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Carrier housing disassembly

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pawied Avatar
pawied Paul Wied
Stockholm, Sweden   SWE
Hi All,

I am replacing my 4.2 pinion and ring gear to 3.72 on my " '61" Sprite.

I thought disassembly would be a bit more straight forward.
I was mistaken...

Any tips on how to remove the existing pinion?
Special tool needed?

Been searching the web, but I apparently am using the wrong search words because every result has to do with re-building and never shows disassembly.

Thanks in advance smiling smiley!


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DSC_2382.JPG    44.7 KB

NaDaDawgRacer John Jones
Waxhaw, NC, USA   USA
If you are trying to figure out how to disassemble the unit then I would say this is a job that you shouldn’t tackle. Unless you truly know how to set up a ring and pinion then you will destroy the gears. I have worked on cars as a hobby my entire life and for the last 30 primarily on Healeys and other British Marques and when I need diff work I go to a guy that specializes in this.


BMac Avatar
BMac Brendan MacRae
Grass Valley, CA, USA   USA
That looks to be an early housing with a fill plug. The 3.7's weren't designed to fit that pumpkin. It can be done but you may want to get a later pumpkin and swap out the whole thing rather than trying to modify an early one.

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pawied Avatar
pawied Paul Wied
Stockholm, Sweden   SWE
Yes, Thanks Brendan.
This is my 1st try at diff work...done most everything else on a car.
Guess it is time to tackle the diff.
I have a long Swedish winter to do the job smiling smiley, so time is not an issue.
I am already on the hunt for a later model carrier.

Jim Gruber Avatar
Riverview, FL, USA   USA
I changed my differential from a 4.2 to a 3.9. Unbolted about 16 nuts, removed axles,did a little oryibg and the center section popped right out. While you are in there change out bushings on radius arm rods. Make sure spacer is installed in the right space. Reseal with a new gasket and Hylomar.

Jim Gruber - Tampa/Riverview FL
Bugsy I - '68 Sprite w BE Bonnet - Gone but not forgotten
Bugsy IV - '60 Bugeye - 1,275+.040 and a 5-Speed - CA Car - 2nd Owner from new -
A truly rust free, garaged in Los Angeles for 57 years Bugeye

Sprite1956 Roger Parry-Jones
Melbourne, Victoria, Australia   AUS

I guess you bought a 3.7 crown wheel and pinion and you planned to swap the inners over. Assuming there was nothing wrong with the 4.2, you are much better off using a later 4.2 case (with worn crown and pinion) to swap them over into. That way you'll keep the good 4.2 as a spare. Late Morris Minors (certainly the 1100 version) should be an alternative source to the Spridget diff. case.

It's a pity you don't live closer. I've just 're-discovered' a bunch of diff's I put under the house 20 years ago. Most are dismantled for the home-built LSD's I was building a long time ago but are useless to me now!

Good luck!


pawied Avatar
pawied Paul Wied
Stockholm, Sweden   SWE
Precisely what I did, Roger.
I bought the pinion and ring gear.
Thought it would be a quick swap...with re-shimming of course.
My investigations were a bit short as I am learning.

If I would have realized earlier, I would have done what you suggested.
I have a limited slip (Detroit locker) in the current assembly that I would carry over, but the pinion could have stayed.
However the bearings were quite worn..2 in/lb pre-load on the pinion only.

I am assuming the newer carrier housing just shifted the pinion center over to account for a larger gear head on the pinion.
Still investigating this.

Maybe milling off a mil or two from the ring gear back could work.
Won't do that until absolutely sure winking smiley, preference is to find a new housing carrier.


pawied Avatar
pawied Paul Wied
Stockholm, Sweden   SWE
New carrier housing found...just waiting for delivery.
Pinion, now with inner bearing, also ready snd waiting.

Pinion inner bearing.JPG    46 KB
Pinion inner bearing.JPG

pawied Avatar
pawied Paul Wied
Stockholm, Sweden   SWE
I finally received the newer model carrier housing, cleaned it up and painted it.
I set the pre-load.
Now all that is left to do is to shim and mount the Detroit locker , but will wait until the weekend so I have all day for a stress-free assembly spinning smiley sticking its tongue out.
Looking for and finding the proper carrier housing, without gearing, was the hardest and longest process so far.
I can also say, this has been an extremely rich learning experience, and happy it is coming together smileys with beer!

Carrier housing painted.JPG    50.7 KB
Carrier housing painted.JPG

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