LT77 Gearbox - What Oil?

[stevoj]

Mix up here then, Adam is presuming you mean the differential oil and i am presuming you mean the gearbox oil called Difflock! Which one?

[v8s4me]

Gearbox oil.

I've just replaced the speedo sender/transducer and it seems to have the same issue as the old one ie no reading until the gearbox oil gets good and hot. I thought the problem lay with the sender so I replaced that. I've also repaired a wiring fault and re-routed the wires to keep them away from the worst of the heat from the exhaust and sharp edges on the casing. Still the problem persists though. Any ideas?

[v8s4me]

The gearbox has been flushed and refilled with the new Difflock. On a short 12 mile drive today the first few shifts from 1st to 2nd happened without any of the usual baulking and crunching, and only a little bit of stiffness, which went once the oil got warm. Shifting through the ‘box seemed smoother as well and I got the impression that this will improve as things get hotter on a longer run. So all in all, a worthwhile improvement.

However, the speedostill won’t read until the oil in the ‘box is hot! I've fitted a new speedo sender (probably unnecessarily), thoroughly checked wiring up to where if goes behind the dash (I’m not taking that off again!) and fitted new connectors. So what is going on here then?

[Belle427]

Just revisiting this as I’ve put some ATF in a rebuilt LT77 and it’s fine when pottering around but when warm the shift from 2nd to 3rd isn’t great.
I was thinking of trying some MTF94 to see if it improves but just wanted to check this is ok to use.
I don’t really want to fork out £60 for the difflock oil to be honest to see no improvement.

[v8s4me]

This is a very old thread and there is much more up to date information on here if you search. But to save you the bother, get that ATF dog pss out of there as quickly as possible and replace it with DiffLock

[Belle427]

v8s4me said:

This is a very old thread and there is much more up to date information on here if you search. But to save you the bother, get that ATF dog pss out of there as quickly as possible and replace it with DiffLock

Fair enough, will take a look. It says there is a 2 week lead time on the website at the moment.
Another forum seemed to suggest it’s this stuff just re bottled.
https://www.opieoils.co.uk/p-1051-amsoil-manual-sy...

Edited by Belle427 on Monday 5th April 18:09

[v8s4me]

If you run a search on the 'S' Forum you'll find some good alternatives to Difflock. But what's the problem with a two week order time? You won't be doing that many miles between then and now will you?

All I can tell you is that when I changed to Difflock it was like having a different gearbox, and a much nicer one too.

[Belle427]

Ok thanks, will get some ordered.

[adam quantrill]

I'm still Mobil 1 0W/40 plus Molyslip.

Have done maybe 50k on it now. But you pay your money and take your choice.

Yes get rid of the ATF, when it gets warm it gets hard to change gear, especially the synchros.

[Belle427]

Difflock ordered, will report back on how good this unicorn p##s is.

[Belle427]

Difflock Oil turned up today and what surprised me is that it’s in a re labelled Fuchs lubricants bottle and is red in colour. Looks like ATF to me.
I doubt this stuff is blended especially for them but may be wrong.

[v8s4me]

Belle427 said:

Difflock Oil turned up today and what surprised me is that it’s in a re labelled Fuchs lubricants bottle and is red in colour. Looks like ATF to me. I doubt this stuff is blended especially for them but may be wrong.

Don't be fooled by the colour; it's not ATF.

[adam quantrill]

Hopefully it won't Fuchs your box!!! ;^)

[Belle427]

adam quantrill said:

Hopefully it won't Fuchs your box!!! ;^)

I Fuching hope not at almost £30 a litre!

[Belle427]

So oil changed today and even though the shifts feel a little smoother the slight crunch when shifting into 3rd sometimes is still present.
It was worth a shot but didn't really work for me, at least I know the oil is decent quality.
Car is only used sparingly in good weather so no big problem.

[v8s4me]

Did you use it for long enough to get the 'box good and hot?

[phillpot]

Even the best oil can only do so much! Perhaps there is an issue with the gearbox?

[v8s4me]

How many miles had you done on the ATF?

[KKson]

Sounds similar to my SEAC which had been standing 15 years before I bought it. I tried every option on the oil front including expensive Difflok. Made no difference. The synchro is worn so a gearbox rebuild is the only answer. As the box was drained when you got it, maybe the previous owner was preparing to strip it out?

[Belle427]

Gearbox was freshly rebuilt from a reputable company.
Run for around 100 miles on the Atf that they also recommended.
No big issue as I said it's just the car is likely to be sold within the next 12 months and this will probably put a lot of buyers off.