The Diesel Stop banner
1 - 6 of 6 Posts

·
Premium Member
Joined
·
142 Posts
Discussion Starter · #1 ·
No 6th gear?? Need help and a little info.
Can't find any diagnostic answers in repair manual.
Posted this yesterday but can't find the post. Disappeared into thin air?


Driving along around 45mph with my '99 6-speed/7.3/4X4 lost 6th gear.

Had just gone into 6th gear and the engine just revved
Up.
Down shifted thru lower 5 gears and all was okay.
Now I no longer have 6th gear?? Feels like I broke some type of linkage.
Can any one comment?
Shifts fine, just no 6.
Can I be lucky or do I need to pull the transmission?

'99sd 4wd/6 speed man.d this yesterday but can't find the post on my NEW transmission problem!
 

·
Super Moderator
Joined
·
26,593 Posts
Are you sure it isn't the clutch? If you're saying there's nothing at all in 6th, and the rest of the gears pull well, then the shift fork may have broken. I believe that 6th has it's own fork, not shared with any other gear.

You can check the clutch by putting the tranny in direct (5th), holding the brake then release the clutch slowly. If the engine stalls, then your clutch is probably fine.

If it's the shift fork, the tranny has to come out and be torn down to fix it. The ZF-6 is kind of a complicated tranny to work on, so I'd recommend finding a shop that's familiar with them, or just find a rebulit tranny to swap in.

Good luck with it.

on edit: I don't see any tranny post by you other than this thread. :shrug03:
 

·
Premium Member
Joined
·
142 Posts
Discussion Starter · #3 ·
Thanks for the reply. The clutch was the first thought but that is fine. It stalls in 5th gear.

Darn I wish it was a 56 Chevy then I could just pull the side plate and replace the fork!

If I pull the transmission do you think I should change the pilot bearing (150K) and the clutch fork, disc, slave cylinder, etc?? Thanks.
 

·
Super Moderator
Joined
·
26,593 Posts
I'd definitely upgrade the clutch fork if yours is the original. Probably the throwout bearing also.

As far as the clutch itself. I might inspect it to see how much is left on the disk, but replacing it is good insurance. If the hydraulics are working OK, then you could defer that, as they're accessible with out pulling the tranny. Not so much for the clutch.

If it was a 56 chevy, you could even pull the tranny without a tranny jack. :lol:

Definitely don't try that with a ZF-6. The thing is monster heavy. It's a 2 man lift even after it's out of the truck.
 

·
Premium Member
Joined
·
142 Posts
Discussion Starter · #5 ·
Not sure yet what is broken in the transmission. But I have started a list of other parts to replace when I get it out.
1. clutch fork & throwout bearing
2. Slave cyl (mine is weeping)
3. Check clutch disc and replace if necessary.
I will make a separate post to tell of a burst brake line when checking the clutch.
 
1 - 6 of 6 Posts
Top