I'm thinking of doing a super T10 experiment

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In my 79 Trans Am. I've got it running decently now. The Borg Warner 4 speed super T10 does not down shift that well. To go down into 1st the car practically has to be just creeping along. I'm guessing the factory gear oil is still in there. I added a bit of Maxlife ATF (12oz out of 40oz capacity) to thin it down and it improved some.

So what kind of fluids should I try in there?

1. I just picked up some Pennzoil synchromesh
2. I have some CVT fluid
3. various ATFs Dex, Merc, Maxlife
4. what engine oils should I try?
5. various additives such as Lucas trans fix

Longevity is not a concern as this is just a toy that will be driven maybe 1-2 k miles per year. So I seriously doubt that anything I put in will mess it up.

Shift quality is the desired result.
 
That transmission was tough to kill but it's something of a sow's ear. A synthetic gear oil in the right viz might help. Try the TA forums, or those for any car which used that gearbox.
 
Originally Posted By: HerrStig
Try the TA forums, or those for any car which used that gearbox.


I have. They all think you're gonna blow it up unless you use old fashioned GL-4 gear oil snot. They think GL-5 will immediately dissolve the brass synchronizer. Lots of voodoo doctors out there.
 
My Corvette originally came with the 4+3 transmission, which was a super T10 married to a planetary overdrive. I hated the way the base 4-speed box shifted. It was too notchy. I tried Red Line MTL in it, but that didn't seem to help much. The most successful experiment that I did with that trans was to replace it with a 6-speed. Now it shifts a lot better.
 
Originally Posted By: turtlevette
old fashioned GL-4 gear oil snot.

is what is partly causing the rough shifting (at least until it warms up). I had a 1980 T/A that I installed an SD 455 with a Muncie M-22 and a 12 bolt axle into. I used synthetic M1 75W-90 in it and it was pretty slick without being too notchy. However, none of the manual transmissions from that era were extraordinarily smooth. I had a friend with a 1980 Z-28 that we installed a Doug Nash into and it shifted like something on roller bearings.
 
How about Red Line MTL 75W80 GL-4?

I used it in an older Jeep with a 283 engine/T-10 combination with good results. The T-10 lived a hard life and never gave any problems.
 
Originally Posted By: turtlevette
In my 79 Trans Am. I've got it running decently now. The Borg Warner 4 speed super T10 does not down shift that well. To go down into 1st the car practically has to be just creeping along. I'm guessing the factory gear oil is still in there. I added a bit of Maxlife ATF (12oz out of 40oz capacity) to thin it down and it improved some.

So what kind of fluids should I try in there?

1. I just picked up some Pennzoil synchromesh
2. I have some CVT fluid
3. various ATFs Dex, Merc, Maxlife
4. what engine oils should I try?
5. various additives such as Lucas trans fix

Longevity is not a concern as this is just a toy that will be driven maybe 1-2 k miles per year. So I seriously doubt that anything I put in will mess it up.

Shift quality is the desired result.



I would not use any of the fluids in your list. Pennzoil Synchromesh is too thin as are the ATF fluids.

I would recommend the Redline 75W85 which is a 12.0 cSt viscosity dedicated MTL with a GL-4 protection rating.

The original T-10 speced a 75W90 mineral oil but shifting in cold weather really sucks with that viscosity.
 
Last edited:
Originally Posted By: MolaKule
I would not use any of the fluids in your list. Pennzoil Synchromesh is too thin as are the ATF fluids.

I would recommend the Redline 75W85 which is a 12.0 cSt viscosity dedicated MTL with a GL-4 protection rating.

The original T-10 speced a 75W90 mineral oil but shifting in cold weather really sucks with that viscosity.


If I don't try something thin, and/or something off the wall, it's not an experiment.

I suspect these heavy oils impede aggressive downshifts even when warm, so I do want to do something a bit out of the box.

I doubt this trans will ever get warm unless I drive it all the way down the cape on the highway, so maybe a thin fluid would provide acceptable wear in a low mileage situation.

Can you look at my CVT fluid question further down the page? I may not do as you say but that doesn't mean I don't appreciate the advise and reasoning.
 
smile.gif


The CVT fluid is just a specialized ATF.

None of the those thin ATF type fluids will provide the friction modification required for synchronized trannys, whereas the dedicated MTL's will.

If you want some dedicated MTLs that are thinner, and wear is not an issue, then try either the Valvoline MTF Part Number [email protected] cSt, or the Pennzoil [email protected] cSt. These will provide smoother gear transitions if shifting is the only thing that is important.
 
The T-5's in the Nissan Z31's specd both atf and gear oil for their manual transmissions. I wonder why?

op8hfn.jpg
 
Originally Posted By: aquariuscsm
The T-5's in the Nissan Z31's specd both atf and gear oil for their manual transmissions. I wonder why?

op8hfn.jpg



I interpret that as saying - Lubes for the following:

Transmission except for Turbo Model - API GL-4 dedicated MTL,

Transmission for Turbo Model - API GL-4 dedicated MTL for the model with an MT, and Dexron for the model with an AT,

Differential - API GL-5 for the hypoid diffy.
 
Yes, if you have to "experiment" with one of the fluids you've listed, I would go with the Pennzoil Synchromesh, even though it is not a full synthetic GL-4.
wink.gif
 
I've been using Amsoil 75W-90 manual transmission and transaxle fluid in the early T10 in my Studebaker Hawk with good results. I've tried straight 90 GL 1 gear oil, synthetic GL5 75W-90 and Redline MTL in the transmission and it shifts the smoothest with the Amsoil in the case.
 
Originally Posted By: 46Harry
I've been using Amsoil 75W-90 manual transmission and transaxle fluid in the early T10 in my Studebaker Hawk with good results. I've tried straight 90 GL 1 gear oil, synthetic GL5 75W-90 and Redline MTL in the transmission and it shifts the smoothest with the Amsoil in the case.


Thank you. That helps me narrow down some of the things i'll try.
 
Is the clutch fully disengaging? My friends 70 Chevelle woundn't downshift as you say. Had 3/8" gap between throwout bearing and clutch fingers, tightened it down to 1/8", problem solved.
I would go with RedLine 75W90 NS GL-5 gear oil.
Designed for "Musclecar applications like Ford Top Loader, Borg-Warner T-10 and Super T-10, and Muncie transmissions."
 
This transmission is very noisy in 1st 2nd and 3rd. Sounds like a dump truck. Almost like straight cut gears. Not bad in 4th. I decided it needs a thick oil to quiet it down and since it's probably worn out.

I just filled it with Coastal 85W -90 GL5. Seems to shift no different than the watered down concoction I had in there (gear oil mixed with ATF). The thicker oil only quiets it a little bit.

I don't think I'll bother with the lite weight synchromesh stuff. I might even add some Lucas in later.
 
Makes sense to me. I did the same thing in an old Camaro years ago, basically shot bearings, and gear oil helped me nurse it another few grand down the road.
 
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