Build The Clustertruck Rides Again - Refurbishing a 1975 Chevota

[RWBeringer4x4]

Other minor victories:

Finally dislodged the pitman arm using my new OTC 8150 Conical Pitman arm puller (there are two out there, you want the big one). I have a replacement from Kurt at Cruiser Outfitters with a 1in. drop, and the proper taper, which will do away with the ghetto-fabulous stacked washers I'd been running previously.

This thing was on there tight, but I was able to get it off with this tool, a breaker bar, and a BFH. The procedure was: tighten it until I couldn't tighten it anymore, the wail on the bottom of the tool with the BFH. Then, re-tighten. Rinse, and repeat, for about 5 minutes - and the arm comes free. This probably could have happened in about 30 seconds with air tools.

I also flared all of my body brake lines, including the "fake" bubble flare as described by @vtgbeemer previously. I think I may have gone a little too flat. I guess we will see when everything is installed:

The double flaring went fairly smoothly - there are a few a little off-center, but not enough, hopefully, to result in leaks. Time will tell!

And in still other news: I further mangled my front differential. Pulled the pinion seal, and took a look at the shim pick under the pinion bearing. The bearing seemed to be in good shape. There were only 2 shims, the big one, and one very thin one:

Now I have to tighten everything back down, and see if, when torqued to spec (150ft.lbs.), bearing pre-load and pinion backlash are correct. The difficulty, of course, is getting the gears to sit still while you try to tighten a spinning flange to absurd torques...I drilled two holes in a piece of wood, bolts the wood to the flange, and used it to push in the opposite direction of the torque wrench. Wood failed at approx. 75 ft. lbs. Splinter explosion, and many expletives, ensued. I'll have to grab some bar-stock and make a metal version of the "tool." Unless, of course, someone has a less redneck method of doing this! Until then, I'm sort of "stuck." I can't move forward with the axle until the diff is reinstalled, and I'm not reinstalling the diff if I can't get it back to spec!

 

[RWBeringer4x4]

Travel is totally consuming my summer - work trips, and vacation. Just got back from a 42 mile hike around the Allegheny Front Trail, just west of Penn State. Actually managed to knock out 14 miles a day, instead of the anticipated 10, which put me home a day earlier. Naturally, I used the spare vacation day to work on the truck. Accomplished a bunch of miscellaneous little stuff.

I've been slowly but surely painting up all of my axle/steering components:

While the paint was drying, I started creating some spacers to install under the caps of the alignment pins, since the heads are not tall enough to make it through the caster shims, and up into their alignment holes. Started out with some grade-8 bolts, then hit them with an arbor wheel until they were about the same size as the cap on the alignment pin:

Once I get a big enough drill bit (looks like I'll need a 7/16 hole in the caster shim for the pin's cap/spacer, my set only went to 3/8 ) I'll confirm fit, then bore out the threads so the spacer sits directly up under the cap. Effectively, this will accomplish the same objective as the extended-head alignment pins sold by some parts houses. It will raise the cap up into the alignment hole in the spring perch:

I also spent some time measuring out the knuckle shims to finally start putting the axles back together. Unfortunately, my measurements left me requiring so many shims, the rebuild kit only provided enough shims for one side. I went back and used the alignment tool again. I got significantly different results, but it still seems like a lot of shims...Looks like I'll have to get more, or re-use the old ones...

Short side shim packs:

Bottom (two thick):

Top (two thick, one thin):

 

[RWBeringer4x4]

The big hold-up, currently, is that my front differential (yes, the one I'll probably never use) is out of spec.

Tested ring-gear backlash. Specs suggest it should be between 0.006in and 0.009in. Mine is at between 0.009 and 0.012in. According to fellow Mudders this is acceptable to run - but I can't leave well enough alone. If it's out, it should probably be adjusted.

Similarly, even with used bearings, my pinion preload should be between 7.8 and 11.3 inch-pounds. With my torque wrench, I'm getting precisely "zero," even when I torque the pinion nut to 160 ft.lbs. (about the top of the tollerance spec).

This means that the preload washer on the pinion will need to be removed, and either sanded smaller, or replaced with a thinner one. My existing preload washer is about as thick as they come (almost 3.0mm). I've ordered a couple of thinner ones. Unfortunately, a wide selection of these shims are no longer available from Toyota. I ordered some additional thick ones, for sanding, if it comes to that.

