TR4/4A TR4 gear box oil

[Adrio]

I am sure this has been asked and anwered but for some reason I can't find it in the archives (I am sure I am not looking "right"). Anyhow, what is the correct oil to use in a Triumph gear box. I remember there is talk of some doing damage to the synchro rings and I have also heard some will not allow the overdrive to work.

Do we need straight weight, non detergent or what. Is there some SAE spec that we can use that the supliers of today will recognize?

Thanks,

 

[Dugger]

I used "Bravo EP90 Gear Oil, a GL4 rated gear oil I got from CarQuest. I checked their website and they have distributors in Ontario. This was the only GL4 rated gear oil that I could find. I have not had any problems with it so far, but its been only 1K miles.

 

[jsneddon]

GL4 = good

GL5 = bad

 

[CraigFL]

[ QUOTE ]
GL4 = good

GL5 = bad

[/ QUOTE ]

A lot of GL5s are hard on brass/bronze but some are not. Moss sells a Redline synthetic GL5 and Redline says it's not harmful.

 

[Geo Hahn]

I use Redline... some use non-detergent 30W motor oil... some 90W gear oil. As noted, avoid the GL5 dinosaur oil.

Mine are not OD... so I cannot comment on whether Redline is too slippery or thin for the OD.

 

[Alan_Myers]

Hi Adrio,

Check out Topic of the Month at www.quantumechanics.com

They rebuild lots of ODs and gearboxes, so I would trust John Esposito's opinions.

The upshot of his article seems to be that 30W non-detergent, non-synthetic oil is what they recommend for freshly rebuilt OD gearboxes. However, his writeup still leaves me wondering about using 20W50 non-detergent, non-synthetic, or maybe 40w non-detergent/non-synthetic in an OD gearbox that has some miles on it.

All TR gearboxes should avoid GL-5 gear oils, due to sulpher corrosion effects on brass parts. Sulpherous compounds are added to extend the pressure capabilities of GL-5 gear oils.

Detergent oils should be avoided in both OD and non-OD boxes because the detergent causes foaming, plus detergent serves no purpose in a gearbox. High detergent oils are useful in modern car engines, but might be deterimental in older designs.

Non-detergent motor oils are most often marketed and sold as "racing" oil. That's because racing engines get their oil changed a lot more often than street car engines, and foaming issues might cause problems in racing engines running at high rpms.

Synthetic oils might cause additional leakage, particulatly in the high pressure environment of an overdrive.

Plus, many synthetic motor oils are very high in detergent to give them "extended life", ruling them out entirely.

Synthetic gear oils might be better, since they don't have detergents. But, I also have concerns about using a synthetic oil with an oil-bathed clutch, such as is found in the Laycock overdrives. I've seen motorcycle clutches ruined by slippery synthetic oil.

Finally, some TR gearboxes have reportedly started popping out of gear when slippery synthetics were used. Draining and replacing with mineral-based oils solved the problem.

Redline might be an exception, because that company goes to great lengths to engineer their synthetic oils for specific needs. Their GL-5 rating comes from other modifiers, rather than sulpher, for example. However, watch that viscosity isn't too high for the Laycock overdrive. I haven't tried it so can't comment based on personal experience. I have used some other Redline products and found them good.

The bottom line is that the OD utilizes the oil for both lubrication and pressurized hydraulic operation. The gearbox itself is just looking for proper lubrication. Moderately heavy oils might be best for lubrication, but bad for hydrualics. Moderately lighter oils work best with the OD hydraulics, but too light might not provied adequate lubrication to either the gearbox or the OD.

Hope this helps clarify and doesn't just confuse matters more!

Alan Myers
San Jose, Calif.
'62 TR4 CT17602L

 

[Dave Russell]

[ QUOTE ]
I use Redline... some use non-detergent 30W motor oil... some 90W gear oil. As noted, avoid the GL5 dinosaur oil.
Mine are not OD... so I cannot comment on whether Redline is too slippery or thin for the OD.

[/ QUOTE ]
Geo & all,
RL MT90 is a GL4 rated synthetic. It is compounded to have low sulfur content & a higher friction coefficient, which is ideal for OD clutches & transmission synchronizer operation. If you want a slightly lower viscosity for cold climates, RL MTL works well. In several years of use, I have found MT90 to give noticeably better synchronizer operation & more positive overdrive operation. I really doubt if detergent or non detergent is much of an issue.
D

 

[Adrio]

Thank you all for the advice on this. I hope to get the spare tranny in the TR4A this weekend so I figure I better get the oil changed in it at the same time. I hope this one lasts longer then the 700 miles the last one did (but that was an other post).

 

[mrv8q]

Per the list, I replaced the 25 year-old gearbox and diff oil in my TR3A with Sta-lube GL-90 oil, for a reasonable $3/quart, from a large, independent autoparts store near me.

I also bought the $5 hand pump that fit the quart bottles; it made the fill process SO much easier!

 

[Dave Russell]

mrv8q,
Sta-Lube GL-90 does not adequately define the lube. The important part is whether it is rated GL-4 or GL-5.

You should NOT use a GL-5 rated oil in the transmission because the high pressure additives, usually sulfur, can harm the brass/bronze parts such as synchronizers & bushings. Use only a GL-4 or lower rated oil in the transmission.

You SHOULD use a GL-5 rated oil in the axle. The high pressure additives help reduce the friction & wear caused by the sliding action of the Hypoid gears. The GL-4 & lower rated oils do not have this additive.

-- Two different ratings for two different locations --
GL-4 in the transmission
GL-5 in the axle
D

 

[mrv8q]

Thanks, Dave, my bad, I used GL-4 for the gear n'rear... I didn't know about GL-5 for the diff; I'll change that out on my next go round. Best, Kevin '59TR3A #58370

 

[billspit]

Don't know about TR-4s but Spits need GL-4 in the diff too I do believe.

I went with Redline MT-90 in the diff. Finally found regular GL-4 at a local NAPA store and used it in my OD trans. Looked all over everywhere for the durn stuff.

 

[Dave Russell]

Kevin & Bill,
I over generalized a bit earlier. It appears that certain Triumphs, Spit, GT6, GT7, & maybe others, have some bronze washers in the rear axle. Don't know about the TR3. In this case, GL-4 would be appropriate. Sorry, my bad!
D

 

[Alan_Myers]

Hi all,

Always a fun topic!

One other consideration, anyone with a limited slip diff will need special lubrication in there. It might be a modifier that's added to GL4 (or whatever), or an oil that's formulated specially for limited slip applications.

Just thought this might be a consideration for some folks. For more info, see what the L.S. diff maker recommends. Quaife has a website, I imagine most do.

Alan Myers
San Jose, Calif.
'62 TR4 CT17602L