hydraulic to mechanical clutch conversion

[Pinger]

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One things that I will point out about this mod is that the 1/8 inch backing plate was not included in my purchase. I could have had one made but that is just something else being twisted in the driveline, so I took the chance of the transmission input shaft not clashing with the pilot bearing..

If that is axial clearance (ie the gearbox input shaft isn't hard against the flywheel) you are talking about then it can be checked with a bit of plasticene/BluTak in the 'hole' then a trial assembly. If there's still some thickness in the plasticene/BluTak left at the end when you dismantle, then you have clearance.

To help me understand what you are doing - you will end up with one half of the bearing stationary (the fork side) and the other rotating with the diaphragm spring fingers but without any preload on the bearing - yes?

 

[dwragon]

If that is axial clearance (ie the gearbox input shaft isn't hard against the flywheel) you are talking about then it can be checked with a bit of plasticene/BluTak in the 'hole' then a trial assembly. If there's still some thickness in the plasticene/BluTak left at the end when you dismantle, then you have clearance.

To help me understand what you are doing - you will end up with one half of the bearing stationary (the fork side) and the other rotating with the diaphragm spring fingers but without any preload on the bearing - yes?

My goal zero contact with the diaphragm spring fingers when the clutch pedal is released, to prevent the bearing from wearing out prematurely. One half of the bearing will be stationary on the fork side, because modifications to the design put a stop bump (To keep the steel ID of the TOB from running and eventually gaulding on the aluminum bearing retainer tube.), but the other half of the bearing will not be rotating with the diaphragm spring fingers because there will be zero preload on the bearing by the fingers.

 

[Pinger]

My goal zero contact with the diaphragm spring fingers when the clutch pedal is released, to prevent the bearing from wearing out prematurely. One half of the bearing will be stationary on the fork side, because modifications to the design put a stop bump (To keep the steel ID of the TOB from running and eventually gaulding on the aluminum bearing retainer tube.), but the other half of the bearing will not be rotating with the diaphragm spring fingers because there will be zero preload on the bearing by the fingers.

Is there not a risk of wear on the diaphragm spring fingers when they come into contact with the non-rotating bearing during initial clutch release?

 

[dwragon]

Is there not a risk of wear on the diaphragm spring fingers when they come into contact with the non-rotating bearing during initial clutch release?

Yes, but a whole lot less wear than on a release bearing that is constantly rotating at the exact rpm of your engine, as long as your engine is operating, like comparing a molehill to a mountain.

 

[dwragon]

Ok, I had to redo most everything, so here goes, and these will be in separate chunks.

I found out that my Scattershield is an Ansen. It did not come with a backing plate, so I had a 1/4 inch U shaped spacer made. I welded it to the scattershield by using two 250 straight six dowl pins to line up the spacer U with the scattershield.

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here you can see that I had a machine shop enlarge the center hole, drill the correct transmission bolt pattern for the nv4500, and weld the 4 gold nuts to the bell housing.

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This is the side bracket for the z bar pivot ball, I guestimated the correct location then drilled the other three holes just in case i needed to make an alignment plate.

 

[dwragon]

Ok, I finally got everything to an acceptable point. I had to change out the 92-95 clutch disc and pressure plate because it simply would not push. I reinstalled the original 1964 to 1995 big block clutch disc and multi tined pressure plate. Then because the National 1697-C release bearing was still too long, welded the 1/4 inch spacer U I had made to the scattershield. I did this by using two dowl pins to line up the spacer U, see previous post. After installing the scattershield again, the National 1697-C release bearing was still too long, so I returned it and ordered the National 1377-C release bearing, which is the GM intermediate release bearing. If no spacer is used, the CC1705C is the bearing to use. After I got the National 1377-C installed, everthing mounted up correctly. I have about 1/8 to 1/4 inch of an inch free movement between the end of the release bearing and the bearing retainer input shaft tube stop.

The heights of the Release bearings are
1.2150 inches +/-, P/T/614018, P/614083, P/614163 / N1716/SA\C1705C/CT24HK slight convex # unknown
1.6093 inches +/-,.... National 1377c slight convex desired SN1178 1377C, N1178, P1377C
National 1697C +/-,.... 1.8180 slight convex desired

Left, National 1697C right, National 614018, not good for a cone tined diaphram presure plate

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[dwragon]

As to the Clutch parts, I used mostly 73-87 mechanical linkage. As to the pedal, I had to cut it in three places, one was part of the swing tube, to get it located further to the passenger side, I saved the part I cut off and added some washers to get a tight fit. I also cut the spring pullback bar off of it, because if the system is correct assembled, it is not of any use except to wear out your ankle, knee, hip, pelvis, and back, and the spring pullback bar was in the way. Then I cut the pedal, which is in the wrong position, to cut, drill, and bolt the original pedal to the 73-87 pedal stub.



I used the stock pedal to z-bar rod without any modifications, as well as the stock z-bar, also without any modifications. I had to make a clutch Z-bar to bolt-on frame bracket out of about 8 inches of 1/4 by 1 inch bar stock, I drilled four holes in it, with the top elongated to enable the drivers side pivot ball to lock into. I also ground off enough on both sides of the pivot ball to allow a 3/4 inch wrench to be used to tighten it down. I then used a vise to twist it to the correct angle to align with the Z-bar, which is set by the location of the passenger side Z-bar pivot ball at the block (Subject to relocation as needed.), then drilled holes in the frame to hold it in place.



As to the clutch fork, I used the truck 55 through 72 cast steel fork. This design is better in that it is stronger than the stamped steel 73-87 design, uses a better pivot ball design and replicable retainer spring, and the tips of the fork can be custom ground to match the release bearing. It is practically impossible for this fork to get out of alignment, or come off of the release bearing like the stamped steel 73-87 design is prone to, especially if the retainer clip breaks. Another point in the favor of the 55 through 72 cast steel fork is that it has two holes to put the adjustment rod at instead of the one dimple on the stamped steel 73-87 design, which often lets the rod fall out. If 3/8 allthread is used, with extra nuts, the rod will never fall out. A final touch is a light amount of pressure by a return spring to take any slack up in the system to keep the release bearing from riding on the pressure plate tines, allowing the throughout bearing to cease moving and stop wearing out prematurely.

 

[dwragon]

important pictures

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showing the location of the bar

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the alignment is not perfect yet, but it does work. I have driven it about 100 miles, 20 of that in town.