Lotus Elan

S4 differential removal issue

PostPost by: Wills » Thu Dec 30, 2010 5:31 pm

I have started the process of stripping down an S4 for a major overhaul. Body and rear suspension removal has gone swimmingly but we have hit a bit of a hurdle at removing the differential.

The rear suspension is removed both sides including the drive shafts. The propeller shaft has been disconnected and removed. The four diff connection points have been removed. The diff is obviously loose in the chassis but i can't get it out. The workshop manual says to remove it from the left side. I can't drop the diff low enough for the upper mounting to clear the top cross member where it meets the left rear turret while also allowing the lower right mounting to lift above the bottom plate of the chassis. It's about 3mm too small.

Has anyone had similar experience or any tips?

Very grateful for responses.
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PostPost by: gjz30075 » Thu Dec 30, 2010 5:50 pm

Yes, I believe we all have. Your procedure is correct; it comes out the left side. Once you find the correct 'angle of the dangle', it'll pop out and then wonder why it took so long.

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PostPost by: oldelanman » Thu Dec 30, 2010 5:54 pm

Hi Wills and welcome to the forum.
Removal and refitting of the diff is a tricky operation and if you use the search function on here you will find lots of previous discussions on this topic. The trick if I recall correctly is to rotate the diff - I think it's clockwise when viewed from above - as you simultaneously roll it off the left side of the chassis. If the chassis has been carelessly jacked under the diff it could be bent upwards and that may make removal more difficult, otherwise persevere - it went in so it must come out ! I have also found when refitting that if you use a couple of layers of heavy gauge polythene between the diff and the chassis it makes it easier to manoeuver and reduces damage to the paint on the chassis itself.

Good luck.
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PostPost by: bluesbrother30 » Thu Dec 30, 2010 6:13 pm

I just went through this with my S-3. Before wasting anymore time, and as Roger said, check to see is the chassis is bent upward around the diff. That is from someone (of course not you) who has put a floor jack under that nice flat area and raised the car. Stand off to the side and check to see is there is a big "whoop" upwards. Mine was bent up almost 3/4 inch and made it impossible to get the diff out. We had to use a small jack to spread it enough to make removal possible. Then during the chassis rehab, spent some time getting it square. Diff now goes in and out w/o problem.

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PostPost by: nebogipfel » Thu Dec 30, 2010 6:47 pm

On my car I had added the upper diff brace (Sprint mod') and found that it had to be fitted in situ, I couldn't get the diff in with it attached, so presumably it will have to be removed first to get the diff out.

It's not standard fittment on a S4 so probably isn't an issue on your car.

FWIW I also found that when the diff was in the correct position it almost fell out and I couldn't understand why I'd had a problem :wink:

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PostPost by: AussieJohn » Thu Dec 30, 2010 10:50 pm

I struggled for ages trying to get mine out of my +2, I had it almost out but stuck so went to have a coffee, when I came back the bl**dy thing was on the ground under the car.
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PostPost by: Dennis 45/9760 » Thu Dec 30, 2010 11:14 pm

At the risk of offending purists . . .

We also found that you could "clean up" the aluminum and steel castings by removing some of the non-functional flashing from the casting process along the parting line at the bottom center. These are non-functional areas and they do lighten the car (less is more). Gives you more clearance (just enough).

We found the unit went back in much easier.

Good luck. As others have written, it went in, it will come out.
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PostPost by: Wills » Tue Jan 04, 2011 5:29 pm

Thanks very much for the pointers guys. No obvious signs of distortion in the chassis so I shall continue to struggle. We left the diff for a bit and removed the front suspension and engine/gearbox instead. I'm about to have a second go.

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PostPost by: miked » Tue Jan 04, 2011 8:01 pm

I have had diff's in and out of Elan Plus 2's and ?lans but I have an S4 project car with a new 26R type chassis and could not get the diff in, no matter how I tried. This was on two work mates at waste height, so no lying down issues.

In the end I pulled it in with a ratchet binder strap. The top cross part dimpled a bit as the top ear passed under. Bit of paint to fix. Presume yours is a Lotus Chassis. I put it down to poor build tolerance.


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PostPost by: elansprint71 » Tue Jan 04, 2011 8:13 pm

AussieJohn wrote:I struggled for ages trying to get mine out of my +2, I had it almost out but stuck so went to have a coffee, when I came back the bl**dy thing was on the ground under the car.

Same thing has happened to me! Of course I had left the oil in- which was all over the floor!

Waggle it about, twist it as suggested, you could even bend the chassis down (opposite of the jacking-up syndrome) to get it out and bend it back afterwards. Double-checking that you have removed the diff-brace; looks like a piece of angle-iron.

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