What the heck did they do to the clutches on the 02s?

[Wally]

Way back when I drove a ZF equipped Dmax. Tranny was a little notchy but the clutch was great. Made the truck really easy to drive. Let off was predictable and the clutch disengaged at almost the same place as it engaged. Based on this I've been trying to get a ZF equipped Dmax for 14 months. I've got it now and this clutch is freakin horrible!!!! Pedal is smooth through its travel so I don't think its an air in the fluid issue. Let off is unpredictable, vague, and just generally crappy feeling. Disengagement is even worse. Sometimes the clutch doesn' actually disengage until the pedal has been on the floor for a second or so. This makes the truck extremely hard to drive smoothly and causes some really embarassing moments as the thing lurches around. Hit any kind of a bump while trying to take off and it is guaranteed to start the dreaded, foot bounce, truck lurch, foot bounce, snowball. The only thing to do when this starts is just push in the clutch, grab a taller gear and try it again. I'm finding that it's much smoother to take off in third rather than second. The thing not disengaging properly also makes it hard to make smooth gear changes, especially from 2nd to 3rd! I drove another 01 last week with the ZF6 and it is mucho better!
Any ideas? Try bleeding the hydraulics? What does the clutch use for fluid?
I would take it to the dealer but their service dept. is staffed with uncaring morons.
Sorry for the long post.

[ 05-12-2002: Message edited by: Wally ]</p>

[IndigoDually]

It sounds like you have an air pocket somewhere. I believe that the clutch hydraulic system uses brake fluid(DOT 3). Slave cyls. can be tricky to bleed. I have found that I have to pry the slave all of the way in with a big screw driver or prybar while cracking the bleeder because the operating range of the cyl. is not totally utilized and a pocket of air lurks at the end of the throw of the slave. You have to bottom the slave all of the way in to get that last little bit of air out.

Hope you can understand this and it helps.

John

[rberner]

I have had no troubles with my zf6 like what you are talking about, it shifts smooth and disengages predictably. The only problem I had was with the peddle squeaking, which eventually stopped.

Love the truck 16,000 miles and still smiling tongue.gif

[NickLeinonen]

if the slave cylinder has a bleader screw like hyrdaulic brakes have, you could maybe use a vacuum bleader to flush the system out.

[DieselsRule]

Wally I know what you mean about the lurch thing, and I have embarressed myself a few times with it. Another thing I noticed is that sometime when your letting out the clutch and you push it back in, it feels and sounds like your missing a motor mount by the way the truck shakes and bangs. I think this motor just has a bit much low end torque for the gear ratio w/o a load. I usually start out in 2nd and do 2,4,6, but have started out in 3rd w/o a problem. The other issue I have is if I go 2,3,4 it never goes into 4 smoothly like either the clutch doesn't fully release or the synchros are gone. However, when it wants to be smooth, this ZF-6 is very smooth, I guess it's just getting use to it. Go Figure. Let me know what you find out.

[MaxRock]

Gentlemen, I have a 2002 DMax/6 speed and do not have the problems that you are describing. It did catch me off guard how close to the floor the clutch engaged, but I have gotten use to that. My clutch is very consistent where it engages and disengages. To me it sounds like there may be something wrong with the clutch in your vehicles. Be careful about adding brake fluid, the reservoir takes DOT 4, not DOT 3.

Good luck with your search, I hope your problems are fixed. This is a great truck and very comfortable to drive, you shouldn't have to suffer with driving such an awesome vehicle.

MaxRock

[DeepVee]

Wally,
How many miles do you have on your truck? My truck was very difficult to drive until the clutch was broken-in. The engage & disengage points were very erratic but got better as I put more miles on the truck. The truck you test drove may have had a clutch that were alrady broke-in.

[trailguide2u]

I bought my 2002 in December and its very smooth. I thought the 2001 I test drove was very harsh and hard to engauge. Makes me wonder if the clutch parts assembly's are the same?

[Wally]

I haven't tried to bleed it yet but it is getting better. Either the air is working itself out or I am learning how to drive it :D .

[mackey_62]

Have 4500 mi. on mine. Besides a few 4th gear take-off stalls, NO complaints here. ( A couple of those 4th take-offs were successful! )Mine feels just like day one.
I have noticed the hard pedal after long runs, say an hour plus. Seems to go away after cooling down?
No long trips, no hard pedal.

Dieselsrule: I've also noticed problem with 3 to 4 shift, Try to let her down to 1000rpm or less before you hit 4. Seems to help. Rest of the shifts are fine. (Except 1 to 2 during break-in, man was I glad to quit starting in 1st.)


Anyone have any comments on changing gearbox fluid yet?

[DieselsRule]

Lately what I have noticed is that the majority of these issues are when the drive train is cold. Once the engine is at normal operating temperature, beside the occasional grind from 3rd to 4rth, everything is fine. I just had the truck for 1 1/2 hour drive and did not experience the hard pedal.

[DieselsRule]

Lately what I have noticed is that the majority of these issues are when the drive train is cold. Once the engine is at normal operating temperature, beside the occasional grind from 3rd to 4rth, everything is fine. I just had the truck for 1 1/2 hour drive and did not experience the hard pedal.

[Wally]

I got under the truck yesterday for so that I could have a look see and complete the bonding process. That's what my wife accuses me of anyway.
I noticed two things. The crankcase is different on this one and there is no place to bleed the hydraulics on the clutch. The slave cylinder is inside the bellhousing with nothing more than high pressure line dissappearing into it. I guess it is supposed to be self bleeding?
Finally got 500 miles on it yesterday so today I'm gonna load it up with the 3300 lb water tank and see if I can't get the clutch broken in properly.
One more thing. The cottonpicking thing has started squeaking :mad: . What is the fix for this?

[Red Diesel]

My clutch is a little harsh at low speeds. It is especially awkward when backing up the driveway and then stopping. If I don't push it in slowly it jerks and feels like something is coming loose. (Like the Engine) I Always attributed it to the torque.

My truck has always been plagued with the creaking clutch. Took it back today to have the ball and socket greased before it got too worse AGAIN. PROBLEM though!!!! They took out the booster cylinder to get at it and the white platsic ball just crumbled. They couldn't get a replacement part today so I am driving a service loaner. WHAT LUCK I HAVE!!!......... At least it didn't crumble on the road.

[Wally]

Yep Red I've noticed the jerking when the clutch is disengaging. Sounds like the whole drive line, engine included, just fell about an inch.
I'm beginning to wonder if the motor and tranny mounts aren't too soft. One thing that aggravates this is the fact that the clutch doesn't disengage when you push in the pedal. There seems to be very short lag. Perhaps about 200ms.
I wonder if the 8.1s with the ZF6 do this? Anyone?

I doubt I'll get a response. ZF6s behind the 8.1 are twice as rare as the Dmax pushing the ZF.

[Red Diesel]

Got my truck back today after almost a whole week. The part came in and the service department installed it quickly. Driving home (23 miles) I noticed that my initial complaint of the creaking was still there; actually worse!! I called the service department and they told me they could do no more. They have no Tech. bulletins about this. I called GM Customer Service (LAUGH) and they will call me back tommorrow to discuss this. They can either fix it or buy it back. GM contends still they have no other complaints about this creaking clutch.