Car jerks on throttle lift off
09-01-2014, 01:21 PM
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Car jerks on throttle lift off
Yet another issue; I hope my car isn't falling apart faster than I can afford to keep it together...
The car has always had a bit of jerkiness when lifting off the accelerator. It's been very mild, though, up until last night, when it was suddenly a lot worse. Any speed, any gear, no matter how gently I try to lift off the pedal, doesn't matter. And I mean just for a second or so immediately upon lifting off the pedal; after a burst of jerking, it smoothes out.
Any ideas on what's causing this?
The car has always had a bit of jerkiness when lifting off the accelerator. It's been very mild, though, up until last night, when it was suddenly a lot worse. Any speed, any gear, no matter how gently I try to lift off the pedal, doesn't matter. And I mean just for a second or so immediately upon lifting off the pedal; after a burst of jerking, it smoothes out.
Any ideas on what's causing this?
09-02-2014, 02:00 AM
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On another forum, two members have suggested that this problem is actually that the rubber center of the clutch has failed, and that the disc is now riding on the three metal center tabs. I don't know enough about the clutch to know if I'm repeating it correctly, but...could this be the problem?
Anyway to confirm or rule out that it's the clutch? Without significant disassembly...
If it is indeed the clutch, should I just replace it with OEM parts or do I have other options? Are there any better alternatives, and if so, what makes them better?
Anyway to confirm or rule out that it's the clutch? Without significant disassembly...
If it is indeed the clutch, should I just replace it with OEM parts or do I have other options? Are there any better alternatives, and if so, what makes them better?
09-02-2014, 02:55 AM
#3
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To rule out if it's the clutch: with the car off and sitting on level ground, put it into 1st gear, and keep the handbrake off. If you can push the car a little bit forward and back then the clutch is broken and only using the emergency tabs.
09-05-2014, 08:17 PM
#4
Do you hear a metal 'clang' when you let off the throttle or shift it into 1st from a stop?
If so, it's the clutch.
My car was jerky sometimes when letting off while crawling through traffic in 1st. New O2 sensor eliminated that.
If so, it's the clutch.
My car was jerky sometimes when letting off while crawling through traffic in 1st. New O2 sensor eliminated that.
09-05-2014, 08:43 PM
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I would describe it more as a thunk than a clang, but describing a sound is kind of subjective.
I hear the thunk now randomly, it's hard to narrow it down to just one or a few set of circumstances. But it does only happen when I'm doing something with the clutch pedal.
I've resigned myself to the knowledge that I'll be replacing the clutch soon. And that I'll be trying it myself. Not looking forward to that at all, but there's no way I can afford to pay a shop for 16 hours of labor on top of the parts cost.
Unfortunately, this task only comes in at #3 on my priority list, so I hope the tabs last long enough to get me through the first two tasks. The first is to reseal the injectors (the #3 injector leaks fuel, very slowly, out of where the injector goes into the engine), and at the same time I do that I'll be replacing all the vacuum hoses, and a few other less critical things that just make sense to do at the same time. My second-highest-priority maintenance item is to replace the rollers, belts, and water pump. One of the rollers or pulleys is making a distinct "you need to replace me now" sound. At the same time I do that, I'm going to reseal the balance shaft housings, as one or both of them are slowly leaking oil onto the block. The one on the exhaust side is almost definitely leaking, and the one on the intake side may be as well, or it may be the air-oil-separator seals that are leaking. I'll be replacing those two seals when I do the injectors and vacuum hoses, since that job requires pulling the intake off, which gives access to the AOS.
I hear the thunk now randomly, it's hard to narrow it down to just one or a few set of circumstances. But it does only happen when I'm doing something with the clutch pedal.
I've resigned myself to the knowledge that I'll be replacing the clutch soon. And that I'll be trying it myself. Not looking forward to that at all, but there's no way I can afford to pay a shop for 16 hours of labor on top of the parts cost.
