gearbox oil change

[Oz2]

Hi All,

My gearbox is not as smooth as my last wedge, which at the time had half the miles as the sx this maybe why......
However a bit fo TLC might be all it needs
What the best oil to use
and
hows the best way to go about it, ive never changed it myself before
I have access to a hoist

Cheers

Adam

[cuneus]

I've had good luck with Castrol SMX-S

There are 2 holes - a filler higher up (make sure you can undo this first) and a drain

I used an oil filler with a flexible tube to inject the new oil

[Barkychoc]

I can recommend this

http://shop.difflock.com/difflock-evolution-fully-...

The difference was amazing.

[carsy]

I`m assuming we are talking LT77`s. I have just started using mine after having it reconditioned, and after much deliberation decided on SMX. Not so sure it has been the right choice. From cold 1st to 2nd is very notchy and doesnt feel great. Other gears are fine. It does get better when warm but to get it warm takes more than a couple of miles, more like about 8 of decent driving. When warm the gears change then feels sticky as though it doesnt want to come out of gear without a bit of force. This is beginning to spoil the driving experience a bit. I know they are famed for bad 2nd gear and being notchy but im sure it should be better then this.

So my SMX is coming out, i think it may be a little too thick. I have heard about Difflock Evolution 1 and have red reports of people being impressed others not so. This is the problem, what ever you read there are as many for as there are against with all the different oil solutions. I think i am going to try ATF. This is after all what TVR used. This is what i have used in the past and not had problems with these boxes. I know there is the thought that it doesnt protect the box so well but im not so sure. You can now get fully synthetic atf such as Redline. The T5 uses ATF and when all said and done it is a manual gearbox with same gears inside.

I dont think you will ever get a straight answer on this one but my next trial will be a good synthetic ATF. and see how it then behaves.

What about good synthetic engine oil. 5/30, 5/40. Many prefer this. I have not come across anybody having bad experiences with engine oil only good ones. Food for thought.

Edited by carsy on Saturday 20th August 18:25

[Mike Brewer]

Ihave read good things about redline mt90.They use it in lotus esprits.Has any one used this as i need to change mine soon....Idid ask a guy that rebuilds Citreon massarati boxes for Esprits.But he was not sure about the Rover box.Cheers all Mike

[adam quantrill]

Ian, you are right about SMX-S being a bit thick when cold, I try and avoid changing gear much until I've done 3 or 4 miles in the morning, but on the other hand the engine is still cold too so it's not really necessary.

If you only do short journeys then this will be a pain. Although ATF fixes this problem I think it's much too thin for the LT-77 and you can get a lot more wear. Personally I have been getting through a lot less gearboxes since changing to SMX-S.

[Barkychoc]

If you're unsure drain the oil you have into a clean container and keep it - you can always go back to it then if you want to.

[carsy]

Good point chris, i take it ur box was as i described mine. Will this difflock smooth out 1st to 2nd. I might have to give it a go.

[adam quantrill]

If you do this then put it an old vegetable oil container. You can then watch the sludge drop out over a few weeks and decant off the clear stuff from the top before putting it back in clean. You can also filter it, I find coffee filter paper works well.

[Oz2]

Cheers guys
First I'd better find out what oils are available here in Australia, but thanks for all your suggestions. It's not undriveable but my last wedge was a lot smoother....... I wish I knew what was in it!
It does improve when warm, I guess we should remember these gearboxes are 20 plus years old.
Thanks
Adam(oz)

[Oz2]

Right, been looking around......
all the oils are named differently out here.......SO
http://www.castrol.com/castrol/multipleproductsect...
please have a look through and compare to the SMX S and that should give me a good idea of which one to go for.
I cant find anything named Difflock here in Oz,Ill look into some of the Aussie oils.
Thanks
Adam

Edited by Oz2 on Sunday 21st August 01:12

[plushuit]

[quote=Oz2]Right, been looking around......
all the oils are named differently out here.......SO
http://www.castrol.com/castrol/multipleproductsect...
please have a look through and compare to the SMX S and that should give me a good idea of which one to go for.
I cant find anything named Difflock here in Oz,Ill look into some of the Aussie oils.
Thanks
Adam


No need to look far.

Castrol SMX-S is great! ...but in the gearbox it was made for, the R380. Being the LT77's successor, LT77 owners hear a lot about R380 gearbox fluid. Ignoret it. Different box entirely. Only the length and the ratios are the same.

LT77s are VERY sensitive to fluid choices..wrong one and you will need to rebuild it. The internal pump cannot manage thicker fluids so the need to rebuild won't take long. Been there, done that. LT77s take Dextron II or III. http://tinyurl.com/3jasrjj

[andymadmak]

I had my wedge gearbox rebuilt by one of the men who designed it in the 1970s - Ken Tomlinson. He told me clearly that the box was designed for gear oil, either a 75 or an 80. The switch to using ATF oil came at the last minute, after prototype SD1 Rovers were taken one winter morning to the Solihull works canteen so that the ladies there could drive them. The complaints that the gearshift was heavy when cold caused Rover to make the switch to ATF - much to the detriment of gearbox life. Indeed if the car had been used to tow a caravan or driven hard then Ken reckoned that the box was a write off and should not be rebuilt if it had been filled with ATF. All the works racing SD1s and TR8s used Motul 80 by all accounts.
After my rebuild the box was filled with Castrol SMX-S and aside from the first half a mile on cold days when first to second was tricky, the shift quality was never less than superb. Anyone still suffering tricky changes after 8 miles has a badly rebuilt gearbox, or possibly a clutch problem imho.

Edited by andymadmak on Sunday 21st August 10:47

[Oz2]

Castrol Syntrans 75W-85
Castrol Syntrans 75W-85
For competition applications where superior synchroniser performance is required. Also recommended for passenger car and light commercial vehicle transmission, transaxles and transfer cases. SAE 75W-85, GL-4
would i be right in thinking this is the Australian version of SMX S, second one down on the left on my link

[carsy]

Yes that will be the one. I think SMX-s has been discontinued and this is its replacement. Best of look with it. I`m still pondering which one to try next.

[Oz2]

carsy said:

Yes that will be the one. I think SMX-s has been discontinued and this is its replacement. Best of look with it. I`m still pondering which one to try next.

thanks Ive just contacted difflock to see if evo1 is available here or if they will send it....

[honestjohntoo]

carsy said:

I`m still pondering which one to try next.

Read this - bring up the PDF, providing your box is not knackered, you wont be disappointed with the result. Mobil 1 0w40 or Castrol RS 5w40 - Both plus Moly.

[carsy]

Very tempting. I`ve heard of a few people using synthetic engine oil all with good results.

[Wedg1e]

I've been using the recommended ATF in my LT77 for 11 years now and at 120,000 miles it doesn't seem to be broken. It weeps a bit, but that's just an excuse to keep topping it up

[honestjohntoo]

Just to clarify, because ATF didn't work for me, I've used the Mobil 1/Castrol RS + Molyslip solution for 15 years now on a box I was quite prepared to scrap because of its bad behaviour. In the intervening period, the box has had 3 oil changes, using exactly the same recipe, except the last time - 2010 - I forgot the Molyslip but have not noticed any difference. Mind you if the hype is to be believed, moly has a long lasting effect. and it remains as good as it was after the first application.

Then again, because I used the Moly gearbox treatment from the get-go, I don't actually know if the resulting dramatic transformation was due to the choice of oil, the addition of moly or a combination of both.

So, my advice comes into the category of "what have you got to lose!" - apart from the cost of a couple of liters of oil plus a wodge of moly, and see how it goes.

If you want to make the best possible fist of it, then do the dynamic cleansing process as well and see how much horrid black stuff comes out from the box. I was quite amazed because, at that time - 1996 - the box was only seven years old.

As for non-spill refilling, simply run a decent sized tube down from the engine bay to the filler hole and pour in the required amount of fluid slowly via a funnel.