Build The Clustertruck Rides Again - Refurbishing a 1975 Chevota

[RWBeringer4x4]

Progress this weekend:

Freshly turned (last year) flywheel mounted up, surface rust from sitting removed, new ARP flywheel bolts torqued down in a star-pattern with locktite. These replace the hardware store grade 8’s and lock washers that had been contacting the clutch springs on the originally setup.

Up next was the clutch - appropriately labeled side toward flywheel:

Then came the pressure plate - even with the centering tool (which wasn’t as tight a fit as I’d like) getting everything lined up and fitting properly took about an hour.

Once everything got lined up, Downey’s Bellhousing got attached:

 

[RWBeringer4x4]

Then the real fun began. This was an enertainging project to do solo...

Using a guide rod on the lower transmission ear, and a crane to hold the transmission, I set out to get everything lined up and installed:

I temporarily installed the clutch slave to hold the clutch fork in place, which resulted in many questions I’ll get back to later.

Then came insertion:

Honestly, I expected this to be harder than it was. All in all from this point to getting everything bolted together took about a half out of jiggling, height adjustment at the crane, and pitch adjustment at the load leveler. It was such a triumphant moment when everything lined up and lurched into place.

Reunited and it feels so good:

 

[RWBeringer4x4]

Up next is where the real trouble began:

I started to install the starter, and found I had a smidge on conflict between the engine block and one of the cast mounting ears. This prevented it from mounting properly.

An hour of filing and test fitting later:

Now for the questions:

1. When I test fit the clutch slave, I noticed that it sits quite high in relation to the fork. I’ll probably add spacers to move it down a bit. However, I also noticed that even with the slave’s push rod adjusted to the shortest possible setting, it’s still too long - it appears it would hold the throw out bearing in contact with the pressure plate. Is it common to have to saw the pushrod down (or make a new one)? The Downey manual doesn’t mention this.

2. As @pb4ugo warned, the springs holding the clutch fork to the pivot seem super weak and loose. I’d tried to get them tighter prior to install but I was surprised at how little clipping force they have on the pivot ball:

Is this normal? I assume the return spring and slave help hold everything in place.

3. I’m sure I’ll figure this out in the adjustment phase, but how much “throw” is there typically in a clutch fork?

The hub has about an inch of movement on the transmission nose. Does the throw-out bearing sit millimeters off the pressure plate normally, or does it sit a long way back?

 

[1Fine40]

3. I’m sure I’ll figure this out in the adjustment phase, but how much “throw” is there typically in a clutch fork?

The hub has about an inch of movement on the transmission nose. Does the throw-out bearing sit millimeters off the pressure plate normally, or does it sit a long way back?
`
On my set up, I only have maybe 3 to 5mm between the PP and the TO bearing when the pedal is not depressed. I think it varies depending on adjustment and the length of the pushrod and how much "throw" your slave cylinder has. I honestly think it is a balancing act between the players. I did have to shorten up my pushrod, but it has been long enough ago, I don't remember how much...but I do remember cutting it and rounding up the cut end.


Overall, it is looking very good from what I can see in your posts! Congrats

 

[RWBeringer4x4]

3. I’m sure I’ll figure this out in the adjustment phase, but how much “throw” is there typically in a clutch fork?

The hub has about an inch of movement on the transmission nose. Does the throw-out bearing sit millimeters off the pressure plate normally, or does it sit a long way back?
`
On my set up, I only have maybe 3 to 5mm between the PP and the TO bearing when the pedal is not depressed. I think it varies depending on adjustment and the length of the pushrod and how much "throw" your slave cylinder has. I honestly think it is a balancing act between the players. I did have to shorten up my pushrod, but it has been long enough ago, I don't remember how much...but I do remember cutting it and rounding up the cut end.


Overall, it is looking very good from what I can see in your posts! Congrats

Thanks - it's coming together, SLOWLY. It's too damn cold and I'm too busy with work right now.

Glad I'm not nuts in thinking the pushrod is too long. Seems like this would be pretty easy to build a "custom" pushrod from a mild steel rod tapped with threads to accept the original adjustment nuts (probably just slightly harder than cutting down the existing rod).

I'm also curious as to how far those clutch fingers move (or are supposed to move) when depressed by the throw our bearing on a low profile clutch.

 

[RWBeringer4x4]

Another day of very slow progress made slower by the fact that nothing fits right...

I started out reconnecting the lower portion of the transfercase shifter. The upper portion will have to wait until the motor is back in the truck.

Naturally, the shifter brace wants to mount to the old cast iron transmission cover, not the newer, thicker, aluminum one.

