ZF6 Issues, please take a poll I am interested in a pattern

[LIMEY]

I'm trying to determine if there is a pattern with the ZF's, i have for the longest time felt that ZF has a known issue with the late model blue tag units in esp. the ZR-1, more so because of the higher RPM's they spin. If i am right, i suspect that 95% of the blue tag owners that have had theire ZF's rebuilt have done so because of bearing seizures, either in 2nd or reverse gear, this is based more on personal first hand experience than anything. I would also suspect that not one single black tag unit ever seized, i'll explain why after you guys post. Regular C4 guys post too. Thanks. Kurt.

[Rkreigh]

I've had 4 zr1s, 1 90, 2 95s, and a 93. yet to have any problems with the zf box. now that I said that, I will probably blow one in the a.m.

what do you believe is the source of the problem. it would be interesting to post this pole on the c4 tech forum too where you would have a larger audience.

thanks kurt

[BlackWidow#2]

Kurt, i'll be interested in the results too!
George C

[92 ZR1]

1991 zr-1 syncros (3rd gear)

[Aaron71771]

My ZF has a tag on it "rebuilt by ZF" so it must of been serviced at some point in its past. I have not had a problem in the 10K miles I've had it.

[DDSLT5]

Granted I haven't put too many miles on mine (about 10K), and very few with the 415, but when the engine was stock, I ragged the living piss out of it, and no problems whatsoever.

Now - I have no idea where to look for this blue or black tag - more info please!! :seeya

[phrogs]

Now - I have no idea where to look for this blue or black tag - more info please!! :seeya

Its on the passenger side of the transmission. There are 2 tags on the tranny 90-92 have a black tag, 93-95 have a blue tag its from the factory with some info about the tranny on it, what it says I cant recall.

[Bigvmaxx]

3 ZR-1s to date... 2 90s and a 91... only 24K logged between the 3 of em... never a problem... except when my foot gets lazy on the clutch when shifting... no option box in your post for no problems... so... this is my expirence so far...
Ted
Sun City, CA

[LoTu5]

Ive had no problems with my 90 box to date at 70,000miles ('Cross my fingers' 'touch wood' 'please God').
I will also be interested, as with all the modifieing that ive done its the only thing ive not modified.
When i was at Jeal&sons a couple of weeks ago Geoff gave a couple of us a quick run-thru on a special cross section of a box in the workshop he uses for demo's....Boy do they look tough.
Whats the Max torque to be put thru one of these?


[Modified by Uk422, 4:46 AM 1/19/2004]

[Rkreigh]

I understand the 93/5 "blue tag" box have a different cut on the gears and a lower torq rating (400?) vs 450 for the early boxes in order to cut the noise. I never really noticed too much noise difference except in the lower gears and the old 90 ZF box reminded me of a "M22 rockcrusher" but it wasn't bad and I got used to it.

however, in the high HP high rev ZR1s, it seem that the early boxes would be better. at BG Paul had some problem with is ZF, but I have not really seen that high a failure rate with the blue tag 93/5 boxes even in the high HP applications.

kurt,

can you pleae elaborate on the differences and why the later boxes have bearing seizure problems??? thanks very much, great post. :confused:

[LoTu5]

Thanks for that Ron , How much can a modified box take?,i also know of owners using 'mobile1' in their gearbox's,i was a little apprehensive of this at first but they dont seem to have any problems.

[8388]

93-95 have a blue tag its from the factory with some info about the tranny on it

Late 93. Early 93 is still has a black tag. Main difference between the two is the way the gears are cut. 90 thru early 93 are a bit noisier. The gears are cut straight vs at an angle. Some believe that straight cut gears although noisier, will hold up better, or take more punishment.

[ZR1 MK]

My 1990 has been trouble free for 39K miles. I use Mobil 1 oil, 5K miles of road racing use, one drag race day with full throttle shifts (approx 7), approx 10 other full throttle shifts and still using original clutch/flywheel.
Mike

[Mikez40]

My 93' has 17,000 miles and has not had any trouble yet. Knock on wood. I do wine the gears out to 7000 rpm's most of the time or close to it. Also been to the drag strip several times. I have my shift light set at 6800 RPM.

[Greybeard ZR1]

Just a note on these plates. If your box has been rebuilt at ZF, it will also have a blue plate located below the I.D. plate (my I.D. plate is black, a 91') The blue plate will have the ZF logo and a notice that to retain warranty you must use factory recommended lube. On mine, between the black and the blue plates there is also a little stainless plate, saying "Re-manufactured for General Motors".

Another tip: If you want to know if the box you have is the original one for your car, look on the driver's side of the main case. At the rear, on the lower half of the main case you will see your cars VIN number stamped vertically.

As for me, I've not had a bit of trouble with any part of the car BUT the transmission. I'm on my 3rd. re-build in 43Kmi. And it's broke right now. Very depressing. But I'm sure the re-builder and I will work it out. Someday I'll post the whole story. :yesnod:

[carter200]

A little touchy to get into reverse but other than that it's sweet :yesnod:

[Mangusta1969]

Limey,

You need to modify your poll to include a response of "No problems to date".

My late 92 ZR1 ZF has 55K miles on it with no problems so far, courtesy of two 475+ HP 368s mounted just in north of it since late summer 1992. The trans/car is on the second clutch, so it gets a pretty good workout from time to time.

I hope Mr. Murphy doesn't strike me down for posting this.

[415LT5]

No problems with my remanufactured GM ZF6. It has about 20K on it with a few really bad missed shifts. You know the kind....where you miss and your soooo pissed that you reach and cram that sucker right back in gear ( not suppose to do that) but you can't help it. :)

Now that I said something I will probably blow it up the next time out.
Oh well, if your not breaking something your not racing.
Later
Joel

[korvetkeith]

I've swapped a ZF6 into my ole '84, so i'm not worried about my power breaking anything. But do have problems with syncros, my syncro in 5th is messed up pretty good cuz my bleeder valve fell out one time and all my fluid came out when I went to slam it into 5th and I ground it like a bastard. The syncro going into third isn't very happy either cuz I used to alway try powershifting it, but I blame that on the stock shifter :D . I power shift 2nd at least everytime I go out and haven't problems there, but I don't remember a time that I messed up the shift either. About 1 out 30 times it will grind in reverse if I haven't pulled the shifter all of the way back. So yes I have abused my ZF6 unmercifully and it still mostly works. One day when I have more money than I do now, I plan a buying a rebuild kit from you Kurt. But I'll deffinately put on the Hurst this time :mad
P.S. Is it true that you sell some kind of steel syncros Kurt?

[A26B]

Kurt,

The poll sounds like a good idea, but I think the results will be distorted by the sheer number of cars produced prior to 93-1/2 compared to afterwards. Even if the late bearings were inferior, the failure rate would have to be enormous to weight the poll as such. For the poll to be of any benefit, you would probably have to "normalize" the results relative to production. :blueangel: