Rear End Lock

[tf95ZR1]

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!

[Jeffvette]

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]

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]

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"

:cry: :cry: :-({|= :cry:


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

[tccrab]

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]

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]

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.

:handshak:

TomC
'90ZR1 #792

[tf95ZR1]

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

[Jeffvette]

Give me a day.

[bobbyhi]

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.....

[tomtom72]

I remember reading a thread here or maybe it was over at CF/ZR1. Same exact thing and Mr. B did the work for the person, he bought a new zf & had Mr. B blue print it and transfer the guts to his old case to keep the # matching.

The interesting thing was Mr. B's theory, at the time, that the small fault in the way the reverse gear gets it's lube combined with the 4.10 gear mod eventually caused lube starvation & thus the gear seized. Mr. B makes a mod to the lube situation and corrects this OEM short-coming. At the time Mr. B put the failure to the extra rpm's that gear turns due to the 4.10 swap-out vs the rpm's that gear would normally turn with the stock gearing.

I think that was the gist of what Mr. B thought about that situation, if my memory is working correctly!:o

Good luck with this Tom!:thumbsup:

Tom

[rbidwell]

There is a transmission on e-bay right now:http://cgi.ebay.com/ebaymotors/90-95-ZF-CORVETTE-ZR1-6-SP-MANUAL-TRANSMISSION-NEW_W0QQitemZ8071353633QQcategoryZ33733QQrdZ1QQcmd ZViewItem

[tf95ZR1]

Thanks, rbidwell
I'm aware of that trans, but I'd first prefer to find one from
someone off the ZR1 net or someone I know.
Ted

[rbidwell]

I agree with your decision to try ZR1 area first. If I and when I have transmission trouble I will most likely send mine to Bill B for repair. That way I know that it will be good for many miles. More money, but worth the cost to me. Ron

[Jeffvette]

Ted, i tried several different resources. None are available to me. Ebay or through Bill B is your best best. Sorry I couldn't help.

[George Maz]

Just had this failure happen to me. Transmission broke and locked up the wheels at 85mph, I'm okay, no accidents. Car towed six hours to Dempsey's shop Evolution Motor Sports. We drained some trans oil, it looked fairly good. He put my car on a lift upon arrival, and already working on transmission removal.

***WANTED a nos or fully built ZF-6 transmission, please contact me or Dempsey with particulars. Thanks.

[GOLDCYLON]

I suggest you call Bill the ZF.DOC @ www.ZFDOC.com

at 602-319-6575 tell him Goldcylon sent ya. Since the R&R is already done he might have one already crated to exchange with ya

[Paul Workman]

Just had this failure happen to me. Transmission broke and locked up the wheels at 85mph, I'm okay, no accidents. Car towed six hours to Dempsey's shop Evolution Motor Sports. We drained some trans oil, it looked fairly good. He put my car on a lift upon arrival, and already working on transmission removal.

***WANTED a nos or fully built ZF-6 transmission, please contact me or Dempsey with particulars. Thanks.

Deja vu...

My M6 locked up on me once too. Bill Boudreau (http://zfdoc.com/) is very familiar with the problem, one not uncommon to some ZF6s (as I recall - some 10 years ago).

If it is the transmission, I'll let Bill B explain better. But, as I understood at the time, the issue might be one of insufficient oiling of the reverse gear; a chronic issue stemming from undersized oil galley to the shaft shared with 6th gear. (the reverse gear spins like crazy, always being coupled to the output shaft, even when the spline is not linked to the reverse gear).

At the time, Bill explained that he reams galleys to a larger size to improve oiling. And, he told me too that if i opted NOT to have him ream the galleys on the replacement xmission that to be sure to use synthetic gear oil in the trans.

It cost me about $2500 (IIRC) for the new trans and Bills special mods. That was then - some time ago.

Good luck!

[George Maz]

I'm sure 4.10 gears mod and 9 hours highway driving leaving Chicago didn't help the situation. Had I known about this potential for failure I would have just transported the car, or cruise control at 55mph the whole way home.
My #1587 has 3.90 gears, probably a safer choice.

