Rebuild th400 or 4l80e?

[Ricko1966]

I installed a temp gauge in my Suburban, back when it was my tow rig and had a 700r4 in it. I ran a fairly large cooler and it was not plumbed through the radiator cooler. The idea being that I wanted to cool the fluid, not put it through a 190* radiator. I often thought about running it through the radiator, because in cold weather, the trans ran at around 100* during normal driving. Working the trans hard in the summer, if the temp got up around 220*, I'd always back off the throttle for a bit until it got down to 190* or so.

Are y'all suggesting that if I ran it through the radiator cooler, it would have ran warmer in the winter and cooler in the summer?

Also, at some point years ago, I saw some chart about trans temps in relation to the life expectancy of the trans. According to it, the life expectancy dropped WAY off with temps over 200* or so. Is there no factual truth to that?

Factory gm used radiator cooler and auxiliary cooler plumbed in series. I think was a 2018. It's how I've done them for decades. Maybe I'm right maybe I'm wrong just how I was taught at work.

 

[bucket]

Factory gm used radiator cooler and auxiliary cooler plumbed in series. I think was a 2018. It's how I've done them for decades. Maybe I'm right maybe I'm wrong just how I was taught at work.

You are definitely right about that. I can't remember seeing a vehicle with an aux cooler that wasn't plumbed in series from the factory.

 

[txaggie]

Yes - never reuse one way assemblies in any transmission unless you like doing the job twice...While the ones in the TH400s/4L80Es are fairly resilient, if your luck is like mine, they will fail on you if you reuse them. Not worth the gamble to save a few lousy dollars, IMO.

Nick,

I am replacing the plastic accumulator piston on the valve body with an aluminum one due to the plastic being cracked.
A bit of a problem, This new aluminum one won’t necessarily fit over the shaft as it’s too tight. Have you encounter this before? It will screw down onto the shaft but it seems too tight.

 

[NickTransmissions]

It will screw down onto the shaft but it seems too tight.

Your new aluminum 2-3 acc piston is threaded? I've never encountered that before.

It should have a smooth bore. You can use a press or vice to compress the spring to install the retainer clip. Test fit the piston without the spring then put a little assy lube on the shaft if it's a bit snug before installing it for the final time.