QuestionI'm having problems disengaging the clutch on my 79 Spitfire. It was very hard to shift when I first bought it. So far, I've replaced the clutch disc, pressure plate, throwout bearing, master and slave cylinders. I bled the system both manually and with a pneumatic bleeder. I tried the bleeding techniques that were given on this site. The pedal doesn't seem to have much travel from its rested position. The clutch lever fulcrum pin is still there. Is it possible that the flywheel is warped?
AnswerHi Michael,
The flywheel is very unlikely warped. The Spitfire and the TR-6 both suffered from dragging clutch making it hard to shift due to BLM not designing the system to push far enough on the pressure plate to release the clutch. At the dealership we had trouble when customers would install an added piece of nice carpet thus not allowing the clutch pedal to go far enough to release the clutch, that is how close most were.
Plus it is very difficult to get all the air out of a clutch hydraulic system. If you used a vacuum or pressure system to bleed the system most likely that is not the problem.
A simple test we used to determine if the air was out of the system was to just push the clutch pedal down by hand and note how much free play there was. Should not be more then an inch or so. Then the pedal should be firm to push by hand and as you push it to the floor it should feel the same all the way to the floor. If it is easy to push at the start and only progressively get more firm then there is most likely still air in the system.
Another possible is that the disk is warped. If you had a difficult time getting the transmission up in to the engine or if you installed the engine and left the transmission in, it is easy to warp a disk and then the disk wobbles and since BLM didn't allow much travel you will have trouble getting the clutch to release.
Also I ran into some aftermarket clutch disks that were too thick due to the spring plates that make up the disk. This extra spring thickness requires that the pressure plate retract further away to release the disk and BLM just didn't take that into account.
As a test to see if it is travel that is the problem. Take a flat washer for a 1/4 inch bolt or 6mm and place it on a block of wood and with a large center punch and hammer deform the washer into a mild cup shape and place it in the slave cylinder piston center with either glue of heavy grease to hold it in place and reinstall the slave cylinder on its pin and into the bell housing. This in effect lengthens the rod. Then check the free play in the pedal to see if it removed any of the free play and if it did try the operation of the clutch.
This is only a test as the washer is most likely not going to stay there long when driving. If that works then you can try to find a piece of steel tubing that just fits over the push rod and you can use a hammer to peen the end closed so it will stay on the push rod.
I have fixed some of the troublesome ones that way. Make sure if you do that to be able to hand push the slave cylinder all the way up by hand when installing it. If you make it too long it will bottom the piston in the cylinder and hold the clutch slightly disengaged all the time.
On the later TR-6 with that problem I was able to use the earlier TR-6 master cylinder which had a larger bore thus it pushed the slave further which corrected the problem but I never did research the Spitfire to see if I could find a master cylinder with a larger bore.
Let me know,
Howard
