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Differential -Options for rebuild and replace?  Rate Topic 
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 Posted: 11-08-2018 01:45 am
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Steve Duncan
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4 speed approaching 120K. Differential is noisy and sloppy. Loudest going downhill. When rear of car is up on jack stands and I rotate one wheel back and forth I am amazed at how much slop is present. Haven't read anything about what happens next or seen anything about rebuilds or replacements. Does it sort of run forever, just sloppier and sloppier?  Can a backyard mechanic adjust it and/or are they rebuildable?  Has anyone engineered a replacement experience like the Toyota transmission swap?  Is this the Achilles heel that finally kills a JH? 

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 Posted: 11-08-2018 09:40 am
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NigelK
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They are rebuildable. All of the bearings are available (at least they are here in the UK) albeit at a price. I had my GT rear axle rebuilt with a Gripper LSD a year ago.

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 Posted: 11-08-2018 12:33 pm
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gmgiltd
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Hi Nigel, coincidentally I am on the hunt for diff bearings - I have already done the wheel end but the diff is getting a bit sloppy. I got a quote from Delta for around 700USD for a full set ( two carrier, front and rear pinion plus seal and gasket) and one from Orinoko bearings in England for the carrier bearings at £56.00 each. They are currently trying to source the pinion bearings seal and gasket. The original bearings were SKF. Do you have any info on part numbers and suppliers?

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 Posted: 11-08-2018 01:35 pm
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NigelK
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Hi Gordon

Speak to Mike Taylor, he sourced the bearings for my diff rebuild (on Trevor’s behalf).

All the best,
Nigel

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 Posted: 11-08-2018 04:13 pm
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NigelK
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Hi Gordon

Based on info from the Vauxhall Viva forum, the following might be helpful (usual internet info health warning applies):

Diff carrier roller bearings - Jensen # 93817, Vauxhall # 2699623, SKF # 415929

Front pinion bearing - Jensen # 93831, Vauxhall # 2682336, SKF # 32206/25B

Rear pinion bearing - Jensen # 93825, Vauxhall # 7141226, can't find an SKF bearing # but either Robey's or Essex Bearings should have them.

Best wishes,
Nigel

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 Posted: 11-08-2018 04:45 pm
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gmgiltd
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Just got a quote back from Vauxhall bearings for a 72-78 Vauxhall Magnum ( 1800-2300cc ) which I hope is the right one.
1. Bevel Pinion Front Bearing at £54.80
2. Bevel Pinion Rear Bearing at £78.00
3. Differential Bearing Number 1 at £64.00
4. Differential Bearing Number 2 at £138.00
All are SKF bearings and in stock
However from this it would seem that there are two different diff bearings and looking at the workshop manual page 29 Fig B11 it shows item 16 bearing on both sides which would lead one to believe that they are the same.

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 Posted: 11-08-2018 06:36 pm
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NigelK
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That’s the right Vauxhall, but I’m not sure why there are two types of diff carrier bearing. There were 2 different Vauxhall Magnum axles used by Jensen, the 3.73:1 cwp version in the 4-sp J-Hs and the 3.45:1 cwp version in the 5-sp J-H and GT. The Vauxhall part numbers I gave you are from the 3.45:1 cwp axle page of the Jensen parts book. I don’t have Vauxhall part number cross references for the 3.73:1 cwp axle. Did the quotation include Vauxhall or SKF part numbers?

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 Posted: 11-09-2018 01:31 am
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Steve Duncan
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My question about if they are rebuildable has been answered. The bearings are available, but at a steep price.
Two follow-up questions:
1. Does replacing the bearings have to be done by a professional shop with appropriate tools, or can a somewhat skilled backyard mechanic do it?
2. When the bearings are replaced does that reduce the slop in the gear lash because as part of the replacement process you end up shimming or whatever the gears back to their original clearances?

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 Posted: 11-09-2018 07:23 am
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NigelK
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Hi Steve

There was a comment on the Vauxhall Viva forum to the effect that Vauxhall axles are easy to work on as all the shims are calculated from factory measurements, so you can simply replace bearings and use the old shims in the same place. This means a competent amateur mechanic can rebuild the axle. I don’t know whether this is true. Perhaps the Haynes manual on the Vauxhall Magnum might offer some advice (or a shop manual if you can find one). You’re probably better off leaving the job to a professional, just for peace of mind.

