6 sp Transmission Problem (C4C5specialist)

[gmjunkie]

(03 Z51)

Driving to my sisters today from my sons (about 40 mi)I was running about 65 with the cruse on in 5th gear and started up a slight grade hear a loud POP and now I have no 5th or 6th gear,1st,2nd,3rd,4th and reverse work fine with no adverse noises.5th and 6th feel like it's going into gear but just make a whirring noise. Got any Ideas,I'm 900 miles from home!

[froggy47]

Originally Posted by gmjunkie

(03 Z51)

Driving to my sisters today from my sons (about 40 mi)I was running about 65 with the cruse on in 5th gear and started up a slight grade hear a loud POP and now I have no 5th or 6th gear,1st,2nd,3rd,4th and reverse work fine with no adverse noises.5th and 6th feel like it's going into gear but just make a whirring noise. Got any Ideas,I'm 900 miles from home!

lurk.

Sorry, no ideas.

[ToolGuy]

Just a guess here, but the 5th - 6th gear syncro is probably gone. I would say its not the gears because if so, one of them would be the issue probably not both.

You could drive the car back home, but MPG would probably suffer since you have no 5-6 gears. Whatever it is, I don't think you can fix it on your own right now.

Has the shifter ever been aligned? If you have access to tools and can take the console apart, if its ever been aligned, you could try it, but it does not sound like it would help to me.

[froggy47]

Originally Posted by ToolGuy

Just a guess here, but the 5th - 6th gear syncro is probably gone. I would say its not the gears because if so, one of them would be the issue probably not both.

You could drive the car back home, but MPG would probably suffer since you have no 5-6 gears. Whatever it is, I don't think you can fix it on your own right now.

Has the shifter ever been aligned? If you have access to tools and can take the console apart, if its ever been aligned, you could try it, but it does not sound like it would help to me.

Hmmm,

The loud pop could just be popping out of gear.

Maybe it IS a shifter alignment, pretty easy to do.

[gmjunkie]

It's not shifter adjustment,Something Broke in the transmission.
I borrowed a car from a old HS buddy to come home and get a few special tools we'll need and my laptop with my GM service programs.
After reviewing the service program,I've determined either the 5-6 shift fork broke(Not likely!) or the fork collar broke off the 5-6 slider.(More Likely) I've seen this on several Ford,Dodge and GM manual transmission trucks! I've been into Muncie's,Saginaw's,Borg-Warner's and Bunches of ZF's,and I've changed out a few C5 clutches,But this is the 1st MM6 that I have to go into up to my elbows,Wish me luck!~!!

[LLC5]

Originally Posted by gmjunkie

It's not shifter adjustment,Something Broke in the transmission.
I borrowed a car from a old HS buddy to come home and get a few special tools we'll need and my laptop with my GM service programs.
After reviewing the service program,I've determined either the 5-6 shift fork broke(Not likely!) or the fork collar broke off the 5-6 slider.(More Likely) I've seen this on several Ford,Dodge and GM manual transmission trucks! I've been into Muncie's,Saginaw's,Borg-Warner's and Bunches of ZF's,and I've changed out a few C5 clutches,But this is the 1st MN6 that I have to go into up to my elbows,Wish me luck!~!!

Good luck!

Hope you find the reason for the fault after disassembly. That's almost as important as the repair.

[c4c5specialist]

HI there,

You can determine what it is by the shifter effort, if you have equal effort in all gears, then the shifter fork is not broken.

If 5/6 can be moved easier, then that is most likely the problem.

Allthebest, c4c5

[gmjunkie]

Originally Posted by c4c5specialist

HI there,

You can determine what it is by the shifter effort, if you have equal effort in all gears, then the shifter fork is not broken.

If 5/6 can be moved easier, then that is most likely the problem.

Allthebest, c4c5

And it had nothing to do with the shifter or fork!~!

Nothing that a new output shaft,5-6 driven gear,5-6 drive gears,5-6 synchronizer,reverse gear,rev synchronizer, a few bearings and c clips didn't fix!~!!