[Yadkin]

Stock 390 engine in my '64 TBird with some minor build-up, probably turning out 350 HP.

I rebuilt the transmission two years ago and it runs perfectly after warm-up. Shifts are firm and predictable, much, much better than before. The rebuild kit I used had some sort of fibrous clutch plates- very different from the factory plates that I took out.

After not many miles the transmission started taking a long time to warm it up. Until warm it fails to shift into third unless I run it about 35 mph and there is no load on it. This issue issue got progressively worse, the warm-ups took 2 miles, then 4, then 6, then 8. I suspected that a cheap grade of Type F fluid was the issue, so I drained the torque converter and dropped the pan. I then found that the filter screen was clogged with clutch plate material. No metal. I installed a new filter, 11 quarts of Valvoline Type F, and that fixed the issue completely.

Apparently the clutch plates are still breaking in and shed material that clogs the filter, reducing pump pressure when the fluid is cold and viscous.

The warm-up issue came back. It happened more slowly than before. I planned, this time, to convert the filter screen to a pick-up and install a remote oil filter on the supply side of the cooling circuit.

So I dropped the pan and guess what? The filter screen was clean. But, a thin layer of black sludge on the bottom of the pan and filter. The fluid is more brown than red. I drained the torque converter as well to get rid of all of it.

Am I applying too much power to the Cruise-O?

 

[Ziggy]

How confident are you on your clearances for your clutch packs?

 

[Yadkin]

Since the tranny operates perfectly when warmed up, confident.

 

[Yadkin]

I installed a remote filter and converted the OE filter to a pickup by removing the fine screen. I found a nice spot on the left, symmetrical with the engine oil filter about the oil pan.

 

[Yadkin]

I put in 10 quarts of fluid and started the engine, shifted through the gears while parked, added an 11th to hit the bottom of the dipstick. Then cleaned up the engine bay with detergent and water, then let it idle for a while to dry before I took it for a test drive. It shifted into third a little late at first but not after four miles like it was doing. I took a 20 minute drive then got back to the house to check the fluid level idling in park- right on the money.

Not really a fair test drive since the fluid was already warmed up- I'll have to do again tomorrow to see if this did the trick.

The old fluid was sitting in my big drain pan for two days so got a chance to settle out. Nice and red on the top level but down on the bottom quite a bit of brown-black material.

The remote filter is a Wix long life so out to do a far better job keeping the fluid clean. A lot easier to change too!

 

[Yadkin]

Some info on gaskets and filters.

I had a Felpo fiber gasket in my spare parts bin so tried that, using RTV black on both sides. I've done that with a rubber gasket at 1/2 of the OE torque spec and it was the first time in 30 years that the trans did not leak. When I did this with the Felpro it split apart at 6#-ft.


I found that NAPA sells an excellent OE style filter kit and pan gasket. No. 1-4995. The filter fit perfectly, unlike the one it replaces that I had to tweak a lot to get both suction tubes into place. A nice gold mesh fine screen (which I removed). The gasket is rubber (or maybe neoprene) of the type I find that actually seals.

 

[Yadkin]

I got a chance to run the car today and happy to report that the transmission shifts normally after about 2 miles. That's not perfect but better than it had been performing.

 

[Yadkin]

Here's a video I made to document the transmission's performance. With ambient temperatures in the closer range the warm-up time is consistently just under 4 miles.

https://youtu.be/zSqcU02rabM

Since I only drove the car once in the 29 years prior to my restoring it I don't know if this is typical behavior for an MX transmission or not.