Well I got everything put back together on the TH400 today, but I'm a little conecernd there might be something wrong.

I got both the drums to line up in the case ok, but it seems when I put the pump on the input/output shafts became very difficult to turn. I checked the end play on the rear output shaft and it was .008, within spec. I tried to get a reading on the front input shaft and doesn't seem to be any endplay it in. After looking at the ATSG manual, it's suppose to have some endplay.

So now what? Is it ok to run it like this or will i stand a change of doing damage? I can turn the rear out put shaft but it takes some muscle to turn it.

if you checked it properly, according to the manual,I would remove the pump and put a thinner thrust washer till you get the right clearance,will do damage.

My guess is that the direct drum isn't completely engaged in the intermediate clutches.

When you bolt it down, it bends the teeth on the last friction in the pack and makes it hard to turn.

Take it back apart...

You can verify the direct drum is completely installed by looking at the spline engagement on the shaft it sits on. It will be bottomed on the splines.

TH400's are always sloppy as far as endplay (stock), so if you have none and haven't done anything to tighten it up, it's likely misassembled.

I took it apart last night and I think the issue is the bushings where the pump slides through. This is a very tight fit since the bushing is new. I'm going to see if there are some burrs or something on it that is causing it to stick.

I think it was assembled correctly, it's just a very snug fit where the forward clutch slides though the pump. In addition, those iron snap rings that fit around the pump seem to be a very tight fit. Not sure if that's also contributing to the problem.

You might get some teflon or "peak" sealing rings, instead of the iron ones.

I would still check the intermediate clutches, be sure you didn't bend the teeth. Common assembly error and will not be good once you put it in operation.

It would be very unusual to not have any front endplay on a stock TH400...I've seen close to .200" of slop on stock units here.

Ok, just tore it apart. Looks like it was the bushings on the pump that were causing me not to be able to get any endplay. I sanded down the edges a bit and the shaft now moves more freely. Problem Solved!!!

Whats so great about the Teflon rings?

The rings don't wear into the drums, the seal better in operation.

Solid teflon are a PITA to install, but the late 4L80E peak rings are nice, snap them on like an iron ring almost and go. Won't wear the drums.