Unfortunately, this task only comes in at #3 on my priority list, so I hope the tabs last long enough to get me through the first two tasks. The first is to reseal the injectors (the #3 injector leaks fuel, very slowly, out of where the injector goes into the engine), and at the same time I do that I'll be replacing all the vacuum hoses, and a few other less critical things that just make sense to do at the same time. My second-highest-priority maintenance item is to replace the rollers, belts, and water pump. One of the rollers or pulleys is making a distinct "you need to replace me now" sound. At the same time I do that, I'm going to reseal the balance shaft housings, as one or both of them are slowly leaking oil onto the block. The one on the exhaust side is almost definitely leaking, and the one on the intake side may be as well, or it may be the air-oil-separator seals that are leaking. I'll be replacing those two seals when I do the injectors and vacuum hoses, since that job requires pulling the intake off, which gives access to the AOS.
09-06-2014, 12:21 AM
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My 0.02 cents:
To test the clutch I would try holding the brake, putting the car into first and left off the clutch a little, then reverse and try again. If this alone causes the jerk, thud or clang I would say it's clutch time.
It sounds like you are planning to, pull the injection system, vacuum system, timing system and ultimately do the clutch. You may save a lot of time and frustration by dropping the motor, doing the timing system with full view of the flywheel and timing marks with super easy access to every nut and bolt. Work on the vacuum lines standing upright in the engine bay, and do the fuel system while you have it down for maintenance.
As a note I pulled the motor from a 944 in a junkyard in just over 6 hours, so it might not be as bad as you think.
The biggest killer of maintenance (in my book) is money and frustration. By getting everything out and easy to get to You remove half of that equation (frustration) and save a lot of busted knuckles and lost fasteners in the process.
In any event best of luck
To test the clutch I would try holding the brake, putting the car into first and left off the clutch a little, then reverse and try again. If this alone causes the jerk, thud or clang I would say it's clutch time.
It sounds like you are planning to, pull the injection system, vacuum system, timing system and ultimately do the clutch. You may save a lot of time and frustration by dropping the motor, doing the timing system with full view of the flywheel and timing marks with super easy access to every nut and bolt. Work on the vacuum lines standing upright in the engine bay, and do the fuel system while you have it down for maintenance.
As a note I pulled the motor from a 944 in a junkyard in just over 6 hours, so it might not be as bad as you think.
The biggest killer of maintenance (in my book) is money and frustration. By getting everything out and easy to get to You remove half of that equation (frustration) and save a lot of busted knuckles and lost fasteners in the process.
In any event best of luck
09-07-2014, 08:41 AM
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The way I checked the clutch was to crawl underneath the rear end, pull the transaxle inspection window plug which gives access to the driveshaft and then turn the driveshaft by hand. If the clutch is good you will be trying to turn the engine over... I had 20 or 30 degrees of slack so knew the clutch rubber center was cracked. My experience is here:
https://rennlist.com/forums/924-931-...ew-clutch.html
I ended up taking the manifold off to get the sensors out, then had problems with leaky injectors, so I suggest doing the injectors after the clutch. I recommend the Renbay injector O ring kit... I wasted a lot of time before ordering their's.
https://rennlist.com/forums/924-931-...lp-please.html
I did my timing belt, water pump two years ago with the engine in, than the clutch last year by removing the transmission, torque tube etc. which I had to do because I had a leaky gas tank so I was able to do it while the tranny was out. In your situation I would consider following drive135mph's advice and pulling the engine, depending on what facilities you have. A lot easier to work on the balance shafts among other things. And you can change your engine mounts easier if necessary.
I don't see what year your car is, if it is a 924S or an early 944 are you sure you don't have gas tank for leaks when you fill it up?
Good luck!
https://rennlist.com/forums/924-931-...ew-clutch.html
I ended up taking the manifold off to get the sensors out, then had problems with leaky injectors, so I suggest doing the injectors after the clutch. I recommend the Renbay injector O ring kit... I wasted a lot of time before ordering their's.
https://rennlist.com/forums/924-931-...lp-please.html
I did my timing belt, water pump two years ago with the engine in, than the clutch last year by removing the transmission, torque tube etc. which I had to do because I had a leaky gas tank so I was able to do it while the tranny was out. In your situation I would consider following drive135mph's advice and pulling the engine, depending on what facilities you have. A lot easier to work on the balance shafts among other things. And you can change your engine mounts easier if necessary.
I don't see what year your car is, if it is a 924S or an early 944 are you sure you don't have gas tank for leaks when you fill it up?
Good luck!
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09-07-2014, 06:18 PM
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Well there's no need to guess or even inspect anymore.
