Component Failures that can cause sticky pull type clutch
12-08-14, 04:19 AM
#1
Component Failures that can cause sticky pull type clutch
I installed a HKS LA twin plate pull type clutch a few months ago. I'm having a few problems with engagement and dis engagement. I installed a Mazdatrix braided clutch line at the same time as the HKS clutch kit.
I also replaced the pilot bearing. I did not replace the throwout / clutch release bearing. I noticed some troubles initially with the bleed before I even had the engine running again. The problem was a floaty / unloaded spot on the top 1" - 1.5" of the clutch pedal no matter how much bleeding was done. This feeling went away after the car was started and driven.
I've since replaced all the brake pads and given the entire brake and clutch system a 100% flush and bleed using 3 bottles of Castrol Super dot 4 brake fluid. The brake pedal feel was awesome straight away, rock hard. The clutch pedal had this same poor feeling on the top 1-1.5" of pedal travel. Start the car drive it around the block, clutch operates correctly with good feel, and all of a sudden the dead spot in the clutch pedal is gone.
Problem #2 On occasion I have smelt clutch burning smells when doing aggressive takeoffs when in my opinion I'm not riding the clutch. Remember this is an awesome quality twin plate clutch rated for 528 ft lbs of torque, and I have a sequential twin turbo car with 13psi on the primary and 10psi once both turbos are switched on.
Problem #3 Is the recent one and the cause for real concern. It seems the system is getting worse, the car is now sometimes, intermittently rolling forward in gear with the clutch pedal down when in gear. I've also had the car rolling at speed, and push the clutch in but the engine rpm does not drop. If this happens when you are stopped and in neutral you can't push the car into gear because the input shaft is turning with the engine.
I'm not sure if I have 1 or 2 different faults going on here at the same time. Problem #3 is not accompanied by any odd clutch pedal feel, and the pedal has felt perfect since the first drive where it seemingly came good for no reason.
I had wondered if I had damaged the pilot bearing on install as it did not feel great on my finger. I have also wondered if the old throwout bearing was a problem, but I figured that would just wurr. Lately I have been wondering if my failure (or one of them) could be the clutch release bearing binding on the input shaft and holding the clutch at whatever engagement it is at, but I figured I would feel that in the clutch pedal. I had also wondered if my slave cylinder could be slightly leaky or even seizing in its bore.
My car is one of the newest FD's with 56000 miles on it and an August 2002 build date.
This has me baffled and I'm not really sure what to do other than replacing the slave cylinder, and then if that doesn't help buying a new release bearing and removing the gearbox for inspection.
I also replaced the pilot bearing. I did not replace the throwout / clutch release bearing. I noticed some troubles initially with the bleed before I even had the engine running again. The problem was a floaty / unloaded spot on the top 1" - 1.5" of the clutch pedal no matter how much bleeding was done. This feeling went away after the car was started and driven.
I've since replaced all the brake pads and given the entire brake and clutch system a 100% flush and bleed using 3 bottles of Castrol Super dot 4 brake fluid. The brake pedal feel was awesome straight away, rock hard. The clutch pedal had this same poor feeling on the top 1-1.5" of pedal travel. Start the car drive it around the block, clutch operates correctly with good feel, and all of a sudden the dead spot in the clutch pedal is gone.
Problem #2 On occasion I have smelt clutch burning smells when doing aggressive takeoffs when in my opinion I'm not riding the clutch. Remember this is an awesome quality twin plate clutch rated for 528 ft lbs of torque, and I have a sequential twin turbo car with 13psi on the primary and 10psi once both turbos are switched on.
Problem #3 Is the recent one and the cause for real concern. It seems the system is getting worse, the car is now sometimes, intermittently rolling forward in gear with the clutch pedal down when in gear. I've also had the car rolling at speed, and push the clutch in but the engine rpm does not drop. If this happens when you are stopped and in neutral you can't push the car into gear because the input shaft is turning with the engine.
I'm not sure if I have 1 or 2 different faults going on here at the same time. Problem #3 is not accompanied by any odd clutch pedal feel, and the pedal has felt perfect since the first drive where it seemingly came good for no reason.
I had wondered if I had damaged the pilot bearing on install as it did not feel great on my finger. I have also wondered if the old throwout bearing was a problem, but I figured that would just wurr. Lately I have been wondering if my failure (or one of them) could be the clutch release bearing binding on the input shaft and holding the clutch at whatever engagement it is at, but I figured I would feel that in the clutch pedal. I had also wondered if my slave cylinder could be slightly leaky or even seizing in its bore.
My car is one of the newest FD's with 56000 miles on it and an August 2002 build date.
This has me baffled and I'm not really sure what to do other than replacing the slave cylinder, and then if that doesn't help buying a new release bearing and removing the gearbox for inspection.
12-08-14, 08:17 AM
#2
RX-7 Bad Ass
iTrader: (55)
It's probably the clutch master cylinder. It has a slow internal leak where it's losing pressure. You can usually pump it a few times and have a solid pedal but after driving a while or just sitting it will lose pressure again.
Parts store hydraulics are a grab bag, I would get a new Mazda clutch master and slave. They aren't too pricey.
The brake master should be fine, so you're good there. You should just need to replace the clutch hydraulics, just bleed that out, and done.
Dale
Parts store hydraulics are a grab bag, I would get a new Mazda clutch master and slave. They aren't too pricey.
The brake master should be fine, so you're good there. You should just need to replace the clutch hydraulics, just bleed that out, and done.
Dale
12-08-14, 01:00 PM
#3
Agreed with Dale. Do the clutch master and slave together. Often if you replace just one the other will fail shortly after. Mazda oem only. The reason this often happens when upgrading the clutch is the heavier pressure plate forces the hydraulics to work harder.
12-09-14, 02:39 PM
#5
Rotary Freak
I've found getting them sleeved is a more cost effective option and for the foreseeable future you won't have to worry about them. Dunno what cast iron is used by mazda now, but it's much more corrosion prone than stuff they were using 40 years ago, have multiple dead slaves and masters from various FDs.
I'm sure a competent hydraulic place could make up a slave to the same specs as the Feed unit too, although always thought the Rx7 had a light clutch pedal, even when hd clutches are installed.
I'm sure a competent hydraulic place could make up a slave to the same specs as the Feed unit too, although always thought the Rx7 had a light clutch pedal, even when hd clutches are installed.
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