Gearbox oil refill plug.

[dapinky]

Okay then to try and finish this post (for now) with some definitive information....... All measurements were taken at 'ride height' on a level garage floor.

Having used the 'D' plug to fill the gearbox yesterday, only to not get anything dribbling out, I did it the 'proper' way today....... and found (like others have mentioned previously_ that the bolt holding the clamp plate for the speedo drive had previously sheared off and the plate was missing - so the speedo drive was held in by gravity and friction (it was all covered in oily crud, so it's been like it for a long time). Anyway, there is about 7 or 8 mm sticking out of the gearbox with a good M6 thread on it (I checked with a new nut), but not enough to get at it to remove it.... so I will fabricate some sort of bodge tomorrow using an M6 female rod joiner to give a usable M6 female 'hole' albeit raised by 20mm so it will need some bent bracketry - can't see it being beyond the wit of man to make something that will work.

Anyway, back to the point of the post - when I got the drive out and the hole cleaned up, I couldn't find my old dipstick in the toolbox. so made up a new version from a length of aluminium plate, 38mm long, with rounded corners - this just fits into the top lip of the speedo drive recess, drilled a 6mm hole in the centre and bolted a length of M6 stud through it, with a pair of nuts locked together 25mm down from the plate (this is the distance I measured from the underside of the speedo housing and the 'MAX' level) the 'MIN' level is 5mm further down, and as the nut is 6mm thick, it's a bit of a measure of how much is needed.... the stud protrudes a further 15mm beyond the nut...... it has about 5" of stud out the top for a handle.

By sitting the plate in the hole, (you can get an arm down between the heater pipe and the coolant tank - it is easier if you loosen the 2 clamps on the heater control valve and swivel it round out of the way) it is easy to check the level of oil.

Filling it up was simply a length of plastic plumbing pipe (15mm PEX semi-rigid pipe) dropped into the hole with a funnel in the end, and pouring the oil in. As I was starting from an empty (or as empty as it is ever going to get without stripping the 'box) I knew that it should take 1.8L of oil (except some books say 3 pints, and don't say if they are UK or US pints, and all 3 quantities are different!) - in fact, the only useful thing I knew is that I had drained 1.7 litres out yesterday - but I didn't know if it had been filled to the correct level, so was really working a bit blind.

I put 1.5L in and then tried the dipstick - it didn't register at all, but I could see oil in the hole..... so I added another 100ml and it just registered. Another 100ml took it to the lower level, and a further 120ml took it to the highest level.

So, now we know that the difference between the lowest and highest levels is 120ml, which may be useful to anyone topping it up.

We also know that it took 1.82L of oil from empty to 'MAX', but anything between 1.7 and 1.82 would be in the right range....... so lets agree that it is a 1.8L capacity, but 3 Imperial Pints will get it to the MINIMUM level!

Okay, so now I decided to see how much I needed to add before the 'fill plug' overflowed...... and so I added oil 200ml at a time and never found out as it got to the top of the speedo hole before it flowed out of the 'D' plug hole. The only way to find out would be to put the speedo drive in, then fill through the fill plug till it overflows, then drain a load out and refill from that quantity until it is the right level, see what you have left and do some maths!

I can't see any point unless someone has literally stuck the speedo drive in with chemical metal or similar in the past and the only option is to fill through the 'D' plug - but in that case, I can assure you that from a drained 'box, just chuck in 1.8L through the 'D; plug and it'll be close enough - but don't wait until it drips out - IT IS NOT A 'FILL LEVEL' HOLE!

Anyway, it's now got the right quantity of new oil in (because I drained it again and refilled it by chucking 1.8L straight in and then checking the dipstick), and I just have to re-fit the speedo drive tomorrow.

[chrism]

Yep this time last year I, too, was seduced - then befuddled - by the D-plug seeming to offer a 'fill level hole'.

I wasn't convinced either so I topped up with 1.8l (Comma 75w/80 GL4 fully synth) through the speedo drive (I recall needing to use a flexible drive on the fixing) and tho' I can't remember how I came by this volume I'm mighty glad that you've confirmed it in a very practical way

So I reckon...

Easy-peazy: From now on folks forget the D-plug complication. Chuck in 1.8l and get a slick gearchange and a much smoother ride...

[jgbff7]

With the head off my engine I am changing the gearbox oil having reasonable access to the filler. My stud is also broken with about 6mm remaining and no retaining plate.

The removal of the speedo drive was not easy but I found the best method was a vertical pull. I protected the jaws of a mole grip with masking tape and managed to get sufficient purchase to lift the unit out easily without damaging the threads. The O ring was very loose and looked very old.

The piece that holds the speedo cable to the drive (looks rather like a long socket) was completey broken and disintergrated as soon as I put a spanner on it. I suspect I shall have to replace the speedo cable.

John

[simonbuk]

What a lovely day i had ..............nothing to see here....

