Rear End Lock - ZR-1 Net Registry Forums

tf95ZR1 · 05-30-2006

Since I'm at work I'll try some keyboard diagnostics before tackling my problem.
While going about 110

without any warning my rear end locked up like I hit the (rear) brakes. I reflexively pushed in the clutch and put it in neutral and slid off to the side of the road safely whew!

I then found that I can only go backwards in reverse normally, but not forward. Any forward gear, slowly letting out the clutch results in no forward movement and boggs the engine badly.
Someone said its the differential (4:10's) where forward the pinion locks out but reverse it "seats." Someone said its the trans as reverse is on a different spline?
Any experience or any ideas?
TIA
Ted Feder
95 ZR1 #106 (Sick)
PS. Easy to back up onto a trailer, hard to remove half shafts to roll back off!

05-30-2006

Damn Ted.

Easiest thing I would suggest is unhooking the driveshaft (after installing the halfshafts) and then trying to rotate the tires backwards and then try forward. That would narrow it down rather quick if it's the trans or the rear end.

I have seen a transmission lock up while driving. Basically the rear bearing seized to the driveshaft yoke. Not exactly pretty. I doubt reverse worked in that instance though.

tccrab · 05-30-2006

Interesting problem. Glad I wasn't in the passenger seat!!!
If I were a gambling man I'd bet the problem lies in the transmission and not in the differential.
I can't for the life of me imagine how a ring and pinon gear will work in one direction and not the other. Even if there's big chunks of gear teeth floating around inside there you'd think it would free spin or just lock up.
Sound to me more likely something has seized in the tranny in such a way that the reverse and forward gears are trying to engage at the same time, except when you put it into reverse.
It could be a shifter issue too, were you banging gears when your world came to a screetching stop? I've had old Muncie shifters that would jam when speed shifting. I remember having to limp all the way home in 2nd gear after speed shifting my '67 Camaro RS too hard.
Good luck and keep us informed!

TomC
'90ZR1 #792

tf95ZR1 · 06-01-2006

I hope Bill doesn't mind me posting his private reply to me,
but this is FYI
I trust his word on the ZF6 as gospel.

Bill Boudreau <billb@zfdoc.com>

"Ted,
Sorry to hear of your problems.

The transmission has seized up for certain.
Inside of the transmission, reverse gear, while not engaged, coasts
(rotates) in the opposite direction as everything else rotates.
If there is an oil level and/or oil condition issue, this is the area in the
transmission which is prone to seizure. What happened in your case is that
the reverse gear has seized to the main shaft. Thusly explaining why you
only have reverse gear propulsion.

I am relieved to hear that you didn't sustain any bodily injuries or
external damage to the vehicle. This can be a very bad failure, injury wise.

Replacement of the transmission is the most practical corrective action for
rebuilding yours will likely cost as much as a new replacement until will
cost.

See Ya,
Bill"

PS Check your fluid levels.......

tccrab · 06-01-2006

Well, looks like the jury is in on the tranny issue, sorry 'bout that.
I'd check with Jeff (Jeffvette), he had access to some new "old stock" some time ago, maybe he's still got some laying around.
There's been one on eBay forever, but if I had my druthers, I'd buy one from a Forum member. Much less likely to get screwed.

I'd also drop a note over at the CorvetteForum, maybe somebody around there has an extra one laying around.
I can't imagine that one would be too hard to find, but it ain't gonna be cheap. Figure on spending *at least* $1500.
I would be wary of buying a used one unless it came from a RELIABLE source.

Good luck!

TomC
'90ZR1 #792

bobbyhi · 06-01-2006

I purchased one of those trannys off ebay over a year ago. New in crate. Had it shipped to my local mechanic and installed. Never had a problem. Very good transaction from the guy. I think he was from GA if I remember. Wouldn't hesitate to buy from again. Just my HO....

tccrab · 06-01-2006

Quote:

Originally Posted by bobbyhi

I purchased one of those trannys off ebay over a year ago. New in crate. Had it shipped to my local mechanic and installed. Never had a problem. Very good transaction from the guy. I think he was from GA if I remember. Wouldn't hesitate to buy from again. Just my HO....

Good to know.
Hopefully this helps Ted out a little.

TomC
'90ZR1 #792

tf95ZR1 · 06-01-2006

Quote:

Originally Posted by tccrab

I'd check with Jeff (Jeffvette), he had access to some new "old stock" some time ago, maybe he's still got some laying around.

Good luck!

TomC
'90ZR1 #792

So how 'bout it Jeff? Anyone else have a good ZF6 lying around?

And Bob, about how much did it cost?

Thanks all!
Ted

06-01-2006

Give me a day.

bobbyhi · 06-01-2006

I think it was $1900.00 plus 55.00 shipping to Minnesota. I sold the old tranny for 750.00 so I think I came out alright. Even if I paid too much the tranny works great and everything is working fine except for the squeal in my brake that is listed on a different thread.....

