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The only problem my Ultra had was a slipping/grinding direct clutch. When you drove the car it would shudder until you let off the gas and let the clutch engage. Sometimes, it would still shudder after for a moment when applying the accelerator. I knew the surface of the direct drive clutch had hardened after 40+ years of sitting in a field, but thought I'd try some additives to see if I could get the varnish and crud off of the clutch. Eventually, after trying everything I could, I tried the TrickShift. This eventually worked after a couple of days of normal driving. (After MONTHS of trying everything else) The shudder and slipping was gone! Since then, all I've suggested is B&M TrickShift fluid. It has friction modifier additives to improve the shift characteristics of all transmissions, and worked very well on the Ultramatic. If you want a firmer shifting transmission, TrickShift is the way to go.

I HIGHLY recommend it even for newly rebuilt Ultramatics, as it's the best fluid I could find. When I find a better trans fluid I will let you know!

Owen, no fluid is going to fix worn bushings, shafts, and the like. Hardened clutches, yes it will.

Thanks, I have a better understanding now of what it is capable of. Of course I know nothing replaces worn metal, but thought perhaps one of it's virtues might have been higher viscosity perhaps compensate though briefly for wear. But now I understand what you observed and thanks for the commentary. Your description of the clutch groan is very good, and exactly what I experienced with Dexron and went away with Type F. No doubt our clutch facings had different histories (experiences) and maybe even different facing materials.

I think where it gets interesting is when replacing soft parts.

Kanter used to advertise his rebuild kit products were all redone with modern GM linings & friction materials--assume it still is- Ultra Dynamics advertises new GM orange- although he advertises as having both old stock and newly relined on some things. Think anything GM would dictate using the fluid GM recommends, but if you still have original parts and cork linings, then they would probably like F better.

Up until 8-10 years ago-and maybe still- you could get some parts from other national transmission parts supply houses and were a combination of original old stock aftermarkets of unknown type and/or clutch disks that were made for other units (Borg-Warner for high range clutches for example). These could be a combination of old cork, new GM and maybe something else thrown in.

Probably with a mix of materials and unknown prior rebuilds possibly all combinations installed in some of the units. That is why some do better with F, & some have better luck with the Dexrons. Could it be the Trick Shift has the magic formula that takes all into account.

To put this into perspective, if you buy a rebuilt transmission from B&M, it is filled or recommended to fill with TrickShift, regardless of make.

On a side note, an old drag racers trick was to use Type F in GM transmissions, as it's friction capabilities is better than Dextron/Mercon. I honestly believe that TrickShift is nothing more than glorified Type F with some extra additives, and blue coloring. (Yes, it's blue, not red)

Owen, I'm glad you liked my explanation, I was afraid it wouldn't be thorough enough.

Up until 8-10 years ago-and maybe still- you could get some parts from other national transmission parts supply houses and were a combination of original old stock aftermarkets of unknown type and/or clutch disks that were made for other units (Borg-Warner for high range clutches for example). These could be a combination of old cork, new GM and maybe something else thrown in.

Probably with a mix of materials and unknown prior rebuilds possibly all combinations installed in some of the units. That is why some do better with F, & some have better luck with the Dexrons

Howard, eureka! - I think you've hit it right on the head as to why some folks have better experiences with one fluid or another, gosh I wish I would have thought of that. The Ultramatic rebuild kits I had and used for years were marketed and marked Lempco, and I know there were other makers or "packagers".

Next time I talk to Dan Kanter who has spend much of his adult life inside an Ultramatic, I'm going to ask him about their GM-like materials and his recommendations for fluids. EDIT- just left a message for Dan Kanter - we'll see what he has to say.