A shot of my home-built torquing apparatus - I believe there is a similar SST, but wedging this lever up against a work bench, holding the bucket still with my arms, and pushing the torque wrench away from the level with my legs is about the only way I have found to tighten the pinion nut to 160 foot-pounds. You have to fight the flange spinning on the diff, and, eventually, the entire bucket spinning against your attempts to torque it. This is probably the most difficult part of the whole process! Unfortunately - finding the proper preload shim will be an effort in trial and error, so I'll get to use this method a lot...

 

[Vae Victus]

Dude. You are scarin' me. Come down and do mine.


...via IH8MUD app

 

[RWBeringer4x4]

@Vae Victus - making progress? I haven't seen too many updates lately! If your summer is looking anything like mine, it's totally understandable...

The great news is, I got notification this morning that all the preload adjustment shims I ordered are NLA. So now I'm really not sure what to do...Pin_Head has suggested sanding down the shim I have until I get proper preload, but this seems dangerous, given that this shim is apparently unobtanium now...

 

[Vae Victus]

Do what Rainman does - take them to a machine shop and get them to make you some. Proper steel thickness, a laser cutter, and voila - no longer unobtanium. Plus, I can buy some too.

Surely a good shop could source steel in almost any thickness.

Oh, and no, time has been limited, and motivation low. I'm waiting on the air compressor to sand blast (quite) a few items, but I do plan to make some progress this weekend and this next week before traveling to the Boundary waters to fish.

...via IH8MUD app

 

[RWBeringer4x4]

Some more slow progress, but progress nonetheless!

I spent a couple hours today sanding fractions of a millimeter off of my pinion preload washer. After three attempts, I managed to sand the washer from 2.98mm to 2.77mm. This, coupled with the replacement of my 0.43mm shim with two new, 0.25mm shims, managed to bring my preload up to the accepted range of between ~7.8in-lb and 11.6in-lb.

Sanding: On a piece of plexiglas I had laying around, I ran the washer over a piece of 220 grit sandpaper, using Mineral Spirits as a cutting agent. I rotated the washer ~90 degrees every 8 strokes or so. This reduced the width of the washer fairly evenly - according to my caliper.

All buttoned up, showing (at long last) the proper preload.

I'm at right about 9.5in-lb to get the pinion moving, right in the center of the tolerance range. There's no discernible play in the pinion, so I'm going to call this done! Time to disassemble the whole shebang (again) to install a new Marlin pinion seal. First, however, I'll need to located a new dial indicator stand, so I can bring the gear backlash specs in a little bit tighter.

 

[RWBeringer4x4]

In typical Clustertruck fashion, for every step forward, there is a step back. I went ahead and installed my new Marlin inner axle seals today:

Much beefier than stock:

Installed nicely with my bearing/race driver kit (I believe this was the 54mm driver):

I then spent some time polishing my balls

And thoroughly lubricating my balls:

And here is where the step backward comes into play:

All those SST measurements I made? All those shims I carefully sorted and measured? Turns out I was way off. With the knuckle installed and torqued to spec (70ft-lbs), I'm only getting about 1/2lb of preload at the steering arm, when I test with a fish scale. Unfortunately, specifications indicat 4.0 - 8.6lbs or so (some folks even say 10lbs). As a result, I'm going to have to take these things apart, and start pulling shims in order to bring the preload back in. This also, of course, begs the question - will my axles even be centered after this? Given that the Marlin seals are already installed - There's no going back and re-measuring a third time with the SST. I guess I'll see how tough these heavy duty Marlin seals really are!

 

[Vae Victus]

What did you do wrong? I don't want to repeat your mistake.

Btw - your axle needs some paint dude.


...via IH8MUD app

 

[RWBeringer4x4]

What did you do wrong? I don't want to repeat your mistake.

Btw - your axle needs some paint dude.


...via IH8MUD app

Trunnion bearing preload is set using shims that sit between both the steering arm and your lower trunnion cap, and the knuckle. They serve to both center your axle in the spindle/axle housing, and set your trunnion bearing preload. The correct number of shims, top and bottom, are determined using the Toyota SST I used back around post #420. The FSM recommends a preload of ~5lbs of pull on a fish scale. Running larger tires (ie:35's), I've seen many recommend upwards of 10lbs.

