View Full Version : uh-oh clutch gettin funny
this is hard to explain but my clutch pedal pushes harder than normal after i get on it hard, I am not talking dead stop burnouts or anything. Lately if I roll into it hard even in 6th and go to push the clutch it pushes harder for a couple times them goes back to normal. Is something coming loose? I had a flywheel put in 5 months ago if that matters I don't know. I am running the pred on the 100hp setting like normal and actually have quit the powershifting after the flywheel was put in. I have been nice to the truck is what I am saying :D Any ideas, I would love to hear them before I take it in and ask a dealer.
Is this an early sign of slippage starting to occure? It seems to bite fine.
Well, I can only guess, but if you are talking about a hard to push pedal, I would bet that you are boiling the clutch fluid in the slave.
Mine gets hard, but after a pump or two on the clutch pedal, all goes to normal.
BTW, is your clutch fluid in the reservior black? That's one sign of overheated fluid.
I think GM has an unofficial fix that involves putting a cooler on the tranny among other things.
BTW, I have not replaced anything yet...
Later....
I have never checked the fluid, how would I be boiling the fluid rolling on it in 6th? Our symptoms sound similiar though. A couple pumps and it softens up. I will check it tomorrow and see whats up. Thanks a bunch for the tip, didn't think I would get a reply since this got moved. come to think of it I was getting on it pretty good and going thru the gears when I 1st noticed this happening so I bet you are correct about the hot fluid. I think it is time to start feeding it less fuel, like the 40hp settting. I bet my fluid is low too. My ex had also made me angry that day so I know I was gettin on it pretty good. Your theory is starting to make perfect sence now. :D
What year is your truck?
I don't have any answers but I suspect it has little to do with how we drive. Mine gets hard after driving long distances and after two 700+ mile trips pulling my enclosed sled trailer recently the clutch acted the same loaded or not. My clutch fluid is black as sin. I tend to believe it is a seal that is getting hard not the fluid. If fluid boils the pedal should get mushy. A seal may swell under heat and may shrink as it cools as the pedal is pumped. This doesn't make sense with what you described so it could be the flywheel cocking slightly because of its construction.
I figure if they don't have a cure I won't take it in until parts are scattered on the ground. Then I'll know what's wrong.
My truck is an 01. The fluid theory makes the most sence to me as the truck doesn't do it in normal driving. When it did it I was really gettin on it and goin thru the gears. I forgot to check it today, too much going on. I will say I am not the easiest on this truck, I don't beat it, but I like to feel the power. I think it is time to back of the power and get used to the 60hp setting.
mackey_62
08-26-2003, 05:29
I always look on here for clutch posts. Waiting for someone to post the cure to this one.
This problem has been discussed many times, as far as I can remember nobody has come up with definitive cure for the "hard" pedal.
Some guys have been in for service on the hard pedal, new fluid, heat tape, new slave etc...
Not sure if anyone has gotten the dealer to try replacing any internals, but I think that is where the problem is.
I would hope GM is close to defining the exact cause by now, its been going on long enough.
I'm still waiting for someone to say they have THE cure, can't stand the down-time waiting for dealer to take pot-shots at trying to fix it.
:rolleyes: and the squeeky clutch is another issue :rolleyes:
I did some searching on Hyd clutches and found two interesting articles. The first is from an article about changing fluid on motorcycles. The second is an article about trouble shooting hyd clutches. The last paragraph talks about a TSB from Ford on hard pedal. I wonder what their cure was?
Are any of you loosing fluid? I've topped off my reservoir twice (in 22 months and 58k miles) but cannot find any fluid leaking anywhere!
The only disturbing thing that my clutch has done was after a 200+ mile pull (w/ 8k lb TT in tow) we stopped for lunch. When we got back into the truck, approximately 45 min later, the pedal didn't engage at approximately 1/2" from the top like normal, it went down about 1 1/2". Scared me, wasn't sure if the truck would pull the TT without slipping. It engaged without any problem. After driving about 30 min, the pedal started engaging at the 1/2" mark. It did the same thing on the trip home. Hasn't done it since (3 weeks ago).
Has anyone had either of these issues?
Thanks,
MaxRock
needbigtruck
08-27-2003, 02:50
I have had the slave cylinder replaced, and the heat tape applied. thanks Jelifsc for the article. I guess we have the "concentric" slave cylinder. I too am waiting for GM to come up with a better answer. For those of you with the transmission oil cooler modification, has that been helping? GM is still hanging on to that "boiling the fluid" theory. My slave cylinder replacement was last fall. I didn't really expierence the hard pedal until July when we went on vacation. I started changing out the DOT 4 fliud about every 3rd tank or so, and that seemed to take care of the problem. It appears to me that something is wearing (the black in the fluid) which reduces what little lubricating effect brake fluis has. What we need is an expert on brake fluid tell us what is going on to make the fluid turn black so quickly. Maybe one of you oil analysis guys could send off a sample of the fluid.
mackey_62
08-27-2003, 05:15
I haven't even changed fluid yet.... :eek:
It only gets bad if driving about 30 miles or more with no shifting, which doesn't happen too often. But by the second shift all is back to normal.
I'm still leaning to something internal, like something inside is heating up or warping or rubbing or .....something, I don't know, just seems like there is too much resistance to be overcome by the Hyd. clutch.
I also have the annoying "chirp/squeek" when releasing the clutch. (yes, I looked, there is no chipmunk tagging along). It is definitly underneath the truck, I think it's related to the heating up of internals/clutch and I believe it is directly related to the subsequent hard shift.
FirstDiesel
08-27-2003, 05:30
I don't have a 6 speed in my Dmax but have 3 sportscars with fluid clutch systems.
Looking at the fluid chaning color as a symptom of the problem is wrong. For some reason this is normal on fluid clutch systems. I can change the fluid on any of my cars and with 1 week it will be black again already. Probably has to do with the low amount of fluid and the high forces it is placed under to operate the clutch.
I would lean towards the fluid getting hot as a problem. I'm not sure what kind of fluid the clutch on the Chevy uses but I fill my systems on the cars with high performance racing brake fluid. Has a much higher boiling point than stock fluid and is much more resistant to moisture accumulation, which is a problem with breake fluids.
Well my fluid is not low and isn't really too black. I went down to the 60 hp level and it doesn't seem to do it. I don't know, I think it is hot fluid. I think the best idea is to drive the truck like a truck and not drive it like a sports car, hahaha.
About the clutch fluid discoloration, I found this on GM TechLink Tech Link Article (http://service.gm.com/gmtechlink/arcv_pdf/8_02_e.pdf)
It mainly deals with the Corvette, but I bet the materials are the same.
Basically, it says the discoloration is normal...
Later....
I wonder if adding brake line coolers would help?
I've seen them advertised before but I can't remember where for the life of me.
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