What gearbox oil for a V8s

What gearbox oil for a V8s

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Discussion

Rsedmonds

Original Poster:

14 posts

58 months

Monday 18th May 2020
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Hi all,
When out driving my gearbox gets tighter and to down shift into either 2nd or 3rd is a lot harder so I thought I’d look at changing the oil in the gearbox as my first port of call. With this in mind I decided to do some research before I dived in, and boy I’m glad I did. There seems to be a lot of passion behind using ATF, dedicated gearbox oil and engine oil with an additives. But the threads I’ve come across are at least 2 years old. So I was hoping you could tell me 2 years on whether you could tell me if the route you chose to go was a good one? Are you still using the same oils now? And how many miles you’ve clocked up using what you choose?

Regards Rob

phillpot

17,279 posts

190 months

Monday 18th May 2020
quotequote all
I don't think much has changed in the last couple of years, still plenty of opinions/suggestions smile

Did your 'research' throw up something called Difflock ? Expensive but some really rate it scratchchin

Rsedmonds

Original Poster:

14 posts

58 months

Monday 18th May 2020
quotequote all
What I saw was more around Various grades of engine oils, Mobil 1 engine oil with moly slip, gearbox oil grades From 70 to 90 but nothing really convinced me. There was no clear statement that said it worked for a long period. Quite the opposite it was all about dismissing others opinions stating that what they use will ruin your gearbox.
So nothing was clear, What’s difflock? Is it any good and will it last? A lot of questions but I’d like to know what I’m putting in will work.

Regards

zombeh

693 posts

194 months

Monday 18th May 2020
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This stuff https://www.difflock.com/oilsandadditives/oils/gea...

I reckon before they put their stickers on it it said "fuchs titan ATF" on the bottle but I've no idea which one and for the few extra quid I was happy to take their word for it on which ATF worked well and lasted ok. Landerover types have had many years of dealing with this stuff and I've only ever taken the one apart.
Gear oils generally don't last forever, they're in quite a harsh environment being squished between gear teeth all the time so changing it every 30,000 miles or so isn't that big a deal.

Why ATF:
The gears in the LT77 sit on needle rollers that are fed via the hollow mainshaft by a pump at the back driven off the end of the laygear. The gears in that pump are as standard made of some horrible plasticy stuff which doesn't appreciate you making it pump cold EP90 in the middle of winter.
You've got a choice of the best oil for the gears and bearings or the best oil for the pump and a decent synthetic modern ATF is a reasonable compromise

I've only put a few hundred miles on mine since I rebuilt the box before I broke first the exhaust manifold and then me

v8s4me

7,264 posts

226 months

Monday 18th May 2020
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I've had my V8S for 14 years. I've tried semi-synthetic gear oil and ATF and Difflock.
Use Difflock!!!! It does what it says in the blurb.
Do not put ATF in your box!
thumbup

GreenV8S

30,484 posts

291 months

Monday 18th May 2020
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v8s4me said:
Do not put ATF in your box!
There is a lot of conflicting advice. Land Rover have recommended ATF in the past. I believe that was to avoid synchro problems when the 'box was cold. I think that advice got adopted by TVR specialists which is why it is repeated so often in the TVR community.

I had my LT77 rebuilt by Ken Tomlinson, the man who designed it. Ken threatened to box my ears if I put ATF in it. It needs proper gearbox oil - that Difflock stuff is the best there is for the job.

v8s4me

7,264 posts

226 months

Monday 18th May 2020
quotequote all
GreenV8S said:
...... I believe that was to avoid synchro problems when the 'box was cold. ....
That's my understanding. The synchros suffer when the ATF gets hot. I think it's because it becomes so thin there's not enough drag on the synchros to make them work properly.


Edited by v8s4me on Tuesday 19th May 09:34

Oldred_V8S

3,727 posts

245 months

Tuesday 19th May 2020
quotequote all
v8s4me said:
I've had my V8S for 14 years. I've tried semi-synthetic gear oil and ATF and Difflock.
Use Difflock!!!! It does what it says in the blurb.
Do not put ATF in your box!
thumbup
Difflock is good stuff but if you are looking for something cheaper, Castrol Syntrans is excellent stuff. I looked at Difflock and then thought I'd give the Castrol a try. It was like night and day compared to other stuff I had tried.

When my car was in Southways for chassis refurb, Richard Kitchen drove the car and said he had never known a smoother changing LT77 gearbox.

As others have said, do not use ATF on LT77 boxes.

One other tip. Remove the gear lever and clean all the grit and old grease from under the white plastic dome type thing, regrease and reassemble.

ETA - Amazon seem to be the cheapest £18.95 with free delivery. Just ordered some myself.


Edited by Oldred_V8S on Tuesday 19th May 11:59

zombeh

693 posts

194 months

Tuesday 19th May 2020
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I had smx-s (syntrans) in mine before I rebuilt it, it was a bit crunchy when cold but I'd put that down to the general state of the box rather than the oil.

OP: how many miles on the box? and has it ever been rebuilt?

phillpot

17,279 posts

190 months

Tuesday 19th May 2020
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Oldred_V8S said:
Castrol Syntrans is excellent stuff.
The first one, 75W90 Paul ?