Clutch BS

[rodneym]

My intermittent problem is back. I know there’s history of talk about the T/O bearing riding the clutch fingers (or not too), how millions of Mustangs can’t be wrong, it’s a Ford design flaw, etc. but I have a couple questions:
No matter how much your cylinder slave pushes/pulls…how much physical release do you need at the pressure plate? Isn’t this what’s paramount? I’m seeing about .022-.025” (hard to get the gauges in at that angle and I don’t want to scratch anything). Is this good? It’s Mcloed gear but I don’t know the model numbers.
Also, my clutch arm is the push forward style, at 8 o’clock (when sitting at the wheel). The first 3/8” (guesstimate) is totally free slop. Should the clutch arm ‘bottom out’ against the bell-housing when the clutch isn’t pushed in? Or do I simply need it to not push against the fingers?
Also, some folks like patrickt suggest a return spring. What are symptoms of not enough, or fast enough clutch arm return?
Thanks!

[Rick Parker]

Regardless of how far the clutch release arm travels to permit (shifting) release of the clutch plate, the T/O bearing should not constantly ride on the fingers of the Pressure Plate while in a released condition. This holds true whether you are using a cable, hydraulic, or mechanical actuation. As long as the T/O bearing is not riding the finger it's OK. You do not want the T/O bearing to constantly be spinning while released. How much free travel at the pedal this translates to depends on pedal ratio's and that of the Throwout lever itself. If the arm is bottoming out before the clutch releases, you may have a combination of mismatched parts (T/O bearing sleeve length) or the pivot post inside the bell housing may need to be shimmed, thus forcing the release arm rearward (drivers side) in an unreleased condition which will then allow more travel before contacting the forward most opening of the bell housing while the Clutch pedal is depressed.

[rodneym]

Rick,
The arm is not bottoming out when pushed. I wasn't clear.
When the clutch is engaged (pedal released-I hope I'm using that term correctly), the clutch arm has about 3/8" free play between hitting the rear most part of the bell housing and where the T/O touched the fingers. Is that what the spring return is for? To make sure you're off the T/O bearing? Seems like most don't use them???
How was my .022-.025" of pressure plate seperation?
Thanks

[Rick Parker]

I think you are OK as long as Clutch is releasing properly and allowing smooth shifting. The spring IS to pull the T/O bearing off of the pressure plate fingers. Generally pedal will have about 3/4-1" free travel before beginning to release clutch (when T/O bearing contacts fingers on Pressure Plate).

[rodneym]

Hmmm...
My slave cylinder's compressed rubber boot was the only real 'pressure' riding on the T/O.
Spring and new adjustment...coming up.
Thanks, Rick.

[DanEC]

The slave cylinder in my ERA appears to be spring loaded (against the TOB) although I haven't had a chance to disect one yet. Basically, IMO you need a return spring to counteract the spring in the slave cylinder. I've heard all of this stuff about Ford Mustangs and constant contact with the
TOB (my daily driver is a 2012 GT) but I'm not buying it. My GT definately has some free play at the pedal. If you have a push forward clutch arm, I would want it resting fairly close to the rear edge of the opening with the clutch out, just to be sure I have plenty of room for the stroke to disengage the clutch.

I believe your .022 to .025 inch disc/plate clearance is in the ballpark for a single disc clutch.

It's probably elementary and hate to mention it - but it's important the slave cylinder is very nearly bottomed out in it's bore when the clutch is engaged - in order to have full stroke when disengaging the clutch.

[RICK LAKE]

Depending on which pressure plate you are running the air gap from .28" to .55" clearance with the clutch engaged. More or less you can cause damage to the pressure plate fingers or arms. As far as TOB riding on the pressure plate fingers, some do and some don't. IMO I don't like contact of the TOB on the pressure plate. With a hydro system the piston retracts like your brake caliper on your car. Perwear out will happen if the bearing is rubbing on the pressure plate and the fingers or diapham are not all at the same plane all the way around. I have the ERA setup and have run a pull of spring for 15 years with both single and multi disc clutches. Have not worn out a TOB yet. Side note, recommend that you guys run have a pedal travel limiter. This stops over extending. Rick L.

[rodneym]

Just to clarify:
"Air gap" is the space between the disc and flywheel when the pedal is pushed?
Thanks in advance, guys.

[RICK LAKE]

rodneym Yes. May have to get long feeler gauges to get in this location. It's a pain. Lakewood, I used the hole of the starter and bent the feeler gauges. I ran in the middle of .44". on single disc and .40" on street twin Mcleod. Good clean engagement and no drag on disengagement. Street you can run a little different. This is race setup for my car. I have a piece of wood behind the pedal as a stop. Even with the clutchless trans, I still use the clutch. This this for a couple of years and sent in the trans for an inspection. G-Force asked if I used the trans in the car. I said about 20 events. No wear or internal damage. May not be the fastest but breakage is kept to a min with my driving ways. Good luck. Rick L. Ps the clutch you are using, do the instructions have a spec in them for air gap?? I would also check with the manufactor. What works for 1 setup, doesn't work for others. Too much or not enough clearance. If there is a defect with the clutch and you are looking for help to warrentty it, They will ask 3 questions, New flywheel or machined, weight of car or truck, and most important setup with air gap used. Been down this road a couple of times.

[rodneym]

Thanks, Rick.
I've been on a couple drives and so far so good but that doesn't mean much.
BTW, I have a Mcleod Super Street Pro. Suggested air gap is .050! I'm at half that!
I'm using a CNC slave cylinder, which I really like quality wise but I need more distance!
Is this where 'adjusting the pivot' comes into play? To get more throw?

[Bernica]

Interesting thread.
I also have Lakewood and went with some of same pain. But, my Lakewood has an inspection plate, so I'm sure I'm missing something here. I ended up buying one of these for $50 or so and was able to watch and record the clutch action from engage to disengage.

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[rodneym]

Bernica,
I have one of those cameras at my R&D lab at work. Maybe it's time to get it oily.
Actually, I can take the measurement I need at the starter window. I have an earlier, 'windowed' QT bellhousing. Not easy but do-able. All I have to do is remove the feelers I need without losing the rest of 'em. And keep them in order !
Want hard? Tray removing the plug at the top of your diff housing w/o removing a panel

Dan,
Didn't forget your help. Don't know how much long term damage those slave springs can do, but, the couple I've seen have thin, week springs, easily counteredacted by the external return spring (as you mentioned).
BTW, I'm at full stroke with 1.125" on the CNC slave. I'd feel better with 1.250", though.

[Bernica]

Sorry about your troubles and frustrations.
This tool may help with your issues on the diff. It won't sinch it down but will help with the getting things in place, IMHO. It has also been invaluable in getting to my speedo drive on my toploader.