Gearbox additives? Thumbs down?

Gearbox additives? Thumbs down?

Author
Discussion

Renaldo

Original Poster:

311 posts

149 months

Wednesday 20th August 2014
quotequote all
Guys, I'm assuming the consensus on gearbox additives, such as Moly Slip, is thumbs down?

It seems to me I read somewhere that these can even cause some harm, by making the internals too slippery for their own good.

Thoughts?

Ron

tomtrout

595 posts

163 months

Wednesday 20th August 2014
quotequote all
Ear plugs would be cheaper but probably pulling out the box and fitting new bearings would be a better.

Renaldo

Original Poster:

311 posts

149 months

Wednesday 20th August 2014
quotequote all
Gearbox seems fine actually. Shifts well. No obvious problems.

Only issue is occasional grinding when choosing reverse -- not a problem now, because I shift into second and then into reverse. No grinding whatesoever, when I do that.

Some gearheads have recommended a high-quality synthetic gear oil as just a better overall lubricant, even for these old gearboxes.

Good idea, do you think?

Ron

Renaldo

Original Poster:

311 posts

149 months

Wednesday 20th August 2014
quotequote all
Mine is a 2500M with the TR6 gearbox...

RCK974X

2,521 posts

149 months

Wednesday 20th August 2014
quotequote all
As I remember....

The general guide to Molyslip (molybdenum disulphide) is that it's a very good lubricant, but not where combustion takes place (i.e. in an engine), as it can burn/oxidize and turn into molybdenum (di)oxide which is an abrasive, and so a BAD idea.

In a gearbox, it probably does very well, but as said, some functions of synchro require a little bit of grip, and so changes can be affected.

If you have box with separate overdrive (Triumph TR6 for example) , DON'T use it, as the overdive unit has clutches inside which need grip to work properly. In fact I have read that some modern (= thinner?) gearbox oils say they are not compatible with hydraulic overdrives.





Renaldo

Original Poster:

311 posts

149 months

Wednesday 20th August 2014
quotequote all
Andy, no overdrive on my car.

Do you have any views on high-quality synthetic lubes for these gearboxes/

Ron

RCK974X

2,521 posts

149 months

Wednesday 20th August 2014
quotequote all
Renaldo...

No....I had boxes with overdrives, and so used the standard EP90 gear oil.

Only ever had a problem once with a box, it was because a tiny piece of metal got stuck in the overdrive solenoid valve. Other than that, all of them worked fine and quiet, not as slick as (Euro) Ford boxes, but still pretty good boxes overall.

As an aside, I'm pretty sure you can swop to an overdrive box without drive shaft/prop shaft mods, if you happen to find one. The overdrive is the same as a having fifth gear, in effect. Later Triumph boxes had a smaller overdive unit, if tunnel clearance a problem.

Fiscracer

585 posts

210 months

Wednesday 20th August 2014
quotequote all
I have used Millers CRX 80/90 which is a semi synthetic in all sorts of old gearboxes without problem. Good on the slippery bits and enough bite for the synchro rings. We did try a Redline clever oil with tiny teflon bits in it - once - and changed back.

griff 200

509 posts

193 months

Thursday 21st August 2014
quotequote all
Totally agree with the above 80/90 may be semi synthetic but no better certainly no ptfe you must have friction on the synchro Rings to speed match the gears so it will change. Richard

Slow M

2,736 posts

206 months

Friday 22nd August 2014
quotequote all
Ron,

I seem to remember something about modern synthetic oil not being compatible with bronze synchronizers. I might be wrong, though.

Best,
B.

Slow M

2,736 posts

206 months

Friday 22nd August 2014
quotequote all
http://en.wikipedia.org/wiki/Gear_oil

Read the section on API GL classifications.

Best,
B.