barry p cook Posted December 31, 2013 Report Share Posted December 31, 2013 We want to change the oil on my sons TR7 gearbox to try and make some improvement to the gear change. I've a couple of related questions which I hope you can help me with; 1. In the Haynes workshop manual I've found 2 capacities for the 5 speed gearbox, one is 2.1l and the other is 1.5l. Which is correct? 2. Is the filler plug also a level plug or do you have to measure the amount of oil you add. 3. And finally any tips for the filling as access looks pretty awful. Many thanks and Happy New Year to everyone, Barry Quote Link to post Share on other sites
Odd Posted December 31, 2013 Report Share Posted December 31, 2013 (edited) Never mind the capacity - fill until it comes out of the fill hole. Refit plug - done. Most important: Never ever fill with hypoid gear oil! and only in an emergency fill with ATF...Fill it with a modern synchromesh fluid. For instance Pennzoil Synchromesh Fluid (which is the best for the Wedge gearbox according to the TWOA) or the identical but much more expensive GM Liquid Gold: "GM Vehicle care Synchromesh Transmission Fluid part no 1#109534465" Edited December 31, 2013 by Odd Quote Link to post Share on other sites
barry p cook Posted December 31, 2013 Author Report Share Posted December 31, 2013 Thanks Odd, That's very helpful. It will make the job a lot easier with the filler plug also being the level plug. I just need some decent weather now as my 4a body shell will need to be wheeled out of the garage whilst we do the work. Cheers, Barry Quote Link to post Share on other sites
REPLIC8 Posted January 1, 2014 Report Share Posted January 1, 2014 The easiest one to find in the UK is Castrol Syntrans Multivehicle 75w-90 (Used to be called SMX-S) Used it in my TR8 and there was no baulking when cold, and very smooth when warm. You can get it in Halfords. Andy Quote Link to post Share on other sites
Alec Pringle Posted January 1, 2014 Report Share Posted January 1, 2014 The late Ken Tomlinson, formerly of the BL works team, knew more about the TR7 and TR8 transmissions than most TR specialists, his knowledge of competition LT77 boxes was possibly unequalled. After a great deal of testing over decades, his unequivocal recommendation of a few years back was to stick with Motul Gear 300, a product he'd used for quite some years . . . . the standard version for road application, and the LS for competition use. It would be interesting to know if anyone has a better or updated suggestion, based on pukka practical research and testing as opposed to anecdote, advertising and theory ? Cheers Alec Quote Link to post Share on other sites
AnthonyF Posted January 2, 2014 Report Share Posted January 2, 2014 Well now gentlemen, I can offer some comment based on experience of both Motul Gear 300 & Castrol SMX-S. I have run Castrol SMX-S in the 5 speed gearbox of my standard (26K miles) TR7 for about 5 years. It is very good, I have found it overcomes the baulking of the shift from 1st to 2nd when cold, although that change is still a little stiff until warmed up, but no grating of gears! When warm it is very smooth in all changes of gear. I have used Motul Gear 300 in my TR8 gearbox (52K miles) for about 18 months now. It is a huge improvement over the ATF that was previously in the box. When cold the box still baulks a little from 1st to 2nd, but that disappears after a couple of miles. This box also used to baulk from 2nd to 3rd even when warm (suspect worn synchro), but that change is now also smooth once warm. In terms of gearbox wear I cannot comment since neither box has been stripped down, but equally both are working well & make no nasty noises! As Alec mentions Ken Tomlinson always recommended the Motul, & no doubt he rebuilt a lot of LT77s so maybe he found it best for preventing wear. Barry, in summary I don't think you would be disappointed with either. In my experience the Castrol seems to work a little better from cold. Both are easily available in the UK (eBay!) compared to the Penzoil & GM stuff. IIRC I used 1.5l in my boxes, don't know where Haynes got 2.1L from, or are they talking about the 4 speed box? For refilling the box, the only good tip I have heard is to get a length of flexible tube & drop that down from the engine compartment, stick it in the level hole & then use a small funnel to pour the gear fluid down the pipe until it runs out of the level hole. Remove the pipe & refit the level plug, and you are done. Quote Link to post Share on other sites
barry p cook Posted January 2, 2014 Author Report Share Posted January 2, 2014 Thanks Guys. I'd looked at previous threads on this issue and had seen Alec's post on Motul 300. I had been thinking of going down that route but the synthetic alternatives seem attractive. Both the Castrol and the Pennzoil get good write ups on the internet. I'll do some more research before I make a final decision and then I'll let you know how we get on. Thanks for all your help. Barry Quote Link to post Share on other sites
Alec Pringle Posted January 2, 2014 Report Share Posted January 2, 2014 Hi Barry, Motul 300 - both versions are fully synthetic lubricants. Ken T had kept abreast of transmission lubricant development since his BL days back in the 70s, regularly testing new products as they apeared - and of course he built an awful lot of competition TR 'boxes and axles in which the lubricants were thoroughly tested far beyond road requirements. Bear in mind that gearboxes might be expected to last no more than a few stages, as opposed to a full day or weekend rally . . . . . Whatever was in Motul 300 seemed to achieve a better result in the LT77 than anything else - that's up to about 5 or 6 years back, when Ken had to finally retire on health grounds. Good to hear Tony's observations from his own experience, first hand comment is always helpful. Cheers Alec Quote Link to post Share on other sites
barry p cook Posted January 2, 2014 Author Report Share Posted January 2, 2014 Ah yes. As soon as I made the post I looked up the Motel 300 and realised that its fully synthetic. It looks as though whichever oil we go for it will be better than what is currently in there. Regards, Barry Quote Link to post Share on other sites
Alec Pringle Posted January 2, 2014 Report Share Posted January 2, 2014 The LT77 will run, after a fashion, on damn near anything resembling a lubricant. How long it lasts is another matter entirely. It is a seriously flawed design, and I've seen boxes in competition fail after a bare few miles . . . . even though running pukka synthetic competition grade lubricant from a renowned manufacturer. Nothing wrong with the lubricant, one that clearly excels in many gearbox environments, it just wasn't liked by the LT77. Obviously the sheer torque of a full house V8 is very different from that of a standard engine, hence the rally box has but a tiny fraction of the life of a road box. Knowing the width and depth of Kens' experience and knowledge, and the amount of practical research he'd undertaken, I'm more than happy to stick with the Motul - even a tweaked road V8 can gobble a gearbox surprisingly quickly, and they are not cheap to rebuild any more ! Cheers Alec Quote Link to post Share on other sites
barry p cook Posted January 2, 2014 Author Report Share Posted January 2, 2014 2l of Motul 300 ordered via ebay. I suspect any of the synthetics would give improved performance and longevity but I've opted for the Motul because there is more direct experience of it in the LT77 box. Delivery expected in about 5 days and will let you know if it improves the gear change. Thanks again for all the replies. Barry Quote Link to post Share on other sites
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