Broken clutch release fork
11-01-10, 10:21 PM
#1
Senior Member
Thread Starter
Broken clutch release fork
After spending a couple days bleeding my clutch hydraulic line to solve a weak clutch pedal, I finally found the real problem. The clutch release fork is cracked right at the pivot point and broken. Granted the fork is 17 years old and my ACT pressure plate has stronger springs, but I have never had a release fork on a standard shift car actually crack and break. Has anyone else had this happen? Is there a stronger release fork available (Mazdaspeed??). The stock one looks like some kind of cast alloy. Most American cars have one made of stamped or pressed steel, not cast material, which can be more brittle.
11-02-10, 08:56 AM
#6
Racing Rotary Since 1983
iTrader: (6)
stock FD clutch is 1200 pounds spring pressure.
typical ACT clutch 2600+ pounds spring pressure.
Exedy double disc 2200 pounds spring pressure but 2X the frictional surface so much more grab w less pedal.
there's no free lunch re rotary clutches unless you are willing to spend approx $1500 on a double disc.
the reason for needing all the pressure is our engines are so compact they have small flywheels w modest frictional surface... so up goes the spring pressure.
many of us (including me) have broken clutch forks. you didn't join an exclusive club.
hc
typical ACT clutch 2600+ pounds spring pressure.
Exedy double disc 2200 pounds spring pressure but 2X the frictional surface so much more grab w less pedal.
there's no free lunch re rotary clutches unless you are willing to spend approx $1500 on a double disc.
the reason for needing all the pressure is our engines are so compact they have small flywheels w modest frictional surface... so up goes the spring pressure.
many of us (including me) have broken clutch forks. you didn't join an exclusive club.
hc
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11-02-10, 09:34 AM
#8
I only laugh because mine broke this summer, too. It's an extremely, extremely common failure when running a heavier duty PP. 
And yes, Ray @ Malloy is a GREAT guy to deal with. 
I actually just bought a very lightly used fork from crispyrx7 here on the forum for 40 dollars which had never been used with an aftermarket clutch. 
I was very close to buying one from Ray, though.Also, thanks for the info on spring pressure howard! Makes me glad that I went with an Exedy twin disc clutch for yet another reason .
11-02-10, 10:20 AM
#9
Senior Member
Thread Starter
Thanks for the info. Howard- I had no idea the spring presure increased that much for the ACT pressure plate. I had to go with it after I started modding the engine and spun the stock clutch due to the added torque. No wonder my left leg gets tired driving in stop and go traffic.
11-02-10, 09:04 PM
#17
http://www.rx7store.net/product_p/zx3-hdr6.htm
11-02-10, 10:46 PM
#18
Senior Member
Thread Starter
broken clutch fork
Running ACT Xtreme(not MaXX Xtreme) pressure plate and ACT street disc.
If there was a market for these, I would weld up some reinforced cold-rolled steel pieces to make a more durable fork. With the dwindling number of FD surviving, I might sell one every couple years.
If there was a market for these, I would weld up some reinforced cold-rolled steel pieces to make a more durable fork. With the dwindling number of FD surviving, I might sell one every couple years.
11-03-10, 02:47 AM
#20
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about how much are those forks? you guys got me thinking since Im pulling out the motor I should do some preventative maintenance and do the fork too. Supposedly I have an almost new "upgraded" clutch, gotta pull it out first to find out.
11-03-10, 04:49 PM
#21
I had that clutch as well. Although mine let go while running this one...
http://www.rx7store.net/product_p/zx3-hdr6.htm
http://www.rx7store.net/product_p/zx3-hdr6.htm
Yeah i def dont have that. Does that clutch make the clutch pedal stiff??
If so, i probably have the entry level ACT clutch because my clutch feels like stock. Or what stock "should" feel cause i never driven an FD with the stock clutch.
The pedal is probably what stock audi's have. Since i had an audi tt, the clutch feel is almost the same.
So am i in trouble?? lol
11-04-10, 08:50 AM
#23
Senior Member
Thread Starter
clutch
ACT Xtreme pressure plate increases pedal feel about 25%. Upgraded clutch fork from Malloy Mazda is $87 plus $8 shipping. Ask to speak to Ray Crowe to get correct part number and mention you are on this RX-7 forum to get the discounted price. (price for STOCK clutch fork is over $114).
I have had three different types of disc/pressure plate combinations on the car. Stock (wore out twice), HD pp/disc from MazdaTrix with center hub springs, but without the flat fillis springs under the friction surface (touchy to engage, but no slippage) and the ACT Xtreme PP/street disc (good drivability and no slippage, harder pedal feel, but apparently a good way to break the clutch fork).
Talked to a couple FD owners who went radical and used solid center hub, 4-puck or 6-puck disc and HD PP and they liked them, except when starting out on a hill or stop and go traffic. The clutch is either fully engaged (rev engine and off you go, or stall the engine) or is not engaged- no gradual engagement and drivability is difficult.
If you drive like your grandmother stay with the stock setup. But since you are reading this we know your driving style is probably a little more aggressive.
I have had three different types of disc/pressure plate combinations on the car. Stock (wore out twice), HD pp/disc from MazdaTrix with center hub springs, but without the flat fillis springs under the friction surface (touchy to engage, but no slippage) and the ACT Xtreme PP/street disc (good drivability and no slippage, harder pedal feel, but apparently a good way to break the clutch fork).
Talked to a couple FD owners who went radical and used solid center hub, 4-puck or 6-puck disc and HD PP and they liked them, except when starting out on a hill or stop and go traffic. The clutch is either fully engaged (rev engine and off you go, or stall the engine) or is not engaged- no gradual engagement and drivability is difficult.
If you drive like your grandmother stay with the stock setup. But since you are reading this we know your driving style is probably a little more aggressive.