[Paul Workman]

I'm sure 4.10 gears mod and 9 hours highway driving leaving Chicago didn't help the situation. Had I known about this potential for failure I would have just transported the car, or cruise control at 55mph the whole way home.
My #1587 has 3.90 gears, probably a safer choice.

Well, I dunno 'bout doing that. That assumes the issue is the rear end IS the problem. Anything is possible, and a recent mod to the rear (new information) certainly raises an eyebrow.

However, to the extent those symptoms are characteristic of a gear change - I can't answer. But, I and others have had that rare honor of experiencing the ZF6 lock-up.

Point is, rare exceptions not withstanding, the ZR-1's driveline is NOT a thing requiring any babying!

[George Maz]

4.10 mod wasn't done recently. The transmission and shifter felt real good. Engine was strong, cams & Corsa sound mean. Any recent work (a ton of it) was unrelated to the transmission, to my knowledge.
Dempsey will have more info when he opens it up.

So, I should look for a replacement transmission with Bill's spline modification?
Or, send him my core for exchange or rebuild?

[A26B]

My transmission (94) seized & locked the complete driveline. Rollback wrecker spotted it close to my lift where I could put a jack under the 3rd member, winched it up to the lift & oiled the rear tires to slide the rest of the way on. Locked up solid just cruising around town.
Sent it to Bill Boudreau for the full ZF Doc treatment.

[tf95ZR1]

Wow, 2006! Deja Vu all over again.
I agree with Paul & Jerry.
My BB trans has performed BEAUTIFULLY ever since.
Smooth, positive shifting, no noise. And like other times
I have broken, I use it as an excuse to upgrade: BB short shifter
is the BOMB! (my kids tell me that's a good thing.)
From what I remember: broke down in the desert. Buddy
took me into town and I rented a U-Haul and trailer.
Backed car up onto trailer and took her home. I removed
the half shafts and pushed my car into garage. Dropped trans
(MUCH heavier than I expected). REALLY fun lining up
trans/splines/shaft lying on your back under car up on jack stands.
I now have a Kwiklift but 2 - 4 post lift with trans jack is best.

PS: Or have somebody like Dempsey or Bill nearby

[GOLDCYLON]

4.10 mod wasn't done recently. The transmission and shifter felt real good. Engine was strong, cams & Corsa sound mean. Any recent work (a ton of it) was unrelated to the transmission, to my knowledge.
Dempsey will have more info when he opens it up.

So, I should look for a replacement transmission with Bill's spline modification?
Or, send him my core for exchange or rebuild?

As suggested earlier I once again suggest you call Bill to discuss the options. It is really is the ONLY smart way forward if you plan on keeping the car. If you haven't done so already I also highly suggest the beam plates upgrade while you are there as well.

[Dynomite]

Jumped from 2006 to 2016. So.....what are the odds and what are contributing factors?

Bill says If there is an oil level and/or oil condition issue, this is the area in the transmission which is prone to seizure.

What are the Oil Level and Oil Condition ISSUES?

Oil Level is obvious but am I to assume some oil levels are significantly below the top fill port?

And.....am I to assume if you have fresh TWS 10W-60 Castrol you are in good condition and have significantly reduced the chance of this Transmission Lock Up to happen?

I have Bill's C4 Beam Plates on ALL ZR-1s :thumbsup:

[oricale]

Hey all!, we are in the process of going through George's car, the transmission is out, the trans oil has been checked, levels were correct and albeit full of bits of transmission, it was clean..pilot bearing is shredded and partially laying in the snout (location of engagement of trans to crank). We are pulling the clutch pack for inspection as well as replacing u-joints on the drive shaft, the event was pretty violent.---more to follow----

As far as modding for 4/10 gears.....I am aware of at least 5 guys on the site that utilize 4/10 gears with no mods and drive 1000's of miles with no issues.

However, if there is a mod that will guarantee a life free from a trans eating itself due to this issue,.. and its proven. I'm all about it:-D.

First drive breakdown blues are a downer:censored::mad:

[George Maz]

Beam plates on both cars already...huge difference in driveline deflection (rear-end kickout), and rising shifter when a rear top plate was lost recently on #1587. Bill made one up for me.

As per your suggestion, I left a message for Bill today. I'm of the opinion to fix it right, fix it once...although I would like to hear everyone's experience. I'm told there are a handful 4.10 geared cars, driven long distances that haven't had this transmission failure occur.

