Dropping the diff?

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KevinW
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Dropping the diff?

Post by KevinW »

Failed first MOT yesterday, couple of silly items I overlooked which are easy fixes, but informed I likely have a rear diff driveshaft oil seal leak which has contaminated the disc.

I know my car (Crendon) is different to Hawk/BRA, but I know a lot of owners run the same Jag diff with inboard discs.

Need to jack up the rear and inspect myself, but assuming the above is correct I am assuming it will be impossible to access the oil seal in-situ?

So I will need to remove the driveshaft, and the disc, propshaft and brakelines - any tips for anyone who has done this?
Not looking forward to it. Looks like my plans for DriveIt day and Stoneleigh in jeopardy now. :(
SirrahBRA
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Re: Dropping the diff?

Post by SirrahBRA »

I think you will have to drop the whole rear axle assembly. I have done this recently, 4 bolts in the the top of the diff, then however it is mounted at the bottom. Remove prop shaft, brake line, hand brake cable and shock mounts and drop down on a jack. Ideally on a hoist, I did it on the ground, car needs to be pretty high. Is heavy and hard to move around.

I needed to take the fuel tank out to access the top bolts.
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peterc
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Re: Dropping the diff?

Post by peterc »

Have never performed this operation but can you not just disconnect the driveshaft on the side affected and lower it down out of the way. Then remove the disk to access behind to change the seal? Depending on the type of hydraulic connection you might be lucky to just ease the calliper away from the disc to avoid opening the hydraulic circuit.
I guess it depends a lot on whether you are happy working on your back.
If you do decide to drop the whole assembly I remember it being rather unstable sitting on the trolley jack so be careful.
I have to investigate my diff leak but currently didn’t think it was a driveshaft seal.
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simonjrwinter
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Re: Dropping the diff?

Post by simonjrwinter »

A motorcycle Jack is the perfect thing to lower the diff. You’re welcome to borrow mine if you’re anywhere near….?
TR6 (V8) Hawk 289 FIA (V8) Doing my bit for global warming.
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clive
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Re: Dropping the diff?

Post by clive »

Off the top if my head, I cannot remember which TV show it was, but I recall one of the Wheeler Dealer, Ed China, type shows showing them removing drive shafts from a Jag IRS. Perhaps a trawl through You Tube might find it.
Cheers, Clive.

(If I'm not here I'm in my workshop or on the golf course!)
StuBaker
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Re: Dropping the diff?

Post by StuBaker »

I did mine last week.
From inside the car, on axle stands. Got a few bruises,
Propshaft was out anyway waiting for new one.
Soak the new seal in diff oil overnight (if leather seal type)
Handbrake on to allow the nut to come off.
Drop the diff oil.
Dot mark the nut and inner shaft to ensure it tightens up to same setting. ( Probably not 100% workshop manual but I'm swapping mine out soon)
Undo the nut and pull off the flange with a two legged puller.
Pull out the old seal. It was tougher than I'd hoped but a couple of screwdrivers did it. There's probably a better seal removal tool out there.
Clean up diff, shaft and flange and knock in the new one. I didn't have any tube to match the seal diameter so I bored a bit of 3 X 2 to fit over the shaft.
Refit the drive flange. I warmed it up a bit with a blow torch just to get started.
Don't bash it with a hammer directly or you'll leave a rash, use a spacer, then finish with nut. Again, I think it better to use a press but he who dares...
Tighten up the nut to original position by dot marks.
I'll look in the Jag manual tomorrow for correct tightening procedure. Probably need to measure end float to a few thou.
Good luck.
StuBaker
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Re: Dropping the diff?

Post by StuBaker »

As I thought, the Jag manual cautions against removing the flange without proper setup of the pinion bearing preload, as the collapsible spacer preloading the shaft also needs replacing. Set up is done internally with the diff in bits.
Wheeler Dealer jobs often make me cringe, so although I did the same I wouldn't recommend it for long term reliability. Your diff may end up noisy and failing.
I'm saving up for a replacement diff from Simply Performance. They seem really good value, particularly when you factor in the set up required to assemble one. And the cost of associated measuring kit.
If I had read the manual first I probably wouldn't have done it!! (Almost definitely)
I was just between jobs and too much time on my hands.
KevinW
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Re: Dropping the diff?

Post by KevinW »

Have finally stopped sulking - disappointed that it won't be fixed for a first long drive up to Stoneleigh, which I was looking forward to. Oh well, the price of ownership - a deep breath and a thank you for all your comments.

I think I may be able to do it in-situ as the Crendon has an access panel behind the seats which will allow me access to the disc calipers etc. Advice from Anthony that runs Crendon Replicas is to attempt in-situ first as no other leaks present. Step one will be to remove the half shaft and inspect and establish if its series I or series II, as I understand there are different seals and bearings. Have been informed that if the seal hardened it may have scored the shaft - we'll see. If that proves impossible, it will be diff out, and I'll replace both.
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