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Rear differential flange removal


Pete Attryde
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Here is how I removed the rear diff flange on my 1996 300 TDi discovery with the rubber 'rotoflex' coupling rather than a conventional UJ.

For safety ensure that the vehicle is onlevel hard ground, diff lock is engaged and that the handbrake is on as well as chocking at least 2 wheels.

First un-bolt the propshaft from the 'rotoflex' this is held on by three large bolts and will require 2x 19mm spanners. Now depending on the reason for removing the diff flange you can either slide the prop back of the central pin and tie it up out of the way or if the prob is be changed as in my case (to a wide angle douple U/J prop.) undo the 4 14mm nuts at the handbrake end (the bolts are captive.). It may be to release the handbrake and the diff lock to allow the handbrake drum to turn for access to the nuts, when they are all undone the propshaft can be removed.

This should leave you with a rear diff that looks like this:-

rearprop001.jpg

reapply the hand brake and diff lock to stop the vehicle moving.

Next to remove the centre pin I used a blowlamp to gently heat the pin to flange joint to soften the loctite used to secure the push fit pin. I then used a long (150mm) M8 bolt and large socket and the new drive flange to make a puller to pull the pin out.

Like this:-

rearprop002.jpg

Tightening the M8 bolt draws the pin out, I found that I had to add an additional spacer to the puller as the bolt seemed to bottom out before the pin came out on the first attempt.

With the pin removed you should then be able to see the 24mm nut that holds the flange to the diff, This nut is very tight, I found that I had to use the vehicle weight to undo it.

rearprop003.jpg

With this undone and removed the flange should then slide out of the diff casing.

At this point it is probably worth replacing the diff seal as per Les's thread here.

Refitting the flange or a new flange is just a case of sliding it down the splines and then re-tightening the 24mm nut to the correct torque setting. The pin then needs cleaning and re-loctiting and then gently tapping into the centre of the flange until it is flush. and then re-install the propshaft.

HTH

Pete.

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Hi all.

According to my copy of the LR D1 WSM the torque spec is 130Nm (about 96 ft.lbs for the metrically challenged). Refer screen dump attached below.

Note that (if fitting a different flange) you should technically check and adjust as necessary the pinion bearing pre-load (with shims - requires partial diff tear-down). This is because these diffs use shims, rather than a collapsible spacer to get the pre-load right. For example, if the new flange is deeper the bearing may be excessively loaded (too tight) and if shorter the bearing will be too loose. Both may adversely affect bearing life and operation, if really loose it could also cause gear-mesh issues. For reference the torque to turn the pinion shaft should be 3Nm in isolation with new bearings (without it meshed to the crown-wheel and no seal), and 1.5Nm if original bearings are re-used (about 26 and 13 in.lbs respectively). That's with the pinion nut done up to 130Nm.

Having said that, I've done it a few times on other diffs without re-shimming and all has worked OK even after hundreds of thousands of kms of subsequent use. I've always checked the end-float as I've tightened up the nut and ensured that I don't tighten it excessively after the pre-load becomes zero (and equally checked that it does actually go to zero). Not really an exact science...

By the way, nice write-up and ingenious "puller" :) Good one.

post-3160-1175593581_thumb.jpg

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  • 1 month later...

Hi Brasco,

I changed the flange on mine because I was fitting a different type of propshaft that required a different type of flange.

However other than that I can't think of a reason to change the flange other than the reasons you have stated and if the flange is that badly worn that it needs changing I would guess that the noises coming from the rear diff would be pretty terrible.

Part of this procedure allows access to the pinion nut which have been known to come loose on some peoples trucks so obviously you would need to get access to re-tighten/ investigate the trouble.

HTH

Pete.

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  • 3 years later...

Cheers for the write up on this, I've just spent the last week sorting out a donut diff to go on my 90 - I should have known it wouldn't be easy!

I had huge trouble getting the pin out - I ended up buying a 1 13/16" socket from Halfords for £13 which fits over it perfectly and can be used with a thick washer and M8 bolt to wind it out.

Getting the pinion nut undone took me and a mate with a breaker bar and a jack handle wedged with some M10 bolts through the prop bolt holes, fighting against each other to get it out (diff isn't on the vehicle, might be easier if it was?). Bent all the bolts but it came off eventually!

The seal took an hour to prise out - tried drilling and getting screws in it, they all pulled out so resorted to a big screwdriver, and pushing the seal inwards to break the rust before levering it out.

Needed the longer prop flange, and having put the seal in I'm not sure if it's gone too far in - it's a lot further than the old one, but having put the flange on I'm wondering whether it needs to go further? This is as tight as I can get it off the vehicle, does it look right? Would appreciate some assurance before I put it all together!

Thanks,

Rich

post-71-128112933212_thumb.jpg

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