LT77 Gearbox oil

[CGCobra]

carsy said:

Have a read of this re setting things up.

http://www.gomog.com/allmorgan/remoteissues.html

Thanks Carsy,

I had actually seen that earlier but much of it didn't make much sense until I've (re)aquainted myself with the remote mechanism. Not sure how much of this I'll be able to do as the box is still in the car. Basically after 5 years of storage I've recommissioned the car recently and just got it MoTd, first trip out I thought I'd destroyed the 'box ax it started being very noisy in 3rd with the stick jumping around like an Ann Summers toy. Turns out the remote bushes had disintegrated (or maybe someone stole them because there was nothing left) and the remote wax completely loose, don't know how I was getting any gears. Anyway while I'm sorting this I thought I'd try and improve the 3rd gear up change graunch, never a problem going down.

I wish t'Internet had been as prevalent when I built this car!

[CGCobra]

So, I've come to do this oil change and fallen at the first hurdle. Obviously the smart thing to do is loosen the filler plug before the drain but I can't find it!

All the photo's I've seen have the filler on the offside just above the part number, I can see the bosses in the casting where this should be but no filler, the casting has not been drilled/tapped here, there is a plug on the rear, aluminium housing with 15/16 AF plug (same as drain) is this it? If is th only likely suspect I can see, located at about layshaft height, maybe a little higher.

I don't understand this, I've managed to fill the box once, although that was thick end 9f 20 years ago.

[adam quantrill]

This is weird we had one other post saying exactly this a few weeks ago - even posted photos and the casting is flat where the filler plug should be (usually)!

Maybe you turned the car upside down last time? ;^)

Well there's a removable plate on top which I think you can fill through, held on by a couple of screws. But it might be hard to get to in situ... possibly if you remove the gaiter.

OK I found this "the filler plug is on the nearside (l.h.looking towards the front) approx half way up and towards the back end of the box near the the speedometer take-off point." does that help? Must be a later style or off a different car where the original position wasn't convenient.

Edited by adam quantrill on Friday 29th July 18:47

[CGCobra]

adam quantrill said:

This is weird we had one other post saying exactly this a few weeks ago - even posted photos and the casting is flat where the filler plug should be (usually)!

Maybe you turned the car upside down last time? ;^)

Well there's a removable plate on top which I think you can fill through, held on by a couple of screws. But it might be hard to get to in situ... possibly if you remove the gaiter.

OK I found this "the filler plug is on the nearside (l.h.looking towards the front) approx half way up and towards the back end of the box near the the speedometer take-off point." does that help? Must be a later style or off a different car where the original position wasn't convenient.

Edited by adam quantrill on Friday 29th July 18:47

Thanks AdamI think that's right.

I eventually found a similar quote, it's all I'm left with in any case, filling from the top would be dodgy as I'd have no way to know the level, although I could use a measured quantity. Hoping to get onto it later today so fingers crossed.

[adam quantrill]

Yeah it should take 2l. I use a plastic pipe and then do it standing up, squeezing from a spare 1l oil bottle with a nozzle. The first litre can go in with no fuss but you have to start watching during the second litre because when it brims it goes all over the floor - a waste of oil apart from anything.

[gmw9666]

I have a couple of these knocking around the garage. Awesome for topping up the gearbox with zero drips :-)

https://www.machinemart.co.uk/p/tool-connection-tc...

[CGCobra]

Well I've run a couple of flushes, when I first took the drain plug out it had quite a fir tree of filings on it, no large pieces though, but nice to see, first flush came out quite brown and a bit glittery although my super strong magnet didn't fish many filings out of the oil, there was a small amount on the drain plug, not drained after second flush, that will be tomorrow now, I'm not too optimistic for this box but it would be handy if it could keep me going until the end of the year so I can replace it in a planned fashion.

BTW, the initial drain removed 1.3L if fluid which seems a bit low, maybe some has leaked out or evaporated over the years.

[adam quantrill]

What was in there (by the look of it) was it ATF? That stuff does tend to leak out.

[CGCobra]

adam quantrill said:

What was in there (by the look of it) was it ATF? That stuff does tend to leak out.

It was ATF, I put it in there, many years ago. Before I started this job there was evidence of oil on the outside of the 'box, pink in colour so most likely ATF.

[CGCobra]

I got the oil/Moly in yesterday. Couldn't really get a ride in until late due to traffic but got out later on for about 40min's, the gear change has improved, I am no longer getting the 'graunch' on third gear which I've had since I started using this 'box, second seems a bit harder to get but this could be due to my unfamiliarity (the car has been off the road for over 5 years) and difficulty getting a good action on the clutch due to the confined area in the footwell and not having my 'proper' shoes available.

I guess I've broken my golden rule of problem solving as I've changed a number of things at once so can't really say if the improvement is down to the oil type, the bushes on the remote or the fact I now have the correct oil level ( about half a litre more went in than came out) but it would have been impractical to have done all of these changes separately. Anyway I'm happy with the new behaviour and never liked the idea of ATF in this 'box.

Thanks to all the contributors here and elsewhere, I really wish the Internet had been so easily available when I built this car!

[General Zod]

adam quantrill said:

And the new oil is Mobil one 0W-40 with a dose of Molyslip.

