Clutch Release Issues

You may have the wrong motor mounts which is putting your Z-bar in a bind.I also have the notched pan and there is about 1/2" clearance between the steering link and the bottom of the notch.That notched pan is very common so I don't think the pan is the problem.Motor mounts should be approx 1 5/8" from the center of the bolt hole to the block mounting surface for your year.I believe there are taller motor mounts for later applications and that may be your problem.The frame mount,Z-bar,block bracket are standard pieces that should work on your car no problem.I would give the Z-bar a close inspection at both ball sockets.If you lose adjustment it usually is a sign of linkage failure or maybe it's bound up enough it's flexing.It takes a miniscule crack for the bar to flex enough to not disengage the clutch.I reinforced my new one before it went in and no problems since.Espescially if you have a heavier pressure plate.The original I replaced had multiple repairs from over the years as well as the used ones I looked at.

slycorona said:

I have a 63 Nova, 327, 11” Ram street high performance clutch/flywheel, short throw out bearing, correct 7:00 o’clock scatter shield and M-21 transmission. For many years I used to run a 3,600 lb, 11” clutch that worked great. When I changed to the new Ram Clutch and flywheel the Z bar broke because it rotated into the steering box.

I tried an adjustable clutch fork pivot ball, and a long throw out bearing.

I tried stiffening the frame side and block side Z-bar pivot mounts.

After several attempts the fixed clutch fork pivot ball worked the best.

The linkage still seems to lose it ability to disengage the clutch after a few driving shifts.

I discovered that I had always used the wrong 68-72 clutch fork.

So I bought a 62-67 clutch fork which is straight and shorter, another Z bar, and Z bar frame pivot mount straight not stamped), block side pivot mount for non nova blocks.

I had to install the frame side pivot mount bracket backwards (slot towards the front) because it pushed way too much against the z bar. I lifted it and checked several times to be sure it did not interfere with the steering box. The linkage still seems to lose its ability to disengage the clutch after a few short driving shifts. The clutch fork has more travel now (about 1.5”) than ever before.


I also have an oil pan problem that may be related. I replaced my front sump pan with a rear sump pan only to have the drag link rub against bottom of the “U” shaped cut out in the pan.
Any advice would be appreciated.
Slycorona

Click to expand...

OK, trying to separate and address each item but still group somewhat together...

the old clutch you say was a 3600lb unit and worked fine for years. a swap of just the clutch and you now are bending/breaking linkage. the old clutch was installed with the incorrect fork? or the new clutch was installed with incorrect fork?

what size is the new clutch and flywheel? with the right bellhousing it'll be a 10.5" unit. what brand of flywheel did you buy? it's very possible the flywheel you bought is thinner than what's needed and the geometry is still off.

what brand of T/O bearing did you buy that is tall? there are only two that i'm aware of and one is incorrect. the only correct bearing is a G1625C.



the left bearing is the std (old number) CC1705C/614018 (new number) the unit on the right is a Six cylinder unit with a rounded face for use with a flat diaphragm clutch... the center bearing is the only tall bearing.

which did you use?

the adjustable pivot, there again are two styles, the std style which covers both of GM's bell housing pivots, the other by McLeod, which will handle a higher adjustment than the factory style pivot.

left & center are GM pivots, right side is the McLeod unit. the std style adjustable will only adjust as tall as the center factory pivot.

which pivot was used?


with the incorrect fork even using the adjustable pivot and a taller T/O you wouldn't have been able to correct the geometry and it's possible the strain has weakened the new Zbar.

use the correct fork and the adjustable McLeod pivot and the new clutch assembly with the recommended T/O. i think what you may have is a thinner than needed flywheel which moves the clutch closer to the engine effectively taking away any level of proper adjustment...

you can pull the front bearing retainer off the trans and with the engine on a jack, place the engine/bellhousing at the proper level to install all your linkage. install the T/O bearing on the bearing retainer, with a clutch alignment tool or extra input shaft, install it all in the back of the bellhousing and connect/adjust the linkage. you can climb into the car and actuate the clutch... if the adjustable pivot needs to be adjusted you're not repulling the trans, an adjustment is quick and easy.

