1960s TH 400 question

[Cadman-iac]

 So for you rebuilders out there, I have a question for you.
 As I understand it, the early 400's in the big GM cars used a 6 disc pack in the forward clutch, but all I've ever seen has had a 5 disc pack. It doesn't matter how you stack them, 6 just don't fit.
 Did they use a thinner piston for the 6 disc units?

 Another question, how much of an effect does eliminating the wave plate with a flat plate have on the shift quality? Is it barely perceptible, or does it feel like a shift kit was installed?
 I'm currently working on one that has a coned plate in both the forward and intermediate clutches, and one of them was broken. I've considered replacing them with waved plates, or just using another flat plate, but I've never tried this before so I'm not sure what the difference will be in the shifting.
 Any suggestions or comments would be greatly appreciated.

 Rick

[bcroe]

The 6 discs fit when a thinner piston is fitted, I
have bought them on Evil Buy to retrofit.  My
experience is they are used on all TH425s, and
with the most powerful engines in a TH400. 

I know the rebuild kits do not have a wavy steel
plate, it must make some difference or the General
would not have used it.  I ALWAYS put the wavey
plate back for a refresh.  At this age a trans
may be apart to refresh the soft seals, not a
serious failure.  I find in most cases the hard
parts can be reused (probably better than new
from Asia).  So most steel clutch plates get 
reused, just change the frictions.  Just using
a new soft kit and some Torrington thrust washers
saves a ton of money.  Bruce Roe

[Cadman-iac]

 Thanks Bruce,

 I've been looking at the friction and steel plates that came out of this transmission and the collection of parts from previous teardown, and measuring the friction plates I've concluded that unless the transmission was totally abused, these can be reused without issue.
 This particular transmission has 185K miles on it, and all the plates are within one or two thousands of what a new plate measures.
 I was concerned about the mileage and thought it was time to go through it and refresh everything, but even the seals look fine.
 I probably could have just done an external reseal and would have been just fine.
 Even the inside of the pan was void of the usual clutch debris pile.
 Given this, would you still replace the torque converter, or reuse it?

Rick

[bcroe]

The rubber seals on the clutch pistons age, I have
seen 400 seals so hard they broke when bent.  If
they leak, lose pressure, and let the clutch slip
much, it could burn up and fill what was a great
trans with black poison (ask me how I know).  So
replacing those high pressure internal seals is
the important thing, external leaks hit my drip
pan.  The shift shaft can rust and destroy its
seal, but new shafts are available. 

You need to get about the right clearance with
the frictions, which should be pre soaked.  I have
a lot of extra used steels in varied thickness,
can usually come up with a good combination,
have sent some out. 

The manual shows how to check converter wear.  I
have had enough trouble with rebuilts, I try to
run the originals at least 200,000 miles. 
good luck, Bruce Roe

[Cadman-iac]

  Thanks Bruce,

I'm already into it, so I'm going through with the rebuild. I've already got the new parts from Fatsco, as I intended to go through everything anyway. I was just curious if this was a normal situation or if I just lucked out. But from the sounds of it this must be normal, unless like you say something went bad internally and wipes out everything else.
This is the 3rd 400 I've done, so it's familiar to me now. I just wanted a more experienced opinion on the converter. I've only replaced one and it was on a 700R4 because my son trashed it.
The other 2 400's were switch pitch, and I reused the converters with no issues.
This one the fluid looked like it had just come out of the bottle, so I thought it would be safe to reuse the converter, but thought I'd ask anyway.
I'll reuse the wave plates as well. The book I'm using says you can eliminate them, but not having ever tried that I'm a bit leary to try, as to remedy any problems means pulling it back out. And it's hard enough to do it once, I don't like doing things twice.
I appreciate your knowledge and input, thank you.

Rick