GUIDE Rear diff to prop oil seal change 1998 Jimny

EDIT, Update 10 months on. I'm happy to report everything is still perfectly fine with the car but sadly, my image hosting has gone wild, I'll try to fix it, I can always email copies, just send me a request.

I couldn't find anything related to this - perhaps its not common.

The oil seal in my rear diff behind the universal flange (which the prop shaft bolts to) is leaking and throwing oil all over.

I thought I'd tackle it myself as it's not going on the road for a few weeks. Heres what it looks like from underneath, you can clearly see where oil has been flung out in an arch and then run down either side of the petrol tank:



Caution notes:
I believe there are 2 different sizes of seal, I've no idea how to tell which one is which or if that's even true. I'll take mine out, measure it up, then decide what to order.

You will need to stop the universal flange from rotating as your trying to undo a 27mm nut - a flat bar with a few holes drilled into it and bolted to the flange should do the trick, so long as you can still get to the 27mm nut in the middle. I tried an impact driver, a good quality Desouter at 9 bar pressure, with no luck, it need proper arm strength and you need room to move while holding the flat bar - three hands might be useful. *EDIT* as Facade mentions below, count the turns when you remove this 27mm nut, it has to go back on to the exact same position - so a windy gun is a bad idea anyway.


First step, check the breather, if its blocked, this could have caused the oil leak or seal to go in the first place do it before you drop the oil, that way if you dislodge and crap into the diff, it will hopefully be carried out by the oil drop. So now drop the diff oil. Mine has flush fitting plugs with 10mm square holes in it - take the top one out first (the filler/level plug), it's twice as tight as per the specified torque, this is normal - make sure your square on and got a confident fit before swinging, these are know to get rounded and stuck - ask on the forum if you have any queries or difficulties. Be ready to catch about 1.5 litres or less of oil, keep your catch pan spotless, you'll want to carefully pour the oil out after a day or 2 of settling, and look at whats in it, any teeth, grit, etc.

I started by marking the front and rear end of the prop shaft and flanges at either end and removed the prop shaft. (I didn't want to leave it hanging from the transfer box)

Next up is the tough bit, the 27mm nut, first straighten out the locking tab, take time and do this properly or it will make the nut seem 10 times harder, DO NOT TIGHTEN THE NUT, it will cause irreversible over tightening of the bearings and require the whole diff to be removed to fix by means of a replacement crush collar. This is a regular threaded nut nothing unusual, EDIT* as Facade mentions below, count the turns when you remove this 27mm nut, it has to go back on to the exact same position - so a windy gun is a bad idea (mine happened to be tightened flush with the shaft end, so I didn't count anything I just took a mental note and will realign the lock tab when reassembling and bobs your uncle (english saying?):




This nut is not mega tight, it's just a pain to get hold of and work on under the car. I used a pair of driveway ramps to give me a extra bit of swinging space, I wouldn't recommend jacking the car up as your going to be doing a fair bit of swinging! Once off, scribe a small mark on the face of the shaft and on the face of the universal flange. Its not a very clear mark, its just a light scribe so you know which way to put it back on - these spines are oil tight metal on metal, so take care not to damage them (at least on mine they are anyway, I think there is a different design out there.

Out with the crank puller (a 6"/150mm), this is a bit stiff all the way as above, it creates an oil seal:



Off she pops! Notice the rings worn in the universal flange's shaft, this is bad news, it looks worse in the pictures as I've not wiped the oil off which is sitting in the worn portion. When I refit the new seal, I will fit it slightly deeper in to the diff than recommended (0.5-0.7mm) to try and wear a new bit of the shaft. If it doesn't work, I'll have to consider a new universal flange or get it in the lathe and sleeve it which wouldn't be a great idea and isn't helpful advice for many:



There is no lip on the inside of the diff and no seat for the seal to sit on, so when removing the seal get a nice big screwdriver or pry bar behind it and give it some stick! mine had corroded in - I like to push a bit of blue tissue behind the seal to prevent crap going back into the bearings. Take care not to scratch the nicely machined housing - although it's not a game changer if you accidentally do. I have a big ass flat bladed screwdriver that gets used and abused for all paint mixing, hammering etc. we all have one right? - I smoothed the sharp edges off it a long time ago with use and abuse which helps prevent scratches.