some aftermarket ChevyII pans are cheaply made... a big name like Moroso, Milodon, Hamburger etc will have a pan with a better cut out area. the centerlink will raise and lower as the wheels turn so that cut out is necessary on that style of pan... the Kevco pan is a rear sump pan specifically designed for a ChevyII but with no cut out for the centerlink.

back to the clutch for a minute... i can appreciate a possible mount issue, too short, too tall... my thoughts are the clutch worked fine before so i'd not think the mounts are an issue...


sorry to be long winded, hope i covered the bases and have helped... check some of this stuff out and we'll see what we can do...

the tree man said:

You may have the wrong motor mounts which is putting your Z-bar in a bind.I also have the notched pan and there is about 1/2" clearance between the steering link and the bottom of the notch.That notched pan is very common so I don't think the pan is the problem.Motor mounts should be approx 1 5/8" from the center of the bolt hole to the block mounting surface for your year.I believe there are taller motor mounts for later applications and that may be your problem.The frame mount,Z-bar,block bracket are standard pieces that should work on your car no problem.I would give the Z-bar a close inspection at both ball sockets.If you lose adjustment it usually is a sign of linkage failure or maybe it's bound up enough it's flexing.It takes a miniscule crack for the bar to flex enough to not disengage the clutch.I reinforced my new one before it went in and no problems since.Espescially if you have a heavier pressure plate.The original I replaced had multiple repairs from over the years as well as the used ones I looked at.

Click to expand...

First of all I appreciate your helpful advice. Just an FYI, the Z bar does not bind nor does it contact the steering box. I had a Z bar that did crack at the block pivot end but that was due to my misadjusting the Z bar and it being forced against the steering box as it rotated. Tonight I installed two new motor mounts from NAPA for a 1963 nova. Just as you said the distance from the block to the centerline of the bolt hole is 1 5/8”. I was hopeful but it did not make a difference. The drag link still rubs slightly against the oil pan. I changed the frame side pivot mount to one that is like the stamped design but thicker and stronger. This did move the Z bar more onto the block pivot ball, a noticeable improvement. With the linkage assembled but disengaged from the clutch fork I have 1 3/8” of travel measured at the end of the z bar arm that connects to the adjusting rod. No binding or contact with the steering box. With the linkage connected to the clutch fork, this travel is reduced to 1”. It feels like every time I depress the clutch pedal I have more and more deformation of the linkage and loss of travel. I can see the block side pivot bracket deflecting as the pedal is depressed. I am going to make a strut from the motor mount bolt to the edge of this block conversion bracket to try and stop the deflection. I hope to have it done this weekend. Can you please tell me how and where your reinforced your Z bar? Was it the arms or the ends of the rotating tube? How did you pick the areas to reinforce?

here is some trans/linkage/clutch info to browse through...
http://s7.photobucket.com/albums/y2...ch-Bell Housing-Linkage info/#!cpZZ1QQtppZZ28

disregard the note on shortening...

the FLYER said:

OK, trying to separate and address each item but still group somewhat together...

the old clutch you say was a 3600lb unit and worked fine for years. a swap of just the clutch and you now are bending/breaking linkage. the old clutch was installed with the incorrect fork? or the new clutch was installed with incorrect fork?

what size is the new clutch and flywheel? with the right bellhousing it'll be a 10.5" unit. what brand of flywheel did you buy? it's very possible the flywheel you bought is thinner than what's needed and the geometry is still off.

what brand of T/O bearing did you buy that is tall? there are only two that i'm aware of and one is incorrect. the only correct bearing is a G1625C.

the left bearing is the std (old number) CC1705C/614018 (new number) the unit on the right is a Six cylinder unit with a rounded face for use with a flat diaphragm clutch... the center bearing is the only tall bearing.

which did you use?

the adjustable pivot, there again are two styles, the std style which covers both of GM's bell housing pivots, the other by McLeod, which will handle a higher adjustment than the factory style pivot.

left & center are GM pivots, right side is the McLeod unit. the std style adjustable will only adjust as tall as the center factory pivot.

which pivot was used?