Once the car abruptly decelerated itself from highway speed cruising in 6th gear, all I had for movement was a crunchy sounding reverse gear. Any forward gears would stall the engine. Then the trans got stuck in reverse, regardless of any shifter position. The clutch has to be depressed to push the car around, so I'm not completely locked up.

[Dynomite]

My transmission (94) seized & locked the complete driveline. Locked up solid just cruising around town.



OK......What caused this or are we driving ZR-1s that can for no particular reason all of a sudden lock up at any time (that would be hell in traffic for sure).

Or are we driving AT RISK ZR-1s that in their history have run for a long while low on oil or oil not changed at any particular interval.

What would prevent this and how often does this occur? what are the statistics?

Or....can we put this issue in the same category as Timing Chain Catastrophic failures (I know of only two) which are extremely rare and equally unpredictable.

[A26B]

Bill Boudreau would be the best one to obtain failure statistics and cause. I recall several failures of transmission seizures over the last 14 years, but it would be a stretch to say it's anything more than than an uncommon occurrence.

Circumstances of my particular failure;
Model: 1994
Mileage: appx 60,000 miles
Lube: original fill replaced with Redline. Original oil was full & clean. Failure occured within 2,000 miles of Redline. I make no claim that Redline was the cause.
Impending failure warning: Slow roll to stop, clutch depressed, no brake, could feel slight abnormal decel & stop with brake. Knew something was wrong & started home. made it about 4 miles.
Conditions: Cruising in town, speed 0~45mph.
Failure: left stop sign, rolling resistance significant, clutch no effect. Seized completely.

[A26B]

.......... Timing Chain Catastrophic failures (I know of only two) which are extremely rare and equally unpredictable[/B][/COLOR].

I am aware of 1 case of timing chain failure that was directly attributed to cam cover chain guide that came loose after powdercoating. Guide (facing removed) was left in place during powdercoating. Loctite may have been affected by heat.

[edram454]

This very thing just happened to one of our forum members as he was driving his car home from Haibecks. It is the transmission. His car only can move in reverse. Will need a new tranny or a rebuild. He had 4.10's and was going at a good clip also for an extended period of time. fyi..

ed ramos #3028:cry:

[8cam]

This is a little unnerving to read. I take my car on extended trips all the time and can't imagine the idea of a lockup at 80mph. I'm doing a little more maintenance this weekend and I think I'm adding a transmission oil change to the list.

[FU]

There is nothing like a ZF after Bill does his magic !

[WVZR-1]

Beam plates on both cars already...huge difference in driveline deflection (rear-end kickout), and rising shifter when a rear top plate was lost recently on #1587. Bill made one up for me.

As per your suggestion, I left a message for Bill today. I'm of the opinion to fix it right, fix it once...although I would like to hear everyone's experience. I'm told there are a handful 4.10 geared cars, driven long distances that haven't had this transmission failure occur.

Once the car abruptly decelerated itself from highway speed cruising in 6th gear, all I had for movement was a crunchy sounding reverse gear. Any forward gears would stall the engine. Then the trans got stuck in reverse, regardless of any shifter position. The clutch has to be depressed to push the car around, so I'm not completely locked up.

I believe that it's maybe important to consider the actual ZF that failed by model #. I don't recall reading about the earlier ZF's having the issue. This car is a '90 and it might be interesting to post the tag # from the ZF. This failure seems a little different than those posted in years past or the HIGHER SPEED of the failure just indicates more severe damage.

Since this one is apparently disassembled it might be wise to accumulate some images of the damage. Exploded/damaged parts should easily be identified in a ZF image by part # or even the item # in the ZF portion of the FSM.

[Paul Workman]

There is nothing like a ZF after Bill does his magic !

TOTALLY AGREE! Smooth as silk - "buttery smooth"!:cheers:

[PhillipsLT5]

Bill B did my trans 50k ago, lots of 1/4 mile, 1 mile, 1.5 mile and road course runs, still great

[George Maz]

Get some ...actually 2.2 quarts.

"It's 10:00pm...do you know where your trannys are?"

