Dismantling the diff - advice, please.

[JohnD]

I've got a diff on the  bench, and I want to remove the rear casing.   Output shafts out, tick; bolts around the edge out, tick;  Split the front and back halves of the diff, tick.

Then it gets difficult.  The WSM says "turn the pinion until the two chamfered portions on the edge of the diff carrier permit withdrawal of the diff housing".

Done that.   By looking through the now open slot between the two halves of the casing, and turning the pinion I can see all of the circumference of the carrier.  Can't see any chamfers on the edge of the diff carrier (the casting that holds all the gears of the diff together), or in the edge of the crown wheel.   One of those is too big to draw the "Hypoid unit", the front of the diff with all the gubbins in it, out of the rear casing.  They foul on the inner edge of the rear casing.

I should say, this is my Quaife ATB unit, but that sits inside the carrier, it's not in the way.  There has to be a way, it got in there!   Please advise?

John 

[RedRooster]

Not sure what you've got, but sometimes you need a spreader, the beam does anyway. 

[Escadrille Ecosse]

John

With the Quaife the carrier is part of the ATB unit. So the carrier is a Quaife and not a Triumph part.

been a while since I have done one of these but have you tried rotating the rear casing a bit

 

[Escadrille Ecosse]

Just now, RedRooster said:

Not sure what you've got, but sometimes you need a spreader, the beam does anyway. 

The spreader is for removing the carrier from the front housing. I've always done that job with a couple of big screwdrivers. Works fine.

[Nick Jones]

I’m reading as you are trying to get the rear housing off, and it’s separated ok but cannot be fully withdrawn?

I don’t recall having this problem…. So I’ve just been out and taken these pics…

 

 

 

which frankly haven’t helped….

Ok, so there’s no carrier in this one, but they don’t stick out beyond the ring and there are no reliefs in the casing I can see.

 

[RedRooster]

It can't be that difficult, I did mine a few years ago. Post a photo of where you are at. 

[Escadrille Ecosse]

Yeah, don't ever remember it being a problem. A bit of wiggling?

9 minutes ago, Nick Jones said:

I’m reading as you are trying to get the rear housing off, and it’s separated ok but cannot be fully withdrawn?

I don’t recall having this problem…. So I’ve just been out and taken these pics…

 

 

 

which frankly haven’t helped….

Ok, so there’s no carrier in this one, but they don’t stick out beyond the ring and there are no reliefs in the casing I can see.

 

The reliefs are on the Triumph carrier Nick, but within the diameter of the crown wheel.

Viz the top photo, is that a special secret type of ATB you have in there

[Nick Jones]

53 minutes ago, Escadrille Ecosse said:

Viz the top photo, is that a special secret type of ATB you have in there

It’s a secret 

[JohnD]

The 'works' in Nick's 'hypoid unit' is soft and squishy, so easy to extract.

Colin, maybe this is a  Quaife unit but it had to get in there!   I have tried rotating the rear casing, but no joy yet>

I have extracted another diff from my store.  Never had it apart before, but it is an OE diff so I'll see in it's any different tomorrow.

This is a Quaife, from a listing on eBay for one  fora GT6:

Those recesses for the bolts that secure the crown wheel look like those I've seen through the slot.  They look deeper than those on the diff carrier in an OE dif :

I've tried to use them for clearance but no joy.   Is that where these "chamfers" are supposed to be?

John

[RedRooster]

It is possible. 

[Escadrille Ecosse]

John

Can't really add much. The carrier flange on the ATB units are slightly thicker than on the OE units.

The 'chamfered portions' referred to in the workshop manual are these slightly 'not round' flat bits.

Like you say though, it went in so it must come out.

What is the rear casing catching on, exactly? Does aligning the bolts in the carrier with elements of the casing help?

Edited August 14, 2024 by Escadrille Ecosse

[JohnD]

Thank you, Colin!   Ain't WSMs great. Would be really useful if they said "chamfered portions (See  Fig 46)" wouldn't it, when that's five pages on!

[Escadrille Ecosse]

6 minutes ago, JohnD said:

Thank you, Colin!   Ain't WSMs great. Would be really useful if they said "chamfered portions (See  Fig 46)" wouldn't it, when that's five pages on!

