S1 Elite rear end drive overhaul

[AndrewWebber]

After a couple of thousand miles with a 'whining' back end I've taken the plunge in stripping out the rear uprights, links, drive shafts, and brake drums and will remove the diff in the next few days. Everything is pleasantly more accessible than on the +2. I drove it into Lotus Bits on route to the November NEC show to let them have listen and the (not quite 100%) consensus after a drive and then wiggle and run up on the lift was the probable cause was the diff bearing on the input. I'm doing a deal with them swopping out some no longer required Esprit parts towards for their services to re bush / bearing the parts, brake parts and a px 'rebuilt' diff. (moving from 4.1 to 3.7). Thankfully everything has come apart reasonably easily, the chassis and swinging arm change it had in 1989 (80k miles ago) probably helping.
My questions relate to :
The prop shaft, as far I can tell from the extensive historical receipt file, this has never been refurbished in the 153k miles the the car has covered, despite there have been 2 gearbox builds and this will be the second diff and drive shafts. It doesn't seem to have any 'play' in the joints but should I have it rebuilt / balanced while it is so accessible to remove ?, I assume it simply pulls out of the gearbox ? if so does oil pour out of the gearbox ?
The rear shock absorbers have heavy rubbing marks from the inside of the springs and yet the springs in appear in the static state to have plenty of clearance ?

Happy new year and thanks for any thoughts.

Andy

[MetBlue]

Prop does just pull out and I'd expect you'd loose a little oil, but there again, isn't a gearbox oil change worth while whilst easily accessible?
I hear often the modern UJ's are not up to the same quality as the OE fitted. The OE ones I've seen have a grease nipple fitted. I'd be tempted to remove shaft and pump some fresh grease in. If the stuff that gets pushed out looks OK and it comes out of all 4 positions,, I'd leave the originals I think.
Tony

[AndrewWebber]

Thanks for your thoughts Tony, I changed the gearbox (and diff and engine) oil just after I got the car a couple of years and 6000 miles ago, but yes may as well do so again. Yes the prop does have the grease nipples so will indeed take it out and have a good look on greasing again.
Andy

[Lotus-e-Clan]

Std Elite rear springs are long but shouldn't coil bind or rub the dampers IIRC. Dampers should have cover on them, mind you.
Possible (theoretical) causes for spring rubbing (just going by the diagram below):

1) top chassis spring mount bent.
2) top spring rubber mount missing/ wrong spec
3) washer 24 missing /wrongly assembled on bottom damper bolt
4) Incorrect dampers fitted with bottom spring mount incorrectly located.
5) tie rod 26 bent or long stud 25 bent, causing incorrect suspension travel ( the driveshaft is fixed so there would be a knock-on effect - quickly worn U/js, stress in rear-wheel bearings and diff)
6) rubber bushes 3 + 27 wrong spec or collapsed/perished worn. NB the compliances in these rubbers are a key design feature to compensate for the designed-in 'imperfect' rear suspension geometry
7) badly repaired / damaged swinging arm (1)

Probably missed something here, but it's food for thought!

[AndrewWebber]

Thanks Peter for your considered reply. It looks as though it is only the right side one that has the rubbing and I've decided to investigate further by taking the spring and shock out in the next day or so.

Here are a few photo's of the work so far. The shiny metal of the shocker casing is evident in the first two.

Andy

[Lotus-e-Clan]

Having seen the position of the rub , I'd also measure accurately, BOTH sides for comparison, the triangles described by

1) ON the CHASSIS: the distance from the swing arm chassis bush centre (3 in diagram) to the inboard rear tie rod location - both sides equal. (suspension off chassis as you have it)

2) On the SWING ARM: the distance from the chassis bush mount hole centre to the outboard rear tie rod / rearward hub stud location hole - both sides equal (swing arms off car)
For a fuller check of each swing arm geo -just in case of distortion, measure both sides:
a) chassis bush mount hole to damper mount hole
b) chassis bush mount hole to forward hub stud mount hole

