Unable to change into gear

[Alistair Francis]

About one year ago (and 5000 miles) I changed the master cylinder, slave cylinder and clutch lines. Basically everything clutch related after the line that goes from the reservoir through the firewall. I bleed the lines and remember it not feeling 100% but after leaving it a day it eventually settled and seemed to be working. Sometimes it's been a little tough to change into gears but I always just assumed that's because it's an old car.

I drove the car on the weekend and it was working fine. Today I turned on the car and can not change into gear. With the clutch in I'm unable to change into any gear. With a little bit of force it feels like the engine is starting to stall if I try to push it into gear with the clutch on the floor. I can change gears with the engine off though.

I don't understand what could have changed recently. I bleed the clutch line again this afternoon and no change. I removed the slave cylinder, applied 10psi force to the brake reservoir and depressed the shaft with the bleed nipple open. I then installed the slave cylinder into the transmission, although I had to loosen the bleed nipple to get the shaft to compress in. I then released the nipple and pumped the clutch, all with pressure on the brake reservoir. It didn't make a difference.

I don't see what else it could be, the brake system appears to hold pressure so I don't think there is a leak. Does anyone have any ideas what could cause this?

 

[IainP]

I'm not that familiar with the Z system, but those are definitely symptoms of insufficient clearance in the clutch, either not enough travel in the piston or, it's not engaged properly.
I'm sure someone with more knowledge will chime in.

 

[Delk]

It does sound linkage related.

On a long shot was there any signs of an issue before you changed the parts? Years ago I had a clutch plate fail and the friction material got wedged around the outside of the pressure plate. Locked up the clutch so it didn't matter what you did with the peddle.

 

[Alistair Francis]

Ever since I've bought the car gears changes have been a little tough. Changing into first or reverse when stopped can be either really easy or take a fair bit of force. Normally if it didn't work the first time I would just go back to neutral and try again. Changing between first and second would be slow as well. I could sometimes feel the syncro kicking in between the gears. Besides that I haven't noticed anything.

Last time I drove it everything seemed fine. It's been parked since then. All that I have done is swapped the tyres, but I don't see how that could cause this problem.

 

[IainP]

Try this, car on level surface, plenty of space in front.
With engine off, put the car in first. Clutch on the floor, handbrake off. Foot above the brake, hand on the handbrake, just in case.

Start the car.

If it moves or, shudders, you have insufficient clutch clearance. Either the clutch is failing, worn bearing or fingers, or, there is a problem in the hydraulic system.

 

[Alistair Francis]

I did think about doing that, I don't really have space to do it safely though.

Any idea how to diagnose a falling clutch? Is it possible that the it would just happen suddenly like this? I inspected the master cylinder today and everything looks fine to me, so I'm suspecting it's not the hydraulics.

 

[FRANKIE]

About one year ago (and 5000 miles) I changed the master cylinder, slave cylinder and clutch lines. Basically everything clutch related after the line that goes from the reservoir through the firewall. I bleed the lines and remember it not feeling 100% but after leaving it a day it eventually settled and seemed to be working. Sometimes it's been a little tough to change into gears but I always just assumed that's because it's an old car.

I drove the car on the weekend and it was working fine. Today I turned on the car and can not change into gear. With the clutch in I'm unable to change into any gear. With a little bit of force it feels like the engine is starting to stall if I try to push it into gear with the clutch on the floor. I can change gears with the engine off though.

I don't understand what could have changed recently. I bleed the clutch line again this afternoon and no change. I removed the slave cylinder, applied 10psi force to the brake reservoir and depressed the shaft with the bleed nipple open. I then installed the slave cylinder into the transmission, although I had to loosen the bleed nipple to get the shaft to compress in. I then released the nipple and pumped the clutch, all with pressure on the brake reservoir. It didn't make a difference.

I don't see what else it could be, the brake system appears to hold pressure so I don't think there is a leak. Does anyone have any ideas what could cause this?

It has been my experience that when clutch components begin to wear, such as the pressure plate or clutch disc, it is first noticed in the higher gears, usually the highest gear first, such as 5th gear. As you are driving along in 5th gear, if the pressure plate isn't providing enough pressure any more or the disc has worn a little thin, then the friction is no longer there and the disc begins to slip while you're driving in the gear and you notice your rpms beginning to pick up as the clutch disc begins to break free. If you didn't notice this happening, then it's not the disc or pressure plate. Generally, if you can't shift into gear with the engine running but can do so with the engine off, then it's the master cylinder, slave cylinder, or lack of fluid. Remember, as you already probably know, the system uses the brake fluid from the Master Break cylinder reservoir and this has to be at least the level where the clutch line attaches to the nipple coming off the master cylinder reservoir. This problem for you must be such a Bxxch as you've JUST REPLACED the components that are in question. I seem to think that I'd check for air in the lines assuming the components are in good working order. I had written in another clutch article about how a 30 year BMW man had instructed me to bleed the system. You can look this up if you wish. Good luck with this. Keep me informed on your progress. I see you're in the US but I forget where you are. Near New Jersey?..............Frankie

 

[FRANKIE]

I did think about doing that, I don't really have space to do it safely though.