with the incorrect fork even using the adjustable pivot and a taller T/O you wouldn't have been able to correct the geometry and it's possible the strain has weakened the new Zbar.

use the correct fork and the adjustable McLeod pivot and the new clutch assembly with the recommended T/O. i think what you may have is a thinner than needed flywheel which moves the clutch closer to the engine effectively taking away any level of proper adjustment...

you can pull the front bearing retainer off the trans and with the engine on a jack, place the engine/bellhousing at the proper level to install all your linkage. install the T/O bearing on the bearing retainer, with a clutch alignment tool or extra input shaft, install it all in the back of the bellhousing and connect/adjust the linkage. you can climb into the car and actuate the clutch... if the adjustable pivot needs to be adjusted you're not repulling the trans, an adjustment is quick and easy.

some aftermarket ChevyII pans are cheaply made... a big name like Moroso, Milodon, Hamburger etc will have a pan with a better cut out area. the centerlink will raise and lower as the wheels turn so that cut out is necessary on that style of pan... the Kevco pan is a rear sump pan specifically designed for a ChevyII but with no cut out for the centerlink.

back to the clutch for a minute... i can appreciate a possible mount issue, too short, too tall... my thoughts are the clutch worked fine before so i'd not think the mounts are an issue...


sorry to be long winded, hope i covered the bases and have helped... check some of this stuff out and we'll see what we can do...

Click to expand...

First of all I appreciate your helpful advice.
Both. I used the incorrect (1968-1972) fork both the 3,600 lb clutch and the new Ram clutch.11” Ram. Understood. I thought the same thing so I removed the clutch and flywheel assembled and benched it and assembled and benched the old clutch and flywheel. I then measured the stack height from the crankshaft mounting surface to top of the diaphragm fingers. They were the same. I also called Ram tech support and they told me how much finger travel it takes to disengage the clutch. I believe they said 3/8”. I took the assembly to work and used a press to check it. It checked out fine.

SKF. It’s a NAPA number N1086-SA. It looks like the incorrect 1697C you show below. Whose number is the G1625C? I can call and have it cross referenced.





The more I look at your pic the more I know that I tried a 1697C
Why? It looks shorterthan the 1697C
Center one was used successfully for years with the old clutch and wrong fork. I tried the right one with both long and short bearings and had problems adjusting so I went back to the fixed ball
I have a shot Muncie housing with an input shaft and bearing retainer. The housing was cut to allow access to the pivot ball adjustment. With the clutch linkage and empty Muncie housing installed it was a great tool. Are you saying that the clutch linkage will bind if this geometry is not correct or wall it simply not disengage due to inadequate travel. This for me is an important question

the FLYER said:

the tech articles mentioned above state a 7° forward tilt is required for proper geometry... from what i understand the ChevyII fork has a negative tilt... so if you throw a protractor up there i'd recommend you initially starting out with at least 14° of forward tilt...

i've been through what may seem to be the same situation you're dealing with... the 7° mentioned in the video isn't correct for our application...

Click to expand...

Thanks for the description on how you reinforced the Z bar. I understand the lever arm reinforcement but not why the tube was cut and how it was strengthened. Can you please help me understand what was done to strengthen the tube? I guess an optimum clutch fork angle still does not eliminate the need to reinforce the Z bar. Do you have a Nova block or are you using the pivot block adaptor? If so did you need to reinforce it?
I pulled by measurements from my former Schaefer 3600 lb clutch to my Ram clutch and see that the stack height of the new Ram clutch is 1/8” higher than the old Schaefer assembly. More reason to revisit the clutch fork angle. I am game for another tranny pull and trying to measure the fork angle. But before I do I want to be sure I understand the T/O bearing information you provided. Are you saying that the only T/O bearing that will work is the G-1625-C or does it matter as long as the angle is correct?
You mentioned a protractor to measure the angle. Do you have any other suggestions on how set this up to measure the angle? It will be at least 2-3 weeks before I have time to pull the tranny. Thanks for the information. Also how do you post pics?

