Clutch Release Fork Cracked!
07-30-10, 07:16 PM
#1
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Clutch Release Fork Cracked!
On my way home the other night as I came to a stop sign just around the corner about a block away from home, I felt a little bit of slack or room where the clutch pedal wasn't completely pressed, so I floor it...then snap! Then the clutch wasn't working completely right after that. Luckily I was close enough from home and clutch was still working about 50%, so I was able to at least get into 1st gear once, then just rolled home with 2nd gear the rest of the way.
I finally had the chance last night to get under the car to have a look, it turned out that the release fork cracked and fractured right at where the pivot point is along with the pin sticking out. I have a spare tranny and the fork is still sitting on it,. Is there a way to replace the fork without having to take the entire tranny out? or I'm pretty much doomed?
Thanks.
I finally had the chance last night to get under the car to have a look, it turned out that the release fork cracked and fractured right at where the pivot point is along with the pin sticking out. I have a spare tranny and the fork is still sitting on it,. Is there a way to replace the fork without having to take the entire tranny out? or I'm pretty much doomed?
Thanks.
07-30-10, 07:39 PM
#2
Racecar - Formula 2000
That is a fairly common failure, especially with the use of a HD clutch. There are upgraded units (better metal) available as stock replacements from Mazda, etc.
Sorry, IIRC, (have not done it myself) you have to pull the trans to replace this.
Sorry, IIRC, (have not done it myself) you have to pull the trans to replace this.
07-30-10, 10:11 PM
#6
Since your pulling the transmission anyway, I recommend ordering a new throw-out bearing and rear transmission seal. Consider a pilot bearing and seal as well...although it isn't as easy to remove and replace as others. None are very expensive.
FWIW, I'm not convinced there is any significant difference in earlier vs. later clutch forks. There is no visible difference that I could find. I think it's design issue (usually breaks at the roll-pin hole) that just fatiques over time. Aggravated by a heavier pressure plate typical in aftermarket clutch packages.
FWIW, I'm not convinced there is any significant difference in earlier vs. later clutch forks. There is no visible difference that I could find. I think it's design issue (usually breaks at the roll-pin hole) that just fatiques over time. Aggravated by a heavier pressure plate typical in aftermarket clutch packages.
07-30-10, 10:34 PM
#7
Since your pulling the transmission anyway, I recommend ordering a new throw-out bearing and rear transmission seal. Consider a pilot bearing and seal as well...although it isn't as easy to remove and replace as others. None are very expensive.
FWIW, I'm not convinced there is any significant difference in earlier vs. later clutch forks. There is no visible difference that I could find. I think it's design issue (usually breaks at the roll-pin hole) that just fatiques over time. Aggravated by a heavier pressure plate typical in aftermarket clutch packages.
FWIW, I'm not convinced there is any significant difference in earlier vs. later clutch forks. There is no visible difference that I could find. I think it's design issue (usually breaks at the roll-pin hole) that just fatiques over time. Aggravated by a heavier pressure plate typical in aftermarket clutch packages.
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07-31-10, 06:14 AM
#9
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Free play
The play was almost non-exist, barely sensible. I would describe it as if there was a thin piece of rubber that was in the way, which made me felt like to floor it to make sure that the clutch was down all the way so I don't grind gears.
I do have ACT Extreme pressure plate and street flywheel.
I've driving the FD as daily commuter for the past few months, so I want to say that stuck in traffic and having to keep the clutch pedal floored for longer period of time and more frequently caused the fork to reach it's stress point faster.
07-31-10, 09:06 AM
#10
Hmm i guess mine is starting to show its wear.
I usually rest my left foot on the clutch pedal instead of the foot rest just in case i have to clutch in in a hurry. And lately i would play with the clutch pedal while driving and there is about an inch to maybe 2 inches of ample free play before i actually have to put effort in pressing the clutch all the way to start engaging it.
Like basically i can go down to the pedals and use 2 fingers to press the clutch with such ease for the first inch or 2 because there is free play. Then of course if i try to press foward more its a bit hard because thats when the actually push effort is needed.
07-31-10, 09:07 AM
#11
The play was almost non-exist, barely sensible. I would describe it as if there was a thin piece of rubber that was in the way, which made me felt like to floor it to make sure that the clutch was down all the way so I don't grind gears.
I do have ACT Extreme pressure plate and street flywheel.
