Gearbox Oil Change

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Gearbox Oil Change

Postby nhaynes » Sun 22.05.2016, 08:03

Gearbox tools3.jpg
My car is a 1992 example with 48,000 genuine miles. I've always wondered if the gearbox oil was changed as I have no record that it has anything else other than the original factory fill. My thinking is that 24 year old gearbox oil may need a change! I'd purchased 2 litres of Castrol Syntrans Transaxle 75W-90 but had been putting off the oil change as I'd red on here was a sod it is to refill the box, well that's an understatement! Lotus really didn't have a strong design for service ethic did they!! Anyway, thanks to everyone whose already posted on here with useful comments, correct tools and removing the coolant header tank are essential. Jack the car up on axle stands so you can safely get underneath, I just jacked up the left side and put the axle stand under the alternative jacking point beneath the bolts securing the rear end of the front suspension rafts to the chassis front cross member (consult WikiLEC) if you're unsure. I also took advise from a member years ago and bought some rubber hockey pucks which I sandwich between the car and the trolley jack and the car and the axle stand for a bit of extra protection to the chassis. Once the header tank is removed you just about have access to the bolt retaining the speedo cable clamp (see picture to see how I did this with all my socket spacers), loosen it slightly and it will rotate clockwise to allow the speedo cable and gear to be withdrawn from the gearbox housing by about 30mm, just enough space to get a hose in to fill up the oil. Now you've confirmed that you can actually get into the gearbox to fill up, you can complete the relatively simple task of removing the gearbox sump plug and draining the oil. The plug is a great big thing on the bottom left side of the gearbox. It has a rubber O ring which squeezes into a chamfer counterbore, worth remembering when you re-tighten. Mine took a fair old force with a long ring spanner to remove, confirming it's never been removed before. To my surprize, 1.8litres of oil ran out into my collection tray (the old kitchen washing up bowl) and on closer inspection, didn't look in bad condition. I didn't test for additives but there was no debris that came out. Once all the old oil is out secure the sump plug and remember the rubber O ring has to be squeezed until you get a metal to metal joint, I couldn't find the specified torque. Now re-fill the gearbox with 1.8 litres of oil (see picture to see how I did this with garden hose and a funnel. Be sure the end of the hose is actually in the gearbox, its worth testing with a small quantity of oil first to make sure it is, you don't want 1.8 litres on your garage floor! In my case I was glad I checked as the end of the hose had indeed come out and so I had to juggle it back inside the gearbox past the speedo cable and gear. Once filled with 1.8 litres, the job is nearly done, remove the filling hose, jiggle the speedo cable and gear back into its home position, rotate the securing clamp back and tight the bolt securing the clamp, again sorry I didn't find the specified torque. Re-fit the coolant header tank and refill coolant. Remove car from axle stand. Job done!
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Thanks,
Neil.
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Re: Gearbox Oil Change

Postby Simon_P » Sun 22.05.2016, 11:43

It is worth making sure that the speedo gear is properly meshed. It is possible for it not to mesh and sit on top of the drive gear whilst appearing to reassemble correctly.

Hidden in a backwater on this web site.... from the old website in the days before the wiki existed.

http://www.lotuselancentral.com/repair/transaxleoil.htm
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Re: Gearbox Oil Change

Postby Candles » Sun 22.05.2016, 20:49

nhaynes wrote:Remove car from axle stand. Job done!


