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Triumph Repair/Clutch/flywheel swapout

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Question
Concerns a 1963 Spitfire refitted with a 1.3 engine. On advice from Spitbits, I upgraded to a diaphragm type pressure plate. The kit includes plate, pressure plate and throw out bearing. The newer pressure plate changes from a two to three dowel arrangement to secure pressure plate onto flywheel.(Had extra later model flywheel) Replaced throw out bearing and noticed the mounting structure for the throw out bearing stands about 1/2 inch taller than the original and the new throw out bearing is crowned to ride on the pressure "fingers" on the pressure plate compared to the lower profile  on the older set up.  (I've got a couple of parts trannies). Reinstalled the tranny without hooking up the drive shaft.
In neutral the propeller flange spins readily and can be held fast with pressure from your shoe. The car goes into gear quite easily,  but stays in drive mode when the clutch pedal is depressed.
I secured the propeller flange from spinning and was unable put the car in gear with the clutch pedal depressed. Ugly grinding noise if I persisted.
I checked the master and slave cylinder. They were operating properly. I even put an extension on to the slave cylinder pushrod to allow the thrown out bearing to travel further to disengage pressure on the clutch plate. That attempt was unsuccessful.
I've had this  63' Spitfire for about 30 years and am pretty familiar with its quirks, but I don't get this one.
Is the 3 pin flywheel so much different from the two pin original? I eye balled them and they seem the same configuration.
I'm using the older aluminum bell housing, that has been on the car  before the upgrade. I have a later cast iron bell housing, and I am wondering if swapping that one out with the aluminum model would make any difference. I'm sure the problem and answer are going to be obvious and I'll have that 'duh' moment. Regards, Mark

Answer
Hi Mark,

I have mixed clutchs, bellhousing etc on other British cars but not the Spitfire and even mated engines, flywheels, clutches and transmissions several times,

When you do this you have to do a lot of accuarte measuring to mate them all together and have it work. Here is the sequence I have to do to get it to work.

First you must confirm that no part of the hub of the disk fouls in the flywheel or flywheel bolts. Then you have to confirm that the end of the trans input shaft fits the pilot bearing in the back of the crank or flywheel, Also be sure the shaft does not bottom out in the back of the crank nor the sholder of the shaft does not come in contact with the pilot bearing.

Next you need to mount the pressure plate to the flywheel with the disk inside and note how far depressed the fingers of the pressure plate springs are. They must not be even close to being flat. A diaphargm type spring gets weaker not stronger when it is compressed too far. The old pressure plate that had the coil springs in it got stronger as it was compressed more by a thick disk.

Next set up blocks on each side of the flywheel of the exact same height and lay a straight edge of any kind across the blocks and measure from the straight edge to the fingers of the prsssure plate. Subtract that measurement form the size of the blocks and you will have an accurate distance from the engine plate to the pressure plate spring. Now lay a straight edge across the bell housing that fits to the engine and you will have a reference point to measure to the reliese bearing. Now measure the travel of the release bearing on it's sleve.

With these measurements you will be able to hand move the release bearing arm to see that you have the correct travel needed to release the clutch. Also note that the release bearing or its sleve that it rides on does not foul on the hub of the clutch disk. If the release bearing slider contacts the clutch disk hub it will prevent the clutch from releasing even thought the pressure plate spring is compressed. Also confirm that the clutch disk slides freely on the input shaft spline before assembling it.

I just finished a real mix of parts. I put a Buick flywheel on an Olds engine and a Mazda RX-7 turbo pressure plate on a Triumph TR-8 disk and a Triumph TR-7 5 speed box on the Olds engine. I had to make my own pilot bearing and an extension for the TR-7 release bearing slider to make it all come out right. Clutch works fine except I also had to shim the pressure plate out from the flywheel by .035" to account for the diffference in thickness of a Mazda disk vs a Triumph disk. You can see that accurate measurements must be done as I outlined to make it work.

Let me know

Howard

Triumph Repair

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Howard M. Fitzcharles III

Expertise

Triumph TR-4 up & Spitfire, and Engine theory

Experience

Dealership line mechanic on MG, Triumph, Jaguar for 15 years, Instructor in commercial mechanics school 2 yr. Product information manager for piston and valve manufacture, Instructor & hotline answer man for import car parts importer 15 yrs.

Organizations
Associate member SAE EAA member

Publications
Import Car magazine

Education/Credentials
ASE Master Auto with L-1 certification up to 2000

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