Gearbox stuff

[Jaba]

I have been investigating a strange transmission related rumble from my newly relaunched Hurricane.
When I came to having a look at the diff as a possible source I came across something which I do not fully understand ( not the first time of course).......................

The issue is the diff bearings in the pic. According to Haynes these taper bearings through which the driveshafts pass have an adjustment to set the preload by using a suitably sized shim between the removable speedo drive adapter (held in my gloved hand) and the left hand bearing, the right hand bearing just sits in the gearbox/diff housing and is therefore fixed.

Without some sort of adjustment the bearings would either be too tight or too loose and either grind or rattle or worse. Unless of course the components of the whole diff assembly are put together selectively to achieve perfect adjustment.

So following my diagnostic path I decided to check the preload by removing the speedo adapter housing to check the size of the shim present as I had removed the housing during the gearbox removal and it could have been lost. There was no shim in there. I then looked at two other gearbox diffs and found no shim present in these either. From this I deduce that the BOL is not correct and shimming is not done any longer.

So how exactly do you achieve that perfect preload of 0.01mm ? And if you fit new bearings things become more difficult.




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[Geoffrey Gould]

Hi, I would be having a Very careful look at the bearing by your blue hand as it looks as if it has been running rather hot being as it is discoloured, is there a gap between the flange on the housing and the diff case, it looks like it in the picture but it is hard to judge, gives the impression that it may be running with too much preload.Measure gap with feelers when just lightly nipped up -- shim minus 0.01mm to give preload? If there is no gap then the rubbish above does not apply and start again.
But I really would check the bearings.
Cheers.
Geoff.

[citronut]

service citroen show the below "ADJUSTING WASHERS SET"

showing only on the speedo drive side bearing


part No., dimentions and description
2357 A4
MGB ADJUSTING WASHERS SET
55 X 62

price and part No.
Part Number Description Quantity Price excl. VAT Price incl. VAT Total incl. VAT Selection
00002357A4 WASHERS SET 22.22 GBP 26.66 GBP 26.66 GBP


regards malcolm

[Vanny]

Most of the details in the BOL relating to the diff seem to be wrong IMHO. I get the distinct impression that the book is based on an early Mk1 and never fully updated for the Mk2, hence talk of holding up the sun gears when removing the drive shafts.

It might be worth having a look in a Haynes for a later model (eg Xantia/406) and see if it mentions the same shimming procedure.

[BX Bandit]

Never seen shims in there Jaba, all be3 boxes I've had apart. So I suspect the reference to shims is based on be1 boxes, perhaps when tolerances were too large to consider a 'one size fits all' approach.

I agree will Geoff that the shell looks rather blued, caution needed me thinks.

[citronut]

service citroen list the shim washers for

DIFFERENTIAL 1,580L AND 1,769L AND 1,905L AND BE1 AND BE3

and they fit all the below models

1 document(s) found for C2
5 document(s) found for C4 PICASSO
3 document(s) found for XANTIA
3 document(s) found for C5
3 document(s) found for XANTIA II
15 document(s) found for BERLINGO (M59)
4 document(s) found for DS3
5 document(s) found for XSARA
3 document(s) found for C5 (X7)
1 document(s) found for BERLINGO
2 document(s) found for C15
15 document(s) found for BERLINGO (M59)
1 document(s) found for C-ELYSEE
2 document(s) found for C3 PICASSO
2 document(s) found for C3
1 document(s) found for XM
1 document(s) found for SYNERGIE
4 document(s) found for BERLINGO (B9)
4 document(s) found for C3 (A51)
3 document(s) found for ZX
1 document(s) found for C4 (B7) - DS4
3 document(s) found for XSARA II
4 document(s) found for BERLINGO (B9)
11 document(s) found for C4
2 document(s) found for C5 II
4 document(s) found for DISPATCH III
1 document(s) found for C3 II
1 document(s) found for BX
1 document(s) found for C4 PICASSO (B78)
1 document(s) found for DISPATCH I & II

regards malcolm

[Thread Bear]

Is this not the very area which is a problem on the Pug 405 1.9 diesel turbo? Especially if used as a towcar. The reason I passed mine on was due to end float that was in the drive but not drive shaft, hub etc. Consensus of brains including Mike the MOT chum, was diff. Eventually the bearing dies taking out the gearing and I am told quite a few 405 went to the scrape with this, beyond economic repair. The 405, little bit more power, lot more weight, tipping over the edge of reliability?

