Build The Clustertruck Rides Again - Refurbishing a 1975 Chevota

[RWBeringer4x4]

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.

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!

So if "preload" is pre-load and will go away anyway, and the truck had previously had zero...(but also no play) logic seems to dictate that with SOME preload, and no play, this thing will still work just fine. Adjusting the ring gear at all may have been a mistake, as this might change the contact pattern, but, as this is the front diff, I'm leaning toward "run it and see what happens."

@subzali - I may end up being "that PO." It's a long drive to the Toyota dealership and I really can't see how running that grade 8 bolt (with proper thread and torque) would cause my diff to detonate...I tend to be pretty perfectionist when it comes to this stuff, but even I can't justify the trip for one bolt...chances are I've screwed something up and I'll be back in here in a couple months anyway - by then I'll have a whole laundry list of stuff to pick up from Toyota.

 

[RWBeringer4x4]

Well, I quit my job (starting my new on on Tuesday)...Decided to burn some vacation time in between, during which I managed to get some time with the truck in.

If you all recall, even after measuring with the SST, I came up way too light on trunnion bearing preload. I finally got around to pulling some shims. On the long side, all that was required was a thick shim removed from the top, and replaced with a thin one. The short side required several more attempts. I ended up pulling a thin shim from both the top and the bottom. Factory preload specs appear to be ~5-6lbs of pull on a fish scale. I've read of many folks here loading them up even higher (particularly with larger tires). So when I got the preload specs below, I considered it "good enough."

Since I'd been pulling the steering arms and bearing caps on and off messing with the shims, I gave the studs a final torque down - I've heard horror stories about broken knuckles due to loose studs. I was shocked to find several of them had definitely backed themselves out. Glad I checked!

Considering the studs bolted down, and the pinion preload "good enough," I greased up the felts, and bolted everything down. Re-used my old retainer rings, and inner metal felt split washer thing.

Steering arms: Cone Washers, flat washers, nuts.
Trunnion Bearings: Lock Washers, then nuts.

Starting to look like an axle again!

 

[RWBeringer4x4]

With that done, I installed the calipers (temporarily) and started test fitting to locate the new soft-to-hard line junction tabs on the axles. Came up with a setup I liked:

Note: The NAPA 38881 lines are LONG, probably too long for my application, but we will make do for now:

Ended up putting the axle back under the truck (that was fun, solo) for a better idea of where the lines would be running. I ended up going with more of a downward angle on the line end than pictured...

I also spent some time under the hood, finalizing the routing of my new brake line plumbing. I know there's a way to make a bubble flare using a double-flaring tool, but I bit the bullet and bought a bubble flare kit. The Proportioning Valve requires bubble (ISO) flares, not double flares like the rest of the truck. I also adjusted the push-rod on my booster to play nicely with the shallower FJ60 brake master cylinder. I used the "grease blob" trick here. Put a blob of grease on the end of the push rod, and adjust it until the grease blob remains uncompressed when you install the master cylinder. It should be set up right when it comes time to bleed everything.

I also created a cardboard pattern for a bracket to strengthen up the plumbing around the proportioning valve - more on that later.

 

[RWBeringer4x4]

I also put my front differential back together for the LAST time (hopefully ever, but we will see if I did more harm than good soon enough).

Lubed up the Marlin Pinion Seal (this helps keep the spring seated, or so I have read):

Then installed it with a deadblow and this fancy installer tool:

Installed:

Then reinstalled the flange, with some Ultra Blue RTV on the splines (again, because I've seen it recommended in a number of places - the splines had not been leaking previously, so this was probably overkill)

And finally, new staked nut (yet to be staked) torque to 150lbs:

One final preload meausrement showed a SLIGHT increase, but nothing I'd consider earth shattering (maybe 13in.lbs.)

 

[RWBeringer4x4]

Finally, today, I had the future father-in-law assist with some welding (and by assist I mean do it for me).

New brake line tabs installed (plus great action shot of the dog-in-law, assisting):

Now it's onward to cleaning up the differential sealing surface, a new paper seal, torque everything down, and then, at long last - PAINT. Starting to see the light at the end of the tunnel!

 

[RWBeringer4x4]

Front axle hard lines have been plumbed in:

Thanks again, @Stumpalama, for the FJ60 T-fittings - they should work nicely.

I also used some air-powered Brillo pads to clean up the sealing surfaces on the axle and differential. The old gasket has, quite literally, melded into the pores of the metal, so I simply smoothed it out and got rid of as much as I could. Going any further would have mean removing metal from the sealing surface. Because of this, I opted to add a thin layer of permatex to the paper gasket prior to reinstalling the differential into the axle. In theory, this should make up for any unevenness left by the un-removable gasket paper. At long last (and with no daylight to spare) I managed to get the diff back into the axle and buttoned up. Hopefully, tomorrow, I can start prepping for paint.

Meanwhile, this guy showed up in the mail the other day. Apparently, I didn't learn my lesson messing with my front diff after all...