What did I do wrong? Well, the SST scores lines in the paint around the shaft - where those lines fall are highly reliant on a couple of things:

1. Using the proper torque specs to tighten down the tool and bearings (pretty sure I was OK here)
2. The condition of the brass bushings in your spindle (they wear over time, and even a small amount of play will affect the scriber position for the tool).

I could also have potentially not measured the gap between the lines (inaccurate caliper?) or something of the sort. In any case, I ended up with WAY too many shims, thus the steering arm and trunnion cap are not "sandwiching" the bearing appropriately, and, as a result, insignificant preload. Shims will need to be removed to adjust.

@Vae Victus - luckily for you, since it looks like you're simply reusing the original knuckes/axles, you should be able to just hold onto the shims that came out, and pay close attention to their orientation. Then, you can simply put them back where you found them - they should be in spec.

And yes, my axles need paint. Before paint, they need brake-line tabs. Before brake line tabs, they need knuckles and calipers so that I can properly orient the brake line tabs. Some of the joys of fitting pieces from 2 trucks together.

 

[RWBeringer4x4]

I thought I might re-address the centering pin spacers in a little more detail. When installing caster shims, these spacers are essential for keeping you Spring centering pin doing what it was designed to do.

Normally, the head of the center pin sticks out of the top of the leaf spring, and up into a hole on the spring mount, centering the axle on the springs and making sure it doesn't slide laterally. The U-bolts do most of the clamping work, but the centering pin wouldn't be there if it wasn't important! When you install a caster shim between the spring and the axle, the head of this pin no longer extends far enough to access the associated hole in the spring mount on the axle:

There are a couple of ways to remedy this: Some folks just take a longer cap screw, and run it through backward. Companies actually sell center pins with taller heads to compensate. I decided to make a spacer out of a bolt. My center pin is a grade 8, 5/16-18 cap screw. The caster shims had to be drilled out to 1/2in so that the screw head (and spacer) would pass through. The head of the pin is just a little larger than 7/16 (which was annoying, since big drill bits are expensive, and I wound up having to buy a 7/16 bit, and then immediately turn around a buy a 1/2).

Next, I mounted the sacrificial grade 8, 5/16 bolt on the center pin, and ground down the outside edges to fit into the 1/2in hole in the caster shim. Turning the bolt on an Arbor wheel made short work of it:

Once the proper outer diameter was achieved (fit snugly in the 1/2in hole in the caster shim), I put the bolt in a vice, and bored out the 5/16 threads with a 5/16 bit.

Boring out the threads allows the new spacer to ride up past the threads on the bolt, and mount flush against the underside of the cap screw head, right where you want it:

With the spacer installed, the screw head will poke up beyond the caster shim, allowing your centering pin to continue to do its job, and keep your axle centered on the springs:

Basic "machining," and it only took about 1/2 hour two make one for each side, all told. That said, I'd seen this issue come up a couple of times here on MUD, so I thought I'd document it.

 

[subzali]

I must have missed it - why do you need caster shims?

 

[RWBeringer4x4]

I must have missed it - why do you need caster shims?

My shackles are a out 3/4in longer than stock. My caster angle is about 0.3 degrees as a result. My Saginaw power steering seems to want more caster than even the stock 1 degree, as it won't re-center itself out of turns. So I'm installing some 2 degree shims while the axle is out to see if they will help tighten up the steering a bit.

 

[Vae Victus]

Nice details Rick. Thanks for the time and effort. This will be helpful for me.

 

[RWBeringer4x4]

My differential continues to increase my blood pressure far beyond what it should be at age 28, but we soldier forth:

Today I took what should hopefully be the final step in "dialing in" my front diff. Previously, I got the preload to within spec for the used bearings in the differential. I finally borrowed a replacement dial indicator from the future father-in-law, And got the diff back in a vice. Ring gear backlash still measured about 0.011. Factory tolerances suggest this should be between 0.004 and 0.009. So, I backed off the locking bolts/locks on the two carrier adjusters (the ring full of holes on each side of the diff). By loosening and/or tightening these rings, you should be able to adjust the gear backlash.

