From: ravalent@mothra.syr.EDU (Bob Valentine)
Subject: Re: TH350 vs. TH400
Organization: Syracuse University, Syracuse, NY
Date: Thu, 28 Jan 93 00:01:28 EST

In article <1993Jan25.121339.15258@miavx1.acs.muohio.edu> dwsmall@miavx1.acs.muohio.edu (Derek 'Enzo' Small) writes:

>I think you'll find that that 400 converteres are suposed to have a
>special fitting on on the face that holds a small trust bearing.  
>You should stay away from using a 350 convert on 400's since the shaft 
>can eventually "drill" a hole trough the front of the converter.  I
>haven't heard of any shaft problems doing this and I've even talked to
>a few guys who have simpley machined the end of the shaft off a bit
>and had no trouble at all, though I don't recomend it.  

  Never heard of that, but I'll add one more fact to the brain bucket.

>The TH350 is a much more reliable and better shifting unit
>than the TH400.  That is why there are so many more kits available for
>it. 
      Reliable and better shifting in stock or rebuilt form?  I've
heard of more dead 350's than 400's, but then of course, there's a lot
more 350's out there than 400's...  In my experience, most 350's shift
either too soft or too hard.  Even with proper downshift cable
adjustments, and a "heavy duty" shift kit, they never feel right.  The
400 in my 71 Olds was a freshly rebuilt I ripped out of a 76 Firebird.
Shift hardness seems VERY related to throttle pressure/load.  Light
throttle, you hardly know it shifts.  Heavy throttle, it WILL chirp
the tires. I'll admit, tho, shift feel is a personal thing.
    Also, seeing as how GM teneded to put the 400 behind big-inch
engines, it must say something for its strength.

>I've rebuilt several TH350's and only one TH400. The TH350 was
>a bit easier to rebuild but not much.  Either one can be done in a weekend
>easy. 
     I've never rebuilt either one.  I'm gonna try it on a junker some
day.  I guess I belive the hype about difficulties...

>TH400 can be made to shift about as well as the TH350 with some minor
>work on the valve body.  With a tranny cooler it should be about as
>reliable.
  
    By "shift as well", what do you mean?   One of the main things
going for the 350 is the control of the downshift.  400's will
manually downshift only if you hit the gas REAL fast, or stomp it to
the floor to trigger the switch.   350's downshift sooner, no argument
there.

>Someone asked about a TH700 a while back and no one else offerd anything
>yet so if you're reading... The TH700 is basically an electronically
>controled version of the TH250 but for front wheel drive vehicles.
  
    For front drivers?  TH700-4R (or R4, I forget) is rear-wheel
drive.  The 700's closet relative APPEARS (outside looks only) to be a
TH350.  The 200-4R is the OD version of the TH200 series.  I can't
wait for the 4L80.  OD version of the TH-400!

>*******************************************************************************
>* Derek "Enzo" Small                   [san.dwsmall]@miavx1.acs.muohio.edu    *
>*                                      Miami University, Oxford, Ohio 45056   *
>******************************************************************************

     _____________________________________________________________
    /\                 -->   Bob Valentine  <--                  /\       
   / /\            --> ravalent@mailbox.syr.edu <--             /\ \      
  /\/ /\  --> 71 Olds Cutlass Convertible: 350/T400/Posi <--   /\ \/\
 /\ \/ /\  "I'm a UNIX addict recovering from a DOS relapse"  /\ \/ /\
/ _\/_/__\___________________________________________________/__\_\/__\   

p.s. - My general ideas on the TH350 vs TH400 are (in street mode) to
use the 400 if it is available.  In my experience, it is more durable
in general form.  400's for Buick/Olds/Pontiac are much more plentiful
than the Chevy only 400.   You'll find short-tail BOPCad 400's all
over wrecking yards, usually out of Delta 88/98's, some Caddys, and