Yeah, I know!

[RedRooster]

I seem to remember having a headache with bearing part numbers and equivalents as the generic kits weren't skf. 

[JohnD]

I don't intend to go that far, RR.    In the incident when the adaptor broke away from the output flange, the little bolts that hold the output shaft and bearing in place also took a beating.   One was broken off, and the plate it goes through bent, while the bolt stub is stuck in the rear casing.  Or rather, it rotates freely on the hole but won't come out, so the threads are stripped.   Rather than drill and recap, I'm going to replace the whole rear casing, and output flanges.

Meanwhile, success!  Jiggling the rear casing - if you can say that about that heavy item - and it slipped off.   No "chamfers" on the heavier Quaife carrier, but then there are none on the OE diff whose rear casing I will re-use!   So much for WSMs!  And quite correct, Colin,  the Quaife diff carrier is heavier and thicker than the OE item.

Oh, and more debris to diagnose.   The Quaife diff rear casing had some of these inside:

They are magnetic, densely black, 1-2mm long (vernier for scale at 2mm), roundish like a lump of coke, and crushable in the fingers(!).

Any ideas?   The Quaife ATB has no play or looseness, but the oilseal on the pinion shaft had given up, and the shaft had got so hot that the  nylon in the nut on its tip had melted!   Is this debris from the seal, from the spacers or what?

John

 

Edited August 14, 2024 by JohnD

[RedRooster]

That must have had some heat through it to melt the nyloc. 

Pinions can be tricky if your using a crush spacer don't use a click-able torque wrench. 

[Escadrille Ecosse]

4 hours ago, JohnD said:

Meanwhile, success!  Jiggling the rear casing - if you can say that about that heavy item - and it slipped off.   No "chamfers" on the heavier Quaife carrier, but then there are none on the OE diff whose rear casing I will re-use!   So much for WSMs!  And quite correct, Colin,  the Quaife diff carrier is heavier and thicker than the OE item.

Good news there John. As for the chamfers, I had a look on the spare carrier I have in the garage and no chamfers on that either. WSM. WTF? Mind you all the spare diff parts I have nowadays are either LSD/ATB or later Marina/TR7 4 speed as these are stronger.

The 'bits'?

If the diff has got that hot then likely the oil coking and picking up any metal particles in the oil. What colour was the oil and how often do you change it?

[JohnD]

This rear casing has no drain plug, as was Triumph's UOP.   That will be corrected before refitting. So I've only topped it up, and can't recall what  the oil looked like.

I know!

John

[Escadrille Ecosse]

Yeah. Likely to be coked oil John.

Always put a drain plug in all of mine. Practical to do on the car if you are careful. 

The diff oil works hard in the small Triumphs. Even harder in competition. And harder still with any type of locking/ATB in competition.

Change the oil every year at least.

Edited August 14, 2024 by Escadrille Ecosse

[rogerguzzi]

Hello John 

                I run mine and I think Nick does to on Redline heavyduty  as these not much oil in our diffs which is ok for just gentle driving to a local show ect but racing or Motorway work soon knackers cheap oil

plus it is expensive but cheaper than Diffs(my rebuilt one has done at least 30k and oil looks ok when I change it every 2 years !) 

I Think its motorways and racing when you need it?(I may be wrong and often are but as I said ealier cheaper than diffs)

Roger

ps it comes out after 2 years looking very near the same so good enough for me?

[JohnD]

Thanks to all, for good advice!

 I'm going to reassemble the diff in its casing, install a different set of output shafts, and then take it to Mike Papworth to have all the bearings and seals outside the Quaife replaced.   And a drain plug !

John

[RedRooster]

Why not do that yourself? 

[JohnD]

Because I  can.

[Escadrille Ecosse]

35 minutes ago, JohnD said:

Because I  can.

[Nick Jones]

22 hours ago, rogerguzzi said:

                I run mine and I think Nick does to on Redline heavyduty  as these not much oil in our diffs which is ok for just gentle driving to a local show ect but racing or Motorway work soon knackers cheap oil

Yeah, Redline shockproof 140. Though not in my ATB diff. That one I’m running a good quality synthetic GL5 140.