Does anyone know - categorically ...? (1 Viewer)

[stcyr]

Hoping some knowledgeable person can help! I urgently need to find out if the mark 1 Sevel vans - C25,J5 & Ducato - have the same differential.
All three come off the same production line but the Fiat engine is different to the Peugeot & Citroen variants and the gearbox is 'different' according to Fiat. Logically one would assume that the 'difference' must concern the bellhousing.
Surely a large manufacturer run by accountants would not produce two different differentials for what is 99% the same vehicle.
I'm aware that gearbox/diff ref.numbers can be checked & compared, but am not in a position to do this - the box on the vehicle only has numbers on the casting which apparently are just that - casting numbers. The little tin plate which apparently should be on the gearbox, is no longer.
The situation is that I've located a gearbox/diff in a breakers yard nearby, on a Mk.1 J5, but can't afford to buy it on the offchance, only to find the diff isn't interchangeable!
And the van is currently filling a large space in the local garage.
Like most garages these days, they only work on part numbers, which is useless because these parts are no longer made, so part numbers are irrelevant.
Despite days of research on the internet I can't find the relevant specs.of each diff.to be able to compare them.
Someone recommended JKTowers - his website states clearly he doesn't give a phone number or give out technical information ... Another recommended No1 Gear (M.Chubb) who deals in parts for old Sevels - I emailed him but await a reply...

I'm between a rock & a hard place at the mo. ... Facts are: all three badge variants are the same apart from the badges & minor trim details. Most mechanical parts are interchangeable apart from the Fiat which has a completely different engine... So there would seem to be no reason for them to go to the expense of designing a diff. for just one of the three.

Does anyone know for a fact if the diffs are interchangeable?

Thanks, in hopeful anticipation!

 

[Theonlysue]

@Geo ?

 

[Snowbird]

The only light I can throw on this is that the J5 is a higher geared vehicle than the Fiat based. Several of the early vans have passed through my hands and the J5 which surprisingly was badged as a Peugeot had a Citroen engine from the CX installed from new and was by far the faster of the bunch.

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[Snowbird]

One guy that may be able to help is Central Axle Services. He specialises in rebuilding diffs, gearboxes and axles. I can personally recommend him. His knowledge on such things is second to non.
http://www.centralaxles.com/

 

[stcyr]

Thanks very much for that recommendation! I spoke to Tim on the phone just now - really friendly knowledgeable guy.
Photos being sent ... looks like we may be getting somewhere!
Hope is that the casings of the diffs are the same so can just be swapped!

 

[Snowbird]

Thanks very much for that recommendation! I spoke to Tim on the phone just now - really friendly knowledgeable guy.
Photos being sent ... looks like we may be getting somewhere!
Hope is that the casings of the diffs are the same so can just be swapped!

Tim is one of the most knowledgeable people I know regarding gearboxes, and final drives. He has rebuilt several diffs for me over the years from trucks to old cars. A native South African that learned his trade many years ago. He is also one of the few that will freely give advice regardless of whether you are having work done or not.

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[Snowbird]

To give you some idea of his knowledge I once sent him a photo of some minute pieces of steel that had been filtered from a diff oil change. He successfully diagnosed where they had come from by the photos, ordered the parts and rang me a week later to take the truck in for repair. He did it whilst I went up the road for breakfast.

 

[tonyidle]

I believe you're thinking too much about RWD vehicles & use of the diff to change the final drive ratio. In a FWD gearbox, normally these days an indirect box, there are many ways to change the final drive ratio only one of which would involve the diff. For example 2.8JTD-engined vans can be supplied with a choice of 5th gear ratios which if changed have the same effect on cruising in top gear as changing the final drive ratio - but obviously have no effect on first to fourth ratios. There's no one-piece laygear so ratio variations can be done by changing any one of gearsets - as well as overall by changing the final drive.

 

[stcyr]

This is on an elderly (1985) Mk.1 Ducato. I just need to know if the diffs. on the J5, C25 & Ducato are the same, so interchangeable. The Fiat engine is different to the Peugeot/Citroen engine so the gearbox is termed 'not the same' as P & C. ... Only looking for a diff as the driveshaft was jammed and the only way to remove the driveshaft was to remove the diff. The splines are still irretrievably jammed and numerous attempts to separate have resulted in damage to the diff 'output'. The only gearbox/diff I can find is on a J5. Just need to know if the diffs on all 3 Sevel engines are the same. As I mentioned above, logic decrees that a company would not make 2 or more diff housings for the 3 virtually identical vans coming off the production lines. Surely only the bellhousing needs to be different to fit the Fiat engine. But need to know for sure before buying the J5 g'box/diff. Don't need the gearbox - probably put on ebay later to recoup some of the cost - just a diff.
Hoping to get a reply from Tim at Central Axle, as recommended by Snowbird, in the morning

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[Geo]

Garages these days due to labour cost only go for the simple fix, not always at the customers request I might add
for example if you had come here with your problem you would be going out with a replacement box even 2nd hand and drive shafts to suite no chance of diff swaps at all
as the time and workshop space required whilst I bugger about with diff variables and compatibility issues is extremely prohibitive. and not a viable solution
these kind of jobs are usualy DIY only. the same as engine swaps from petrol to diesel etc far too many variables for a business to work with.
after all as nice as i want to be to my customers time and space is money either yours or mine and you dont want to be paying mechanics waiting time or dead ramp fees
basic rule of thumbs here but, Yes manf do indeed fit many varying ratios to the same box depending on the final build and planned use,
Second hand searches
Want a pull your house down box, look for a Tipper, Want a long leggy cruising box, look for a Mini Bus, Want a general all rounder look at Panel Vans
and then pray the long legged version you think you found is not a previous transplant from a tipper
The only real way is to start stripping and counting teeth. next best order new from the dealer, again hoping your box is an un adulterated origininal
Part number will be of little use on anything over 10 years old and a gear box rebuilder would be my choice, drop him the box off and let him fix it then pay Garage for removal and re fit if you cant DIY
Geo

 

[stcyr]

Thanks Geo ... Problem is that the van is in the workshop minus the diff which was removed to get the driveshaft off as it wouldn't just knock out as it should. There are very few old Ducatos in France - naturally most people here went for the Peugeot or Citroen versions. Hence the hen's-teeth situation. The only box & diff in a few hundred kms radius is on a J5. Unfortunately, the garage had to remove the outer part of the diff as the splines wouldn't separate. New parts are no longer made for '80s vans. The catch22 situation is: if I buy the box/diff from the breakers then find the diff is physically different to the original we're no further forward. The diff itself is ok - it's just the outer bit with the splines for the driveshaft that's been damaged trying to separate the shaft from the diff. I just need confirmation that only one diff housing was produced for all 3 engines - which logically would be the case ... thought being that they would only need to use a different bellhousing to suit the Fiat engine ... at this stage any difference in ratios is not too important (it's an old non-turbo van anyway, just need it to be mobile ............

 

[stcyr]

These are the bits that won't separate, and are now damaged ...

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[stcyr]

The diff itself is ok