TH400 troubles

[aaron1009]

Recently while cruising, I lost almost all drive power. Truck eventually stopped pulling at all. Coasted to a parking lot and put it in park. Back into drive and it caught, pulled, then stalled. From then on, when cranked and in park, the truck sounded like it had dropped a cylinder. Put into any drive gear (including reverse) would cause the truck to stall abruptly. Cranked in neutral, the truck ran normally.

Sounds like it's time to drop the tranny. Alright, here's my question. Is the TH400 in the 1009's at all different from any other TH400 found in Chevys from the 60s-80s? I imagine it has a shorter tailshaft, but that could be swapped from my old TH to a used one I bought, correct? Or is the TH in our 09s different to the point I should just drop it off at the shop and have a professional rebuild the one I have?

TLDR: Would a TH400 I bought from Joe Junkyard bolt up with no problems?

 

[rnd-motorsports]

The trans it self is no different from any 4x4 trans, the dif. will be becouse of being a deisel the gov. springs will be dif If you pop out the gov from yours clean it make sure no problem and install in the other trans you will not notice any dif I would get a new converter to use ( for a deisel) becouse of the stall speed for a deisel. Will be good to go.

 

[aaron1009]

You said a 4x4 TH400...is there a mechanical difference besides a shorter tail shaft and the diesel gov? Thanks!

 

[rnd-motorsports]

NO, But the normal person can't change out the tailshaft you have to completely take trans apart to change the output shaft is the first itam to go into an empty case! If you can handle that then there is no dif.

 

[cjtroutt]

Have your trans Rebuilt put all the good parts in it up date to TH-475.
I done my with all the best parts to up date mine and also over halled Trans fer case to
all done for $1800.00 total.
works as HD Trans should.

 

[wallew]

Have your trans Rebuilt put all the good parts in it up date to TH-475. I done my with all the best parts to up date mine and also over halled Trans fer case to all done for $1800.00 total. works as HD Trans should.

OK, what is a TH-475? I gotta ask.

I'm all for HD and I'm probably going to start rebuilding my spare TH-400 - the parts are NOT that expensive. And a DVD is available to step you through both the disassembly and reassembly with loads of direct video on exactly what to do. I've got the skill set. And MOST of the tools. Probably have someone do the machine shop stuff. But that would be it. I will do the rest. Like I said, this is my MV of choice, so I might as well KNOW how the inner workings of the drive line all work. Individually and together.

As this is my MV of choice, I might as well learn this rebuilding skill. That and a rebuild on the NP208 and then I'm going to take on the 6.2L rebuild.

So, what did your guy do?

 

[rnd-motorsports]

the primary difference is the planetary units has straight cut gears in the t-475 unit. Tranny case is a bit beefier in the bell area

The straight cut gears reduces the side loads generated in the gear train of the tranny under a heavy load like a large motorhome.

The straight cut gears have a bit louder whine too

 

[rnd-motorsports]

If you want the actual trans all that I have seen or dealt with have a rather large HD cast into the bell housing you can get the planetary sets to put into a reg 400. As stated by CJ

The 66 mud truck I have has the 475 set up as stated by cj but I used a divorced 205 for the strenth becouse of the 5:13 gears and 5000 stall loads put on the trans. with no issues!