My 2003 Pontiac Vibe (sister car of Toyota Matrix) has 80,000 miles on it. For the last two days, withing the first five miles of driving cold, and only in 6th gear, it seems as though the clutch slips for only a second. For that second the engine revs up an extra 400 or 600 rpm, spools back down, and doesn’t do it again. All other gears work fine, never any slip. Clutch pedal seems to have normal movement, and engages around where it always did. I live in Maryland, so this has started to happen in around 30 degree temperatures, if that makes any difference. I don’t want to take the car in this close to Christmas, but will if this seems potentially disasterous (as in leaving me stranded). Does this sound like clutch, transmission, my imagination, or something else? Is the car likely to suddenly break down? I realize you can only give educated guesses, but that is what I am looking for, no guarantees.
I would guess that if the clutch were slipping, it would do it in all the gears, or at least any time the torque generated was too much it to transfer through the pressure plates.
Well it could be your imagination, but it sounds to me like the clutch is starting, I repeat starting to go south.
Back in the old days when I drove cars that had marignal clutches they would slip in 4th first (only had 4 speeds forward then and we were glad to have that many! 
) Then after a while it would slip in 3rd, then 2nd, and when it started slipping in 1st it was time to change the clutch.
You might try not shifting into 6th until the car is fully warm the low temps may be making the problem worse, and do not try to accelerate in 6th, downshift. The less you allow the clutch to slip the longer it will last.
Thats the other thing. It doesn’t slip when I shift, but when I am going at a smooth, steady pace. It does not slip on the shift.
Have you checked the fluid level? When cold, trannies seem to be more sensitive to a low fluid level.
Start with the easy stuff.
The fluid level of a manual transmission will not have any effect on the performance of the clutch system. If we were discussing an automatic trans you very well could be right. But with a manual this advice does not apply.
dauerbach Actually it slips 100% while shifting. When you push on the clutch pedal the pressure plate stops pushing on the clutch disc, and the engine is independant of the transmission shaft. When you take your foot off of the clutch the pressure plate presses on the clutch. At this point there should be 0% slip. The clamping of the disc between the pressure plate and the flywheel is what couples the engine and transmission. When the pressure plate does not devlop enough pressure either through wear, a hydraulics not fully releasing, or the pressure plate springs weakening the clutch can slip. What happens then is when power is applied the engine torque can overcome the reduced pressure on the clutch disc, and the engine revs but the car does not speed up. This will happen first in the highest gear because that gear has the least mechanical advantage.
Maybe Gary T will pop in here and can tell us if there is any known issues with the clutch systems on your car. I am thinking that just maybe the hydraulic system has some issue when the car is cold.
Actually I’ve been having the same type of problem. A couple of months ago if the car, a 96 Ford Escort, in third gear would rev really high for a second. However, this would only happen when the car had sat for a few days, if I drove it every day it did not happen. Plus it would only happen once, maybe twice then it would not happen again. A few times it happened in 2nd and 4th so I figured the clutch was going.
Now though it hasn’t happened in at least a couple of weeks, and I’m in Maryland as well and it’s been quite cold around here. Is this just a clutch and not a whole transmission, and is it going to be very expensive to repair? I’m now at the point where I’d have to look at the cost of repair or getting a new car.
This is an odd one and frankly I don’t know what the explanation is.
The fact that it happens only with 6th gear suggests two possibilities: a transmission problem with that gear, or a clutch problem just starting to show up.
If it’s a gear problem, it’s one I’ve never experienced or heard of before. It would somehow have to engage enough to seem normal, then disengage enough to allow the revving up, then re-engage and act normal. Unless there’s some new aspect to this transmission design that I’m not familiar with (which I will grant is possible), I don’t see how it could be. However, if it is a gear problem, it could be dealt with in the short term by simply not shifting to 6th. I don’t see how it could cause a breakdown.
If it’s a clutch problem, it’s following the typical pattern Rick mentioned, starting to slip in high gear/high speed/high acceleration (any or all of those conditions). But it’s quite unusual for this to happen when just driving along and not happen when starting to accelerate immediately after shifting into the gear, and it’s quite unusual for it to happen only when the car is cold. Nevertheless, with the info at hand, this seems to be the most likely scenario. If it is a slipping clutch, it will get worse as Rick described.
While clutch hydraulics will often show their weakness when cold, they cause an opposite symptom – failure to fully release the clutch, resulting in difficulty or impossibility shifting into gear when the car is not rolling. A clutch hydraulic problem won’t cause slipping, nor will it show up only in one gear.
Thanks for all the information. I will just keep driving until it gets bad enough to actually take in for repair, or at least diagnose. If I brought it in now it seems likely that it would cost alot of money to try and figure out what is wrong, with no guarantee of success.
I just had one more thought. When you are driving (and not shifting) you don’t leave your foot resting on the clutch pedal do you? If you do, don’t. Your left foot belongs on the floor unless you are shifting.
No, never. When I learned to drive a clutch I was told in no uncertain terms to never have my foot on the pedal unless shifting, unless I wished to purchase a new clutch every 10,000 miles.
That is odd, because my old Shelby Z had a similar problem as the OP, and it was fixed by adjusting the fluid level. A year later, same problem, and the fluid level was topped off. Eventually, a fitting was repaced and the tiny leak was gone. Never added fluid again, never had a slip either.
If the clutch is hydraulic and requires fluid (it goes into a master cylinder, just like the brakes…and even uses DOT3 Brake Fluid), if the fluid level gets low, the clutch will eventually slip. The engage point in the clutch pedal will get higher and higher until it’s not completely engaging when the clutch pecal is out.
You have that backward. If there is not enough fluid in the master cylinder and air is introduced into the hydraulic system the clutch will not release. The hydraulic fluid level does not affect clamping force. (At least on any clutch system I have ever seen)
As far as the friction point moving (“engage point”) as the disk wears, it gets thinner. As it gets thinner, the pressure plate has to travel less to disengage the clutch, and the friction point gets higher. You are correct that when the friction point is at or almost at the top the clutch is history.
If on the other hand the friction point gets closer to the floor as the car gets older it is probably wear in the clutch activation system. * It could be a bad master cylinder, slave cylinder, or air being introduced into the system (low fluid or vibration induced). Or it could be mechanical wear in the clutch pedal or clevis pin. When the pedal gets to the floor, the clutch will no longer disengage, and it will be hard / impossible to shift into gear at a stop without grinding and other problems.
- I have seen a spring blow out of the center of a disk and cause this problem, but this was a sudden change, not a gradual one.