Building one good diff out of two.

[martinjflint_2327]

right finally rejoined, now i can annoy folk on here instead of facebook again!

 

1971 gt6 mk2 rotoflex with rover V8 and 5 speed box

- weak link is the diff. trying to avoid putting the subaru one in that is sat on garage shelf.

 

So as some of you know I ejected the rear of my diff out the back of the car a while ago, got a temporary diff and now finally took that out to begin (some kind) of rebuild. Both are now stripped on the bench leaving just the pinion in each.

 

What I have:

- my 'original' 3.89 ratio GT6 six bolt housed diff with front large castle nut - so I have a solid spacer.

- It has large carrier bearings and a very nice tight but smooth differential in it with copper shims

- the rear housing as said was shattered by a pinion tooth wedging under crown wheel -  so I have another 6 bolt tail I will use.

- My pinion has lost one of its baby teeth but the CW looks okay.

- This diff WAS nice and quiet.

 

The temporary diff

- is the holy grail 3.63 but with a spitfire front bracket, 4 bolt rear case, and a shallower nylock front nut - so it should be a collapse spacer.

- it has smaller carrier bearings and the differential is sloppy with approx 0.8mm of play moving a single gear in/out

- The crown wheel has a bit of burring at the edge of the troughs of about 7 teeth and a scored line on the edge of the wheel (not the teeth) of     the same number of teeth.

- This diff whines on load of acceleration or deceleration.

 

 

Any advice at this point is appreciated.

I cant afford to get the diff sorted by someone brilliant so as neither owes me anything I wish to try myself to make a tough (as possible diff with what I have.

 

This is what I think i should do:

 

1. use my GT6 front housing

2. use my spare 6 bolt rear case (tapped for a drain plug)

3. use the 3.63 CWP matched set (even thought potentially still noisy)

4. use my solid spacer (doing all the difficult pre-load and shimming i know will need doing)

**** Can you use a solid spacer on a pinion that uses a collapse spacer?? ****

5. Use my gt6 carrier with the larger bearings

6. replace all seals and bearings.

 

Questions:

 

1. will the solid spacer go on the pinion off the other diff? (solid is a stronger)

2. are the output shafts stronger on the gt6 diff? (the shafts look the same but the spitty one has sealed bearings)

3. I'd read that the later (TR7 4 speed) carriers were stronger, but are they stronger than my gt6 one?

 

 

Thank you everyone :-)

[PJM Stag]

Talk to Mike Papworth he knows all about diffs, what is possible and what is not, satisfied customer, nfi

[KevinR]

The collapsible spacers (156903) are still available, so the 3.63 diff should be easily rebuildable.

 

You can also drill and tap the extra two spring mounting holes in the case of the 3.63 if you need to