Just in case I really screwed something up, I made reference marks on the settings I started with. After some finagling, I found a backlash of ~0.007-0.008. To get this, I wound up only moving one adjuster, tightening it 3 "notches." Adjusting using the other side would have involved loosening the adjuster, and it felt a little too loose for comfort. Plus, by moving both I could only get it to about 0.009.

I measured backlash on a couple different teeth, and the measurements were consistent.

Dial indicator reading my (slightly tighter) backlash.

Carrier bearing preload adjuster, reference mark indicates the 3 "notches" tighter. Other side was left in place.

A note on these dials: they are TIGHT. You will need a tool that spans across the diamter of the adjuster, then connects to a long handle so you can provide adequate torque to move the adjuster wheel. Most of the "pros" on this forum build this with a socket attached, so they can measure torque, etc. while setting up the gears. In Rick's ghetto-fab mobile garage/workshop, I use no such tools. Instead, that long iron bar with two bolts in it I used to hold the diff flange in place a few posts back? Yup...that works here too...

With that, everything should be dialed back in, nice, tight, and ready to run. However, in typical "Clustertruck" fashion, this SOB had one last gift in store for me. Last thing I had to do was tighten the locking bolts/locks back down on the adjusters. This bolt is supposed to be torqued tight (70ft.lbs). which seems like an AWFUL lot for such a small (M8x1.25) bolt. Not sure if the torque wrench failed to "click" properly, or if the bolt was just on its' last legs, but I got to deal with a FUN extraction:

Luckily, the bolt had JUST been out, and with about 30 minutes of drilling with ever increasing bits (and getting more and more nervous) the broken bolt finally removed itself. I also think I kept the metal shards out of the diff...

The replacement bolt, while not quite right, should do the trick. Needless to say, this time I just went by feel (as tight as I dared). Hopefully, these things stay in place...

 

[subzali]

I don't know where you got 70 ft-lbs from. I read through the manual and the only indication I could find for torque was the standard torque values in the back. It said 8 to 16 foot pounds for that size bolt. The cap Bolts are 79 foot pounds but this bolt not a cap Bolt


...via IH8MUD app

 

[Stumpalama]

I don't know where you got 70 ft-lbs from. I read through the manual and the only indication I could find for torque was the standard torque values in the back. It said 8 to 16 foot pounds for that size bolt. The cap Bolts are 79 foot pounds but this bolt not a cap Bolt


...via IH8MUD app

I'm with Subzali here. Those bolts are only supposed to be snug, enough to flatten the lock washer and put some tension on it.

 

[RWBeringer4x4]

Must be confusing this bolt with something else in the service manual. I know the carrier cap bolts are listed at 70ft.lbs. but I thought these were too. I agree with both of you - it doesn't make sense and I should have gone with my gut -the bolt is way too small for 70 ft.lbs. Anyway, crisis averted. Aside form looking a little redneck, the bolts are in snug now.

The latest question is whether all of this messing did more harm than good. The preload was way too low, and now sits at about 8.5-9in-lbs, but this was before I realized the FSM spec of 7.3-11.6in-lb is for just the disconnected pinion...I messed with the shims and installed with the carrier/ring gear attached. So really, total preload should be closer to 20in-lb, it sounds like. The ring gear backlash is dialed in, but now I'm not sure if I just succeeded in messing up the contact pattern.

This is one of those "best if left alone" situations...highly frustrating...

 

[pb4ugo]

I personally would not have done anything w/it if the pinion was tight, meaning if it didn't have any play in it & backlash is close. The optimum PREfix is "PRE" load. The "pre" load will eventually loosen up or go away after it has been run for a while. The contact pattern may have changed, did you check to see what it was b4 you started working on it? I don't think it would of looked like it did when it was originally setup, because that was many miles ago & gears wear on each other. I'd stick it in & see if howls.

 

[subzali]

At this point if you're worried about it it wouldn't be that hard to pull the ring gear out and check the pinion preload by itself, the put the ring gear back in and set the backlash again. While you're at it and taking your time you might as well get the proper fastener from Toyota for that retaining clip bolt. Don't go down the path of "that" PO!