New Tremec TKX 5 speed

Discussion in 'U-shift em' started by 87GN_70GS, Nov 6, 2020.

  1. bobc455

    bobc455 Well-Known Member

    For what it's worth, for decades I drove a 2.56 behind my 455. And honestly the engine could have worked great with much taller gears and a lockup convertor. Granted I've had EFI forever so I've had good engine control. But remember that the modern 3800 engines, which are half the size, do great at 70MPH and 2000RPM going up fairly steep portions of highway. So a 455 pushing an A-body down the highway takes SO little effort for our huge torque-monsters. After enough time with the 2.56 gears I wished I could have gotten some 2.29 gears or even put a GearVendors before my 2.56.

    If I hadn't been pushing so much nitrous, I would have gone for a 200-4R with lockup in front of my 2.56's.

    The engine now sits in our '73 LeSabre with 2.73 rearend & 28.5" tires- and even with the 5000# car (which often tows a car trailer so total load is around 9,000#-10,000#) the tall 2.73 gears are no problem at all for long highway cruises.

    In other words don't worry about a 0.64 top gear with 3.42's (=2.19), our big V8's are barely working on the highway and detonation shouldn't be an issue. Especially with a manual transmission where your converter isn't slipping at low RPM's. And if you are climbing the Rocky Mountains and worried about detonation, you can always drop to 4th gear.

    Just one guy's (unpopular) perspective...

    -Bob C.
    69GS&M21 and Dano like this.
  2. Dano

    Dano Platinum Level Contributor

    You may be correct but I think with an automatic (non lock-up) it's a different story than with a manual (hence why the factory geared the manual cars higher). My only experience in this regard is blowing up the factory 3.23 in my '70 350 4-sp @ the '86 Nationals and finding a Chevelle rear on a Sunday (even got it delivered to the Ramada & a ride into town for some parts w/the guy) that was either 2.56 or 2.73. We made it home (across the Appalachians) but that car/engine did not like those gears at all. On the other hand, I went across the same mountains in my '70 Skylark w/factory 2.56 or 2.73's w/no issues whatsoever. Similar I guess w/my truck (7.3 IDI/manual/4.10). It does not like hills when loaded - I think an automatic w/3.73 would be handle it just as well (until the trans burned up of course).
  3. TrunkMonkey

    TrunkMonkey Well-Known Member

    Take all you can up top. The car won't care and you will not be full throttle screaming at +100 miles an hour for it to matter.

    Get the first gearing right for your combination, and never look back. (cuz you know their behind you...)

    My '64 Lark has 3.54 rear. 26.5 tires and the T-10 had 1.51 first. I was either breaking them loose when starting off, especially on any inclines, or having to slip the clutch way to much in stop and go driving.

    The 3.27 is perfect. (wide ratio) I can almost let the clutch out in first without any accelerator pedal, So, longer clutch life.

    I just can't offhand recommend that to you with 3.42 gears and a BBB, since my '64 has a nailhead.

    The curves on the two engines could be different enough.

    My '68 Lark has a BBB and auto with 3.42, and it is very different "feel". (It gets sideways real easy)

    Hope someone with a comparable manual, 3.42 BBB in an A-body can chime in and help narrow your focus. :)
    69GS&M21 likes this.
  4. 72inPitt

    72inPitt Member

    My TKX from SST shipped yesterday
  5. knucklebusted

    knucklebusted Well-Known Member

    What's it going in? That one looks like it is a hydraulic throwout bearing and center-mounted shifter.
    69GS&M21 likes this.
  6. 87GN_70GS

    87GN_70GS Well-Known Member

    From researching a couple installs of the TKX on some chevelles, it looks like the proprietary STX offset shifter from SST is about the only way to keep from having to cut the tunnel to prevent the shifter turret from hitting on cars with offset shifters. It looks like the stock tremec center mounted shift turret will hit the tunnel instead of coming up thru the factory offset opening.

    And it looks like we need the center of the shifter where it mounts to the shift handle to be 17-5/8" back from the trans mounting face and 2-1/2" to the left of trans centerline.

    Attached Files:

    Last edited: Feb 21, 2021 at 1:26 PM
    69GS&M21, Dano and Paul Massicotte like this.
  7. ilikebmx999

    ilikebmx999 Well-Known Member

    Do the tko shifters fit on the tkx? I can’t find info if they do or not but the plates look similar. If so there are offset hurst shifters.
  8. 69GS&M21

    69GS&M21 Silver Level contributor

    Thanks for sharing your perspective, Bob. All opinions are worth considering, IMO.
    bobc455 likes this.
  9. 69GS&M21

    69GS&M21 Silver Level contributor

    From Modern Driveline? What did you have to do to get that? Here is my checkout page from my cart:
    • Ground (UPS): $135.38
  10. TrunkMonkey

    TrunkMonkey Well-Known Member

    That was how it totaled on the invoice, and it shipped UPS ground.

    The purchase was May 2019, and I suspect due to all the mess for the last year has impacted that.

    I also called and spoke with James prior to placing the order, so that might have had affected the total.

    Call and talk to someone and see if they will give you a break. :)

    Cuz, that's like 948 dollars in dog money!

Share This Page