Gearbox lube

[Mark McCombs]

With my doors now permanently fitted and the seats installed, more serious shakedown running has begun.

So far, so good; Oil pressure ranges from 50 at idle to 60 when driving; playing with top shims from Doug in the Bishops box but it seems pretty good with little play. I just need to see how firm the steering should feel with different thicknesses.

Now:

I switched to Red Line 75-140 gear oil in my gearbox early on; Maybe too early, as I didnt get a good feel for the standard 140 wt.

However, it seems like I have a little more first gear whine with the red line, and thinking about switching back to the standard 140 wt.

Any input appreciated before I drain off the synthetic Red line. It shifts fine, second is fairly quiet, third and fourth are noiseless, but it feels a little 'thin' as I go through the gears, if that makes sense.

Thanks-
Mark TC8126
Hot Ohio

[Steve Simmons]

All I can offer is that I switched from a regular 140 gear oil to Redline 75W-140NS and didn't notice any real difference. One day I felt it was smoother and quieter and the next day I thought the opposite. So I figured it was all a matter of expectations. In other words, in my head.

Set the steering for center. You don't want ANY resistance at center. The ends will take care of themselves as you turn the wheel.

[Duncan M]

Mark-
I assume you are using the flat top plate, like I am, and not the Tomkins kit? On the BC box, did you get the front (end) plate shims adjusted first? Always do that first. Looking for close to zero end play of the worm. If too tight, the steering can bind and destroy the ball bearings/cages. If too loose, the worm will move forward and back (slop) and also destroy the bearings/cages, but the steering will never be right if the first adjustment is not well done.

Not sure what Steve means by no resistance at center steer. When adjusting the top plate shims, you are looking for a little bit of resistance-- only at center steer. When adjusting the box on the bench, or with the front wheels up in the air. At center steer (straight ahead driving) the design of the original worm, and the ones made up by Bob G in Canada, the sector shaft should rise up slightly-- and rub against the top plate. Only at center steer. The Buell article https://www.mg-tabc.org/library/Buell-T ... 3rd-ed.pdf discusses the box starting on page 9, and talks about the top plate adjustment on page 10. You are looking for just the right amount of rub at center steer only, for a properly adjusted top plate.

[Steve Simmons]

I think I overstated what I was trying to say. What I meant is that you don't want to make it physically tight in the center. A bit of drag is fine, but some people continue tightening it up in an attempt to make it as responsive and play-free as a modern car, and what they end up doing is damaging the peg and worm. It's a very fine line between loose, perfect and tight.

[JonnyP]

Mark,
I run standard 140 in mine and I would use exactly the same words as you to describe the noise levels and shift quality. Once hot it feels a little ‘thin’, so maybe it doesn’t make much difference what’s used…..

[Duncan M]

Hopefully the transmission in your TC will always have a first gear "whine." First and reverse gear are square cut. I know some old timers that would call that gear cut "English cut gears." When you hear a whine in top gear just driving along, you will know someone put 90W in there.

I found regular GL4 140W caused extensive foaming in the transmission. After a good drive the dipstick registered foam. Brand was whatever O'Reilly's sells. Maybe 140W back in the 40's and 50's had Pb or something in there to prevent foaming?