th400 upgrades?

[78 Chevyrado]

My trannys started slipping and has no braking in 2nd.  Can't find the problem doing what the service manual says (clutches shot i bet) so pretty soon I'll be having the tranny rebuilt.  I basically want a stock rebuild.  It's a turbo 400 in a '78 c20.  I usually get a shift kit for a TH350, but this one shifts tighter already so I'll probably skip the shift kit. 

One day I'll have the GM 260HP/325ft.lb. crate engine in it.  definately not too much for a th400, but I can be rough on it.  When i get on the freeway on ramp, I'm already doing 80mph before I hit the bottom, and when i pass I hurry up and get it done.   Now and then I may tow up to a 8000lb trailer, but mostly it's just a daily driver.

What I'm wondering is what "can't do without em" upgrades do yall recommend, with links if ya have them.  I know the list can go on for days,  but I want to only upgrade what really needs it for longer tranny life.  I have a tranny cooler behind the grille.  I'll be sticking with a stock converter.  All I can think of right now is upgrading the clutch pack.   I have a shop around here I goto for EVERYTHING tranny related and I want a list of stuff to ask them when I take it to them to price it.

[Donut]

The last TBH-400 i had I couldn't kill so I really don't know.   I read a lot about rebuilding my turbo 350, dual feeding the direct clutches was a biggie.  I ending up purchasing a tranny due to time constraints.  I believe this holds for the tbh 400 also.  Try here.http://www.hotrodders.com/forum/th400-build-tips-pics-145318.html good rebuild info and his posts were extremely helpful.

[Blazin]

A shift kit improves fluid flow, extending the life of the trans, keeps it a little cooler too. thats what my buddy that dose rebuilds told me once. I would go with one. You can get a shift kit that doesn't bang gears.

[DnStClr]

I think any time you can help keep a tranny cooler you're doing it a bunch of good. Rather than suggest to the rebuilder what he should do, I would have to defer to his expertise as to what a good rebuild consists of. But I would make sure he's a qualified tranny mech, certified and all that, ya know.

[gbskunk2006]

I had the same problems with my tranny, add in there that it wouldn't backup when cold, and would never kick down when I needed the extra kick in the rear.  I decided to buck up and take it to a tranny specialist here and after a couple of weeks of driving, it was money well spent.  I haven't decided on what I'm going to do for a future power plant but for now feels like I'm driving a brand new truck.

The shift points are higher and a lot crisper (almost feels like I have a shift kit).  It kick's down on demand, and I can drop it into 2nd and immediately feel the breaking when I need to preserve my brakes (that's the next job on the to do list).

Key thing would be to tell the dude exactly how you plan on using your vehicle and the type of loads you expect to carry.  However, from what I was told and little research I've done, the Turbo 400 is almost bullet proof

Good Luck!

[cucvtrucks]

All I run are th400 trans, I ask for a shift kit, the brass screen filter, the 4l80e sprag and that has been enough to handle 600+ horses in my s10. From past experience, I have had a few 400's that clog the filter with normal wear material, all transmissions will put material in the fluid much like brake dust, it eventually if not changed will clog the filter, in turn makes the pump starve and whine, slow to engage in gear, if not addressed early will cause trans to burn up the clutches due to lack of enough fluid pressure to lock them up. I have had some last for quite a while when they started to clog and I would change the fluid out and switch to the brass screen filter instead of the felt one.
Hope this helps, Cortney

[joesgarage71]

I think any time you can help keep a tranny cooler you're doing it a bunch of good.

 This is true, but a transmission needs heat also. Make sure you run your cooler lines through the radiator cooler. On start up I always warm the transmission up in N before driving.