Great write up! With a name like that, you should write a manual :lol:
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Re: Gearbox Oil Change

Postby HJ2 » Sun 22.05.2016, 20:53

:lol: :lol: :lol: :agree:
If you always do what you always did, you always get what you always got
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Re: Gearbox Oil Change

Postby lotusflasherman » Mon 23.05.2016, 13:49

Torque for Gearbox Drain plug is 39 Nm or 29 lbf.ft (Section TDH Page 7)

Note the Speedo Drive retaining plate bolt is only 6 Nm / 4.5 lbf.ft so don't eat 3 Shredded Wheat... :lol:
Phil

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Re: Gearbox Oil Change

Postby roy666 » Sun 25.04.2021, 12:31

High All – I thought I would tag onto the end of this one rather than start a new trail. I’m in the final throws of refurbishing the nearside suspension, which included a refurb of the drive shaft as well. I’ve drained the gear box fully now, although I wasn’t able to do it with the engine warmed (the car has been up on jacks for 2 months) and I notice the oil is really quite black. Is this normal? Is there a way of flushing out the gearbox other than, I suppose, pouring in more oil through the speedo hole for it to come out of the drain hole (bit expensive on oil!). Also, I’ve seen mention of making sure to change the driveshaft oil seal on the gearbox, on the De Roure site I identify it.. or find a part number. Any thoughts much appreciated. Cheers Mike.
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Re: Gearbox Oil Change

Postby Simon_P » Sun 25.04.2021, 13:39

The oil seal is no.11 on the gearbox assembly dwg.

I think that the original spec was the same as the engine oil which is basically the same as gear oil with aditives to make it GL4. So you could flush with fully synthetic engine oil. Personally I wouldn't bother anything that didn't come out with the oil is probably better not disturbed.
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Re: Gearbox Oil Change

Postby roy666 » Sun 25.04.2021, 14:00

Thanks Simon - I will leave it alone. Which diagram on DeRoure..47.07a? ta M
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Re: Gearbox Oil Change

Postby Twayblade » Sat 03.07.2021, 11:40

above info really helpful in advance of carrying out a gearbox oil change.
I've just changed mine as a precaution, my M100 has done 37400 and I acquired it a few miles short of that back in Feb this year. Just in case its useful to someone else I found using a length (460mm) of 21mm PVCu overflow pipe and a funnel an easy way to refill the tranny with 1.8l of 75W-90. You have to move the speedo drive clear of the hole so the pipe can locate properly but this is not a problem, just be careful not to contaminate the drive assy with dirt or dislodge any dirt into the speedo drive aperture.
Now, I have to admit i haven't had chance to road test yet but the point made by Simon about the possibility of incorrect meshing upon reinsertion of the drive is bothering me. I would hate to think that getting this bit wrong could result in damage or chewed bits of debris ending up in the tranny, is there a way to verify the speedo drive is located correctly with out driving the car or does anyone have further advice on this particular aspect?
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Re: Gearbox Oil Change

Postby robertverhey » Sun 04.07.2021, 22:56

Have done this job a few times and never an issue with the Speedo gear sliding back in easily. I too use the articulated extension socket method and funnel with pipe. The seals are readily available GM part, several sellers on eBay eg https://www.ebay.com.au/itm/153711210055

Buy a couple, they are easily damaged on first attempt. Mine was, and then I made up a suitably sized drift.

Robert
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Re: Gearbox Oil Change

Postby TorqueHorse » Mon 05.07.2021, 02:20

For the driveshaft oil seals, I just did these, and this technique worked for me (and while I had the engine pulled, I think you still have similar clearance from the underside with the prongeron removed). I went out and grabbed a 50mm socket, and scavenged a bit of 2" pvc pipe laying around, a wood block, and my trusty F bar clamp (~5" throat).
Image
Yes, it was a bear to get everything in place and lined up while tightening, but eventually I got firm pressure being applied to both seals. One of the seals seated itself, just with me tightening the clamp; the other got started and then I could go around and strategically whack it in as needed.

Previous attempts with other things as drifts just by themselves didn't really work for me; they would just end up going in crooked.
Image

Hope yours go in even easier :)
-Matt N
'90 FED M100 -mid resto
Chassis Exterior FrSus RrSus Engine Trans Wheels Steering Brakes Cooling Fuel Ventilation Exhaust Interior
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Re: Gearbox Oil Change

Postby par » Mon 05.07.2021, 13:04

Leaving the new driveshaft seals in the freezer overnight also makes it easier to fit them.
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