78 Big 10 on Wide Fives

[hewittca]

SCOTI, I really like that 4-link idea. Nick, I think we have your first upgrade once we get this truck to driver status.

[SCOTI]

Originally Posted by hewittca

SCOTI, I really like that 4-link idea. Nick, I think we have your first upgrade once we get this truck to driver status.

There are a few choices online for 'pre-fabbed' laser cut mounts that are worth investigating these days. I get the DIY effort but sometimes pre-fabbed stuff allows focus on other areas that do require full shop effort.

I bought my rear 4-bar kit used. The front mounts (2pcs/each side) were missing so w/me wanting to be able to possibly reverse things, I made my own.

[GoSki]

Alright, so something I need to mention about my order of operations for how I built this truck. In short, it is out of order and doesn't make a lot of sense to the 3rd party viewer.

My reason for the order I did things boiled down to one factor, my severe lack of space to do a build like this. In the last few years I moved from a rural area with plenty of space, to a suburban area with much less space, and much less (zero) tolerance for car parts in the yard. I also have what is the new definition of a "3 car" garage, this is only true if you own 3 smart cars. Anyway, what I am trying to say is I don't have a lot of room, and you all know that once you disassemble a truck, it turns into 3 trucks worth of space. So, the order in which I decided to build things centered on getting the truck back into a more consolidated form as fast as I could, to give myself more room to work on the thing. It is because of this that the next thing I decided to do was clean up the cab, paint it, and get it back onto the chassis. This step would allow me to start to mock up the suspension with some body panels bolted back in place, so I could get an idea on ride height.

So now I had to make the decision on the color, and honestly, it wasn't much of a decision for me, I always knew I wanted the truck to be a two tone green and white. My favorite color combo on this era truck is actually two tone blue and white, but the vision I had in my head for this one was green. So we did it.

Now, I know that the "patina" thing is a hot and cold subject, and the "manufactured patina" is even more of a hot button. I'll say that I'm no different, I have spent a lot of time critiquing fake patina, and maybe even more time saying I didn't think it could be done well. After all that talking, I decided we were going to try it, and I'd like to ask you guys to hold your breath for a little bit longer until you see what the truck looks like now, before you make your decision. It's going to take me a few more days of uploading to get there, but I think we (mostly Corey) pulled one off that is pretty believable. You're about to see just the cab, which was actually painted a year ago in real time.

Last thing to mention, the truck did have some pin holes in the cab corners and a few along the rockers and in the floor, I DID NOT fix this rust. I wire wheeled it down and rust treated it, and left it at that, knowing I was going to be re-rusting some of those areas for the overall look of the truck. This is my disclaimer before you guys see a truck stripped all the way down, and some rust spots ignored on the rebuild.

I built a cart to transport the cab because I did most of this work at locations other than my house, so I ended up hauling this cab all over the place on my trailer to get the job done.





I spent a full day wire wheeling, scraping, and cleaning the bottom of the cab, then we treated it with Rust Mort, and I epoxy primed it before hitting it with Raptor Liner. Another thing to mention, I elected to Raptor Liner the bottom of the cab with body color tinted Raptor Liner, I only did this because I wanted the "kick panel" portion of the floor board to be the same color as the firewall, because you can see it from the top side looking into the engine bay, if not for this, I would have just used black.







The next thing was the inside cab floor, same process, wire wheeling, cleaning, rust treatment, epoxy primer, and green Raptor Liner that is just going to get covered up with tan carpet.





This one lets you catch a glimpse of Corey's old ride sitting in the background.

[GoSki]

Now it was time to paint, but first I had to fix some rust holes at the bottom of the windshield frame on both sides, I could not leave this alone, it had to be fixed. I just cut out the old rust, made some filler pieces, rolled them in the slip roll and persuaded them with a body hammer, and I had both lower corners fixed.



We epoxy primed the whole cab (mostly). This was the first step in the operation to preserve some patina. We faded the primer as we went up the A-pillar and B-pillar and did no primer at all on the roof. This was part of the plan to retain the natural roof aging.

I then sprayed the entire inside of the cab and dash with the green (Medium Lime)

Then it was time to spray the white areas on the outside, giving enough overspray to mimic how we thought the factory would have sprayed it, and fading up the pillars, then we taped it off and sprayed the green, doing the same fade job as we went up the cab towards the roof.

The amount of paint laid down is more than what ends up on the truck in the end, as we later remove some during the "artistic" portion of this job.

[GoSki]

Next I ran back up to Corey's house and retrieved my frame (6 months after leaving it there)

We brought it back to my house and gave it a flat black paint job. (I'm not into shiny stuff, even on the chassis).







Then we set the cab back onto the frame





In this picture you can see I refurbished the vacuum brake booster and brake master cylinder, they both were working great when I drove the truck home, so I elected not to replace them, (at least not right now, we'll see how it goes once I'm driving this thing)



And then a fairly big moment at this point in the build, as I got to see what it might look like with the tires and wheels placed roughly in their home.

[GoSki]

At this point in the build it was around Christmas of 2024. I had some time off work and decided to spend it doing some of the "free" stuff on this build. Unfortunately I didn't take any photos of it, and I should have. I mostly cleaned up factory parts that I knew I was going to be reusing. It was a lot of interior parts, to include all of the HVAC duct work and the interior wiring harness.

Since the cab was already painted, I was able to install most of these parts back into the truck once I had them cleaned up and painted.

Another time consuming task I took on during this time was to clean up all the hardware that bolted this truck together. In hindsight I should have spent the several hundred dollars on the full hardware kit, but I was trying to scrape out some savings wherever I could. I made use of the cabinet blaster and Evaporust to get this done.

