75cj5 Ford FE motor - clutch won't disengage

[brandonwsmall]

Hi All,

I have a 75 CJ5 which the PO installed a Ford FE motor (supposedly a 390). After working on it all winter 2015 I drove it for a few weeks, but it had a lot of clutch chatter and continuously got worse. Eventually I lost my pedal and wasn't able to shift. I immediately suspected the clutch was burnt out and needed replacement. I have original mechanical linkage btw, and bellhousing and clutch fork are Ford components with the engine, everything outside is CJ.
I replaced the clutch with a Zoom performance kit which included throwout and pilot bearing. The original set up had a 3 finger pressure plate and the new kit has a diaphragm style, otherwise everything looked the same. Since the install I have not been able to get the clutch to disengage when pushing the pedal unless I adjust the throwout way in, having constant pressure on the PP fingers. It looks as though I need about 1.5" more travel to disengage (guesstimate). I have replaced the clutch rod with new linkages (pedal to bellcrank) and have rebuilt the bellcrank pivots. I've tried different threaded rod adjusters from the bellcrank to the clutch fork to see if I could get it by adding more length, no luck.
I've removed all components numerous time to inspect for a mistake, but haven't found anything to date. I'm confused how it worked originally with the 3 finger PP and the original clutch disc but will not now. Of course makes me think I have an incorrect part, maybe the PP is not correct? I ordered parts for an old 66 ford big block, there wasn't a lot of model options on that motor, so it covered most of the spectrum.

I'm sure there's more to add, but that's what comes to mind. I'd appreciate any input!!!!

 

[mriplaybass]

2 questions. Did you measure the height of the pressure plates when you had them laying on the bench? Your new pp might be lower than the old one, thereby requiring additional travel. Second, do you have the correct throw out bearing? If the distance from the fork to the diaphragm is not correct, exactly what you are describing will occur. Sounds like this might be your problem.
The problem with swapping in different engines, transmissions, etc., as all of us here know, is that changing something like a clutch is no longer as simple as going to your local auto parts house and picking up the right parts. Something as simple as a clutch change, unless you are using exactly the same parts you took out is, by using a different type of part, even though it will bolt up, does not mean it will work. The different part may not be directly compatible with the existing linkage, bell crank, even the pedal arm itself.

 

[Hedgehog]

Mr. Bass more than likely has the answer. You appear to still have your old parts. roughly assemble then and measure from the pivot point on the throw out bearing to where the flywheel would be. Do the same with both new and old parts. More than likely there will be a difference between the two. If you have a good parts place in town like NAPA go to them. Throw out bearings can be had in different lengths, it sounds like you need a longer one.

Also, since your clutch was problematic before you completely lost your clutch. Check the geometry of your linkage pivot points up at the bell crank. This is difficult to write understandably. A small difference in angles will make a big difference in your clutch. for instance if the input angle is high your clutch will be more difficult to engage. If it is to low you won't get enough throw or movement to the rear to move the clutch fork enough to fully disengage the clutch plates.

Clutch forks also come in different lengths, short ones move more, long ones move less.

Then there is the mundane question of where your pivot point is, I'm unfamiliar with the Ford pivot. Is there the possibility that you lost the pivot bearing?

There is no real reason for this, but I've had better luck with three finger clutches than I have with diaphragm clutches. I've had troubles with bending the diaphragm fingers, for me, clumsy, yes .... working alone, yes. Therefore I prefer three finger clutches.

I'm sure there will be some advice towards installing a generic hydraulic clutch mechanism. I have no dog in that fight. Hydraulics are initially expensive, but they ignore frame flex in high stress 4 wheeling situations. Many really love a hydraulic clutch.

Also, did you replace the pilot bearing/bushing? Also, a chattering clutch replacement should include resurfacing the flywheel.

 

[brandonwsmall]

2 questions. Did you measure the height of the pressure plates when you had them laying on the bench? Your new pp might be lower than the old one, thereby requiring additional travel. Second, do you have the correct throw out bearing? If the distance from the fork to the diaphragm is not correct, exactly what you are describing will occur. Sounds like this might be your problem.
The problem with swapping in different engines, transmissions, etc., as all of us here know, is that changing something like a clutch is no longer as simple as going to your local auto parts house and picking up the right parts. Something as simple as a clutch change, unless you are using exactly the same parts you took out is, by using a different type of part, even though it will bolt up, does not mean it will work. The different part may not be directly compatible with the existing linkage, bell crank, even the pedal arm itself.

Thanks mriplaybass!! I'm hoping for good feedback like this.

I did compare the two pp's like you said, I had that thought that maybe the new one was maybe not as "tall" as original, the fingers match the height of the diaphragm fingers lined up with a straight edge on the table. I looked into maybe a Novak adjustable throw out bearing also, but I'm not sure I have the room in there for a much larger bearing!? The new bearing is just about identical to the original also, but I agree with your thought of maybe a throw out bearing issue. I'll get an accurate measurement of the two anyway to be sure!

And I agree on the swap and the prob with getting the "right" parts, big PIA! I wish maybe the po had installed something more standard, but I do also appreciate the uniqueness of it.

I also had a concern that maybe the flywheel was machined too thin, too many times? I had it done a great shop, so I don't suspect they would have intentionally, but who knows. It's so strange to me that it worked almost as it is, with the exception of the pp different style, maybe I should focus on that?

 

[mtnwhlr]

And you are sure you didn't have the clutch disc backwards?

 

[brandonwsmall]

Good point mtnwhlr, but yes, checked twice.


Sent from my iPhone using Tapatalk

 

[mtnwhlr]

I thought so but thought I would ask.

 

[brandonwsmall]

Great question, I'm not beyond that realm of mistakes by any means!


Sent from my iPhone using Tapatalk

 

[brandonwsmall]

Mr. Bass more than likely has the answer. You appear to still have your old parts. roughly assemble then and measure from the pivot point on the throw out bearing to where the flywheel would be. Do the same with both new and old parts. More than likely there will be a difference between the two. If you have a good parts place in town like NAPA go to them. Throw out bearings can be had in different lengths, it sounds like you need a longer one.

Also, since your clutch was problematic before you completely lost your clutch. Check the geometry of your linkage pivot points up at the bell crank. This is difficult to write understandably. A small difference in angles will make a big difference in your clutch. for instance if the input angle is high your clutch will be more difficult to engage. If it is to low you won't get enough throw or movement to the rear to move the clutch fork enough to fully disengage the clutch plates.

Clutch forks also come in different lengths, short ones move more, long ones move less.

Then there is the mundane question of where your pivot point is, I'm unfamiliar with the Ford pivot. Is there the possibility that you lost the pivot bearing?

There is no real reason for this, but I've had better luck with three finger clutches than I have with diaphragm clutches. I've had troubles with bending the diaphragm fingers, for me, clumsy, yes .... working alone, yes. Therefore I prefer three finger clutches.

I'm sure there will be some advice towards installing a generic hydraulic clutch mechanism. I have no dog in that fight. Hydraulics are initially expensive, but they ignore frame flex in high stress 4 wheeling situations. Many really love a hydraulic clutch.

Also, did you replace the pilot bearing/bushing? Also, a chattering clutch replacement should include resurfacing the flywheel.

Thanks hedgehog!

I am also leaning towards a longer throughout bearing after reading the input from you guys! I still don't understand why, I've read that the diaphragm clutches actually take less travel to disengage. I guess if the throw out needs to be longer and the one i have came with the new pp them that just means that it's due to the different "jeep" linkage setup that the ford parts aren't compatible with? Does that make sense?

The ford bell housing doesn't have a pivot ball, rather just a clip style pivot and that's in good order.

And I did replace the pilot bearing, yes. And double checked it's measurements when I once again had everything.

I think I'll research some longer throwouts if you guys would agree. I roughly measured about 1.5" of travel more needed at the "bottom" of the fork so I'm thinking that's less distance needed at the bearing.

 

[mriplaybass]

Had the same problem when I put a Buick 231 into a 59 CJ5 . Once I put a longer throw out bearing in instead of the one that came with the clutch kit, everything worked fine.

 

[brandonwsmall]

Had the same problem when I put a Buick 231 into a 59 CJ5 . Once I put a longer throw out bearing in instead of the one that came with the clutch kit, everything worked fine.

Great! Seems to make sense to me, I'm gonna give it a try asap!

 

[Hedgehog]

Mr. Bass and I have had similar experiences. I put a Buick 231 V6 in an '80 CJ5 and had to play around with the T-Bearing and fork before finding the correct combination. It was no fun at all, but when finished the 231 was a great engine for a CJ.