMF Team
  • PipPipPipPipPipPipPipPipPipPipPip
  • 10,169 posts
  • Location: NSW
  • Local Club: South Australian Moke Club

Posted 24 June 2020 - 07:24 PM

Most of the later gearbox caps were gasketless, but not all. I would caution against working off what is presently in there and measuring. There's some info here;-

 

http://www.theminifo...kets-important/

 

However, as you are possibly fitting another cap, this will likely be all out the window,

 

I've done many cap swaps, more or less as Cooperman has suggested.

 

As Cooperman has pointed out, the Bearings themselves do much to located the caps, so, with that in mind, I sometimes dispense with the dowels that are fitted to the gearbox case and reply on the bearings to locate the cap in one plain.

 

As well as the Bearing Tunnels, you also need to check the alignment between the two faces for the side plates as these need to be dead flat and on the same plain otherwise it may leak Oil and it will wear the bushes in the side covers in short time,

 

Also the bore for the shifter input shaft, otherwise, it will forever leak. These need to be very very close as the seals used only have a very small range for misalignment and if an anti-leak kit is fitted, the action of the shifter will be very stiff.

 



#9 KTS

KTS

    One Carb Or Two?

  • TMF+ Member
  • PipPipPipPipPipPipPip
  • 1,030 posts
  • Location: Herts

Posted 24 June 2020 - 08:09 PM

Right so had a little look.
Need some more precise measuring tools but it looks dead on ( this is with out using a gasket)

Should I defiantly be using gaskets??

Pictures paint a 1000 words so have a peek..

Cheers

Kai

 

looks pretty good indeed from those photos 






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

Mini Spares