LT77 Gearbox oil

[TV8]

I found this great for the Rover gearbox on my last car. Much smoother gear changes and importantly, no crunching on track when the oil got hot as it did with what was in there before (and that was fresh oil, not old)

https://www.difflock.com/evolution1

[adam quantrill]

andymadmak said:

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?

Yes the Moly here is working as an EP additive. Note that Mobil 1 is known for quite reasonable shear qualities but I wou'nt use engine oil on its own - I did this once with a Rover P6 four speed box - it was great for a hundred miles or so but then shredded itself.

andymadmak said:

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?

Yes I was considering this too - many people have reported leaks from the top (selector) when using ATF. Maybe Mobil 1 could have affected the rear seal where the oil appeared to be splattered round under the car.

What probably didn't help with the box I have just extracted is that there's no top breather - looks like it was deleted by the time the E suffix boxes came in. So the box will be "pumping" i.e. pushing out air (and oil) while it warms up.

[andymadmak]

adam quantrill said:

What probably didn't help with the box I have just extracted is that there's no top breather - looks like it was deleted by the time the E suffix boxes came in. So the box will be "pumping" i.e. pushing out air (and oil) while it warms up.

That is very curious. My old wedge (400se) was one of the last built in 1991, and the gearbox on that still had a top breather. From memory the SX cars were all built in 89 and 90?

[adam quantrill]

Yeah it's '89. The box is the type with filler above drain plug on the same side. I reckon there were a few variants of LT77 for different RWD applications independent of the suffix on the serial number.

[drak ula]

adam quantrill said:

Yeah it's '89. The box is the type with filler above drain plug on the same side. I reckon there were a few variants of LT77 for different RWD applications independent of the suffix on the serial number.

hi adam and all, sorry to dredge up old post again, only just come across this, i have never liked the gearchange in my wedge (lt77), it doesn't grind or graunch or crunch, it's just very slow and heavy, i find it impossible to do a fast gearchange even from 1st to 2nd let alone 2nd to 3rd. the old 4 speed box in my mk1 transit has a slicker sweeter change let alone my bmw 5 series with short ratio quick shift kit. it is so slow it spoils the rest of the car for me, i like changing up and down a box quickly when driving enthusiastically, so am excited to discover this thread with the mobile 1 and moly mod, but having read through it all can't see anywhere where it says how mucg moly to put in? so how much moly goes in with the 2 litres of mobil 1? can't wait to try this!!!

[KKson]

I've used Mobil 1 and Moly on both of my Wedges and noticed a vast improvement. The Moly comes in a tube similar to a large tube of toothpaste. One point of note but I did flush both boxes with white spirit and ATF three times before it ran reasonably clean.

[350zwelgje]

Seems it is the clutch that is "slow" and probably causes what you are experiencing.
Does this mean the box is not the issue, don't know.
In a Rover SD1 6-cylinder it feels a little bit better, put probably due to lower power and only a smitch of the TVRs torque.
You need to take time to shift unfortunately. So I 'wait' until I can go to fast road throttle again...
Had some instances that it felt the clutch is slipping (new clutch), it isn't, it needs time.
Flywheel is lightened, no change, probably makes it worse. So perhaps another type of clutch can help but haven't heard about that.
Are the shifting forks still ok? On mine, original box, third is getting more difficult to engage in general and think the rest as well, which is probably due to 200.000km use.

Hope you still can enjoy it for what it is, it is not perfect and that is what I like about it as it is mad enough already: on the continent they don't have a clue what it is and what is happening when you enjoy yourselfs within legal limits. They still think I am racing....., only due to the noise, which that happens at any speed and especially during acceleration as you know

Rob

[mrzigazaga]

I would check gearbox bushes before chucking engine oil into a gearbox!...

[KKson]

mrzigazaga said:

I would check gearbox bushes before chucking engine oil into a gearbox!...

Yee of little faith....... I'd rather be using state of the art modern oil rather than old style gearbox oil, developed in the stone age.

[mrzigazaga]

KKson said:

Yee of little faith....... I'd rather be using state of the art modern oil rather than old style gearbox oil, developed in the stone age.

Yes I agree on one point Keith, the oil is after all for automatic boxes, ATF...however engine oil and gearbox oil are two different viscosities for a start, both contain minerals and additives formulated for that particular application, both have the correct heating and cooling properties and more importantly a "Shear" factor..Molyslip is an anti-shear product...so personally I would and probably will use a good quality MTF for manual transmission ..I had what seemed a slack gearbox/clutch but turned out to be the remote gearbox bushes, now I can quick change from 1st to second before the engine has gulped for more air...

Just saying might be worth checking for slop or play in the bushes first...and hey...its a free world...put whatever you like in your Wedge...

[adam quantrill]

Getting back to the question of how much molyslip I put in half of a 65ml cartridge (leaves enough for another oil change especially if you buy the oil by the gallon).

My current box is on this formula too, and going well on it.

Don't forget the "no load" flushing stage, this removes a load of crud from the box.

[andymadmak]

mrzigazaga said:

KKson said:

Yee of little faith....... I'd rather be using state of the art modern oil rather than old style gearbox oil, developed in the stone age.

Yes I agree on one point Keith, the oil is after all for automatic boxes, ATF...however engine oil and gearbox oil are two different viscosities for a start, both contain minerals and additives formulated for that particular application, both have the correct heating and cooling properties and more importantly a "Shear" factor..Molyslip is an anti-shear product...so personally I would and probably will use a good quality MTF for manual transmission ..I had what seemed a slack gearbox/clutch but turned out to be the remote gearbox bushes, now I can quick change from 1st to second before the engine has gulped for more air...

