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Workshop manual late MkIII, axle info


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Slightly annoyingly, I've just bought a new workshop manual for Triumph GT6 Mk1,2&3 and Vitesse 2-litre, because I wanted to know the settings and assembly detail for the diff internals - and I needed a new one anyway.  I find the addenda for Mk3 simply gives a diagram, no info about the collapsible spacer, torque settings etc.  Have I missed it somewhere? - or do I need to buy a book for Spitfire 1500 just for a couple of paragraphs?

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Thanks for that, Colin - very helpful.

I'd be grateful if somebody could clarify the torque settings for me.  The ones that are confusing me are the setting for the setscrews joining the main diff cast casing to the main rear casing - I thought that might be 'hypoid housing to rear axle housing', but if that's the case, what's the setting for the hex sockets which hold the rear axle output housings to the main housing?  Just finger tight, lean on a hex wrench best you can, or??

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Finger tight for the side axle plates to case; I've never torqued them. No need to overtighten but they seem good enough when tightened by hand along with a new spring washer.

Hypoid housing is the differential carrier ie the bit with all the gears; rear axle is the rear case where the side axles attach so yes you're correct.

For the front collapsible spacer, I think (never had one myself) and none of my manuals are that modern!

 

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For the collapsible spacer type there is no nut torque. This is because you gradually tighten the nut until the correct bearing preload is achieved. That is measured by determining the torque needed to turn the pinion assembly and should be done with the carrier out.

If you just want to change the seal, you need to mark the nut, flange and shaft. Then undo carefully counting turns. After swapping seals, screw the nut back on the same number of turns, to you marks.

Nick

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As an aside Nick, if you have got the carrier out but not changed the pinion bearings just the seal would you tighten the nut to get the correct pinion torque or just to the previous marked position? I ask because the nut position will almost certainly end up different in each case.... 

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I agree that you would get different positions. To achieve the as-new preload you would likely have to tighten the nut/collapse the spacer a little more.  However, you should return the nut to its previous position. You should not preload a used bearing set to the same degree as a new set.

Nick

Edit: Probably irrelevant aside, but I once owned a Dolly 1850, which has basically the same diff. The pinion seal leaked..... a lot. So I bought a new seal. But when crawled underneath to sort it I found significant play in the pinion bearing. The nut didn’t appear to have moved. I was surprised as there was no whining or vibration. Anyhow, more in hope than expectation I pulled the flange off, fitted the new seal and refitted the flange, tightening the nut just enough to remove all the play. Then topped up the oil and crossed my fingers. It was fine. Between us my brother and I put another 50k on the car. Plenty went wrong with it, blew two gearboxes and one engine.... but the diff was fine!

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Unusual as I assume the Triumph design is that their preload torque is calculated to be enough to stop any play developing during the life of the diff. However I suppose each one is different and as you say I would definitely make sure that after removing a flange the nut is always torqued up sufficiently to ensure no chance of play....

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I think with the collapsible spacer its pretty difficult to get it wrong even if you get mixed up with the marks made before strip down. As you do up the nut its going to go much tighter as it comes up against the spacer which wont have changed from its original crushed length....

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I was only changing the pinion seal on a 3.63 (1500) diff, not the bearings as these felt OK as far as I could tell and I really don't want to get into CRP setup at this stage of the job.  It's a s/h diff so I've no idea if it was noisy or not before I started.  I centre punched the pinion shaft, nut, flange and casing so got all the marks lined up for reassembly.  Just half a flat off alignment, it started to go properly tight, so I got it all lined up and everything feels good.  I won't know if it's OK for ages as today I've been spraying the underbody with Terotex 2000 after masking up the chassis with the entire rear end stripped out, so it'll be a week or two before the axle goes back in - then I've the front end to do before I drive it.

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nipping the nut tight to the original spacer without compressing any more will be fine

what you dont want is overtighten and overload the pre load as this will seize bearings   , 

so nipped up should be ok     its the old balance act no free play no increase in pre load 

so i agree its the pre load is the gold , but as you are working on an assembly a measure of what the assembly gives first is a good idea 

and you can compare the before and after     you are not going to strip the diiff out and cause more hic ups in the process just to check the pinion pre load 

do the assy ,  even a bit of string round the coupling and a fishing spring balance will work

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That's an excellent read but doesn't cover the late models with the collapsible spacer; I've read so many accounts over the last few days of how to set them up, but nothing concrete that I could post to help Roger with the certainly of being the proper method.

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9 minutes ago, Colin Lindsay said:

That's an excellent read but doesn't cover the late models with the collapsible spacer; I've read so many accounts over the last few days of how to set them up, but nothing concrete that I could post to help Roger with the certainly of being the proper method.

