• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

TR2/3/3A TR3B Transmission Fluid top-off

Share this page

P

PSUTR3B

Senior Member
Offline
I am not sure of the weight of the transmission fluid now in the car. From inserting a bendable item into the side hole on the transmission the fluid appears clean but could use a top-off. The manual calls for 50 weight. Since I do not know the weight of the fluid now in the transmission, is there any harm in topping-off with 50 weight? I would much prefer to not drain and refill.

Gary
 
how about you just drain it all out and refill it. they dont hold that much oil plus all the metalic bits are in the bottom

Hondo
 
The manual for your car calls for "GL4 Hypoid" gear oil, either 80 or 90, not 50 weight motor oil. You're looking at an earlier manual.

And mixing motor oil with gear oil is more likely to produce compatibility problems. There are a lot of differences in the additive packages, and they may negate each other. If you don't know for sure what is in there, it's much safer to drain and refill.
 

Attachments

  • 24874.jpg
    24874.jpg
    37 KB · Views: 295
Just for my own clarification, my original shop manual (part number 502602) specifies 30 weight for UK and either 30 or 50 weight for overseas depending on temperature. Did the specification change on later cars to gear oil? I've just changed fluid in my 56 and used 30 weight non-detergent oil (same as I use in my TR6). Is this not a suitable lubricant for the transmission?

Gearbox_Overseas.jpg


Gearbox_UK.jpg


Cheers, Mike
 
A note of caution...the manual specifies changing the oil on a schedule for a standard box. As long as you stick to regular changes, all is good. If, however, the box has gone well past the change interval, then just top it off. Do not change it! Here is the reason:

As you drive ( and occasionally grind a gear or 2), the filings slowly collect in the box. If you change the oil frequently, the filings all stay suspended enough to come out in the change. If you don't, the filings become trapped in a sludge build up in the case, within the countershaft etc. If you then change the oil...the filings come loose all at once and trash the bearings immediately.

I have twice changed gearbox oil in old boxes. Both times were a disaster. The first time the countershaft scored through and broke within 2 days. The second the box started making a hissing bearing noise the next day. A teardown reveal metal filings in all the bearings. Both boxes had magnetic plugs...showing they may help, but will not save the box.

So, if you know the history and the box has seen regular changes, then keep it up. If not, I highly recommend just topping it off.

John
 
mgedit said:
Did the specification change on later cars to gear oil?
Click to expand...
Yes. The chart above was extracted from the 1959-onwards TR3A/B owner's manual, P/N 501528, 6th edition.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:] I've just changed fluid in my 56 and used 30 weight non-detergent oil (same as I use in my TR6). Is this not a suitable lubricant for the transmission? [/QUOTE]
That has been a hotly debated topic for many years. But the factory recommendation clearly changed to gear oil, and stayed that way through the end of TR6 production (and TR7/8 I believe).

The legend as I heard it is that the factory was having problems with too many thrust washer failures under warranty, and felt that the "hypoid" (aka extreme pressure, aka EP) gear oil would help protect them. Since the thrust washers are a known weak spot in the TR2-6 gearboxes, that makes sense to me.
 
Thanks for the help. I did find a maintenance record that showed it was filled with 80-90 gear oil, so I topped it off with that. It really needed very little until it was coming out of the side drain hole. I was looking at the old spec for 50 weight and I appreciate the help. Is 80-90 gear oil the same as hypoid gear oil?

Gary
 
Are we talking about the transmission or the differential? My understanding is that the Hypoid gear oil is for the differential, but that the transmission takes something different. Earlier threads touted the desirability of RedLine 90 for the transmission.

Or am I missing something?
 
In a nutshell, The term "hypoid" refers to the type of gears found in the differential, which work under high loads and a wiping action at the tooth face that tends to squeeze out and remove the oil film between the teeth. "Hypoid" oils (which we call gear oil in the US) are designed with extra additives to help protect the gear teeth under these extreme conditions. But those additives can also be helpful in other high load situations, hence many manual transmissions also specify gear oil.

Redline MTL and MT-90 meet the GL4 requirements, which means they qualify as hypoid gear oils. But they are specifically designed for use in manual transmissions, where the synchro rings require a certain amount of friction for proper operation. More info at
https://www.redlineoil.com/content/files/tech/MTL%20and%20MT-90%20Tech%20Info.pdf
 
Is it the MT-1 rating that is important in selecting a manual transmission lubricant?
 
Based on a number of these threads and talking to people like Mark Macy and others, here's what I use:

Transmission with overdrive: Red Line MT-90 75W90 GL-4 Gear Oil. (I drain and refill every 8000 miles)

Differential: NAPA Premium Performance Gear Oil SAE 80W-85W-90. (I drain and refill every 6000 miles)

Engine: Brad Penn Grade 1 Racing 20w50 Semi-synthetic motor oil. (I drain and refill every 2000 miles)
 
Back
Top