3) ON REAR TIE ROD: tie rod bush centres - both sides equal (tie rods off car)

[Marten]

Having seen the position of the rub , I'd also measure accurately, BOTH sides for comparison,

Have the springs shiny rubmarks on the inside? I'd suspect the topcover on the shock first

[AndrewWebber]

Thanks very much for the comments on the shock wear marks. I've taken the (right side) spring and shock out this morning and it appears that both the rubber top cover (there is no metal top cover on the Koni shocks fitted) and also the spring are rubbing the shock casing. There are clear marks / polishing on the inside of both the rubber cover and the spring where they are 10mm or so around the circumference on 3 coils approx. mid way up /down). The rubber top spring seat 'wedge' is fitted and it appears the correct way round (as per the drawing in the manual) up inside the chassis leg, albeit it is quite indented where the spring sat (4m or so). Investigation on dimensions etc. will continue in due course. The inner and outer link bushes are squashed a mm or so each off centre as is the lower bush in the shock, this may of course be more under load.

I'll be dropping the links, bearing carriers, shafts, diff into Lotus Bits on Monday and will also show them the shock and spring for comments. (beyond my credit card number and the low value of my redundant Esprit parts!)

Andy

[AndrewWebber]

Has anyone ever successfully replaced the prop shaft end oil seal in the Lotus (Maxi based) gearbox with the box in situ ? Having pulled the prop out I'm tempted but don't want to make things worse by attempting the impossible! I would remove the exhaust for better access if going to do it. Similarly is it possible to replace the gearbox mounting rubber with the box in situ (suitably supported)?....'project creep'

Thanks Andy

[AndrewWebber]

I've managed today to change the rear (output shaft) oil seal in the gearbox in situ today (exhaust off), but can't quite lift the gearbox high enough on a jack to get the old soggy rubber mount out to replace with new. There is a cast rib on the top of the gearbox tail shaft that is now touching the inside web of the chassis central box and so I can't jack the gearbox any higher to get enough clearance to lift the old mount up and out. I think it needs about 10mm more clearance, certainly to get the new one in. Anyone any ideas? The 'Spyder' chassis on my +2 has a removable gearbox mount cross member on the chassis for the same reason, sensible improvement!

Meanwhile I now have the refurbished 3.7 diff, rear brakes and prop shaft ready to put back in. Bearing housings, suspension links, drive shafts a couple of weeks away yet.

[AndrewWebber]

Having now got the diff back in position in the chassis I thought I record how I did it.

4 post lift, wheeled trolley, giant Jenga pack (could be large wood block). Main issues I found was getting the pre fitted brake pipes at the back of the brake cylinders past the flanges on the Y of the chassis (it maybe easier to fit them after?) and the lift cross bar position meaning I had to have the diff a couple of inches further towards the front of the car until high enough to pull it rearwards, thereafter sitting partly on the lift cross bar (then finally trolley jack) and partly on the 'Jenga' pack then finally on a screw jack to raise the last inch or so onto the front bolts with new bushes / washer pre fitted and held on the bolt temporally with small cable ties.

To my surprise I managed to get the handbrake clevis pins in fairly easily from the side / above, my hand over the top of the brakes (having slacked the adjustment on the handbrake rods in advance) and then the R clips in with long nose pliers from below (I had a couple of spares to hand incase I dropped / lost some but got them in first time)

I hope to collect the other refurbed parts of the drive line / rear suspension from LB next Monday on the way to work in Stafford for a few days.





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Andy

[Pete Boole]

Great job Andy! I also found moving the diff forward first is the only way to get it back in. Good to hear you got the pins in OK!

Pete

[richardw]

Seconded Andy - you’re doing a great job!

[AndrewWebber]

The real test will be if the noise has gone!

[AndrewWebber]

There's been a bit of a delay while I got the Koni dampers checked, re-bushed and set up. First side now back together:



Other side tomorrow.