Triumph Repair: Triumph TR7 Heavy Clutch, clutch master cylinder, clutch pedal

Question
QUESTION: Hi Howard:

Thanks again for all the advice on my TR7.

I am continuing to work through the car to resolve its issues.  One thing I've noticed is that the clutch seems overly-heavy.  It operates and does not slip, however it seems overly-heavy.  

Given your experiences with TR7s, do you remember if their clutches are this heavy?  Can you perhaps suggest a diagnosis procedure?  I was thinking first about disconnecting the clutch pedal from the clutch master cylinder pushrod to see if the bushes are binding.

Thanks,
Matt M.

ANSWER: Hi Matt,

That is a good start to determine if there is a problem. The TR-7 has a clutch release bearing slider that moves on a tube mounted to the front of the gearbox and sometimes that tube gets rusty and the slider is hard to move. Usually when this happens the effort to depress the pedal is harder then it is to slowly release the pedal. However if the pedal is as hard to hold steady or release as it is to depress you may have an altered hydraulic system meaning some one my have installed a larger bore master cylinder then the original.

Several master cylinders look alike and that was a normal fix for a TR-6 when that clutch could not release well.

I don't have the specs on the bore diameter but you might contact Moss Motors to see if they can give you the bore diameter of the repair kit and that would enable you to measure you cylinder to see if it is the correct one. A large bore master cylinder will give more throw but be harder to depress.

After you run your test of the pedal shaft binding that would be my next step.

Howard

---------- FOLLOW-UP ----------

QUESTION: Hi Howard:

Thanks for the timely reply and information.  

In regard to pedal effort, it seems to be equal upon pedal depression and pedal release.  

I was working on the car last night.  I disconnected the clutch pedal from the master cylinder pushrod.  The clutch pedal appears to rotate quite freely with no binding.  Therefore, I believe the issue is "downstream" from the pedal.

I will look into the master cylinder and see if it's a larger bore.  I can easily call Moss and see if they can give me that measurement.  I'm assuming that the bore of the master (on the car) can be measured without removing it?  I will look into that.

I will do these next steps before additional diagnosis.

If you have any other ideas/advice, I would appreciate that.

Thanks again for the help.

Matt

Answer
The fact that the pedal has a lot of pressure on the release also tends to rule out a sticking release bearing slider too.

It will be difficult to measure the bore diameter without removing the master cylinder.

Another possibility is that a previous owner installed a heavy duty pressure plate. Are there any signs that the car was modified in any way for use in auto cross or such?

I have never measured the pedal pressure to be able to give you a lbs figure to gauge if yours is too high or not. Except for Jaguar all the British and Italian sports car dealerships I worked on over many years were all straight stick cars and I don't remember the TR-7 being any harder to depress then any of the others. So I can't give you a bench mark to go by.

Howard