Clutch Problem

[Mike Boucher]

I've got an 86 Mustang with a supercharged 347 and a SPEC stage 2 clutch, that was installed about 1,000 miles ago.

It has a McCleod bellhousing and last night I noticed the clutch slipping badly. The clutch fork isn't moving freely and is all the way up against the bellhousing opening towards the back of the car. I literally can't move it back further to allow the clutch to engage lower. It has a adjustable clutch quadrant, but if I recall correctly, if it's screwed all the way "in", it wouldn't bring the engage point lower. I don't think it can get screwed in anymore at the firewall.

I literally just got the car running again and am losing my mind with this thing and am hoping it can be something I can fix without having the trans dropped.

Any ideas? I can take a pick of what the clutch fork looks like/position in relation to the bellhousing, if that would help.

It slipped a little when I had the clutch installed, but after I backed the nut on the clutch fork out a little, it fixed it. Now I don't have any room to "back it out" further.

 

[FastDriver]

Spec stage II is rated at 567 ft-lbs of torque. Are you overpowering that?

Please take a picture of the adjustment nut and clutch fork. It's hard to understand what you're saying.

However, if the throwout bearing is not in contact with the pressure plate, then the clutch will have to come back out. If that's the case, sorry for the bad news.

Anytime the clutch is slipping, even a little, stop driving and fix it immediately. Burning up the clutch will make replacement necessary.

 

[Mike Boucher]

I'm at 490 RWHP, so should be OK with not overpowering it. I know it's pretty close though. Totally understand what you're saying about this being hard to follow and I'll snap a pic. I had my wife push the clutch in while under the car, and while fully depressed/engaged, it covers about 1/2 the opening in the bellhousing, but when released I hear it clicking against the bell housing edge that's at the furthest point towards the rear of the car.

It just seems to me that for some reason the fork isn't far enough forward or the bellhousing opening isn't clearance right for my setup.

Again, the explanation is probably confusing as well.

 

[Mike Boucher]

Quick question. What clutch fork would be appropriate recommended for my setup? It's a McCleod bellhousing, tremec TKO 500 trans with a spec 2 clutch. I'm thinking the fork I'm using that was in when I put in a Centerforce DF clutch might not be right for the Spec. I'm flying blind here though.

 

[FastDriver]

I do think I get what you're saying. If the clutch fork is fully releasing to the point that you have a gap between the T/O bearing and the pressure plate, and the clutch fully disengages when depressed so that there is no rollout on flat ground while revving, then there's not much else that can be done.

I'm sorry, I dont have or know the correct part number for the clutch fork.

 

[Mike Boucher]

That's what I'm afraid of. This would be 2 clutches that went out after less than 2,000 miles.

Any recommendations on what clutch I should go with, if it's bad? I did take a dremel and tried to shave a little off the bellhosuing and fork to create more clearance, but gave up quickly and I figured this wasn't going to have any effect.

 

[FastDriver]

If you've had two clutches go out, back to back, then you probably have a geometry issue of some sort.

When you push the clutch, the fork should go from the point where there is an air gap between the T/O bearing and pressure plate to the point I mentioned where you have no rollout on flat ground. The clutch fork should move through a range that makes it perpendicular to the input shaft and parallel to the flywheel at approximately half way through the pedal's travel.

I think a lot of folks have had luck with spec clutches, and I see nothing wrong with the brand. However, at your power level, I think you might just be over powering that spec stage 2 clutch. 490 at the wheel is pretty darn stout. The torque is actually the more important figure. Now you can divide that figure by 0.85 to get your hp and torque at the crank. You might be right at the limits. My recommendation would be to refer you to my tranny shop, promotion powertrain, and take Walt's or Wally's advice. If you'd prefer to do it based on an internet stranger (me), then I'll throw some ideas at you.

First, an aggressive quadrant with a high ramp rate, like the one from Ram Clutches or promotion's double hook will give you a bigger window from fully disengaged to fully engaged. Second, make sure you have a firewall adjuster with a wide base, like the one from UPR, or promotion. I actually prefer the UPR one, because it's just as wide, but easier to install. Third, get specifically the Steeda clutch cable. I also trust Maximum Motorsports clutch cables, but the Steeda cable will let you use either hook on the promotion quadrant and fine tune the firewall adjuster so that you don't have to overextend it. It also makes quadrant and cable installation easier. The important thing with clutch cables is that you need one you can be certain will not stretch and affect the adjustment. Fourth, get an adjustable pivot ball so that you can fine tune the adjustment of the clutch fork and get it operating in the window I specified up above. Fifth, if you can't resolve the issue with your current clutch, move up to the spec stage 3 clutch. There are plenty of other good brands out there. Centerforce is also well regarded.

