ZF 6-speed problems (sorry)

Discussion in 'General IH Tech' started by Justin, May 11, 2006.


  1. Justin

    Justin Farmall Cub

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    First of all I need to apologise for asking a Ford question on an IH website, but the technical minds and talent in this community are far superior to what I can find on any Ford website. (I fully understand if the forum moderator wants to dump this post!) I figure there's plenty of people here with the Navistar engines, so this is not totally non-IH related.

    Having shifting problems in my wife's 99 F-350 SD 7.3 6-spd CC Dually. About 99k on the odometer. Bought the truck at 30k assuming original clutch, and have not touched the clutch since. Almost 100% tow miles with 2 to 5 horse trailers or 20k equipment flatbed (it works hard)

    Started having problems getting it into gear about 20k miles ago, like the synchros were not allowing it into gear. Drained original fluid and switched to royal purple synthetic hoping to free things up. The problem is intermittent - when shifting it slides into neutral fine, but won't go into the next (or any) gear at times. You're left stuck in neutral which can be vary scary when you're on a packed interstate towing horses.

    When it's operating normally, there is a fair amount of resistance when shifting - like you apply pressure and need to wait 2-3 seconds before it will slide into gear.

    My guess is a problem with the synchronizers. I understand what they do, but not completely clear on how they do it. Seems about the same in all gears, so I expect it's a fluid issue and not one bad syncho (I'm assuming each gear has it's own syncho gear) Based on use and mileage, I would not be suprised if a worn clutch has some impact (no slipping yet, no other reason to suspect clutch was bad)

    Any ideas??

    I'll post this one the FTE site as well - I expect the typical response to be something completely useless and dumb like "switch to an auto" :rolleyes:
     
  2. John Donnelly

    John Donnelly Administrator Staff Member Administrator Moderator

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    I think you need to evaluate your clutch condition. I doubt very much the transmission is at fault here.

    -John
     
  3. shawn davis

    shawn davis Binder Driver

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    sounds like you need to do a clutch job.
     
  4. benmaples

    benmaples High Wheeler

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    My votes for clutch job also or trade it in on a used 6.0 with the A/T [allison I think] Now that's a workhorse with the heart of an IH.
     
  5. Bill Bennett

    Bill Bennett High Wheeler

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    Have you checked the clutch pedal linkage for clearance/freeplay?
    Bill Bennett 68 Travelall
     
  6. ruderunner

    ruderunner High Wheeler

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    This vehicle should have a hydraulic clutch release. Step one is to make sure the resevoir is full and it should take dot3 brake fluid (double check that, it should say on the cap) If the resevoir is full try bleeding the system, there should be a bleeder screw sticking out of the bellhousing. While bleeding look for brake fluid leaking out of the bellhousing, if it leaks then the trans has to come out for slave cylinder replacement and a new clutch while you're there. Also a quick peak under the dash to check for a leak from the back of the master cylinder wouldn't hurt. Not sure if 99 still had dual mass flywheels but they should be done with the clutch so be prepared to open your wallet WIDE.
     
  7. Justin

    Justin Farmall Cub

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    Thanks for the replies.

    I figure I won't be losing much by doing a clutch now since I'm pretty much at 100k.

    I've read an article somewhere about ditching the dual-mass flywheel for a soild replacement. Anyone have experience with these?
     
  8. Foy

    Foy High Wheeler

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    Justin-
    I'm in for clutch, also. Hopefully linkage, but possibly time for a replacement, especially at 100K miles, 7-8 years out of the factory, and if there has been a lot of city driving and/or heavy towing.

    You said you hadn't found a good site for Ford trucks. I have an 02 F350 diesel with an automatic, and I've been very happy with the tech knowledge over at www.thedieselstop.com. There are a number of vendors listed there for clutch replacements for your ZF, too.

    Good luck,

    Foy
     
  9. benmaples

    benmaples High Wheeler

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    As with all Ferds I replace the slave cylinder when doing a clutch & vice versa so whichever it may be you need the pull trans & get after it :rolleyes:
     
  10. Sozzy

    Sozzy Farmall Cub

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    The 5 speed "torque shift" is a Ford unit...
     
  11. Patrick Morris

    Patrick Morris Lives in an IH Dealership

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    Sozzy, you know this thread is 11 years old, right?
     
  12. scoutboy74

    scoutboy74 Lives in an IH Dealership

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    Whatchu talkin' 'bout Willis? These things have dates on 'em?
     
  13. Sozzy

    Sozzy Farmall Cub

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    How did I miss that? Derrr... sorry
     
  14. 64desertscout

    64desertscout Farmall Cub

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