That cutting of the Z-bar does not apply to you.I believe that was to fit in an aftermarket front clip or something.There is not enough room in a stock clip with stock steering box for that type of gusset.I think my horseshoe bracket will solve any problems as far as the flat stock tearing the tube. I'm using a Chevy2only block bracket without modifications and with a long adjustable pivot the cheap short release bearing worked.I had all kinds of problems with clutch geometry because I used a thin,lightweight flywheel with a balance plate behind it for my external balanced motor,aftermarket pressure plate and custom Kevlar disc and scattershield.With the fork tilted forward it was almost hitting the pressure plate.I had quite a few posts with FLYER and eventually got things resolved.If you look at the stock clutch fork it is canted rearward slightly from the pivot ball to the release bearing.I ended up installing my fork using the adjustable pivot ball at 90 degrees out of the bellhousing assuming the bend in the fork will give the desired rearward tilt between the pivot and release bearing as per the Hurst article.All the other forks I have looked at are pretty much straight or even a little forward canted so having the fork exit the bellhousing forward makes sense but may not exactly apply to a Nova.Anywhos,suffice to say the clutch works great with smooth progressive feel and no on/off switch touchy crap.It was a lot of fartin' around though and I got right tired of that tranny diggin' into my belly under there.

use this info for posting pics...

http://www.stevesnovasite.com/forums/showthread.php?t=27716

you're using the 7 O'clock bellhousing/scattersheld, right?

OK, say the bell housing is OK, you have factory style zbar, upper & lower rods & clutch fork... with the aftermarket parts, whatever they may be, you're experiencing geometry issues. the linkage parts are flexing/bending. this is caused generally due to the fork angle being off which increases the leverage forces and the force is more than the parts can tolerate...

to correct it it may take a number of things or just one. you'll have to mock it up and check it...

lay a protractor on the bell housing in a way that you can look inside the housing and see the fork, clutch & T/O bearing. with the bearing lightly resting on the clutch fingers look inside and try to see the angle of the fork compared to the protractor. it should have a forward facing tilt. ok say it doesn't (you have excessive leverages, the fork probably isn't on the correct forward tilt) the way to correct it is with the adjustable pivot, adjusting the pivot taller or towards the engine will move the leverage point. if you still can't get the forces/leverage/fork angle correct you may need to use the taller bearing in conjunction with the pivot to move the whole assembly closer to the engine... personally i think if you set it at 14° you'll be ok. my own car is set at 7° and i need to give it more forward tilt. i set mine as instructed in that video mentioned and it's just not enough...

the raised finger or raised diaphragm clutch you're using requires a flat faced bearing. it's pictured above as the CC1705C. that's the old BCA number, it's changed to a 614018. it's a std, factory style T/O. the taller bearing, 1697C is for a flat diaphragm clutch. it is not interchangeable with the raised fingered clutches. it'll prematurely wear the fingers and you'll lose the clutch. the only two tall flat bearings are either a McLeod type adjustable bearing which you'll find is made for Fords & Chevy's and fits neither fork/bearing retainer properly... the other choice is an obscure application for a mid 60's Chevy/GMC truck. that's the G1625C bearing. CenterForce sells it with a different MFR's numbering system but it's the same as the BC/Timken etc bearing. they sell them in the cases where the geometry requires a taller bearing.

the front bearing retainer on your transmission unbolts. do so. do you have a spare splined input shaft? or what do you use for an alignment tool?

slide the fork, t/o bearing etc together and install 'em. slide the bearing retainer into the bellhousing and then insert the clutch alignment tool... adjust the pivot, check the angle. lock down the pivot, climb in the car and actuate the clutch (no tranny installed use just bearing retainer off trans to locate t/o bearing, block bellhousing/engine up and connect all clutch linkage) a friend under the car can spin the disc with the splined input shaft/alignment tool if you're getting enough actuation. as you release the clutch with friend spinning see where the pedal is, how far off the floor when the disc locks by the pressure plate.

you'd like at least 1" off the floor when disc/pressure plate lock. if it's too close to the floor you need a little more adjustment on the pivot.


pretty long winded... hope i understand this stuff m'self! LOL!

hope i helped. i'll try ta clarify if ya have questions good luck.