Page 2 of 2 FirstFirst 12
Results 21 to 22 of 22

Thread: No more manual transmissions in a Duramax - why?

  1. #21
    Join Date
    Oct 2001
    Location
    Myrtlehead, TX
    Posts
    414

    Default ZF 6 Forever

    My six speed has 300,000 on it and never been worked on. The dual mass flywheel is another story. I went through many till I found a single piece at South Bend Clutch.

    I just replaced my transfer case (again) and Mr Good Wrench pulled the 6 speed to look for other trouble, and with 30,000 on this new single piece flywheel the surfaces looked new. the machine grooved was still there. Gotta love it!

    Mike

    PS I do get leg cramps in city trafic.
    2002 GMC, Pretty Dark Blue, 4x4 / 3500, ZF6, 115 gal spare tank and Rockets... (My Other One): Flying Fuel. I got three engines and a 52,000 gallon tank, how many you got?

  2. #22
    Join Date
    Feb 2000
    Location
    Montana
    Posts
    11,382

    Default

    The 6-speed manual GM used in the 2500HD/3500 diesel pickups was identified as a "ZF S6-650". The "S6" identifies this as a 6-speed. The "650" identifies the input torque limit.

    As has been mentioned here, the originally introduced flywheel was a problem. An updated flywheel was released in July 2004 that was designed to increase life, improve friction control and reduce transmission input shaft wear.

    Here's a clip from an article I wrote in 2004:

    The ZF S6-650 six-speed manual transmission first became available in GM's 8.1L & Duramax equipped 2500HD/3500 series pickup trucks beginning in the 2001 model-year. Lower cost, improved fuel economy and a performance advantage in certain situations are among the more important reasons owners express when selecting the ZF six-speed. The S6-650 is also available on C4500 & 5500 medium duty trucks.

    ZF S6-650 Key Features:
    • Designed specifically for high torque pickup trucks.
    • Synchronized in all gears.
    • Dual-cone synchronizer in 2nd and 3rd gears.
    • High helix angle gearsets provide high contact ratio and quiet operation.
    • Lower shift forces w/ tight shift pattern.
    • Lightweight integrated aluminum housing
      (front, center & rear).
    • Center bearing support for improved durability.
    • Reverse & 1st gear location improve maneuvering ease.
    • Overdrive 6th gear shift lever position located forward and away for improved passenger comfort.
    • Gross Combined Vehicle Weight Rating up to 26,000-lbs.
    • Left & right ISO/SAE 6-bolt Power Take-Off ports.
    Jim

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •