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  #1 (permalink)  
Old 12-08-2020, 06:32 PM
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Default Clutch fork travel?

Greetings forum members. Former CC forum member. Havenít been here in awhile as my Shell Valley was laid up with a busted tranny that turned into a Ďlets replace the motor while weíre at ití project.... that that lasted years...

I just put a new crate motor in my 2003 Shell Valley (347 SBF). It was a long block and so needed flywheel, clutch, PP, water pump, intake, dizzy, etc. I purchased a Ford Performance clutch kit (M-7560-A302N) with Ford Performance flywheel. I figured all diaphram pressure plates for SBF were basically the same but apparently thatís not the case.

I did not measure old part .vs. new part, but it seems the fingers of the old diaphram PP sit higher than the fingers of this Ford part. Additionally, it didnít seem like the new TO bearing I bought was compatible with the clutch release fork (which is apparently a mid 70s F100/150 clutch release fork) so I used the old TO bearing which looked fine.

When I bolted up the Lakewood scattershield the clutch fork basically bottomed against the rear of the scattershield. So when pulled to the backmost position, it was just touching the fingers of the PP. The clutch fork pivots on a bolt held by U shaped bracket. That U shaped bracket itself bolts to the scattershield and holds the pivot bolt.

My attempt to fabricate a solution was to space out the U shaped bracket away from the scattershield. (Move the fulcrum point). I added a 3/8Ē spacer. My release fork has a 2:1 ratio and so the 3/4Ē of pull travel translate to 3/8Ē of push on the pressure plate. That was my guess. I installed the motor, tranny and drive shaft, etc. crossing my fingers... But 3/4Ē of fork travel where it connects to the slave cylinder isnít enough... I cannot dis-engage the clutch...

Does anyone know what amount to fork travel is required to get the pressure plate to release? I failed to compare the height of the old .vs. new TO bearing, but the new one just didnít seem like it was correct for the release fork that I have. I suspect the new TO might have been thicker/taller than what Iím using now. Maybe the solution is change out the pressure plate?

My clutch is hydraulic, I think itís both a master combined with a pull style slave (?Wilwood?). Any advice/recommendation is greatly appreciated. The car is finally together just in time for the first snow!
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  #2 (permalink)  
Old 12-09-2020, 05:28 AM
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Each clutch as you have found out is a little different and bent finger diaphragm clutches are the most so. To really find out the answer to your question accurately, I would assemble your flywheel and clutch on the bench, put in in a hydraulic press with the TO bearing on top or some piece of heavy metal to represent the TO bearing. Then mount a dial indicator on the bearing and measure how much the clutch has to be cycled to get an average of .030 gap between the disc and flywheel measured with a feeler gage. The press will probably have to cycle the clutch a little less than 1/2”.

It seems that most slave cylinders have about .9 to 1” stroke. A lot of clutch forks behave around a 2:1 lever ratio but that might vary with different manufactures. I would assume most internal slaves must be able to stroke around 1/2” without problem.
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Last edited by DanEC; 12-09-2020 at 05:32 AM..
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Old 12-10-2020, 06:22 AM
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Default Thanks, darn ...

Thanks for the reply. I donít have a hydraulic press ...I suppose i could try to conjure something to do the press on the fingers and try to measure the amount press down to get 0.030Ē release. It must be several hundred lbs of pressure to do so. Thereís a local transmission shop, maybe theyíd do measurement.

Itís a new Ford clutch 10 1/2Ē , I just didnít expect this variation. The old clutch disc is an 11Ē made in China combination... so Iím moving from non-OEM to OEM...

I may have to wait until spring to get the tranny and clutch out... Iím dreading removing the tranny as I had a very, very difficult time getting it to mate to the scattershield and clutch disc. Took 4 weekends even with a tranny jack ...I could easily mate the tranny to motor when the motor was out the car, but I was not able to put the motor and tranny in as a combination... So I had to put the motor in, then install the tranny. Nightmare compounded with inexperience and a good dose of incompetence mixed with the Ďmagicí of a kit car...

Thank again.
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Old 12-10-2020, 07:48 AM
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I’m not sure I know which end of the clutch fork you are most interested in movement to full release. I know from my ERA with 12” McLeod diaphragm clutch that it takes about .9” of slave rod movement to cycle the clutch.

For trans removal, if doing it from the underside, I would get a couple of 6 inch long bolts and cut the head off of and round the cut ends slightly. Remove the transmission bolts at top and thread them in for the transmission to glide back on until it’s out of the clutch disc. Then during replacement put them back in and raise and hook the transmission on them. Then you can maneuver the rear of the trans to align it to go into the disc and hopefully slide right home. However, those plastic disc alignment tools are notorious for not working very well. The best tool is an old cut off input shaft if you can find one. If you can’t, I would have the clutch fork hooked up and hydraulics bleed if necessary. If the transmission hangs up and doesn’t slide into the pilot bushing, first put the yoke in with the transmission in first gear and rotate the yoke a little to see if it’s just a spline hang up. If that doesn’t work, have someone slowly push in the clutch while you are wiggling the transmission in, and as the disc starts to release, it will self-align.

Good luck
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Old 12-11-2020, 06:02 AM
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Default Thanks again

I appreciate the suggestions. I found a few videos of the pressure plate measurement showing how itís done on a hydraulic press. I guess Iíve read about it as I know Iíve run across the numbers for disengagement away from the flywheel in thousandths . What was done to measure was pretty straight forward, I just donít have a hydraulic press.

Yep, I conjured those long bolts putting them into the scattershield and hanging the tranny on them. I just could NOT get the tranny installed no matter how I pushed, raised, lowered, twisted the tranny. I never thought to rotate the motor a bit and try, rotate and try, ... Iíve probably only done a hand full of clutch placements ever... I know I had to fiddle a bit or twist the tranny a bit but it was a matter of just of a few seconds and shuunk, the tranny slid in Not so here. It was an absolute nightmare. I tried. My good friend tried. My adult son tried.. I was so frustrated I just decided to bolt the darned thing in and wound up destroying the needle pilot bearing, which then was another nightmare to get out... Basically a tragic comedy of errors over a 4 or 5 week period. I was apoplectic ... My son, in a final attempt, took out the align/hanger bolts and just heaved the tranny into place. He twisted it and bam, it sunk in. Probably less than 10 seconds when it worked...Just like I remembered.

In any event, I have several options.
1. Do as suggersted and get this thing measured out by a shop. I think if I removed it and took it to a tranny shop, it wouldnít cost that much for them to measure it out for me.
2. I found the Ford Performance Parts website and fired an email off to a help line. they also have a chat line, so maybe those supposed experts can tell me how much fork travel I need.
3. Go to a hydraulic throwout bearing. There are apparently several kits for the Tremec T5 that I have. Maybe in the grand scheme thatís a better solution. But you know at this point Iím so gun shy, Iím afraid to try anything. Such a change for me. When I was young Iíd tear into anything fearlessly. The thought I couldnít fix something never entered into my mind ... not so anymore. Kit Cobras humble you.

Thanks again, Dave
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