Clutch Pedal Adjustment Questions

[Gary L]

This is on my seventy six 2+2. Occasionally, after sitting for awhile I seem to lose the prime on my clutch pedal. I had this problem when I bought the car a few years ago so I put a new master cylinder and slave cylinder on it and bled all the air out of it. Well, it still occasionally happens so I have to pump the pedal a few times and then it "catches".  So I don't know why it occasionally does this even after putting a new master and slave cylinder on it.

But then I thought I'd check my pedal adjustment. According to the service manual, the first thing I checked was the distance from the top of the pedal to the toe-board (travel distance), which should be 8.78".  The problem is, after backing the pedal stop all the way off, the pedal is still only about 8".  I can't see how the pedal could ever come out as far as 8.78". The brace that holds the stopper isn't adjustable. Anybody else have it where the pedal can't be backed out to 8.78"? And it's not the master cylinder rod that's stopping it from coming out more. A little confused!

Thanks

[Gary L]

I should have mentioned above, when I say I measured from the toe-board, I mean from the medal pedal stop for the clutch to the top of the of the clutch pedal pad. Am I measuring from the wrong points?

 

[Zed Head]

When you say "lose prime" do you mean that the pedal is up but when you press it ti goes to the floor without actuating the clutch cylinder?  Or do you mean the pedal has dropped to the floor and has to be lifted up and pressed a few times before it stays up?  Is any fluid lost or does the fluid level stay the same, even though the "prime" is gone?

Don't know what "prime" means.

[Gary L]

Sorry about that -- what I mean is that the pedal is up but when I press it it goes to the floor with no resistance and doesn't activate the cylinder. It does come back up but I have to pump it many times to get it to work correctly, which is does after that. There doesn't seem to be any leaks and the fluid level is fine.  MOst of the time it will work fine for months, but now and then it will act as above.

[Patcon]

You replaced the master cylinder and the slave cylinder, did you use remanufactured parts or new parts?

[Gary L]

That was a few years ago so I'm not sure but I think I bought new aftermarket from the Z store. May be I should have gotten genuine Nissan?

[Zed Head]

39 minutes ago, Gary L said:

Sorry about that -- what I mean is that the pedal is up but when I press it it goes to the floor with no resistance and doesn't activate the cylinder. It does come back up but I have to pump it many times to get it to work correctly, which is does after that. There doesn't seem to be any leaks and the fluid level is fine.  MOst of the time it will work fine for months, but now and then it will act as above.

There are actually two seals in the master cylinders - one to push the fluid and another to keep the fluid in the bore after the pusher seal passes the reservoir port.  Sounds like your pushing seal doesn't have  tight contact with the bore and is shrinking/relaxing to smaller diameter in the bore when there's no activity to create back pressure.  I bet a new seal or new MC would fix the problem.  I think that there's a variety of seals and cylinders out there though and the remans might use a bigger seal.  Best bet might just be a new MC.

[Gary L]

Thanks again Zed H. So if I get another MC, would you recommend a new OEM, new aftermarket, or re-manufactured?  I see NAPA for example has some that aren't to costly. If I remember correctly tho, it was a real pain getting that pin back in the clevis due to the tight spaces.

 

 

[Zed Head]

I couldn't say, my opinion has no backing, I've gone cheap.  I think that I have an OReilly MC in my car and it has worked fine, but have been burned on a reman slave cylinder.  It was dirty inside and failed within about 8 months.  Considering the difficulty of replacement I might go with one of the better known brands.  I don't know who's out there these days though.  

[Freez74]

I purchased a clutch master cylinder from Rock Auto, it was very cheap and works fine.  I did have to swap the pushrod from the original cylinder to the replacement one, for some reason the aftermarket pushrod was too short.  No problems otherwise.

[Gary L]

Any thoughts on the pedal height adjustment issue I mentioned above. Am I just measuring from the wrong points? The reason I thought I'd check that is because there is a warning in the SM that talks about an incorrect MC rod length could block port .....

[Freez74]

My clutch pedal pad is 9 inches from the floor pan with no carpet, so it seems 8 7/8ths with a floor covering is about right.  I have about 2 3/4 inches of rod inside the firewall to the clevis adjuster.  It looks like you have the short rod, do you still have the old master cylinder?