[Tuga2112]

What a lovely day i had ..............nothing to see here....

nothing that a MIG machine and a old hub nut cant fix in a few seconds....

[simonbuk]

My initial comment was rather differernt ! I was filling up quite happily and getting towards the last few hundred ml without incident. Then i spotted the dribble, thought it was from the drain plug socket but it was coming from higher up, the drive shaft oil seal. I realised that after i had to take it back out once it clearly hadn't popped back in fully, popped it back in and dried everything off.
Needed a tad more oil as i lost a bit on the floor so some new stuff arrived today.

What a nice easy job to do today i thought - top it up and forget about it for the rest of the time i own it - whoppee - what a simply rewarding job this would be...................

I finished topping it up to the correct level and went to put the speedo cable back for the last time and secure it. Was fumbling around trying to find the retaining plate to swivel it back into location ......nope, nope, couldn't feel it - its gone . Spent the last couple of hours trying to find it but no joy. Has it fallen into the gearbox ??

Well i could be truely f*cked here.

Waiting for a new magnetic pokey thing to see if i get lucky and pick it up from a place i can't see/reach but i believe i've looked everywhere.

What are the chances of me getting it out if it has dropped into the box ?!

Is there any space around the gears for it to fall to the bottom or is it going to be jammed somewhere ?

Could I pull the driveshaft out and hope that i can see it/retrieve it ?

Oh blimey what a day...........

[chrism]

Simon I remember changing my gearoil a while ago and can't remember seeing a hole big enough for that plate to fall down.
I'm not far from you and I've got a magnetic pick-up tool you can borrow if you need it before the w/end.
I've also got an endoscope you can borrow, too..

[simonbuk]

Draper Endoscope 31758 with magnetic attachment - I owe you EVERYTHING !!!

I literally would have been at breaking point if I hadn't of found it and had to remove the box again

[Tuga2112]

how good is the quality of the image ? does it allow you to save the video and extract it to the computer?

[simonbuk]

how good is the quality of the image ? does it allow you to save the video and extract it to the computer?

No download facility, only live viewing.

[simonbuk]

Does this look like the standard retaining plate on the speedo cable ? I'm sure mines be tampered with

IMG_20260131_131533943_HDR~2.jpg

[chrism]

Here's mine, from a '90 SE.



Your S2 might be a little bit more rectangular but it's essentially the same?
Doesn't it just swing around and hold the speedo cable into the 'box when the bolt's tightened down?

[simonbuk]

Mine hasn't got a nut on top, I've got an extra brace bit that clamps down on top that bolts to the side of the casing. Doesn't look Lotus ! I'll take a photo tomorrow.

[chrism]

Now you've got me thinking...it might have a slight 'L' shape along the top edge of my pic, pointing downwards?

A bit vague, I know. I changed my g/oil in Aug '22. I seem to remember that 'nut's' the top of the bolt that tightens it down? (And where's yours?)

It did feel it looked a little bit 'Heath Robinson' at the time...

[Simon_P]

Simonbuk, it looks like someone has made you a nice new one! they are usually like chrism's with either a screw or a stud and nut.

Yours doesn't appear to be securing anything Chris.

[chrism]

Hi Simon_P, yep I think I must have stopped to take a photo (or undergo stress-counselling ) after finding ways of wrangling that bolt loose.

I think that might be a pic of when I must have turned the plate to one side before pulling out the speedo cable, then pouring in the g/oil...

Edit:- just checked: After g/oil addition and the cable being plugged back in, the little square plate then swings around 90* anticlockwise to lay across the flange of the speedo cable drive to hold it firmly in place after the bolt's been tightened - that's the Heath Robinson bit imo. ie no L shape; it's just a square plate - with a bolt through it (in my case)

[simonbuk]

This is my specialist piece of equipment that holds the retaining plate down !!

IMG_20260201_125123985_HDR.jpg

[chrism]

Yep that looks like a little bit more Heath Robinson-ish. Isn't there a bolt hole where mine is?

It looks like your rectangular plate could fit like mine does if there was a bolt through it. (It's actually difficult to see how yours works?)

In any case my speedo drive was a tight push fit and this plate just seems to 'top it off'.

[simonbuk]

Yes there is a stud which they plate can go on but it's not very long in length, if I put a spring washer on top there's no space left for a nut to go on. Couldn't risk/attempt to see if the stud would unscrew so left it.

My contraption bolts into the side of the gearbox and the threaded part/bolt comes down on top of the small plate holding the Speedo cable down.

[chrism]

Well they're both primitive ways of making sure the speedo cable stays in place - and they both work.

Just a thought, why bother with a spring washer? If the nut can purchase the thread, put some thread sealer on the short stud and sympathetically wind it up. I doubt there'd be any forces on it to pull it apart in normal use.

OR stick with your tried-and-tested contraption (now) knowing the story behind it (which might be difficult to get out for the next gear oil change tho').