Much chipped paint and coaxing with a hammer later, I finally got it close enough to clamp in place and get a bolt in:

Next up came custom building a shorter clutch slave pushrod. Starting from 3/8” rod stock, I tapped about 2 inches of M10x1.25 fine threads. This would accept the guide but and stop nut from the original rod.

Then, I cut it to size, and chamfered the back end down with a bastard file so it would index a bit better on the slave piston. I will probably clean this up a bit, but for test fitting, this did the job.

I’ll still need to add a notch or stop to hold the boot in place - that will come later.

Then I set out trying to finagle everything into position. Downey makes a lot of cool stuff, most of which is phenominal, but I don’t love this bracket. Even at max adjustment, the rod is at a pretty bad angle to the fork. Given the short distance between the two in this setup, it makes things prone to binding. Either the rod won’t sit down in the piston cone, or the nit doesn’t want to index in the clutch fork.

 

[RWBeringer4x4]

In addition to needing a shorter rod, the slave and clutch fork are now too close together for the stock return spring bracket to function properly. So I built a new one from 16ga steel. It’s not pretty, but it will be virtually invisible once it’s mounted. I will probably give it a coat of paint to keep it from rusting.

All said, this setup holds the throw out bearing MAYBE 2mm off the pressure plate. It’s really close. That said, given the odd angles everything is running, I suspect about 1/2 the piston throw will be used just moving that 2mm. Hopefully there is enough left to actually move the diaphragm

A couple more tweaks and I’ll be (at long last) ready to load it back in:

The whole setup makes me a bit nervous - the angles aren’t great and I’m concerned with the throw. Seems like it will be a VERY fine line between riding the bearing on the pressure plate and having sufficient throw to move the fingers. I trust Downey worked this out in his design but it seems like it would be prone to binding up and not activating properly.

By the way - how much force does it take to move that diaphragm? Obviously there’s no hydraulics hooked to this yet but I don’t see any movement forcing the bearing into the diaphragm by hand. Never messed with a clutch before so this may be totally normal...

 

[brian]

that vertical misalignment is going to need attention, the slave piston is not going to withstand that very long at all.

 

[RWBeringer4x4]

that vertical misalignment is going to need attention, the slave piston is not going to withstand that very long at all.

Yes, the issue is a bolt below the slave mounting the bracket to the Bellhousing. I may have to get creative and countersink it. I initially had spacers under the bracket, and above the slave, but the bolt was problematic.

 

[1Fine40]

You might consider pinging Mr. Jim of Downey fame...maybe he has seen a solution for this before??

Cheers!

 

[RWBeringer4x4]

I’ve nagged poor Jim incessantly about this conversion. Trying to give him a break! I think I gave a solution that will work ultimately.

I countersunk the rear bolt hole in Jim’s bracket, to allow for the slave to be mounted lower and more in line with the fork:

This resolved the bad downward angle on the pushrod, but naturally, the return spring bracket was now too low, causing a bad angular pull by the spring. So I made yet another spring bracket:

So now everything is (fairly) in-line, though the relationship between fork and rod is still awkward.

I also had a fundamental misunderstanding of the spring behind the slave piston. This, apparently, needs to be fully compressed - which means I will be able to lengthen the pushrod, which in turn will help hold the clutch fork to the pivot.

The drawback is that it looks like I’ll only have about a mm of clearance between the throw out bearing and the pressure plate. Hopefully that’s normal and sufficient to maintain clearance and avoid the issues I had before.

 

[1Fine40]

Just for reference, I use the AA adapter housing, and this weekend, I was under the truck for something else and decided to see how much clearance I had between the adjusting nut on the pushrod and the clutch fork without the spring attached. Surprise, it is probably about
2 mm, maybe slightly less at that point, but it does allow the TO bearing to be fully disengaged from the diaphragm fingers so that is all I am worried about anyway. Pedal freeplay is adjusted inside the truck to suite my taste I guess. Seems to be roughly 3/4" before I encounter resistance. I like your creativity with fixing issues as they come up! Nothing about this is plug n' play!

Cheers!

 

[velillen]

Progress is progress and you are doing great! And at least you are doing it out of the 40! I just finished up (just have to bleed the clutch) a clutch replacement and timing belt on the commuter car. Was not fun man handling the transmission around and having to crawl on my back to do everything. At least the transmission was only 50 pounds and not the 100 ours seem to weigh!

As for your question on being able to move the fingers by hand...I doubt you can. Least not without really trying. I tried a bit while showing the gf how a clutch works (just the pressure plate flat on the ground) and couldn't move them (wasn't trying that hard to be fair)

 

[RWBeringer4x4]

Progress is progress and you are doing great! And at least you are doing it out of the 40! I just finished up (just have to bleed the clutch) a clutch replacement and timing belt on the commuter car. Was not fun man handling the transmission around and having to crawl on my back to do everything. At least the transmission was only 50 pounds and not the 100 ours seem to weigh!