Please don't spend too much time looking, Colin - it's not a job I'm doing right now (at least I hope not!).  I'd like to know for future reference more than anything as my original 3.27 diff has definitely run the pinion bearings - the pinion flange has a definite roughness when turned, and the diff whined very noticeably when I had it in the car.  I was planning to do a bearing replacement to see if that cleared the whine, but none of the books I have found tell me how to do that on a diff with a collapsible spacer in place of the earlier shim pack.

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Just my own curiosity, Roger... too cold to do anything else this morning except keep warm and drink coffee but it's something I'd like to know, just in case. I've a spare 3.63 diff in the garage and might use it some day, especially since the GT6 diff has started to whine at low speeds.

 

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Just now, Colin Lindsay said:

Just my own curiosity, Roger... too cold to do anything else this morning except keep warm and drink coffee but it's something I'd like to know, just in case. I've a spare 3.63 diff in the garage and might use it some day, especially since the GT6 diff has started to whine at low speeds.

 

It's certainly cold... I'm in the middle of sorting out my newly-purchased GT6's underside.  I have it over the pit and have removed the entire rear suspension (it had a 1500 spring, wrong camber), diff, complete axle etc. so it's down to bare chassis allowing full access to the body underside.  I've stripped this of all old underseal and paint etc., repaired a few slightly over-zealous old welded repairs and removed all the old seam sealing.  Luckily I've found no significant rust - probably a legacy of it spending the last 44 years in a heated garage, and doing 97k miles in that time - so before Christmas I applied a surface converter and replaced the seam sealer with Sikkaflex 221 (I have an air applicator for this, otherwise it kills your hands).

Yesterday was the planned day for the Terotex 2000 application (application temp:  10-25˚C), so I had to head off to Screwfix to buy a second electric fan heater for the workshop.  It was certainly cold in the pit, but 2-3 hrs of running the heaters got it up to temp.  I avoided glancing at the electricity meter yesterday...  I got the stone-chip applied fine, and it's now had 24hrs to dry so I'll go and shoot some Carmine Red over it today.  Then it's a blast of Dinitrol 4941 and I can reassemble the rear end, with the 'new' 3.63 diff, on which I've replaced all three seals and the output bearings and fitted a drain plug.  Hopefully I haven't disturbed the pinion bearing preload too much.

It's a little bit warmer today, but drinking coffee and finding a book or two to consult definitely appeals more than trying to breathe through a mask in a 2˚ workshop with the heaters running!

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33 minutes ago, Roger K said:

It's a little bit warmer today, but drinking coffee and finding a book or two to consult definitely appeals more than trying to breathe through a mask in a 2˚ workshop with the heaters running!

Coffee works for me; 'Er indoors is on the settee with a blanket, stove blazing AND a hot water bottle. And she's STILL cold. Outdoors is lovely in the sun with the frost crunching underfoot. I was out tidying the garage and sorting out various parts and it's warm enough, but the other roofspace above the old garage is freezing and the electric blow heater is rubbish. If anyone is ever looking to buy one avoid the £15 rubbish from Tescos on the left - that flat vent thingy that can be laid flat or stood upright, and go for the round version at £19, which is far better. My daughter swapped them a while back, I can now see why, so I've just gone and swapped them back again. If I'm only in the roofspace for fifteen minutes I can't be bothered waiting for the thinner heater to warm up. I'd warm the room faster just by breathing out.

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when they stripped out one of our dealers i won two 4 kw over  showroom door  fan heaters 

these need hard wiring if you use  full power but in 1/2  they resort to a more normal 2 kw but the fan shifts far more hot ait than a domestic unit 

you can boost to 3kw if youre brave 

the garage one is hard wired via a  cooker socket 

Toastie 

Pete

 

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The little Screwfix workshop heater's quite impressive - you can point it up or down, it'll give 2.5kw max and has a thermostat.  The fan is pretty powerful and it was only 40quid, but not up to your showroom door heaters by the sound of them!

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1 hour ago, Colin Lindsay said:

Just my own curiosity, Roger... too cold to do anything else this morning except keep warm and drink coffee but it's something I'd like to know, just in case. I've a spare 3.63 diff in the garage and might use it some day, especially since the GT6 diff has started to whine at low speeds.

 

I searched why bearings need to be preloaded as its counterintuitive. Turns out, apart from removing any risk of freeplay under different temperature conditions, it also ensures full contact of the bearing surfaces. This is logical as in the case of a tapered bearing the angles of the inner and outer race surfaces can never be exactly the same so the roller will tend to only run on part of each. By preloading you essentially force the components together to maximise the contact of the rollers and races which spreads the load and increases the life of the bearing👍

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I understand all that - but you don't normally preload tapered bearing sets in wheel bearings.  Why the difference, I wonder?  Maybe because the wheel bearing relies on grease, whereas the axle bearing is running in oil, so lubrication is better?

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