Is this a fluid/clutch/master cylinder/tranny problem?

[Roadster Guy]

Changed the factory fill tranny fluid in my ZF 6 speed late last fall before storage and replaced it with Castrol synthetic TWS10W-60. I have 32,000 miles on the car. This spring I noticed a couple of weeks ago after the car had sat a few days a whine in the tranny as I headed out one day in first and second gear and then it was gone. Today, I fired up the car after it had sat a few days and as I went up the street there was the whine and then a louder mild howling noise. I clutched a few times and changed gears and then it was gone and was gone for the rest of the drive.

Anyway, things don't seem 100% normal. My transmission has never whined in any gear before ever in the 3 years I have owned it. And it made zero noise at idle and still does. It still shifts smoothly and is always easy to get into gear--even reverse. The clutch always seemed to catch about half way up and now it catches closer to the top but still engages 3/4 up I'd say. It never pops out of gear. However checking things out today I noticed when driving I can shift from any of the first four gears back to neutral without clutching!! Actually, I have never tried that before (because I am sure the shift was always locked in gear), but it does seem kind of wierd, though maybe it is normal, but I doubt it. I can just pull or push on the stick towards neutral and bingo, I'm in neutral. There is no noise or anything when I do that. Makes me think maybe think something is not right. The clutch pressure feels light to me, not at all heavy to push on.

Just checked the clutch fluid and it is full, but it looks oily and dark and not clean to me. Checking the records I know it is at least 5 years old, maybe 7. Is it like brake fluid that gets moisture in it and loses its efficiency? I changed every fluid in her last fall except the clutch fluid.........

I have never had a drop of leaking fluid under the car ever. I know the clutch fluid needs to be changed, but would that alone cause what is starting to happen?

I don't think the last fall tranny fluid change is part of the problem. Maybe the master cylinder is letting in air? But, if so could that cause gear whinning to come and go?

I don't know much about transmissions/clutches so any feedback would be appreciated. Hoping to catch this before any major damage is done. And especially now when the nice weather is here!
RG

 

[96CERon]

Similar issue

Changed the factory fill tranny fluid in my ZF 6 speed late last fall before storage and replaced it with Castrol synthetic TWS10W-60. I have 32,000 miles on the car. This spring I noticed a couple of weeks ago after the car had sat a few days a whine in the tranny as I headed out one day in first and second gear and then it was gone. Today, I fired up the car after it had sat a few days and as I went up the street there was the whine and then a louder mild howling noise. I clutched a few times and changed gears and then it was gone and was gone for the rest of the drive.

Anyway, things don't seem 100% normal. My transmission has never whined in any gear before ever in the 3 years I have owned it. And it made zero noise at idle and still does. It still shifts smoothly and is always easy to get into gear--even reverse. The clutch always seemed to catch about half way up and now it catches closer to the top but still engages 3/4 up I'd say. It never pops out of gear. However checking things out today I noticed when driving I can shift from any of the first four gears back to neutral without clutching!! Actually, I have never tried that before (because I am sure the shift was always locked in gear), but it does seem kind of wierd, though maybe it is normal, but I doubt it. I can just pull or push on the stick towards neutral and bingo, I'm in neutral. There is no noise or anything when I do that. Makes me think maybe think something is not right. The clutch pressure feels light to me, not at all heavy to push on.

Just checked the clutch fluid and it is full, but it looks oily and dark and not clean to me. Checking the records I know it is at least 5 years old, maybe 7. Is it like brake fluid that gets moisture in it and loses its efficiency? I changed every fluid in her last fall except the clutch fluid.........

I have never had a drop of leaking fluid under the car ever. I know the clutch fluid needs to be changed, but would that alone cause what is starting to happen?

I don't think the last fall tranny fluid change is part of the problem. Maybe the master cylinder is letting in air? But, if so could that cause gear whinning to come and go?