05-30-2006	#2
Jeffvette Guest Posts: n/a	Re: Rear End Lock Damn Ted. Easiest thing I would suggest is unhooking the driveshaft (after installing the halfshafts) and then trying to rotate the tires backwards and then try forward. That would narrow it down rather quick if it's the trans or the rear end. I have seen a transmission lock up while driving. Basically the rear bearing seized to the driveshaft yoke. Not exactly pretty. I doubt reverse worked in that instance though.

05-30-2006	#3
tccrab Join Date: Oct 2004 Location: Folsom CA Posts: 1,657	Re: Rear End Lock Interesting problem. Glad I wasn't in the passenger seat!!! If I were a gambling man I'd bet the problem lies in the transmission and not in the differential. I can't for the life of me imagine how a ring and pinon gear will work in one direction and not the other. Even if there's big chunks of gear teeth floating around inside there you'd think it would free spin or just lock up. Sound to me more likely something has seized in the tranny in such a way that the reverse and forward gears are trying to engage at the same time, except when you put it into reverse. It could be a shifter issue too, were you banging gears when your world came to a screetching stop? I've had old Muncie shifters that would jam when speed shifting. I remember having to limp all the way home in 2nd gear after speed shifting my '67 Camaro RS too hard. Good luck and keep us informed! TomC '90ZR1 #792 Last edited by tccrab; 05-30-2006 at 08:43 PM.

06-01-2006	#4
tf95ZR1 Join Date: Aug 2005 Location: Northridge, CA Posts: 1,453	Re: Rear End Lock I hope Bill doesn't mind me posting his private reply to me, but this is FYI I trust his word on the ZF6 as gospel. Bill Boudreau <billb@zfdoc.com> "Ted, Sorry to hear of your problems. The transmission has seized up for certain. Inside of the transmission, reverse gear, while not engaged, coasts (rotates) in the opposite direction as everything else rotates. If there is an oil level and/or oil condition issue, this is the area in the transmission which is prone to seizure. What happened in your case is that the reverse gear has seized to the main shaft. Thusly explaining why you only have reverse gear propulsion. I am relieved to hear that you didn't sustain any bodily injuries or external damage to the vehicle. This can be a very bad failure, injury wise. Replacement of the transmission is the most practical corrective action for rebuilding yours will likely cost as much as a new replacement until will cost. See Ya, Bill" PS Check your fluid levels.......

06-01-2006	#5
tccrab Join Date: Oct 2004 Location: Folsom CA Posts: 1,657	Re: Rear End Lock Well, looks like the jury is in on the tranny issue, sorry 'bout that. I'd check with Jeff (Jeffvette), he had access to some new "old stock" some time ago, maybe he's still got some laying around. There's been one on eBay forever, but if I had my druthers, I'd buy one from a Forum member. Much less likely to get screwed. I'd also drop a note over at the CorvetteForum, maybe somebody around there has an extra one laying around. I can't imagine that one would be too hard to find, but it ain't gonna be cheap. Figure on spending at least $1500. I would be wary of buying a used one unless it came from a RELIABLE source. Good luck! TomC '90ZR1 #792

06-01-2006	#6
bobbyhi Join Date: Jul 2005 Location: Mendota Heights, MN. 55120 Posts: 983	Re: Rear End Lock I purchased one of those trannys off ebay over a year ago. New in crate. Had it shipped to my local mechanic and installed. Never had a problem. Very good transaction from the guy. I think he was from GA if I remember. Wouldn't hesitate to buy from again. Just my HO....

05-30-2006	#1
tf95ZR1 Join Date: Aug 2005 Location: Northridge, CA Posts: 1,453	Rear End Lock Since I'm at work I'll try some keyboard diagnostics before tackling my problem. While going about 110 without any warning my rear end locked up like I hit the (rear) brakes. I reflexively pushed in the clutch and put it in neutral and slid off to the side of the road safely whew! I then found that I can only go backwards in reverse normally, but not forward. Any forward gear, slowly letting out the clutch results in no forward movement and boggs the engine badly. Someone said its the differential (4:10's) where forward the pinion locks out but reverse it "seats." Someone said its the trans as reverse is on a different spline? Any experience or any ideas? TIA Ted Feder 95 ZR1 #106 (Sick) PS. Easy to back up onto a trailer, hard to remove half shafts to roll back off!

06-01-2006	#9
Jeffvette Guest Posts: n/a	Re: Rear End Lock Give me a day.

06-01-2006	#10
bobbyhi Join Date: Jul 2005 Location: Mendota Heights, MN. 55120 Posts: 983	Re: Rear End Lock I think it was $1900.00 plus 55.00 shipping to Minnesota. I sold the old tranny for 750.00 so I think I came out alright. Even if I paid too much the tranny works great and everything is working fine except for the squeal in my brake that is listed on a different thread.....

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