I've driving the FD as daily commuter for the past few months, so I want to say that stuck in traffic and having to keep the clutch pedal floored for longer period of time and more frequently caused the fork to reach it's stress point faster.
I do have ACT Extreme pressure plate and street flywheel.
I've driving the FD as daily commuter for the past few months, so I want to say that stuck in traffic and having to keep the clutch pedal floored for longer period of time and more frequently caused the fork to reach it's stress point faster.
Or at the start of the clutch push with your foot like in my post above??? ^^^
07-31-10, 10:22 AM
#12
Racecar - Formula 2000
Hmm i guess mine is starting to show its wear.
I usually rest my left foot on the clutch pedal instead of the foot rest just in case i have to clutch in in a hurry. And lately i would play with the clutch pedal while driving and there is about an inch to maybe 2 inches of ample free play before i actually have to put effort in pressing the clutch all the way to start engaging it.
Like basically i can go down to the pedals and use 2 fingers to press the clutch with such ease for the first inch or 2 because there is free play. Then of course if i try to press foward more its a bit hard because thats when the actually push effort is needed.
I usually rest my left foot on the clutch pedal instead of the foot rest just in case i have to clutch in in a hurry. And lately i would play with the clutch pedal while driving and there is about an inch to maybe 2 inches of ample free play before i actually have to put effort in pressing the clutch all the way to start engaging it.
Like basically i can go down to the pedals and use 2 fingers to press the clutch with such ease for the first inch or 2 because there is free play. Then of course if i try to press foward more its a bit hard because thats when the actually push effort is needed.
BTW, once the fork is cracked, complete breakage is usually not far behind.
07-31-10, 01:18 PM
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The thin rubber feel is after already pressed the pedal down, which work normally and there was no problem shift, but it felt like there was just a little bit more room to be fully pressed. So I did and it's just a tad more then snap~
08-01-10, 12:54 PM
#15
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Release Fork Reinforcement
https://www.rx7club.com/fabrication-250/reinforcing-clutch-fork-782823/
Thanks for the tip and I need to figure out how to get this done...
08-02-10, 02:47 AM
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That was new casting process, right? not a new design or anything...
08-03-10, 10:40 AM
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Found it and nice work!! But I don't have access to any workshops to fabricate stuff myself unfortunately...
https://www.rx7club.com/showthread.php?t=782823
Thanks for the tip and I need to figure out how to get this done...
https://www.rx7club.com/showthread.php?t=782823
Thanks for the tip and I need to figure out how to get this done...
Hmm...I remember seeing a thread with pictures comparing different FD forks were found, but can't seem to find that thread anymore. It appears that Mazdatrix also carries one with part number 16-520B-N315, but not sure if that's the updated fork or not:
http://www.mazdatrix.com/f93-95.htm
This is the only thread that I found talking about the updated fork this type around:
https://www.rx7club.com/showthread.p...%2Bfork%2Bcast
I attached couple photos of the clutch fork just taken off from the spare JDM tranny I have in the garage. Not sure if I can reinforce it using the same method like the other fork. It looks like a pretty strong cast already. Wouldn't any added material and welding end up get in the way or even alter it's strength in a bad way?
08-03-10, 11:15 AM
#21
I have had success removing that engineering flaw--the roll pin hole--by filling the tension side hole (underside, the one facing towards the rear) and/or plating over it. You can TIG it up with SILICOLN BRONZE rod. I did this to an early fork and it has held up fine now for several years in daily use behind a very heavy ACT Xtreme pressure plate.
Back in the '90's, I repaired one that was completely broken in two with this method and it worked fine for many years without any further indication of failure.
Note that the rest of the Mazda casting is fine. It is a high quality cast steel and welds up very nicely, if care is used.
08-04-10, 07:24 PM
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I have had success removing that engineering flaw--the roll pin hole--by filling the tension side hole (underside, the one facing towards the rear) and/or plating over it. You can TIG it up with SILICOLN BRONZE rod. I did this to an early fork and it has held up fine now for several years in daily use behind a very heavy ACT Xtreme pressure plate.
Back in the '90's, I repaired one that was completely broken in two with this method and it worked fine for many years without any further indication of failure.
Note that the rest of the Mazda casting is fine. It is a high quality cast steel and welds up very nicely, if care is used.
Back in the '90's, I repaired one that was completely broken in two with this method and it worked fine for many years without any further indication of failure.
Note that the rest of the Mazda casting is fine. It is a high quality cast steel and welds up very nicely, if care is used.
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