Any idea how to diagnose a falling clutch? Is it possible that the it would just happen suddenly like this? I inspected the master cylinder today and everything looks fine to me, so I'm suspecting it's not the hydraulics.

PS. Have you ever noticed any fluid leaks under the car? Perhaps it's possible that you have a tiny leak in the clutch hose going down to the slave cylinder allowing hydraulic fluid to escape or air to be sucked in???.............Frankie

 

[Alistair Francis]

Hey Frankie thanks for the info. This is my current state (I'm partly just thinking out loud now )
- I don't think there is air in the system. I don't see how air could suddenly appear overnight. I have also bleed it since this happened and it didn't make a difference. It's possible this recent bleed didn't work, but even so I still don't see how air could suddenly be introduced.
- I don't think there is a leak. My brake fluid level is full and was full. When I was pressure bleeding the system I didn't notice the pressure dropping either. I might pressurise test the system once more just to double check.
- I have a steel clutch line, so it can't be ballooning

This leaves me with two possibilities. Either the relatively new master/slave cylinders have somehow broken or the clutch bearings have failed inside the transmission. Both clutch cylinders are FTE, which is a well regarded brand AFAIK.

I don't have a history of the car, but judging by some of the other components its possible the clutch has never been replaced. So it doesn't seem infeasible that the bearings have failed.

PS: I live in California Frakie, so unfortunately not close to you.

PPS: I haven't noticed any leaks, I didn't look that hard though, so it's possible but I'm not sure what could be leaking

 

[FRANKIE]

Hey Frankie thanks for the info. This is my current state (I'm partly just thinking out loud now )
- I don't think there is air in the system. I don't see how air could suddenly appear overnight. I have also bleed it since this happened and it didn't make a difference. It's possible this recent bleed didn't work, but even so I still don't see how air could suddenly be introduced.
- I don't think there is a leak. My brake fluid level is full and was full. When I was pressure bleeding the system I didn't notice the pressure dropping either. I might pressurise test the system once more just to double check.
- I have a steel clutch line, so it can't be ballooning

This leaves me with two possibilities. Either the relatively new master/slave cylinders have somehow broken or the clutch bearings have failed inside the transmission. Both clutch cylinders are FTE, which is a well regarded brand AFAIK.

I don't have a history of the car, but judging by some of the other components its possible the clutch has never been replaced. So it doesn't seem infeasible that the bearings have failed.

PS: I live in California Frakie, so unfortunately not close to you.

PPS: I haven't noticed any leaks, I didn't look that hard though, so it's possible but I'm not sure what could be leaking

PM time. I'll send you my cell.................Frankie

 

[GZed]

Alistair, your symptoms sound just like I experienced on my 2.8 a while back: could not select any gear with engine running, but could with engine off. Check your clutch mechanism by 1) selecting first or reverse (depending on how much space you have in front or behind you) with clutch pedal depressed and engine off. 2) With clutch still depressed, crank the engine on the starter. If clutch is ok engine will start and car will not move. If clutch is not ok the car will kangaroo forwards or backwards - only a foot or so - but be ready to switch off and use the brake pedal. If engine fires up and car doesn't kangaroo, you can test the clutch action by slowly raising and depressing the clutch to see where the biting point is. Mine was perfectly normal, meaning the problem was in the gearbox. Reading the excellent thread https://zroadster.org/threads/sticky-gear-change.19521/ (in the knowledgebase) this seems to be quite a common problem, especially on 2.8 manual gearboxes. The culprit is the detent springs, but before you despair too much it is quite often cured simply by changing the oil for automatic transmission fluid, then getting some miles in to get things lubricated and loosened up. Worked a treat for me, as you'll see if you scroll right through to the end of that thread.

 

[andyglym]

I did think about doing that, I don't really have space to do it safely though.

Any idea how to diagnose a falling clutch? Is it possible that the it would just happen suddenly like this? I inspected the master cylinder today and everything looks fine to me, so I'm suspecting it's not the hydraulics.

In 5th Gear at a relatively slow speed, 30 MPH or so, floor the throttle, if the revs dramatically increase relative to speed your clutch is slipping and thus worn.

 

[Dino D]

In 5th Gear at a relatively slow speed, 30 MPH or so, floor the throttle, if the revs dramatically increase relative to speed your clutch is slipping and thus worn.

My clutch is showing its wear a bit differently - no slip if I do that.

However put two adults in it and a full bore shift between 1st and 2nd it slips!
So probably very early stages still...it’s cheaper to ditch the passenger than change clutch so that my solution for now

 

[IainP]

I did think about doing that, I don't really have space to do it safely though.

