ok when its time to install my new clutch (its an act race disk n pressure plate) would it be smart to replace the fork ive read a couple of threads with people breaking theres. also read along the lines that there is an updated one?? could someone shoot me a link i cant find an oem one even. thanks.

 

I think they just tend to fatique over time, generally breaking near the roll-pin. That's probably accelerated with a stiffer aftermarket pressure plate.
IIRC other than a slightly different casting number I couldn't see any visible difference between the original fork and the one I replaced it with. Call Malloy Mazda and ask for Ray. 1-888 533 3400.

 

Call Ray, he has the newer versions in stock


later

 

My guess is that the updated fork is made of a better grade of cast iron.

Otherwise it looks identical. I should start making and selling a billet fork.

Dave

 

If your serious, your welcome to my original I changed out a few years ago. I'm pretty sure I have it somewhere.

 

I have a couple laying around.

I'd have to test a couple to failure to decide if billet steel would be better or not.

I would think such a part would only get the interest of those who've already broken theirs.

Dave

 

thanks hey for ***** and giggles how much am i looking at? a rough estimate, its becoming the money pit but lovin it like mick a dees lol.

 

Early versions had casting imperfections that lead to cracks. The new one looks the same but is supposedly stronger. Honestly I have never broken one myself, but have seen many break, especially when running stiffer pressure plates. I like to change it as preventative maintenance when performing a clutch job. Should be around $100, maybe a bit less.

 

The problem lies in the design. The spring retainers are pins that pass thru the forks and center rod.


later

 

Before going to the trouble and expense of testing an aftermarket billet unit it might be interesting to see if anyone has had a failure with the replacements.

 

From experience, definitely check out if there's a stronger version out there. Mine broke earlier this year and the tranny specialist told me they have a fairly high failure rate. I didn't know if there was a stronger one and I needed the car running again so I went with a new OEM part. I can post pics of mine when I get home today.

 

Yes, the pin creates a stress concentration. The failures I believe are fatigue failures that take some time to develop. How quickly depends on the perfection of the material and the load it's subjected to (how heavy a clutch you're using).

But all components have stress concentrations and maybe this is a case where you just have to live with it and rely on a strong material to handle the stress.

I can't think of any way to improve on the OEM design in terms of performance. Making it lighter/stronger would only help save overall weight on the car, so that's hard to justify.

So like Jim said it would tell a lot to know whether anyone using a heavy clutch has failed the updated fork. Unless the updated forks are still failing (I haven't heard of it, but my ears aren't exactly tuned for it) then the updated fork is still perfectly suitable.

Dave

 

Just to bring this back up a little...

I started thinking about this the other day while looking at my own fork. It's a newer fork I picked up a couple of years ago. It's only had about one year of driving and one half assed track day. I'm running a Exedy twin carbon sprung hub.

I don't recall seeing this at all, but the heat stress at the tip from what I assume is a lot of heat cycling may be a little concerning. I don't recall seeing this on my old fork.

With these heavier clutches, has this been any cause for concern?

 

The picture is dark, but I assume you're talking about the discoloration at the fork tips. This is flame hardening done to improve the wear of the material there.

David

 

As an additional data point, the original clutch fork in my last FD broke when used with an ACT Street/Strip clutch. That is a reasonably mild clutch. The car and tranny had 123k miles. The clutch only had about 3,000 miles of street use and the stock flywheel was used. No burnouts or abuse on the clutch during those 3,000 miles.

I haven't had any issues with the newer fork but haven't had the tranny out to inspect. I'll be installing a new trans around April and will try and report back on what the clutch fork looks like.

 

Thanks. I couldn't remember if that's how it was out of the box.

 

I agree with Dgeesman, that is flame-hardening. I don't think you have anything to worry about. I, like Gracer, also broke my original clutch fork after an ACT SS swap. It broke right near the roll pin. I have been running my replacement OEM clutch fork without issue for several thousand miles now.

Charlie

 

Broke mine with a mild clutch upgrade, I didn't put the clutch in, but I assume the previous owner with me had a combined 15k miles on the clutch with the total mileage of 55k. Both the replacement and the original had the hardened heat treated tips.

 

Interestingly enough, I'm still on my original clutch fork.

~53k miles stock clutch
~50k miles ACT street/strip clutch
~15k miles Spec sprung 6 puck clutch

I have however had one broken when I was driving a good friends FD with an ACT s/s, with very high mileage, like 150k. My dad had his break with his ACT s/s, at about 110k ish miles IIRC.

 

Just to add some more confirmation on the heat discoloration question...my original (1992 build date) clutch fork that I replaced with a 5th gear synchro job was discolored just like that. And so was the replacement (supposedly updated) clutch fork from Ray.

 

If someone came out with a billet version taht was significantly stronger, I would buy it depending on price.

Otherwise, I doubt a new fork would fail quickly at all even if it is used with a heavier pressure plate. My guess would be instead of 100k miles, maybe 50k?

Which really wouldn't be that bad.

This is all pure speculation. I have a new clutch fork going in my car with my new fw/pp combo.

 

I previously wrote an extensive thread on how to repair and/or reinforce this fork. The problem with the fork is the some bonehead at the factory put a roll pin hole in a most highly stressed area of the part. This is where the crack will normally start and emanate from.

These forks are made of a high grade cast steel and have been flame hardened (as pointed out) at the contact areas. This material can readily be welded if you know what you're doing.

I have successfully repaired and reinforced my forks using a TIG process, silicon bronze rod and stitching the weld to avoid excess heat. Eliminate the tension side roll pin hole and plate the side of the pivot area for extra strength. This also had a nice benefit of firming up the clutch feel by reducing fork deflection. For an extensive explanation search for the other thread.

 

I have never had one to break but I did make oillite brass bushings to replace the stock plastic bushings in my fork .

 

Where is this thread you wrote about stiffening the factory fork? I've searched...and found nothing.

Is this recommended? Anyone else have any thoughts?

 

I don't know the thread number, but I'd search on "broken clutch fork." I'll check to see if I've saved the thread.

In my own experience, I repaired one that was in 2 pieces, and it was in the car for 5+ years as a daily driver and still seems fine. Since then, I replaced the tranny; I reinforced an unbroken fork and it's been in the car for 1-1/2 years now (~15,000mi.), once again as a daily driver with lots of clutch use. The pressure plate is an ACT Extreme.

If I can't break it, no one will.