For the flush procedure read here:

Strange gearbox/clutch problem

Stupid question, but you mean Mobil 1 engine oil? Thanks

[adam quantrill]

Yes.

Despite my recent box failure (it spat the oil out and I didn't notice) I still recommend it - did over 30k on it. And it's going into the next box too.

[General Zod]

adam quantrill said:

Yes.

Despite my recent box failure (it spat the oil out and I didn't notice) I still recommend it - did over 30k on it. And it's going into the next box too.

Good enough for me. Cheers.

[KKson]

Both of my gearboxes now running Mobil 1 with Moly and they are lovely and smooth and no cold baulking.

[General Zod]

Here's another LT77 question - do they all have the filter? I am doing the oil on my SD1 Vitesse and there appears to be no third plug leading to a filter. Fill plug is different too- not a square bolt and in a different place. Gearbox has reverse at left and forward, so must be LT77. I was expecting a downwards facing 24mm bolt rearwards of the others but nope.

[andymadmak]

adam quantrill said:

Yes.

Despite my recent box failure (it spat the oil out and I didn't notice) I still recommend it - did over 30k on it. And it's going into the next box too.

I am a bit mystified by this. 30k on a gearbox is nothing, even an LT77!
I can understand the enthusiasm for an exotic oily solution, but the reality is that your gearbox failed prematurely.

According to the designer of the gearbox, Ken Tomlinson, the thing was designed to use MOTUL 80 gear oil, and they even used this very successfully on the (rather more highly stressed) gearboxes in the SD1 Vitesse racers and the TR8s. Ken told me that in the absence of MOTUL 80 then Castrol SMX-S should be used.

I grant you that the shift is a bit reluctant for the first mile or so on very cold mornings, but once warm it's a delight, and the gearbox lasts forever!

ATF is an abomination and should never have been used, but surely using an engine oil in a gearbox, with all the shear stresses involved is not a good idea?

[ElvisWedgeman]

andymadmak said:

adam quantrill said:

Yes.

Despite my recent box failure (it spat the oil out and I didn't notice) I still recommend it - did over 30k on it. And it's going into the next box too.

I am a bit mystified by this. 30k on a gearbox is nothing, even an LT77!
I can understand the enthusiasm for an exotic oily solution, but the reality is that your gearbox failed prematurely.

According to the designer of the gearbox, Ken Tomlinson, the thing was designed to use MOTUL 80 gear oil, and they even used this very successfully on the (rather more highly stressed) gearboxes in the SD1 Vitesse racers and the TR8s. Ken told me that in the absence of MOTUL 80 then Castrol SMX-S should be used.

I grant you that the shift is a bit reluctant for the first mile or so on very cold mornings, but once warm it's a delight, and the gearbox lasts forever!

ATF is an abomination and should never have been used, but surely using an engine oil in a gearbox, with all the shear stresses involved is not a good idea?

Thank you for confirming my suspicions. The only difference being I use MTF fully synthetic. The gears glide in and out except when initially very cold on a winter morning.

Tony. TCB.

Edited by ElvisWedgeman on Thursday 13th April 10:08

[batman400]

I'm using Castrol Syntrans which I believe replaced SMX-S, I put it in the previous box that sounded like a washing machine on spin if you left it in Neutral and it was a lot quieter than the stty ATF that came out of it. I've since replaced the box with a later LT77 from a Griff 500 and I'm using the same oil.

[adam quantrill]

andymadmak said:

I am a bit mystified by this. 30k on a gearbox is nothing, even an LT77!
I can understand the enthusiasm for an exotic oily solution, but the reality is that your gearbox failed prematurely.

Let me clarify.

1. When I got the car it has some oil in the box. This may have been ATF I would have to look through old posts etc.
2. I then put SMX-S in it. Mileage between 10k and 20k? I had problems with cold morning crunching, and hot long drives it would be reluctant to shift (e.g. coming back from BBWF). Otherwise better than ATF.
3. At around 50k miles on the box I put in the mobil 1 + moly. All previous symptoms at extremes went away. Now the box is at 83k miles. When I drained it prior to removal around 20ml of oil remained, this is what caused the failure.

[andymadmak]

adam quantrill said:

andymadmak said:

I am a bit mystified by this. 30k on a gearbox is nothing, even an LT77!
I can understand the enthusiasm for an exotic oily solution, but the reality is that your gearbox failed prematurely.

Let me clarify.

1. When I got the car it has some oil in the box. This may have been ATF I would have to look through old posts etc.
2. I then put SMX-S in it. Mileage between 10k and 20k? I had problems with cold morning crunching, and hot long drives it would be reluctant to shift (e.g. coming back from BBWF). Otherwise better than ATF.
3. At around 50k miles on the box I put in the mobil 1 + moly. All previous symptoms at extremes went away. Now the box is at 83k miles. When I drained it prior to removal around 20ml of oil remained, this is what caused the failure.

AHA! Thanks for the clarification. All understood. Nevertheless I still question the use of Mobil 1 as a transmission oil. I am not an oil expert but my understanding was always that the structure of transmission type oils allows it to cope better with the very high shear forces inside a gearbox. That's not to say that mobil 1 cannot cope at all, but it's not designed for the application. Perhaps the Molyslip helps with the situation?
I was also under the impression that the seals have to be of a type that can accept the chemical properties of the oil, - is it at all possible that you lost your transmission oil because a seal has broken down?