I don't know much about transmissions/clutches so any feedback would be appreciated. Hoping to catch this before any major damage is done. And especially now when the nice weather is here!
RG

I think I experienced this same problem when I changed the trans fluid on my 96 CE. I had changed it before to Castrol and didn't hear it. This time I would get a noise that sounded like a shaft running in a dry sleeve bearing. This happend for about a week for about 20-30 secs every morning as soon as I left the driveway. Now it is gone??? Not sure, but maybe there is some area in the ZF that gets dry initially after draining fluid.

 

[Roadster Guy]

Just got off the phone with my mechanic after briefing him on this tranny issue. He thinks it is not clutch (hydrallic) related at all as the fluid level is fine, the shifter goes in and out of all gears fine and stays in gear and the clutch catches about half way to three quarters of the way up. I asked about what 96CERon said about a possiblr dry area in the tranny after after a fluid change but he said he said no to this. He was not sure about being able to shift out of gear while driving into neutral with no clutching...he felt that did not sound right to him.

As I live near to his shop he suggests trying to see if I can immediately swing it by next time it happens so he can hear it. He feels he would have to hear it to really say what it might be. He thought opinions from this site are useful as well.

I think I have maybe narrowed it down to one of two things:

I am suspicious about the new 10W-60 castrol synthetic fluid that is in the tranny. I never had this whine before that change. Is it possible that as it is a 10-60 synthetic and the previous fluid was the factory fill which i think is a 5-40 that on cool or cold mornings the fluid is thicker and takes longer to splash around in there because it is thicker? More so right after the Vette has sat a few days which was the case in the two instances so far?

Or is it a linkage thing inside the tranny that's maybe related to being able to shift out of gear with no clutch when running?

RG

 

[Chris Kennedy]

I would recommend going back to the factory recommended lubricant---this may be one of those times that it is just best to stick with stock and leave it at that.

/s/ Chris Kennedy
Houston, Texas

 

[JEFNLSA]

I would contact Bill Boudreau @ www.zfdoc.com. This guy really knows his stuff when it comes to ZF trannies. His # is listed on the web site. Call him....
Tell him Jeff from Phx sent ya....

 

[Roadster Guy]

Chris, you know, I was thinking about that as the tranny noise had never occurred prior to switching to the synthetic fluid......I am going to contact Bill as Jeff recommended to get his take on this....can't hurt. Jeff thanks for the recommendation.............much appreciated ....still like that black LT4 of yours! Just wondering here....Do you have synthetic fluid or GM fill in your tranny? Can you pop the shifter out of gear into neutal while driving without clutching?:ugh

 

[JEFNLSA]

Jeff thanks for the recommendation.............much appreciated ....still like that black LT4 of yours! Just wondering here....Do you have synthetic fluid or GM fill in your tranny? Can you pop the shifter out of gear into neutal while driving without clutching?:ugh

RG

I'm runnin' the Castrol in mine. (courtesy of the ZFDoc)
Never tried to pull her out of gear w/o the clutch & I'm a bit leery to try that.
I'd definitely get Bill's take on that.

Thx for the comment on my car.
I've had it for about a year now and have been personalizing it to my tastes. I think I'm just about there...yeah right :L No really, it's nice when you get her where you want her.

See ya
Jeff

 

[Roadster Guy]

Can shift without clutching more than I thought!!

Jeff, get this. I sat in the Vette and with the engine off I can shift around in all the gears without clutching! Is that strange or what? I can't do that in my wife's car (BMW) that has a 5 speed. And yet I can drive the Vette around (with clutching) and it is shifting and running great and there is no whine today. Maybe a very faint one in first and second, but I am not sure because it is either super faint or it is my brain doing it cause I am so obsessed right now with the tranny. Anyway, I emailed what was going on to Bill and I left a voice mail asking him to check the email for details. I sure hope he can offer some sort of explanation because this is kind of flipping me out.....:W

Thanks again for the suggestion to contact him. I will post his response if and when I get it.
RG

 

[JEFNLSA]