[5ABI VT]

When I bought my 93 LT1 car this happened to me as well. 3 days after buying it :cry: . I did however spend the first 2 days trying to hit 300km/hr and I needed to use 6th because of the 4.10 gears. [-X

[Paul Workman]

My lockup was a "blue-tag" ZF in my std 95 LT1 Vette. Has anyone had this problem with the older square-tooth xmissions, and mabye the 1990s specifically??

[5ABI VT]

Mine was a 93 black tag. I've since never used 6th for anything but the lightest throttle for freeway cruising. I even dropped my rear gears to 3.73s in my 93 with its 8000rpm lt4 stroker I built so I wouldn't ever need 6th and since the trans is essentially a 5 speed anyways it works out as 5th tops out way too high anyways.

[Hog]

5th gear wound at 8000rpm would be 201mph. Yeehaww smoking for sure.

I've not heard of the F-body guys having these 6th gear issues with their T-56's.

Hmm, this sounds scary. Does Mr Boudreau's rebuilds focus on this problem area?

[George Maz]

Dempsey at Evolution Motor Sports, has me back on the road with the same 610Nm type transmission swap completed, Spicer joints, Fluted pilot bearing, Amsoil Syncro-mesh fluid

...and special thanks to Bill Boudreau Zfdoc, Mark Haibeck, and Rockland Gear ZF for their advice & instalation notes.

[oricale]

Dempsey at Evolution Motor Sports, has me back on the road with the same 610Nm type transmission swap completed, Spicer joints, Fluted pilot bearing, Amsoil Syncro-mesh fluid

...and special thanks to Bill Boudreau Zfdoc, Mark Haibeck, and Rockland Gear ZF for their advice & instalation notes.


I wanted to wait for George to post:cheers:

I the drive-system is in and ops checked for about 15 miles, still a few more odds and ends to tie up, but I REALLY ENJOY diving this car!!. As George said, New Spicer's, An Early 90' black tag 610 Trans, New FLUTED Pilot bearing(would you like to see the old one??????:eek: ),AMSOIL trans fluid and a case of XL 10/30.Special care is always taken with mating and drive-line measuring during installation.

**Will post pics asap**


George did well with the Corsa, combined with the cams and porting this car is a BEAST.

I will put some HI-RPM testing in tomorrow, then when George gets down here we will set him up with another dyno run.

Dempsey

[oricale]

Test drove Georg's 90' about 130 miles with NO issues!,.. feels like a cammed-Corsa piped ZR1 should feel(tests of: High RPM driving, 90-100MPH in both 5th and 6th,low and high load at gears, smoothness of shift and positive pattern, we then temped, checked C beam torque and trans oil checks after run). The rear 4/10's do whine at 5/6th gears at about 50 and up(cut pattern?. But over all it is a ported, polished, cammed and piped car. You get what you ask for=D&gt;)

http://i917.photobucket.com/albums/ad18/oricale/Mobile%20Uploads/2016-06/20160614_194413_zpshaitk0ns.jpg (http://s917.photobucket.com/user/oricale/media/Mobile%20Uploads/2016-06/20160614_194413_zpshaitk0ns.jpg.html)

Whats that you say??...The pilot bearing?....are you sure?..(please remove small children from the room:dontknow:)

http://i917.photobucket.com/albums/ad18/oricale/Mobile%20Uploads/2016-06/20160608_181844_zpsdjh8qbk6.jpg (http://s917.photobucket.com/user/oricale/media/Mobile%20Uploads/2016-06/20160608_181844_zpsdjh8qbk6.jpg.html)

Interior is worked just a bit, seats, A/C cleaning and removal of dash-rug!(dash cover--history!)
http://i917.photobucket.com/albums/ad18/oricale/Mobile%20Uploads/2016-06/20160606_170736_zpsv86drdxi.jpg (http://s917.photobucket.com/user/oricale/media/Mobile%20Uploads/2016-06/20160606_170736_zpsv86drdxi.jpg.html)

http://i917.photobucket.com/albums/ad18/oricale/Mobile%20Uploads/2016-06/20160614_194140_zpsgewwjfm6.jpg (http://s917.photobucket.com/user/oricale/media/Mobile%20Uploads/2016-06/20160614_194140_zpsgewwjfm6.jpg.html)