clutch fork swap?

[anthony_c]

• recently installed a new clutch and slave cylinder into a 5 speed and i'm having trouble getting the clutch to fully disengage.
  
• the problem visibly manifests itself at the slave cylinder. when the pedal is fully depressed i'm only getting 1/2"+ of travel at the fork.
  
• pushrod at the master cylinder is fully extended.
  
• the transmission has been pulled again and we've verified that all of the parts are for a 5 speed coupe. collar and pressure plate match.
  

current theory is that the pushrod on the new slave cylinder is just too short.

the mechanic has suggested using an adjustable slave and fork from a 240. has anyone tried mating a 240 fork to a 280 collar, bearing, and clutch?

Edited November 25, 2013 by awconroy

[240260280z]

I have seen this with other aftermarket slaves. You are correct. Typical mainland china quality.... looks like a master, feels like a master but it isn't a master.

This happened to me on my RAV4. I just took a longer rod from a spare Z master and swapped. A lot of these parts are interchangeable on Toyota's, Nissan's, Mazdas and Hondas.

[240260280z]

You should send that bill for pulling the transmission and all your time troubleshooting to China.

Seems like our suppliers are content to pass that crap onto us.

Can you imagine if it was the brake master and it was too short.... sadly I bet it has or will happen.

[anthony_c]

well, before we all start blaming a nation of several billion people for my clutch problems...this slave cylinder was purchased from Courtesy Nissan.

I also bought one from Arizona Z and it was identical.

[Jarvo2]

I've got the opposite challenge! 1972 240z with a 1977 280z 5speed. I'm using the 280z clutch, pressure plate, collar, and non-adjustable slave. The clutch seems to disengage very quickly (within the first third of pedal travel). Basically I only have to push the clutch pedal down 2 inches and I fully disengage. The clutch doesn't seem like its slipping at all (4th at low speed, throttle floored and now slipping). Any thoughts on this one?

[EuroDat]

You wont need a fork from a240Z. The 240 and 280Z clutch forks are the same dimensionally except the early 240Z has an extra eye on the outer end for the return spring and the 280Z doesn't have a hole for the pushrod to go through. That version also has the adjustable push rod.

I had a similar problem with the slave cylinder I replaced a year ago. The push rod was too short.

I removed the two bolts holding the slave cylinder and pushed it towards the clutch until it bottomed out. I measured the distance between the holes in the slave cylinder and the threads in the bell housing. Then it was simply a case of measuring the rod and adding the difference. I made it 10mm shorter to allow for clutch wear which would push the slave cylinder back.

Chas

[Diseazd]

It seems to me if the clutch, collar and fork and slave cylinder are all from a 280Z ( these have been confirmed) the clutch should work. I always install 240Z clutches in my 4 and 5 speed transmissions, so I use the collar, fork, pressure plate/disc, and slave cylinder from the 240Z with the ability to adjust. I've never installed a 280Z clutch, but with no hole for the plunger rod to go through the fork, there is obviosly no adjustment. From what I understand, awconroy is saying with all his 280Z clutch parts assembled, the fork arm still has an inch or so of play between the end of the plunger rod and the contact dimple in the fork arm. I suggest that he drill a hole in the center of the dimple so an early 240Z slave cylinder could be used to give you adjustment to take up the slack ( I set mine at 1/8 inches clearance). That being said, he needs to drill a hole slightly larger than the slave plunger rod diameter in the clutch fork dimple and install a 240Z slave cylinder....you could then adjust the plunger rod to attain the 1/8 inch clearance that the FSM calls for. Still have no idea why his existing set up doesn't work. Make sense?

Edited November 25, 2013 by Diseazd

[EuroDat]

I've got the opposite challenge! 1972 240z with a 1977 280z 5speed. I'm using the 280z clutch, pressure plate, collar, and non-adjustable slave. The clutch seems to disengage very quickly (within the first third of pedal travel). Basically I only have to push the clutch pedal down 2 inches and I fully disengage. The clutch doesn't seem like its slipping at all (4th at low speed, throttle floored and now slipping). Any thoughts on this one?

One easy test you can do. You don't even have to have the car on stands. Reach under and push the clutch fork into the slave cylinder. You should be able to push it in about 10mm.

This is not the clutch pedal free travel explained in the manual. This is the extra travel needed for clutch plate wear. You will probably find it has no play and the pressure plate is partially engaged.

I would also check the clutch pedal adjustment while your at it. Make sure the return spring pulls the pedal back to the stop and the pedal has 10 to 15mm free travel.

Chas

[EuroDat]

Hardway had similar problems with a replacement master and slave cylinder for his 240Z. It was the adjustable type. The master cylinder rod was clearly a lot shorter than the original. He took a photo to show the difference. See post #107 http://www.classiczcars.com/forums/open-s30-z-discussions/47863-lime-green-machine-restoration-thread-1972-240z-2.html

Chas

Edited November 25, 2013 by EuroDat

[anthony_c]

@diseazed: there is no gap between the slave pushrod and the dimple, they are in contact. however the slave cylinder and pushrod cannot move the fork far enough. i'm only getting about 1/2 of travel before the slave "runs out". it just doesnt have a long enough reach.

@eurodat: i actually can push the fork forward and compress the slave. the car is disassembled and somewhere else at the moment, but i vaguely recalling that distance being a half inch or better.

i called courtesy nissan again today and read the part number back to them. they confirmed that this is the correct slave cylinder.

[EuroDat]

I quickly checked mine since its now on stands in the garage while Im replacing fuel line insulators. The slave cylinder has its own internal spring which pushes it back out when you let it go.

I can push the slave cylinder push rod in and measured it with a tape measure how far it came back out. It was 7 - 8mm. The stroke was about 33 - 34mm.

If your getting more than 1/2" free travel that could be some of the problem, but it wont make up the 35mm stroke the manual states. Thats about 5mm plus the 12.5 (1/2") travel you have comes to about 18mm which is about half what it should be.

Is the clutch pedal free travel adjusted according to the manual specs?

And is the system free of air?

Chas

[anthony_c]

i confirmed that the pedal height is set at 8 3/4 according to the fsm

the master cyl connecting rod is almost maxed out (just a few threads left)

the pedal is contacting the bumper when not depressed.

the line was completely drained, cleaned, refilled, then bled several times. then bled a few more.

i did not check the pedal free-play adjustment though.

giving serious consideration to buying a bench grinder and some roundbar and just making a longer pushrod.

Edited November 25, 2013 by awconroy