Is my ZF-6 telling me something?

[MaxACL]

After the replacement of my Transfer case the service manager commented that the transmission shifted great and that I must be shifting without the clutch. Well I DO use the clutch and never thought of not using it. So, for a period I did some shifting without the clutch and although I did pretty good, I would sometimes make it grind and once in a while it would jerk the whole truck when it would go into gear, this, with a 36 ft camper. So I started using the clutch again.

But now I have a noise I

[More Power]

I've forwarded this thread to ZF. Let's see what they have to say.

MP

[More Power]

ZF responds:

"If you can get some additional information, we might be able to troubleshoot this guys noise problem. Shifting without the clutch can really generate a lot of heat, which could result in a serious bearing problem.

Special transmission testing:
Because this person is participating in The Diesel Page BB forum, we assume he has a diesel engine. As he stated that there was a previous transfer case problem, we also know it is a 4X4. I would ask that the customer operate the transmission with the transfer case in neutral, and then shift into all the gears. Can this noise that he has mentioned still be heard? Listen to see whether there is a gear where there is more or less noise present.

Back to a normal driving mode:
Is there any noise present while the foot is on the clutch pedal? What rpm is the noise present and in what gear. We need much more descriptive events to help us understand the noise condition.

If you can get more information, we may be able to help. I would prefer to not offer any further diagnosis until we get some additional information.
Thanks,"

[DeepVee]

My ZF started to make noise around 20,000 miles. This is an 8.1L/ZF with a stock clutch, solid flywheel and no mods. Noises began with a chatter coming through the shifter handle at highway speeds in 6th, 5th & 4th. Sounded like something rattling in the shifter assembly or gear noise coming through the shifter handle. I took it into the dealer and was told all was normal. Next I started to get an awful growling noise when I put a load (5,000lbs) on the drivetrain in any gear at any speed; chatter noise was also still there. The growl was most predominant as I initially accelerated in a new gear, loading up the drivetrain. I again took it into the dealer and they agreed to open it up. The tech found the pressure plate heat checked & cracked and stated the input shaft gear was pitted along with the input bearing/race and an additional bearing/race on the main shaft. GM replaced my clutch, surfaced the flywheel, and installed a new input shaft and bearings/races. Initially it was fine, the chatter was still there but the growl was gone. Well over time the growl has returned. I'm now at 45,000 miles and the growl still reappears every once and a while. I'm frustrated and can not determine what in the hell causes it to happen; heat, load, city traffic. I can tow 5,000 lbs. and never hear the growl, then I drive the truck unloaded around town and the growl returns. Then the next time I get in the truck the growl is again gone, very strange.

BTW, GM had to install another new clutch and new flywheel around 37,000 miles. Everything looked OK when it came out; it just stopped working one day and would not go into gear. All this clutch crap makes me wonder if most on my noises and problems are related to the factory GM clutch. Could it be getting hot and slipping? Explaining why I had a cracked pressure plate at 20,000 miles. I think we all know there is excessive heat build up in the front of these GM ZF's.

MP, is there an easy way to get in touch with ZF? Email? Will they respond to a ZF owner?

[ 12-02-2004, 08:17 AM: Message edited by: DeepVee ]

[More Power]

DV,

ZF is an advertiser here on this web site. You can contact them through the link found in the Advertisers Section (http://www.thedieselpage.com/vendors/main.htm). They occasionally read the posted BB messages, and have answered my emails in the past when we were trying to help people.

MP