Best wishes,
Nigel

Last edited on 11-09-2018 10:56 am by NigelK

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 Posted: 11-09-2018 11:02 am
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NigelK
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From the rear axle chapter of the Haynes manual for the Vauxhall Magnum "This chapter has so far shown how to replace bearings and oil seals for the half shafts and the pinion oil seal, as these are considered to be within the average owner-driver's competence and facilities. We do not recommend that owners go into more complex problems of pinion to crown wheel settings, differential gear settings, differential side bearing replacement, or pinion bearing replacement".

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 Posted: 11-09-2018 02:52 pm
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Steve Duncan
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Thank you,this has been very helpful. It's clear that undertaking a project of this magnitude will not only be expensive but also require the services of a professional mechanic with experience in rebuilding differentials. Mine is noisy and sloppy, but something I will have to live with for the foreseeable future. My new rule will be to only drive it with the top down, to minimize the auditory reminder of the state of my car.

Cheers,

Steve

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 Posted: 11-10-2018 08:54 pm
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redracer
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Steve: the shop manual is not too bad for the diff(as well as the 4 spd. tm. section; engine section is rather poor). DELTA used to sell a "differentia;l pack" years ago; not sure if they do anymore. If y9u have a reasonable mechanical aptitude, you may try this yourself. Look through this section and maybe call a friend who can help?

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 Posted: 11-10-2018 10:31 pm
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Steve Duncan
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Thanks, I'll look it over. One thing that makes me reluctant is the ability to get the proper parts. When I purchased the car the seller told me he had replaced the differential and when he did so he had to replace the driveshaft as well. So I think there is a good chance my four speed transmission is now mated with a 5 speed differential. Not sure how to tell the difference. Are there part numbers on them? Other clues? Wouldn't want to spend the dough on parts till I knew for sure.

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 Posted: 11-11-2018 12:00 am
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redracer
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As Nigel pointed out, there was the 3.73 fro the 4 spd and 3.45 for the 5 spd. Have a friend rotate the tire 10 turns and see how many revolutions the driveshaft turns.
As for the seller replacing the driveshaft, the very earl J-Hs had the smaller and easy-to-break smaller(MGB, I believe) "U" joint. We have replaced many of the early diffs with the larger "U" joint holder so the corresponding part for the driveshaft would have to be replaced as well to match.

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 Posted: 11-11-2018 09:43 am
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NigelK
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There should be a letter stamped on the top of the diff housing, just behind the pinion seal. If the letter is a K it’s a 3.73:1 cwp axle. If the letter is a D it’s a 3.45:1 cwp axle. Very difficult to see the letters unless the axle is off the car and on a bench however.

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 Posted: 11-12-2018 05:39 pm
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Steve Duncan
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I live in a condo in Seattle but keep the car at a beach house on the rural Oregon coast, 4 ½ hours away. So, I need to noodle through all my potential Jensen projects well in advance. I’ll be back down there for New Years and will try to determine whether I have a 3.73 or a 3.45. But after speaking with Delta since they told me the bearings for a 3.73 are the same as for a 3.45 (?) I’m not sure it matters much. I’ll also go through the manual to assess the scope of the project and my level of confidence. If the bearings aren’t pressed in, and no special tools are required (can anyone confirm this?) I’ll probably go for it next spring.

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 Posted: 11-12-2018 09:01 pm
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gmgiltd
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From what I can make out on the diff you should not need anything pressed in - someone jump in if that's wrong. I think the pre load shimming is the thing you have to be really careful about most. The wheel bearing and bearing retainer collar need to be pressed or shrunk on. I tried half shaft in the freezer (-18C) and bearing in the oven (+180C) and it did not work. Was not amused and my wife had total sense of humour failure. Ended up making, in the absence of a press the simple tool pictured which worked. The bearing retainer could be heated much more with propane and slipped on no problem - have a damp rag handy so there is not too much heat transfer to the bearing.
Gordon

Attachment: RWBearing.jpg (Downloaded 24 times)

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