Jeff, get this. I sat in the Vette and with the engine off I can shift around in all the gears without clutching! Is that strange or what? I can't do that in my wife's car (BMW) that has a 5 speed. And yet I can drive the Vette around (with clutching) and it is shifting and running great and there is no whine today. Maybe a very faint one in first and second, but I am not sure because it is either super faint or it is my brain doing it cause I am so obsessed right now with the tranny. Anyway, I emailed what was going on to Bill and I left a voice mail asking him to check the email for details. I sure hope he can offer some sort of explanation because this is kind of flipping me out.....:W

Thanks again for the suggestion to contact him. I will post his response if and when I get it.
RG

RG

Coincidentally I was @ Bill's (ZFDoc) last week. He was doing a little work for me (shimming & greasing ZF for better/tighter shifting). When he was done he was going through all the gears (engine off) w/o the clutch so obviously that can be done w/ this tranny.

Hang tight cuz he will get back to ya' & take care of your ?'s. There is nothing he does not know about the ZF 6spd & the clutch hydraulic system. :dance

Jeff

 

[Roadster Guy]

Hey, now that is a relief to know that yours can shift around without clutching while sitting. I guess mine always did obviously, but I never thought to do that without clutching. I am curious to see what he says about being able to pop it from gear into neutral while driving without clutching..you are smart not to try it....safer just to ask him..I mean...maybe that is also normal and I never realized it. Anyway, you are right and I shall sit tight until I hear from him. By the way, it was also good to hear what you said earlier about him putting the Castrol in yours like I did to mine....that then is not an issue as far as he is concerned.
RG

 

[JEFNLSA]

By the way, it was also good to hear what you said earlier about him putting the Castrol in yours like I did to mine....that then is not an issue as far as he is concerned.
RG

That is what he uses exclusively. :dance There is not a more informed source on the ZF than this guy.

BTW...CE...LT4...Vert = I'm jealous! :L

 

[Roadster Guy]

Great news from Bill!!!

Jeff, Bill just emailed back already. What a terrific response. I may as well just copy his email below for you to read as he has explained the whole thing clearly and put my mind to rest. I mean at least now I know what is wrong and what needs to be done.

BTW yes mine is a CE...LT4...Vert..plus...every option from climate control (PEG package) to F-45. Only missing the run flat option..just in case you want to be really jealous:L .
Anyway, thanks tons again for referring Bill....a super guy....here is his reply:



This is a simple one.



Your input shaft pilot bushing is causing this cold start screech like sound for certain.

The pilot bushing has accumulated a glaze build up.

No harm will come to any of the components while this condition is present.

It’s just irritating to listen to.



When you get around to replacing the pilot bushing, be sure to install a fluted pilot bushing so as not to have this condition occur in the future. Use GM P/N 10125896 .



Don’t worry about hurting anything if you don’t get around to fixing it right away.



See Ya,



Bill Boudreau



I thanked him by email and I hope as many people as possible on this site that need servicing can take their Vette to him and at the very least recommend him. BTW his website is really informative.

Anyway, now I am wondering how big a job it is to replace the pilot bushing. You know? I don't want to ask Bill as it is not urgent and he has already gone out of his way on this.

Ok, I'm going to finish up my paperwork on this desk over the next hour and then go out and fire up the Vette for the drive home..might take the long way....beautiful and sunny out there today.....
RG

 

[JEFNLSA]

Cool RG, glad to hear that you got some answers. Don't be afraid to ask Bill for more info as the ZF is his baby and he loves to share his wealth of knowledge on anything concerning such.

He is way cool and I am lucky to have him in my neighborhood. In fact, I'll be seeing him in a couple weeks for a ZF fluid change. What would take me two hours takes him 15 min.

Later
Jeff

BTW....YES, JEALOUS! :L
I've got the stripped down model but boy does she go!

Enjoy the weather!

 

[Roadster Guy]

Ok Jeff, you take care now. And there ain't nothing nicer than a shiiny black 96 coupe wearing custom chrome wheels....especially one packing an LT4!
RG