Lotus Elan and Lotus Elan Plus 2 Forums

The early diff shafts break with both Donuts or CVs. By now even in gently driven cars they need replacing

cheers
Rohan

Thanks for all of the tips so far guys.

I have both CV drive shafts off now and it feels like it's the left output shaft that is broken, as I can't feel any gears moving when I spin it. I have ordered a slide hammer and puller to help ease the bearing out (once the circlip is removed).

If it's a clean break I might try to replace both while the diff is in situ, but ideally I would like to take it out and give the whole area a good clean at the same time as checking for shrapnel in the diff.

The workshop manual says to remove the rear seat back to access retaining bolts under the fuel tank as part of diff removal - is that really the case? My rear seat back appears to have a couple of rivets holding the lower material in, so won't budge at the moment!

Many thanks,

Rich

When I changed out the 3.77 to a 3.54 on my P2, I removed the fuel tank straps and propped up the the front of the fuel tank with a couple of pieces of wood. Made it easier to get access to the bolts. For removal of the axles, I used a heat gun to warm the aluminum case, which help release the bearings. I did make a disc, for slide hammer use, to bolt to the axles in case removal became difficult, but very little persuasion was necessary.

Thanks very much Rob, it sounds like it is a must then. It's a shame to start taking apart a very well put together interior!!

All,

When I undid the prop shaft from the front of the diff, once all nuts/bolts were out and I release the two plates from each other, a load of greenish oil/fluid came out, which I wasn't expecting to see. I guess that has come from the diff itself, but is it supposed to be there? Maybe I have a seal that is leaking at the front of the diff.

I just posted on the other "diff removal" thread that, though everything is released, the bolts are still going from the diff up through to the fuel tank - I guess I have to remove them completely from underneath?

Many thanks

Rich

'When I undid the prop shaft from the front of the diff, once all nuts/bolts were out and I release the two plates from each other, a load of greenish oil/fluid came out, which I wasn't expecting to see. I guess that has come from the diff itself, but is it supposed to be there? Maybe I have a seal that is leaking at the front of the diff.'

The answer is no and no Rich. The oil is not supposed to be there and it is not leaking past the seal. The oil is travelling down the splines of the pinion and the flange, past the pinion nut, and filling up the void between the 2 flanges. And low and behold, when you separate the 2 flanges, the oil that has gathered in the void goes everywhere.

To cure this malaise, you need to undo and remove the pinion nut completely. Clean up the recess in the flange that the nut fits in with some solvent, then run a bead of silicone in the recess and refit the flange nut. Your biggest problem will be getting a socket on the nut in situ, and then doing it back up to the correct torque.

Good luck with it.

Leslie

Just to add to that, Miles recommended putting some Wellseal on the nut thread and splines when reassembling.

Regarding the nut, should it not be straightforward to loosen / tighten on a bench with a metal bar bolted to the input flange to brace it?

Thanks very much guys, I figured it wasn't right as there is no way to "put" grease/oil in there!

Once I have the diff out of the car I will follow your guide, as that area under the car does show some signs of a leak, so this must have been one of the places.

Many thanks again, you guys are a great resource, without you, I wouldn't tackle such big tasks!

Rich

The oil under your car and diff Rich, probably did not emanate from the void. As you noted, a sizeable quantity escaped when you parted the 2 flanges, and it was always a surprise to me whenever I removed a dif from a car, just how well those 2 flanges sealed together.

I think you will find that when you undo the nut and then remove the flange itself, that a groove has been worn in the shaft of the flange, by the seal. In any event, you will want to replace the seal. Should the shaft have a groove, find someone with a lathe who can dress it for you. New seals are very forgiving, size wise, so don't worry if the shaft has to be taken down by up to 60 thou. A new seal can cope. Grease the new seal, do not oil.

Re re torqueing, you will need to do the nut back up to the original torque, and then a fraction more. If you do not do it up enough, the diff will whine like err indoors.

Leslie

Thanks Leslie, that all makes sense. I will take a look once I get the blooming thing out!

Kind regards

Rich

When getting it out be careful that it doesn't drop on you, the pesky thing weighs about 19Kg.

Will do. Thanks Bill!

Update: the diff is out!

I spent an entire evening getting it out because the left bolt that goes through the chassis has corroded itself to the diff housing. In the end I had to cut it off between the diff and chassis (where the two large spacers are), which took quite a lot of work!

Now it's out I can get it cleaned up before getting the output shafts out, but I still need to remove what's left of the bolt. Any ideas? I guess strap the diff to the bench, a bit of heat and try turning it, or tap the cut end with a hammer to try to dislodge it? I have liberally applied WD40 to try to help release it.

One of the circlips is broken, so is missing the hole to locate my pliers, so that's another challenge!

Pics of the bolt:

Be careful tapping the bolt through - support the diff ear or you risk snapping it off. It's alloy and is a known weak spot.

Wouldn't hurt to find a diff brace bar before you reinstall.

If the bolt does not tap out easily with a suitable drift I would heat the ear gently to a couple of hundred degrees and tap again. If it still does not move I would drill down the centre of the bolt about an inch and spray Loctitie "freeze and release" down the hole after heating the ear again. That heat expanding the aluminium plus chill shrinking the bolt should break the corrosion rust bond and allow the bolt to be tapped out if the previous steps failed

You should not have to drive it hard and as previously said support under the ear before tapping on the bolt with a drift.

cheers
Rohan