Transmission woes!!!

[1Cobra427]

'77 C20 2WD w/ TH400...Ran trans fluid low by accident and after refill it never shifts right, been told flush would not help w/ no history on the truck and good fluid it still shifts enough to pop my neck each time. Rebuild or replace? Don't want fancy gears or performance stuff, just equal to what I have now. Advantages to rebuild/replace. where to go for quality? I am transmission novice!!! Help from experts please!

[crashz]

Likely an accumulator is somehow stuck. Based on that, and possibly a 40 year old transmision, I'd be tempted to rebuild it. Have a reputable local transmission shop go through it, replace wear parts, seals and any defective hard part, install a new torque converter (they do get worn over time) and install a new fluid cooler, bypassing the radiator cooler. i like to add a transmission temp guage on each of my rigs too.

The 400 is supposedly the easiest transmission to rebuild, is plentiful, and has been around since the stone ages. Usually they can be done for a good price with modern wear parts.

[walkerb]

Originally Posted by crashz

Likely an accumulator is somehow stuck. Based on that, and possibly a 40 year old transmision, I'd be tempted to rebuild it. Have a reputable local transmission shop go through it, replace wear parts, seals and any defective hard part, install a new torque converter (they do get worn over time) and install a new fluid cooler, bypassing the radiator cooler. i like to add a transmission temp guage on each of my rigs too.

The 400 is supposedly the easiest transmission to rebuild, is plentiful, and has been around since the stone ages. Usually they can be done for a good price with modern wear parts.

When you say bypass the radiator cooler, are say not use it at all?

Im not sure I would do that, even with a one with a fan. Why not tap it in after the radiator?

[TheBlueBomber]

Originally Posted by crashz

The 400 is supposedly the easiest transmission to rebuild, is plentiful, and has been around since the stone ages.

Something tells me that a few members on here will take that the wrong way... LOL!

[crashz]

Originally Posted by walkerb

When you say bypass the radiator cooler, are say not use it at all?

Im not sure I would do that, even with a one with a fan. Why not tap it in after the radiator?

After a rebuild, the stock radiator cooler can still hold particles in it, even when flushed. So many rebuilt transmissions fail due to debris left within the coolers, that many transmission shops require a seperate cooler or radiator replacement. Plus I feel that it adds heat to the transmission when the going gets really hot. In really cold climates, it helps to pre-heat the transmission fluid and get to operating temps quicker, but I feel this is only really needed in very cold climates.

But, I would not run any automatic transmission without a cooler! Generally I find the largest cooler (30K lbs GVWR) I can and stick it in front of the radiator. Another choice (have not tried this yet) would be to add a spin-on filter after the radiator cooler and then another auxillary cooler. A transmission temp guage is also money well spent. If you can keep fluid temps below 180, the life of the fluid and transmission is greatly extended.

[crashz]

Originally Posted by TheBlueBomber

Something tells me that a few members on here will take that the wrong way... LOL!

True! Sorry - the end of that sentence shoudl read "...and has a rich history!"

[1Cobra427]

I do not hear much talk about replacement. OK by me as a rebuild may be cheaper. What is the best way to find a reputable shop as I live in a small town and not much to choose from. I do live near Atlanta but I am more about quality work and willing to drive a little bit to get it right. I plan on keeping the truck and want this past me so I can play on something more fun on the truck!

[1Cobra427]

Transmission woes are behind me. I took about 2 hrs yesterday and drove the truck a mile loop and each time at starting point I crawled under truck and adjusted the pressure sensor 1/2 turn and go again. Like a light switch...I thought I would never find the sweet spot but it finally smoothed out. It shifts like a new truck! Thanks forum and peoples help, so much knowledge at my fingertips was a big help!