Your ZF6 makes noises or won't shift, what to do?

[tomtom72]

Yea, Hats off to Tom for this write up! Thanks Tom!

I have some things I've been wondering about with reguard to our zf6 box.

It seems to me that the #1 source of failures can be traced to our hydraulic clutch system not being 100%. I think we all are aware of this one & the recent GM quality control issues with repl. parts....beware & be carefull!

Also it seems that the #2 source of failure can be traced back to this "reverse gear" lack of adequate oiling. Anyone have any info that they would like to share as to 'what exactly is this issue'??? As I understand it this issue relates to the fact that 6th & rev share 'something' and it gets very little lube if the trans is in 6th at high speeds? This lack of oil leads to a welding of 6th to the (?) shaft and locks up the trans??? I guess I'd just like some light thrown on this issue, ya know what not to do or what to do to prevent this, short of rebuilding a working trans as a preventative measure. TIA!

Sorry TC, don't mean to hi-jack your thread. I just figured maybe we should have our trans stuff in one thread for easier reference use.


Tom

[tccrab]

Originally Posted by tomtom72

Yea, Hats off to Tom for this write up! Thanks Tom!

I have some things I've been wondering about with reguard to our zf6 box.

It seems to me that the #1 source of failures can be traced to our hydraulic clutch system not being 100%. I think we all are aware of this one & the recent GM quality control issues with repl. parts....beware & be carefull!

Also it seems that the #2 source of failure can be traced back to this "reverse gear" lack of adequate oiling. Anyone have any info that they would like to share as to 'what exactly is this issue'??? As I understand it this issue relates to the fact that 6th & rev share 'something' and it gets very little lube if the trans is in 6th at high speeds? This lack of oil leads to a welding of 6th to the (?) shaft and locks up the trans??? I guess I'd just like some light thrown on this issue, ya know what not to do or what to do to prevent this, short of rebuilding a working trans as a preventative measure. TIA!

Sorry TC, don't mean to hi-jack your thread. I just figured maybe we should have our trans stuff in one thread for easier reference use.


Tom

Let me add the 3rd most common source of failure....
Not depressing the clutch completely to the floor when power shifting.

The PO of my Z loved banging 2nd gear at WOT to see the tires smoke. In fact, that's what he'd do so show his friends how powerful the car was.
By the time I got the car (it only had 9500 miles on it) the 2nd gear synchro was already damaged.
I tried to powershift it exactly twice and that was all it took to finish the job.


Tom

[tomtom72]

Oh yea, every now & again I go to Bill's site and read the write up he has about that subject!

I call it the "How to properly use your zf6" instructions....my fav quote from Bill is "you have to get in the clutch pedal..and it has to bounce off the floor."

Ofcourse the amount of $ to either fix or replace or replace and fix a zf6 is a motivational factor for me to drill myself with Bill's instructions! I sooo do not want to have to do what you did Tom.....specially alone & on the garage floor!

Tom

[WVZR-1]

I believe there's substantial faulty "assumptions" regarding the "blue and black" tag ZF's. The "true blues" probably only found their way into the '95 & '96 C4's!
The difference is in the transmissions internals and isn't necassarily ID'd by the "color of the tag"! '94 cars have "lift rings" for reverse and are I believe the last of the "black tag" transmissions but the internals are not to be confused with the early 610Nm transmissions.
The build needs to be "confirmed" from the ZF tag ID on the transmissions.

[tccrab]

Originally Posted by wvzr1

I believe there's substantial faulty "assumptions" regarding the "blue and black" tag ZF's. The "true blues" probably only found their way into the '95 & '96 C4's!
The difference is in the transmissions internals and isn't necassarily ID'd by the "color of the tag"! '94 cars have "lift rings" for reverse and are I believe the last of the "black tag" transmissions but the internals are not to be confused with the early 610Nm transmissions.
The build needs to be "confirmed" from the ZF tag ID on the transmissions.

The whole "lift ring" vs. "no lift ring" has nothing to do with the transmission. That particular feature lives in the shifter assembly.
You can transplant a lift ring shifter into a blue tag quite easily.

If you re-read my original post you will notice that I didn't say "All Blue Tags Don't Have Lift Rings", I quite clearly said "The Later Model ZF6's Don't Have Lift Rings".

Tom

[WVZR-1]

Ted,

Look again!

I said I believe cars thru '94 have production "black tags"! I said "true blues" were used I believe in maybe only '95 + cars and are the only "crash thru" boxes. Check and I'm quite sure you will find the ZF-047('93) box is a 540Nm box with a "black tag" and a ZF-081('94) box is a 540Nm also with a "black tag"!

The statment : "93 1/2 + are "blue tag" is faulted, it could/should state they're 540Nm boxes!

I'm not disputing a lift ring couldn't be removed! There are I believe three components that make the "blue tag" shifter unique: the lever, the cardan joint, and the primary shift shaft. These three pieces are used in only 087 & 089 builds that are in '95 + cars.


Maybe more simply stated: Not all "black tags" are 610 Nm (450 ft lbs) but ALL "blue tags" are 540 Nm (400 ft lbs)!

The build determines the trans to be 610Nm vs 540Nm "NOT THE COLOR OF THE TAG"!! I believe that to be "FACT"!!

[tccrab]

Hmmm..

You've got a valid point.

Thanks for your input.

Tom

[Aurora40]

Interesting about the tags. So if you have a black tag, assuming it hasn't been opened up, how can you tell if it's a 610Nm box or a 540Nm box? Is that rating on the tag?

[WVZR-1]

Bob,

The ZF assembly number appears on the tag. I'll post the assembly #'s that correlate to the years. That's one of the reasons I wanted to correct the information. There are many "black tags" out there and they're advertised as "black tags" (which they are) but they're not the 610 Nm boxes. I've seen some disappointed buyers!
Ted's thoughts are very widely accepted as the way it is around the various circles and if you don't own a ZF the conversation means little or nothing to you so it gets passed on. The were a couple occasions recently on the CF where fellows posted with '94 cars that had "black tag" ZF's and the general accepted response from responders were it was "likely changed". It just "ain't so"!

[WVZR-1]

From my notes on another computer I'll just stick with the LT5 S6-40:

thru '90 the part # on the tag should be 1052 000 031, '91 1052 000 035,
'92 1052 000 045 now the confusion, early '93 1052 000 045. These are all 610 Nm assemblies.

later '93 1052 000 047, '94 1052 000 081 These I believe are "black tag" 540 Nm and still have "lift ring"!

The only LT5 crash through "blue tag" '95 1052 000 087. No lift ring.

I guess I'll be embarrassed as hell if this isn't correct but I do believe it should be. I would guess there will be some crawling under the car this weekend!

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One other point that interests me. I never thought you could just swap a connector to use the later speed sensor in the '90 cars. I thought the '90 cars were maybe 2000 pulse DC (sq wave) and the '91 and later 4000 pulse AC (sine-wave). I don't know this to be fact but it's the way I always thought it. I went to a good bit of effort to buy an original spare from Vauxhall for a Carlton that shared the ZF transmission with the Corvette. It arrived in an original Delco package. It was a very good find and the parts guy from Vauxhall was astonished that I found him. He had NO ZF stuff and the Carlton people I've corresponded with say the parts are likely harder to find in GB than they are here.