Rover Gear Box Oil
Discussion
I did a gear box oil change over the weekend. and in the Steve Heath Tvr Book, it say to use Castrol SMX. But now when it cold it hard to get in to gear but once warm up it ok. it did say some oils have this problem but not the Castrol smx. have they change the oil. or should i be using automatic fluid as in the T 5 box
I had SMX in my box for a few years. The recommended oil for the Rover box by Castrol Germany is now Transmax-Z. Shifting when cold is greatly improved, i don't have to put the box in first and second before switching to reverse. With the original oil and with SMX this was never possible.
Fred
Fred
The castrol 75W-90 SMX oil is thicker than the ATF when its cold so the first few changes will be stiffer than with the ATF, this will disappear after a few miles. When I worked for a gearbox manufacturer I spoke to the head of development for Tremec who now make the T5, he told me the only reason ATF is used in a manual gearbox is to cut costs.
If a big manufacturer (like ford) can common up on lubricants wherever they can it saves them money, as long as the vehicles can get past the 3 year warranty then they're in the clear.
This might sound like spoiling the ship for a pennysworth of tar and it is, but Mr Tremec said on the new mustang it saved ford 5 dollars per vehicle and when you make 3 million mustangs......
ATF is rubbish as gearbox oil and the amount of abuse a TVR box gets means that its already on its design limits, the 75W-90 oil will provide miles better protection for the gears and bearings but will reduce synchro mesh performance when its stone cold.
In the T5 and the rover box there are instances of the gears running directly on the shaft, so there is no true bearing, you rely entirely on the lubricant to stop stuff welding together. Its no co-incidence that Cerberas and Griff 500's are known to weld 5th gear to the shaft on the T5.
Take your pick, either have a crunchy first gear for the first 2-3 miles
Or use ATF and have to rebuild the gearbox.
Up to you of course
Matt
If a big manufacturer (like ford) can common up on lubricants wherever they can it saves them money, as long as the vehicles can get past the 3 year warranty then they're in the clear.
This might sound like spoiling the ship for a pennysworth of tar and it is, but Mr Tremec said on the new mustang it saved ford 5 dollars per vehicle and when you make 3 million mustangs......
ATF is rubbish as gearbox oil and the amount of abuse a TVR box gets means that its already on its design limits, the 75W-90 oil will provide miles better protection for the gears and bearings but will reduce synchro mesh performance when its stone cold.
In the T5 and the rover box there are instances of the gears running directly on the shaft, so there is no true bearing, you rely entirely on the lubricant to stop stuff welding together. Its no co-incidence that Cerberas and Griff 500's are known to weld 5th gear to the shaft on the T5.
Take your pick, either have a crunchy first gear for the first 2-3 miles
Or use ATF and have to rebuild the gearbox.
Up to you of course
Matt
Edited by 350Matt on Tuesday 4th December 20:14
While I agree in principle, I'm not totally sure I would be so dismissive of ATF... I have a T5 that has done 100k+ miles on the stuff. Meanwhile a T5 running 75W90 needed new synchros etc after 45k miles. In Rover box land, I have broken boxes with both ATF and 75W90. If anything, the ATF boxes lasted longer so I am pretty sure there are other factors such as how often is the gearbox oil checked and changed and gear change style that determines when a box will fail. Engine torque is another major input as well.
So just because the box has ATF in it, it doesn't necessarily mean that the internals will fail automatically and the sky fall in. Equally using 75W90 doesn't make the box unbreakable. So those running ATF needn't worry and rush out for 75W90. Yes the concensus seems to be going towards 75W90 but equally 10 or so years ago it was ATF as gear box oil was seen to be too thick to circulate correctly when cold and the crunching when cold caused premature wear. "Plus ca change, c'est la meme change" as they say across the pond.
For the record I am now running on 75W90 in two of my TVRs and ATF in the third.
So just because the box has ATF in it, it doesn't necessarily mean that the internals will fail automatically and the sky fall in. Equally using 75W90 doesn't make the box unbreakable. So those running ATF needn't worry and rush out for 75W90. Yes the concensus seems to be going towards 75W90 but equally 10 or so years ago it was ATF as gear box oil was seen to be too thick to circulate correctly when cold and the crunching when cold caused premature wear. "Plus ca change, c'est la meme change" as they say across the pond.
For the record I am now running on 75W90 in two of my TVRs and ATF in the third.
I think the comments are all valid, but modern synthetic oils have raised the bar and flow much better when cold. I do believe however that comparing synthetic brands with the same specs is a minefield, and would try a recommended product rather than a generic spec, unless you want to be a guinea pig?
Dave
Dave
Argent said:
Wasn't it the case that ATF was recommended for the LT77 because it has an internal circulating pump that can't cope with high viscosities at low temp?
I thought that initiallly since it appears to be the logical conclusion but sadly the truth is rediculas and involves dinner ladies. Andymadmak should be along soon with the full story.JR said:
Argent said:
Wasn't it the case that ATF was recommended for the LT77 because it has an internal circulating pump that can't cope with high viscosities at low temp?
I thought that initiallly since it appears to be the logical conclusion but sadly the truth is rediculas and involves dinner ladies. Andymadmak should be along soon with the full story.
TVR handbook on the Rover box says SS80 gear oil.
Richard Thorpe (wedge guru) reckons to use a special brew he concocts himself
Ken Tomlinson (the man who designed the box for the Jaguar Rover Triumph division of BL (or whatever its called this week) reckons you should be using 75 gear oil (he strongly points to Motul brand)
Ken's the only bod I'd really listen to on the subject. After all, as the designer he should know what was intended. The box was designed for 75 oil. The switch to ATF was a bodge by BL, devised to counter criticisms amongst weak SD1 drivers that they could not change gear when the car was cold. No engineering testing was done with the new oil grade - in fact the only testing was to take some SD1s to the works canteen at Solihull to see if the ladies there could master the change on a cold morning!
ATF simply does not protect the box enough. It allows too much heat to be generated, especially in high torque applications (such as TVRs)
Did I read all this in a book? No! Ken told me himslef, face to face, - when he rebuilt my gearbox.
It now runs SMX-S, and is smooth, cool and quiet. (But a little tricky for the first couple of miles when cold)
HTH
Andy
I tried 75w90 (SMX I think) in the Rover box on my early Grif 500, but even in summer it was an absolute bitch to get into gear when cold (1st-> 2nd -> 1st especially bad). Double de-clutching was needed and it still wasn't keen. It was ok when warmed up but just unbearable when cold to live with on a day to day basis, especially for trips of only a few miles.
Changed back to the ATF stuff and the gear change was sweet again!
If I was doing lots of track days / longer runs I might try the 75w90 again, but for day to day use, when not thrashing it, the ATF works better in my car.
Changed back to the ATF stuff and the gear change was sweet again!
If I was doing lots of track days / longer runs I might try the 75w90 again, but for day to day use, when not thrashing it, the ATF works better in my car.
Gassing Station | Griffith | Top of Page | What's New | My Stuff