 

[DPV7070]

Axle is looking good! I get dizzy when I think about all the work to convert to FJ62 knuckles...

Oh, replace the fill and drain plugs while you don't have any axle lube with these. Cheap insurance (magnetized):

Disregard the aluminum gasket unless you're putting these in your t-case. These are super cheap and come out a lot easier than using a 24mm socket and busted knuckles...

 

[Stumpalama]

Lookin' good! Happy I could contribute to the build. Keep the momentum going!

 

[RWBeringer4x4]

Axle is looking good! I get dizzy when I think about all the work to convert to FJ62 knuckles...

Oh, replace the fill and drain plugs while you don't have any axle lube with these. Cheap insurance (magnetized):

Disregard the aluminum gasket unless you're putting these in your t-case. These are super cheap and come out a lot easier than using a 24mm socket and busted knuckles...

Already have them - Converted the transmission over a little while back. They're definitely an improvement. I've never seen the aluminum gasket. The T-case doesn't have them yet - the shop that re-sealed and installed a new T-case in this truck when I first bought it said the head-head replacement plug I bought didn't fit. I always assumed they just forgot, and I haven't bothered to drain the case to find out. Good thing, I suppose, if these aluminum gaskets are required.

 

[RWBeringer4x4]

Well, this was pretty much my Sunday...About 3 hours of grinding with a braided wire brush and the 4 inch grinder for the axle. I also took a hand-held wire brush to the differential housing. Given all the gussets, nooks, and crannies, I decided it might make more sense to get rid of the rust flake on the diff housing, then hit it with a rust converter as opposed to spending hours trying to dig out every last little bit of rust.

Cleaned axle:

Yes, I managed to catch that brake tab with the wire wheel at a bad angle. Bent the tab over and actually exposed a bad weld. So unbent it, cleaned it up, and re-welded it. Seems much more solid this time.

The areas I couldn't get with the grinder, I got with sandpaper, at least to the point where the surface rust was smoothed over. Anywhere I couldn't completely eliminate the rust, I hit it with converter.

Primed Axle:

The rust converter needs 48 hours to work its magic, and dry. Of course, 48 hours from now the weather channel is calling for rain... Then, it will be coated in the "Rust Encapsulator" by Eastwood (I'm trying to stick to the Eastwood paint system, since that's what I started with).

Once converted, encapsulated, and otherwise covered, I'll be able to put a coat of chassis paint over the whole axle, and toss this thing back under the truck for final assembly!

While I was waiting for the paint to dry, I doused the rear diff bolts in penetrating oil and got the nuts backed off. Rear axle is getting the same treatment next.

 

[Vae Victus]

Nice job dude. I'm not going to use the sand blaster (I keep telling myself) on the rear axle when I do that. With the front axle, I used the dremel tool and some really small wire wheels and other bits to get the hard to reach areas.

Phosphoric acid (paint prep spray on-wash-off-type stuff) works pretty well as a pre-primer for those rusty areas too). Home depot has some pretty cheap in a large bottle, which I transfer to a spray bottle.

That Diff housing is a b|tch, no? I'm swapping mine out for a 3.70, so have not done it yet.

Thanks for the help on the phone today re the pre-loads on the trunions. I'm going to just put them on and measure them.

 

[RWBeringer4x4]

Nice job dude. I'm not going to use the sand blaster (I keep telling myself) on the rear axle when I do that. With the front axle, I used the dremel tool and some really small wire wheels and other bits to get the hard to reach areas.

Phosphoric acid (paint prep spray on-wash-off-type stuff) works pretty well as a pre-primer for those rusty areas too). Home depot has some pretty cheap in a large bottle, which I transfer to a spray bottle.

That Diff housing is a b|tch, no? I'm swapping mine out for a 3.70, so have not done it yet.

Thanks for the help on the phone today re the pre-loads on the trunions. I'm going to just put them on and measure them.

Thanks! I'd agree to avoid the blaster for the actual axle housings. I have heard that they leave sand (and thereby grit) in all the orifices, which can translate to seal/bearing damage down the road if it gets into the wrong place.

I'd be willing to bet money that the Eastwood Rust Converter product is just an aerosolized phosphoric acid compound - it smells like Phosphoric Acid (I've spent years working in labs, very familiar with the smell).

The Diff housing - it is indeed! heavy and full of nooks and crannies you can't reach (not to mention annoyingly particular gears). Have fun setting it up, I stared into the abyss too long, and finally just tightened up the Pinion and threw it back into the axle. We will see if I did more harm than good. I'm already months behind schedule on this project, so I decided to go with the "if it ain't broke, fiddle with it til you probably break something, then run it" approach.

Call anytime! I still have a lot to learn but I'm happy to assist in whatever way I can. Always good to hear from a fellow cruiser head!