Just saying might be worth checking for slop or play in the bushes first...and hey...its a free world...put whatever you like in your Wedge...

This ^^^^^^

A sloppy or vague change is more likely to be selector bushes (or at least they will be a factor)
A very draggy change could be a clutch issue - not all wedges are fitted with the right clutch for the model!

And you're quite right about the different types of oil. Mobil one is an engine oil, not a gearbox oil. Gearbox oils are formulated to run at lower temperatures than engine oils, and are designed to cope with the shear forces exerted by the gears, engine oils are not.
Hardly any major motor manufacturers use engine oil in their gearboxes, so I've never truly understood the fascination with doing it in TVRs.

The LT77 had the ATF 'solution' imposed upon it by a panicky BL marketing department that decided a 'lighter shift' was required. We all know what a disaster that turned out to be. The designers of the box originally specified 75/80, and there are some very high quality 75/80 gear oils available that will do the job in an LT77 all day and all night, without issue. Motul and Castrol probably make the best. It's worth remembering that the racing Rovers and Triumphs which used the LT77 all used Motul 80..

Mobil 1 + Moly is like brewing your own formula. It might be fine, but what on earth is the point? The right stuff is out there.

[adam quantrill]

Agreed, changing the gearbox oil won't fix a wobbly remote selector linkage, so check this first.

Most oils I have used over the years are fine most of the time, but I always had problems with these two scenarios:

- driving off cold, on a frosty morning, for the first few miles.
- driving on a hot day for a long distance - the usual one being coming back from BBWF.

In each case the gearchange would be difficult, syncro could get iffy, etc.

After trying quite a few official gearbox oils, mainly 75W, the best one I had found was Castrol SMX-S.

However it still suffered in the hot or cold range. When I changed to Mobil+Moly, the last problems were fixed.

It's not _like_ brewing your own, it _IS_ brewing your own formula. But it was tested out by the Rover SD1 boys too before coming here.

I don't know many other wedgers who use their cars in the winter, and I have no reason to continue testing different oils, so I suspect that even if there are better "official" gearbox oils out there, we won't have enough testing done to find out if they also fix the extreme hot and cold scenarios.

But if you do use any other oils, please do post your results up on this thread, so others can have a go.

[mrzigazaga]

I must say Adam that I have used mine on some very very cold days and only once in the last 6 years of owning the 350i, (the ford box only suffered from worn nylon bushings on the 280i ) have I experienced a bit of stiffness in the gear department, but hey once the engine has warmed up after a gently drive and all that V8 heat has been passed down the transmission tunnel..happy days...I had the old stuff drained out and replaced with new...again using the ATF as a basic oil for now, with a view to use a better quality MTF.

Having the remote gearbox bushes replaced, which had almost disintegrated, changed my gear change from a very embarrassing crunching duck gearbox to a very smooth clean as a coppers whistle quick change..so now can floor it and make her lift her skirt with a definite roar of approval...

Whether the Rangey boys or SD1 crew do it is irrelevant to us really as we are talking TVR Wedge..all have different hot and cold issues.

Please do not think I am being ambivalent, as what people do with their P&J is their business...just saying its not for me

Incidentally do you use any other oil for the S102 other than the specified very expensive aircraft grade Klubber grease?....I bet you dont



Thanks

Ziga

[andymadmak]

mrzigazaga said:

.I had the old stuff drained out and replaced with new...again using the ATF

You're brave! ATF is the wrong oil for LT77s in high torque, high heat applications such as wedges (TBH, ATF is simply the wrong oil for the LT77 full stop)

[adam quantrill]

Yeah I have to agree. I'm surprised that you were having cold-running problems on ATF, as it's quite thin even on the coldest day. Where I found ATF really horrid is when the box gets very hot - long run on a hot day.

I got through quite a few boxes on my 350i's when using ATF, back in the day before we knew better, and I put a cumulative 80k+50k = 130k miles on the 350i's, they have tended to last better on SMX-S or (latterly) the Mobil.

[mrzigazaga]

andymadmak said:

You're brave! ATF is the wrong oil for LT77s in high torque, high heat applications such as wedges (TBH, ATF is simply the wrong oil for the LT77 full stop)

Yeah I know..at the time I was trying to find a good alternative...its on the list within the next 6 months though...

[mrzigazaga]

adam quantrill said:

Yeah I have to agree. I'm surprised that you were having cold-running problems on ATF, as it's quite thin even on the coldest day. Where I found ATF really horrid is when the box gets very hot - long run on a hot day.

I got through quite a few boxes on my 350i's when using ATF, back in the day before we knew better, and I put a cumulative 80k+50k = 130k miles on the 350i's, they have tended to last better on SMX-S or (latterly) the Mobil.

Yep me too Adam...mind you it was frickin cold that morning...Dont have a problem once its hot or on long drives...but am seriously going to change the ATF...after all as Andy said...even that is totally wrong for it..But still not going to use Mobil 1 and Molyslip...

[adam quantrill]

Castrol syntrans on the flea 2l for £27. Should leave you with a half bottle for topping up...

Al least the ATF will have given it a good flush!

If you save it in an old vegetable oil bottle, the crud settles to the bottom after 6 months, and you can decant the good stuff from the top ;^)

[mrzigazaga]

Looks like good stuff..out of interest...im under the impression that there is a removable plastic filter in the lt77 ..of which I have a new if needed...is this right or is it only on the LT77s?


Cheers

Ziga