One of the things you've gotta be careful about is whether the rest of your drivetrain is up to the task of handling your engine's torque output. Putting an aggressive clutch on a T5 will only result in finding a new, more expensive weak link. But if you've got a TKO, and 31 spline axles, I'm sure you'll be fine.

 

[Boostedpimp]

Not sure if I understand your issue but I know when I had a lakewood bell I had to use a larger shift fork... like this one https://www.astroperformance.com/product/clutch-fork-extendedreinforced/

 

[Mike Boucher]

Thanks for all the input/explanation and now that I spent some more time looking at the quadrant, I think I have an adjustable cable, but didn't get the adjustable quadrant, if that's even possible. I really hope I didn't fry this clutch. I've broken it in lightly and haven't even done any hole shots/power shifts, but I guess if the geometry is wrong, which I'm assuming it is, that it's a possibility. Do you guys have any experience with the McCleod clutch kits, like this one.

https://www.summitracing.com/parts/mcl-75205/overview/year/1986/make/ford/model/mustang

Looks like it can more than handle the power and thinking it might work well with the McCleod scatter shield. I hope I don't have to go this route though. I remember when we pulled the trans with my brother-in-law that has a lift, that we did replace the pivot ball and believe got an extended clutch fork as well. That was with my Centerforce clutch though.

I do have a TKO 500 with 10 spline output and will look to see what my story is with the cable and make sure I get a firewall adjuster.

Thanks again for everything and I'll take some pics now.

 

[Mike Boucher]

Here's pics of the bellhousing/clutch fork and the cable.

 

[Mike Boucher]

Here's pics of the bellhousing/clutch fork and the cable.

 

[FastDriver]

Damn. Hard to tell much from the angle. ideally you want to look at the clutch fork in relation to the pressure plate. If your clutch fork has to go that far back to disengage the T/O bearing from the pressure plate, something's definitely wrong. Either that's the wrong bellhousing for your application (less likely), or your pivot ball is far longer than it should be (more likely). However, I cannot tell from the pic whether the T/O bearing is disengaging. Is it?

 

[Mike Boucher]

Damn. Hard to tell much from the angle. ideally you want to look at the clutch fork in relation to the pressure plate. If your clutch fork has to go that far back to disengage the T/O bearing from the pressure plate, something's definitely wrong. Either that's the wrong bellhousing for your application (less likely), or your pivot ball is far longer than it should be (more likely). However, I cannot tell from the pic whether the T/O bearing is disengaging. Is it?

Yeah. I'm sure it's hard to tell. I've got another pivot ball I bought and when the trans gets pulled apart, I'll see if the Lakewood adjustable pivot ball makes a difference. I'm pissed and it sounds like the last clutch wasn't put in correctly or didn't use the right pivot ball.

When I got it back, the clutch fork was only slightly forward from where it is now. I gotta find a Mustang mechanic near Philly.

 

[Mike Boucher]

Question though. Doesn't the pivot ball limit how far "in" the clutch fork travels and not how far back it goes when disengaged?

 

[FastDriver]

I'm out west, brother. Can't help you with a good mechanic out there. But maybe one of the guys in your area will chime in.

If the pivot ball is far too long, then it would require an extreme angle before it disengaged from the pressure plate. I haven't personally seen this issue where the clutch fork contacts the back of the bellhousing before, but the only things I can think of that would affect the angle of the clutch fork would be how deep your bellhousing is, how far into the bellhousing the clutch PP is and how long the pivot ball is. What bellhousing do you have?

 

[Mike Boucher]

Got it and think I'm following you. It's a McLeod bellhousing. I'm bringing it back to the place I had the clutch installed and depending on what they say, I might end of taking it to another place I found.

 

[FastDriver]

McLeod. I had one of their goldish colored scatter shields that I bought back in the early 2000s. I thought that might be the same bellhousing I was seeing. If so, something's definitely wrong with the geometry. I had that bellhousing with a spec clutch an no problems. No grinding required, except to clear the long tube headers on the passenger side.

Sorry for your trouble friend. Can't you see whether the T/O bearing is fully disengaged if you look into it?

 

[Mike Boucher]

Got it and really appreciate your help. I think I bought this bellhousing in 07. I'll see if I can tell if the T/O bearing is fully disengaged, but know it's a pretty tight space to see much.

Is there anything specifically that will show me that it is or isn't?

 

[FastDriver]

A lift would help, but you should be able to see the pressure plate and throwout bearing through that clutch fork window. I'm just having a hard time believing you'd go through all the trouble of cutting up the bellhousing if nothing was contacting the PP.

 

[Mike Boucher]

Got it and I'll see what I can do. I just thought maybe the fork needed a little more play, so tried to clearance it with the bellhousing. I didn't cur much of anything on either the BH or fork. I realized quickly more was going on than I initially thought.