As for your question on being able to move the fingers by hand...I doubt you can. Least not without really trying. I tried a bit while showing the gf how a clutch works (just the pressure plate flat on the ground) and couldn't move them (wasn't trying that hard to be fair)

Thanks! Yes, I’d much rather be doing this out of the truck. I understand there will be some fine-tuning when it goes in and gets hydraulic pressure added, but I figured it is far better to figure out the nuances now than once it is bolted in. It’s my greatest fear that this engine will have to be drained and pulled again once everything is hooked back up.

My biggest concern is the loose clutch fork spring but I think it won’t be a concern once everything is pressurized. I just can’t see those little wires being responsible for holding the clutch fork onto the pivot on their own.

As for the spring question - I actually tried it on the pressure plate I pulled out as well with no luck. I think it really needs that hydraulic force.

 

[RWBeringer4x4]

Finally making some moves! I recruited the wife to help me get the driveline back in the truck.

With the starter and the transfer case both hanging on the passenger side, this has been a real pain every time. The crane wants to constantly move to the left, and as soon as you take the weight off he crane (either setting it on the mounts or pushing up with a trans jack) the whole assembly wants to slump to the passenger side. Makes it tough to get the mounts aligned and bolted in.

All’s well that ends well though!

Last up was “gluing” on the propeller mount and rear cover with RTV ultra black. Not sure what the torque should be on these studs. It’s a gasketed connection so I didn’t want to overtorque, but it’s also holding my engine in the truck - which made me want a more positive hold than the 10-12 foot pounds a normal gasket likes...

Since I am now running a long water pump and new brackets and pulleys, I was able to push the engine toward he druver’s side a full inch. This will help to further align the driveshafts:

A shot from inside - I’m pretty happy with where the shifter has ended up. I will need to do a final check with the transmission tunnel to really determine the extent of the repairs necessary.

 

[RWBeringer4x4]

Checking for parallel between the transfer case and the flanges. The blue line is a plumb line from the center of the differential flanges. The yellow yard stock is the same, dropped from my transfer case flanges. They’re about an inch and a quarter offset, and just about dead parallel.

this actually took a really, really long time this time around. Even though the 283 and 350 share a block, for some reason getting everything aligned this time was really tricky...it was like the engine mounts suddenly didn’t line up anymore (which makes no sense). I’d get two corners down, and the other two would sit high, or I’d get three down and the last’s bolt hole wouldn’t line up.

I finally got all the upper and lower bolts started, used quick-grip clamps to position everything, then tightened it all down. The mounts all “pulled” into position but I’m still a little concerned that some sat about an inch high of the cushion when others were resting on the cushion. The mounts are all straight and level. All I can figure is there is some sort of frame twist or something with the truck on the ground throwing things out of Wack.

 

[RWBeringer4x4]

This photo posted strictly to get @reddingcruiser off my back about the damn parking brake

Started working with the walker Y-pipe tonight. Just like everything else, this doesn’t fit right and will require some massaging to get installed...

It’s off by a good 1.5 inches (too wide in the “Y.”

I loosened up a manifold to get some free-play to get the flanges mounted. By going basically to the end of the manifold bolts, I can get the flanges on.

Then I screwed the manifold bolts back in to try and press everything back together. This worked, but I suspect it created this new problem - the pipe now contacts the oil pan...

I also suspect the extra long studs on the passenger side to accommodate the heat riser spacer may be a bit too short. I can probably back the stud out of the manifold a bit (I hope) to get enough room to put the nuts on.

Fingers crossed, if I install the exhaust donuts it may buy me enough space to clear the oil pan.

After “pressing” the y-pipe using the exhaust it is now significantly closer. What I will probably have to do is either massage the pipe a bit further to get everything lined up, or loosen the manifolds up, install the y-pipe and donuts, then screw in the manifolds.

This will definitely work, but it may make getting an accurate torque read on the manifold bolts difficult as there will be outward pressure pushing back.

Thoughts?

 

[pb4ugo]

I wonder if the y pipe was assembled wrong or bent. The pipe should fit better than that. Mine just slid on. Try your old one and see if it has the same issue.

 

[reddingcruiser]

Looking real good!

 

[RWBeringer4x4]

I wonder if the y pipe was assembled wrong or bent. The pipe should fit better than that. Mine just slid on. Try your old one and see if it has the same issue.

The old one is still attached to about 8 feet of exhaust rusting in my driveway. I suppose I could cut it off to try it, but just comparing the walker pipe to the old homebuilt one on the driveway, the spacing is about identical.