Yesterday while driving the engine revved up, as if I had pushed the clutch pedal in. I pulled to the shoulder and confirmed that clutch pedal in or out, it mad no difference, the engine just free wheeled. However, with the clutch pedal all the way out (not pushed in at all), there was a clunky noise coming from underneath mid front...right about where the clutch was...and a smell of burning clutch friction material.
So I think it's pretty clear now that the clutch is now my #1 priority.
Yesterday while driving the engine revved up, as if I had pushed the clutch pedal in. I pulled to the shoulder and confirmed that clutch pedal in or out, it mad no difference, the engine just free wheeled. However, with the clutch pedal all the way out (not pushed in at all), there was a clunky noise coming from underneath mid front...right about where the clutch was...and a smell of burning clutch friction material.
So I think it's pretty clear now that the clutch is now my #1 priority.
09-08-2014, 02:26 AM
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I'd have you covered if you could use a 951 disc...I always keep a couple spares in the bin.
09-08-2014, 03:05 AM
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Nope, 951 disk is larger diameter and needs lots of parts swapped to fit it to an N/A, not the least which are the bellhousing and the clutch fork, as well as the flywheel and pressure plate.
09-08-2014, 04:16 AM
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I'm having a bit of difficulty deciding if I should get the "clutch super kit" from Pelican (http://www.pelicanparts.com/catalog/...TCLUTC_pg1.htm) or the "complete clutch kit" from 944online (http://www.944online.com/cgi-bin/ASI...42+clutch-9442).
The 944online kit includes the flywheel bolts, and is lacking the master and slave cylinder, which is fine for me because the slave cylinder was (allegedly) replaced right before I bought the car. And I'd like to not get into the hydraulics any more than I need to. So the 944online kit is probably what I'm gonna go with, unless anyone has any better ideas. Are there any other parts I'll need?
The 944online kit includes the flywheel bolts, and is lacking the master and slave cylinder, which is fine for me because the slave cylinder was (allegedly) replaced right before I bought the car. And I'd like to not get into the hydraulics any more than I need to. So the 944online kit is probably what I'm gonna go with, unless anyone has any better ideas. Are there any other parts I'll need?
09-09-2014, 04:37 AM
#14
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Also look at:
vertex: http://www.vertexauto.com/SubCategor...ch%20Kits.aspx
autohausaz: http://www.autohausaz.com/search/pro...3@Clutch%20Kit
your local CarQuest store.
You should definitely replace the rear main seal (aka rear crank seal), and the pilot bearing. Also a good idea would be to replace the guide tube for the release bearing, the fork bearings, and the fork shaft.
You can reuse the fork shaft if it doesn't have any depressions in it. You can pull it out to inspect it before you even start the job (just have to unbolt the slave cylinder and move it aside first).
You can also reuse the guide tube (if you're really on a budget) by bolting it back on at a different angle, so a fresh part of it gets used.
A lot of people say you must use new bolts for the flywheel and pressure plate. Well, the PP bolts aren't stretch bolts so I don't see why they'd need replacing. And I've reused FW bolts without issues but they are cheap enough anyway.
Have some moly grease and anti-seize paste handy for the job.
Consider doing the bellhousing notch mod while you have it out.
vertex: http://www.vertexauto.com/SubCategor...ch%20Kits.aspx
autohausaz: http://www.autohausaz.com/search/pro...3@Clutch%20Kit
your local CarQuest store.
You should definitely replace the rear main seal (aka rear crank seal), and the pilot bearing. Also a good idea would be to replace the guide tube for the release bearing, the fork bearings, and the fork shaft.
You can reuse the fork shaft if it doesn't have any depressions in it. You can pull it out to inspect it before you even start the job (just have to unbolt the slave cylinder and move it aside first).
You can also reuse the guide tube (if you're really on a budget) by bolting it back on at a different angle, so a fresh part of it gets used.
A lot of people say you must use new bolts for the flywheel and pressure plate. Well, the PP bolts aren't stretch bolts so I don't see why they'd need replacing. And I've reused FW bolts without issues but they are cheap enough anyway.
Have some moly grease and anti-seize paste handy for the job.
Consider doing the bellhousing notch mod while you have it out.
01-06-2015, 11:45 PM
#15
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sorry to be so dumb, but what is the bellhousing notch job all about? Any posts in any threads about this? My bellhousing is sitting on my garage floor right now..color me clueless...Thx Tiger 03447