It'll stay like that for a few days so I packed it out with tissue and taped the end up with masking tape (and obviously put the drain and fill plugs back in)

Here's the removed seal and another useful shot, It has 3 inner lips and a large outside one.





When reinstalling, tighten the 27mm nut back to the spot where the tab was folded in, as said above don't tighten in past this, there is a crush collar inside, over crush it, and it will need replacing, and/or wear your bearings out quicker - this is rough approach, the manual depicts removing the drive shafts, popping the whole diff out and using various special tools to measure and set the preload on the bearing - this might be beyond many, I don't want to do it, it will take a fair amount if time and accuracy. It's leaking as is, I'll try this mildly rough approach of just putting a new seal on, and tightening the 27mm nut back to where it was. If it only lasts half as long as the last one, that gives me 37,000 miles........ if it doesn't work at all, I've lost a few hours of my free time, and a seal that's price is insignificant in the grand scheme of the full blown "by the book" job.

I hope this makes sense and helps someone. Any suggestions from anyone or tips and tricks, let me know and if I'm not about I'm sure a moderator can edit this post and update etc.?

Thanks for sharing & taking the trouble to photograph the job, another for the 'sticky' cupboard imo .......

Yea , great description , I have rebuilt both my front & rear axes , renewed all the bearings & seals in both ,,,,, I knew their was a seal their , if I had seen his beforehand I would have done this one too , I thought it was a specialist job

Thanks

Gjmcleod wrote: Yea , great description , I have rebuilt both my front & rear axes , renewed all the bearings & seals in both ,,,,, I knew their was a seal their , if I had seen his beforehand I would have done this one too , I thought it was a specialist job

Thanks

It is really, (you should fit a new crush spacer, then set the preload by measuring the torque to turn the bare pinion) but as long as the nut goes back exactly (count the turns), without ever going past the final position it will be fine. Once you go past, the crush spacer will be too short.

You can buy tin sleeves to superglue over the worn flange from bearing suppliers, but the idea of moving the seal to a new place is a good 'un. Once you get wear grooves, the new seal won't last long.

When I was a Landrover boy I used to change the seal in the Salisbury axle by measuring the force to turn the flange and getting that to be the same as before. (That was a proper seal too made out of leather, and you had to soak it in oil first, or it would leak more than usual )

Can anyone help me get the Suzuki Part number for the 40x72 seal, I'd rather use genuine as this one's lasted 72,000 miles! It has this extra v seal built in to the face the mates with the steel dust cup on the universal flange, it was spotless past this seal so it was obviously doing a good job of keeping dust and crap out - I'm not sure how much Suzuki will want to charge me, but I think I'll just get it paid in the hope that I don't have issues again.

facade wrote: or it would leak more than usual )

LOL - its the little things like seals and bearings that have moved on a lot that enable us to make the big things these days!

I've updated the post with your tip about counting turns, thanks. Mine happened to be flush with the shaft end, I just took a mental note without thinking, the pitch is about 0.7mm at a guess so there's no way I'll go to far or not enough it will be obvious.

No worries

I've not done a suzuki, but usually the flange just slides off, then you'd never get an extra turn as it would go massively tight- it does take a lot of force to crush that spacer, but if you are actively tightening against resistance pulling the flange back on you might go a fraction too far without realising.

Once that spacer is crushed the first time, you are only just nipping up against it the second time, not locking the nut tight.

A brilliant guide and the pictures are ace. Nice one.
My Pinin is a bit of a weeper and looks much the same proposition to fix which makes this guide really useful but I think I'll wait till it is spewing oil before I go at it.

I've been informed the photo's vanished. I've done my best to try and upload some new relevant ones, some may be referred to but are missing, sorry.

Very helpful indeed. But how do I get the flange back in? I certainly can't want to hammer slowly? TIA.