More T-56 stuff.

From: Jon Steiger (stei0302@cs.fredonia.edu)
Date: Mon Dec 21 1998 - 13:29:05 EST


  Ok, I've been doing some more research on this tranny thing...

  I checked out the Summit and Jegs catalogs. They have a
Richmond 6-speed tranny, but they don't call it the T-56, so
I'm guessing its not. ?

   Ummmm... Just before I sent this message I went off and did
some more research... The T-56 appears to be made by Borg-Wagner, NOT
Richmond. Oops. :-) Unfortunately, that still doesn't clear up much
of the confusion.) The SR-71 Dakota web site calls their tranny a
T-56 6-speed on one page, and a Richmond 6-speed on another page.
So natually, I assumed it was a Richmond T-56. So, either both
Richmond and Borg Wagner make a tranny called the T-56, or the
SR-71 page is wrong. Either way, I'm still confused. ;-)

  The overdrive gear ratio in 6th is .76 by default. (My NV-3500's
5th is .729, so this 6 speed would actually raise my RPMs!) Not
what I want to do at all! The Jegs catalog says optional overdrive
ratios are available from .62 to .91. If my calculations are
right, a .62 6th gear would have me cruising at about 1830RPMs
at 70mph with my 3.55 rearend. (Currently, I get 2150RPMs at
70mph in 5th) [ .729/.62 = 2150/x ]

  Here is what I came up with for RPMs resulting from various
rearends with my NV-3500 and a Richmond with a .62 6th gear;

sorted by rearend ratio:
--------------------------------------------------
   Trannny Rearend Approx. RPM @70mph

    NV3500 3.55 2150
   Richmond 3.55 1830

    NV3500 4.56 2760
   Richmond 4.56 2350

    NV3500 4.10 2480
   Richmond 4.10 2110

sorted by tranny:
--------------------------------------------------
   Trannny Rearend Approx. RPM @70mph

    NV3500 3.55 2150
    NV3500 4.10 2480
    NV3500 4.56 2760

   Richmond 3.55 1830
   Richmond 4.10 2110
   Richmond 4.56 2350

  So, it looks like if I had 4.10s and the Richmond, my
crusing RPMs would be about the same as they are now. (They'd
drop about 40rpm) But the .62 6th gear ratio isn't enough to
compensate for a 4.56 rearend; it would raise my cruise rpms
by a full 200rpm. (Still much better than the 610rpm they'd
raise with the NV3500 though...)

  Another concern I have is that the Summit catalog said its rated
to take 450lb-ft of torque. What's the deal there?? I'm probably
not all that far off from 400lb-ft now, and I plan to churn out
much more than a measly 450lb-ft!!! Does anyone know the torque
numbers for the Viper? Its gotta be more than 450lb-ft... Isn't
it? If that's the case, this tranny being sold by Jegs and Summit
doesn't appear to be the T-56.

  Soooo, if its not, where can I buy a T-56, and does anyone know
anything about how much it might cost, and what the gear ratios
are?

  Thanks very much in advance!

                                              -Jon-

  .--- stei0302@cs.fredonia.edu ----------------------------------------.
  | Jon Steiger * AOPA, DoD, EAA, MP Race Team, NMA, SPA, USUA * RP-SEL |
  | '96 Dodge Dakota v8 SLT CC (14.58@93.55), '96 Kolb FireFly 447 |
  `--------------------------- http://www.cs.fredonia.edu/~stei0302/ ---'



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