Does not answer the question though.

[Jaba]

Thanks for the replies. I think I am getting near to an answer ??

@TB See below.

@Geoff : The pic is of a duff gearbox that I took the diff off of to have a look at how the thing went together. I dont know if the marks on the bearing are overheating or simply the sealant used to make it oiltight. But either way this box and the bearing are damaged as it was run (not by me ) with bolts from the gearbox to engine which were never tightened up so that eventually either the clutch release bearing never actually disengaged the clutch or the RH driveshaft came out engagement with the diff .
But thanks for the suggestion, the BX gearbox is less of a mystery now.

@bandit : You confirm my experience that these shims are not fitted during manufacture.

@Vanny : Yes the BOL needs 'interpretation' I have looked at a Xantia manual and this mentions the shims as well, so they do or might at least exist.

@citronut : thanks for the info that the shimsets are listed. This proves somewhat that they are obtainable if needed.


So what I distill from this is that shims are available to adjust the diff bearings but they do not seem to be fitted ever in the factory.
I can only assume that a selective assembly is used and the speedo adapter housing is available machined to give the correct preload. I can't believe that the whole diff housing in the gearbox is machined accurately enough to give a perfect setup as there must be tolerances in the manufacture of all the components, never mind when the diff bearings are ever changed, to need some sort of compensating adjustment for.

None of the above really matters unless the diff is removed for any reason. But if it is then we are now more aware of potential eff ups.

In the meantime I still have this unusual rumbling transmission whine to sort out. But not until the spring as some things BXwise can wait.

[electrokid]

I still have this unusual rumbling transmission whine to sort out.

Chatting with Andy Baker (Andy's Autos, Woking) when my BE3 failed there can be any symptoms from "complete and sudden failure" where the car has to be recovered and bits of gears and castings swept off the road, to "failing but still driveable" which is what mine did.

On my GB a tooth seems to have fallen off one of the gears in the diff, got between the diff and the casing and punched a hole in the ally casting between the diff and the clutch housing, and cracking the diff housing for good measure. This allowed GB oil to leak slowly out which made the GB whine when it ran out of oil - still driveable without any clocks / judders etc ! Good luck with the fix.

[BX Bandit]

I can only assume that a selective assembly is used and the speedo adapter housing is available machined to give the correct preload. I can't believe that the whole diff housing in the gearbox is machined accurately enough to give a perfect setup as there must be tolerances in the manufacture of all the components, never mind when the diff bearings are ever changed, to need some sort of compensating adjustment for.

None of the above really matters unless the diff is removed for any reason. But if it is then we are now more aware of potential eff ups.

In the meantime I still have this unusual rumbling transmission whine to sort out. But not until the spring as some things BXwise can wait.

The speedo adapter won't be machined to match Jaba for several reasons but mostly due to the fact that the parts can be manufactured within the necessary tolerances. When cold there should be some play anyway so that they don't become stressed when hot/expanded.

It would be worth checking the intermediate bearing on the o/s drive shaft as this certainly gives a rumble when it's failed. Not heard one whine though.

[electrokid]

Although it's almost certainly not the only thing that does it - it certainly whines when the GB runs out of oil - but mostly when it's almost completely dry so if you put some GB oil in the top vent - even 250ml will quieten it down until it runs out again.

[citsncycles]

I've also had one (albiet a BE1 box) have the diff bearings fail and the diff chew its way out the housing - apart from an oily smell and high gear oil consumption it grove from Gloucestershire to Lincolnshire and back towing a small caravan and hauling a load of bicycles.