 

[madoc1]

just finished reading the whole thread. I also have a 75 chevota.. you have done an awesome job so far!will keep watching.

jim

 

[RWBeringer4x4]

just finished reading the whole thread. I also have a 75 chevota.. you have done an awesome job so far!will keep watching.

jim

Welcome aboard! I'm learning as I go, and trying to post both successes and failures for the benefit of others. Feel free to PM me with any questions - always happy to (try) and assist, and as you well know, our "hybrid" trucks have all sorts of unique issues.

 

[RWBeringer4x4]

Another couple hours of work tonight. FINALLY have the front axle in primer. Just a couple top coats to go before I can load it back onto the springs.

With the front diff finally out of my patented "diff bucket," the rear diff could come out:

Read on MUD about breaking the diff loose by applying pressure with a floor jack under the pinion to flex the assembly up, and break the seal. This worked like a charm!

With the rear diff in the bucket, I was able to inspect it a little more closely. Really, all I checked tonight was the pinion. There was some DEFINITE side-to-side play in the pinion (albeit minor) and zero preload. I'm hoping this hasn't quite translated to bearing damage, yet.

I pulled apart the pinion/flange assembly. This was all significantly looser - I didn't even need a puller to separate the flange from the pinion shaft, like I did on the front. A clear sign of the much harder life your rear diff lives as compared to the front one.

With the nut/washer/flange off, I pulled the grungy (albeit still intact) seal:

This brought me to the hear of the issue, the bearings and spacers.

 

[RWBeringer4x4]

The Bearing (Koyo) didn't appear to be in too horrible shape - no roughness to the spinning, although it does seem a little "loose" in the cage.

I also wound up with the usual thick spacer, plus one thin shim. Unlike the front, there is SIGNIFICANT wear on these shims, indicating that they've likely spun. Neither had disintegrated yet. but there are definite wear marks.

Skinny shim measured 0.43mm. My replacements are 0.25. Hopefully I can simply replace the thin shim and get the proper preload (unlikely).

The thick shim will, once again, most likely need to be sanded down a little to bring the preload back up, and hopefully eliminate any further play in the rear pinion.

Once I have the pinion addressed, This differential will get the same treatment as the front one - I'll check backlash with the dial indicator. If it's close, I'll leave it alone. If not...well, I'll cross that bridge when I come to it...

If all appears kosher with the ring gear, I'll yank the spiders, and install the Aussie locker.

 

[RWBeringer4x4]

Had some rough weather over the last few days - but I tried not to let it stall me too badly.

I pulled the rear axle seals:

The used my fancy, 5-foot long bearing driver to knock out the wheel bearings:

With the diff out, you just thread it through the housing, and hammer:

I damaged the cage on one bearing, but I have replacements, so I wasn't trying very hard to preserve these ones. If you are, make sure you're hitting them on the outer edge, not the thin portion of the cage over the rollers. In either case, the "pipe trick" worked great. Probably took 10 minutes to get through the seals and bearings:

 

[RWBeringer4x4]

Since I was stuck indoors, I decided to "modify" my monte carlo calipers with a 4 inch grinder.

This will allow me to route the rear soft lines 90 degrees away from the calipers, as opposed to straight out the front of the casting, as they were designed to do.

They will need a little touching up, otherwise, everything went smoothly.

 

[RWBeringer4x4]

Today, we got a good break in the weather. So, at LONG LAST I got the front axle top coated. I'm happy with the results:

Once this stuff hardens, I'll load it back under the truck, and finish building the knuckles and brake lines with everything bolted back in.

I also spent some time polishing a few turds. No reason to put paint on these parts, aside from the fact that the flash rust was negatively affecting my obsessive compulsive tendencies.

I'll still need to get the bottom of the steering shaft. Just have to figure out how to best isolate it when I spray it. I just used Duplicolor silver caliper paint. Should be able to hold up with the high heat atmosphere next to the exhaust, since it was designed to withstand brake heat.

 

[RWBeringer4x4]

Lastly, just a little review of using the "grease trick" to set your brake booster rod to the appropriate length. Too long, and the brakes will never fully release. You wind up with a hydraulic pressure build-up, which in turn causes the brakes to drag or remain locked. You can pretty well eyeball the "rough" depth of the booster push rod by just feeling it bottom out against the back of the master cylinder. Once it gets in closer, you need to "fine adjust" so that there is a very small gap between the end of the rod and the master cylinder.

You put a ball of grease on the end of the push rod:

Then you tighten down your master cylinder to spec:

Then remove it. If the grease ball remains intact (wasn't squashed on contact with the master cylinder) then you have a gap. The trick is to keep doing this and fiddling with it until you have a gap, but not a gap that is far too wide, and that will leave a lot of "dead pedal" before your brakes actuate.

I've read that a lot of people need to trim their pushrods to work with 80-series master cylinders. I did not have to do this for the FJ60 cylinder. I had to shorten the adjuster screw on the push-rod a LOT from the 40-series cylinder setting (down to about 3 threads exposed) but no cutting required.