Any idea how to diagnose a falling clutch? Is it possible that the it would just happen suddenly like this? I inspected the master cylinder today and everything looks fine to me, so I'm suspecting it's not the hydraulics.

You obviously don't have a worn clutch, 'clutch slip', that's something entirely different. That's caused by too much clearance or insufficient pressure. Hard shifting is caused by the opposite, insufficient clearance.

I would try what Frankie said above and if it reacts as he suggests, change the oil. Hopefully that cures it. If you don't have a great deal of space, put a couple of house bricks six inches in font of all the wheels, that way the car can only move that amount, if it moves at all.

If you can get someone to help you, check under the car that you really are getting sufficient travel at the slave cylinder.

If a previous owner has been 'riding' the clutch, driving along with their foot resting on the pedal, that puts just enough pressure into the system for the bearing to contact the pressure plate. That causes wear to the face of the bearing, and to the surfaces of the fingers which release the pressure plate. Usually, but not always, it results in a noisy bearing. It can eventually allow the fingers to bend slightly, that means when you press the pedal, the clutch isn't disengaging enough to let you change gear. One of the telltales is changing the hydraulics does nothing. If left long enough you tend to end up with total clutch failure, often accompanied by spectacular End of the World noises as one, or more, of the fingers bend permanently/detaches/catches the bearing.

Some cars you can get an endoscope in to have a look at the fingers, no idea if you can on a Z though.

 

[FRANKIE]

Alistair, your symptoms sound just like I experienced on my 2.8 a while back: could not select any gear with engine running, but could with engine off. Check your clutch mechanism by 1) selecting first or reverse (depending on how much space you have in front or behind you) with clutch pedal depressed and engine off. 2) With clutch still depressed, crank the engine on the starter. If clutch is ok engine will start and car will not move. If clutch is not ok the car will kangaroo forwards or backwards - only a foot or so - but be ready to switch off and use the brake pedal. If engine fires up and car doesn't kangaroo, you can test the clutch action by slowly raising and depressing the clutch to see where the biting point is. Mine was perfectly normal, meaning the problem was in the gearbox. Reading the excellent thread https://zroadster.org/threads/sticky-gear-change.19521/ (in the knowledgebase) this seems to be quite a common problem, especially on 2.8 manual gearboxes. The culprit is the detent springs, but before you despair too much it is quite often cured simply by changing the oil for automatic transmission fluid, then getting some miles in to get things lubricated and loosened up. Worked a treat for me, as you'll see if you scroll right through to the end of that thread.

He has a 1.9.................Frankie

 

[Alistair Francis]

Hey everyone, thanks so much for your advice, especially Frankie for talking to me.

I remembered that last time I did the clutch I vowed that I would never change a clutch cylinder on my car again. So after bleeding it again with no change I gave up and took it to a mechanic. The mechanic said "Check your z 3 found clutch pressure plate malfunction , release arm bent ." so he is replacing the clutch with a Sachs clutch. I'm not sure yet if the flywheel needs replacing. I don't have the gear to take the transmission out, so I'm now glad I took it to them instead of changing all the hydraulics again.

What I don't understand though it how it broke while the car was parked. I jacked the car up from all four jack points to change the tyres, but I don't see how that could be related.

 

[t-tony]

Hey everyone, thanks so much for your advice, especially Frankie for talking to me.

I remembered that last time I did the clutch I vowed that I would never change a clutch cylinder on my car again. So after bleeding it again with no change I gave up and took it to a mechanic. The mechanic said "Check your z 3 found clutch pressure plate malfunction , release arm bent ." so he is replacing the clutch with a Sachs clutch. I'm not sure yet if the flywheel needs replacing. I don't have the gear to take the transmission out, so I'm now glad I took it to them instead of changing all the hydraulics again.

What I don't understand though it how it broke while the car was parked. I jacked the car up from all four jack points to change the tyres, but I don't see how that could be related.

Probably down to nothing more than coincidence Alistair.

Tony.

 

[FRANKIE]

H

Hey everyone, thanks so much for your advice, especially Frankie for talking to me.

I remembered that last time I did the clutch I vowed that I would never change a clutch cylinder on my car again. So after bleeding it again with no change I gave up and took it to a mechanic. The mechanic said "Check your z 3 found clutch pressure plate malfunction , release arm bent ." so he is replacing the clutch with a Sachs clutch. I'm not sure yet if the flywheel needs replacing. I don't have the gear to take the transmission out, so I'm now glad I took it to them instead of changing all the hydraulics again.

What I don't understand though it how it broke while the car was parked. I jacked the car up from all four jack points to change the tyres, but I don't see how that could be related.

Happy to see it sorted out.................Frankie

 

[Alistair Francis]

Got the car back with new clutch plates, a new flywheel and a replace shifter seal. Everything seems to be running well and the gear changes feel a little smoother then I ever remember them being.

 

[t-tony]

Great news Alistair, let's hope that's the end of your worries. Just give it a little while to "bed in".

Tony.