Side note, I'm sure most of you are familiar with the old square body sticky steering wheel situation. I stumbled upon a good way to clean that up. I soaked it in Evaporust for a total of 72 hours, pulling it out at every 24 hour mark and giving it a really good scrub with SD-20 degreaser and a stiff nylon brush. After 3 days of this I was left with a perfectly clean steering wheel that had lost most of its black color and was now more of a grey. I fixed that with some black SEM color coat. To my eye, the wheel looks basically brand new.

[GoSki]

More Tomorrow......

[GoSki]

Originally Posted by Getter-Done

Nice work.

Hey, Thanks!

[SCOTI]

Lovin' everything so far. I understand the logic within the steps.

[clay68c10]

Nice work, love the green.
I also have no room and understand the challenge.

[GoSki]

Okay, time to talk about pedals, and most importantly the number of them. The answer to this is always 3, regardless of application. Yep, I know that modern autos are in fact better, they have 10 speeds, shift so smooth that you can hardly feel it, and keep you at the right rpm all the time, buuuuut, I don't care. It's always 3 for me, whether it is a tow rig, a sports car, a drag car, a circle track car, an 18 wheeler, an off road rig, whatever it is, 3 pedals. Now, let me climb down off the this soap box (mostly because my company owned truck is an auto) and talk about my 3 pedals.

I started looking on the internet for a set of manual OEM pedals and discovered that they are pretty expensive. I also intended on a hydraulic set up over the mechanical linkage ( a deviation from my 80's theme, I know) Regardless, these factors pushed me into just making my own out of the automatic set that came in the truck.

I started by measuring the brake pedal arm and drawing a duplicate of that profile in CAD, then I cut it out on the CNC plasma and I had a starting point.



Once I had the clutch pedal arm blank, I started to mock it up in the pedal hanger.







Then I started to work on a way to extend the pedal hanger weldment to accommodate the 3rd pedal.

[GoSki]

Once I had the pedal hanger extended and reinforced, I went to work on finishing up the clutch pedal arm.

I machined a pivot sleeve on the lathe, then bored out the undersized CNC plasma hole to the correct size to accept the sleeve. Then it was a matter of placing the arm where I wanted it in the Y direction (cross car) to set my space to the brake pedal.

Then I bent a small return on the bottom of the pedal arm, and fabricated a clutch pedal pad.















This picture here you can see that I cut down the automatic brake pedal pad

[SCOTI]

That is some 'next level' fab work right there.

[Shifty One]

Your work is like Fonzie levels of cool...

[GoSki]

Originally Posted by SCOTI

That is some 'next level' fab work right there.

Thanks, I appreciate this.

[GoSki]

Originally Posted by Shifty One

Your work is like Fonzie levels of cool...

Thank you

[GoSki]

Once I got to this point with the pedal assembly I had to test fit it into the truck and look at the clutch master location.







I sourced a "generic" clutch master cylinder with a bore and stroke that should work for most of concentric internal slave cylinder/release bearings. The amount of release bearing travel I will need is going to depend on the pressure plate I choose, and whether or not it is a self adjusting style. This will decide my initial gap between the bearing face and the pressure plate fingers, these factors will dictate how much fluid volume I'll need. I swore I made an excel sheet that showed the volume displacement math for the bore and stroke on the different master options, but I can't find it now, so you'll have to trust me.



After some very careful inspection with my eyecrometer, I decided on a pivot point location that put the master in a spot on the firewall that appears to be almost in the same location that the push rod for the mechanical clutch assembly would have gone.

Since I needed to drill a "hole saw sized" hole through an area that already had a large hole, I had to come up with a way to guide the Rotabroach.



I made a template of the master cylinder mounting boss, then transferred that onto a piece of sheet metal with a small pilot hole in the center. I bolted this to the inside of the firewall and was able to use that small pilot hole as a drill guide to drill out this offset hole.

[hewittca]

hey there's Bluey making an appearance! Why'd you let me sell that truck?

There are some details here that I didn't see along the way. Three pedals for the win!

[GoSki]

Next step was to machine the push rod extension and drill the mounting hole in the clutch pedal arm.

I built a mini mock up firewall by transferring the master cylinder mounting location onto a sheet of aluminum using the pedal hanger assembly mounting holes as my reference.

This let me bolt everything up in a vice in the correct location and easily work on it.

I machined a push rod extension with LH and RH threads so that I could adjust the length like a turnbuckle.





Then I made an adjustable pedal stop so that once I finally get the clutch system together and bled, I can adjust this stop to touch at the exact right place to prevent over travel of the master cylinder piston that might cause premature wear.





Then I welded it all up and shot it with some paint.















I might machine a very thin tapered spacer to give the heim some more rotation room to the side of the pedal arm, but right now an AN washer appears to be offering the clearance it needs.

[GoSki]

Originally Posted by hewittca

hey there's Bluey making an appearance! Why'd you let me sell that truck?

There are some details here that I didn't see along the way. Three pedals for the win!

You had your mind made up on that one!!

[GoSki]

At this point I turned my attention back to the suspension, I had the cab back on the chassis, and I had one bed side partially shortened. I knew I would need to set the rear to its approximate height with a bed side on, so that I could bolt on a front fender and get an idea of what would look good on the front height.

I started this by disassembling the rear leaf packs, cleaning, painting, installing new rub pads and new bushings. I knew I was going to be doing what was equivalent to an axle flip and then I was doing a 2" drop shackle in addition to that.

This truck is a Big 10, so it had the big 8 leaf packs, during the process of rebuilding them, I removed two leaves. Once I had the packs put back together I finally noticed that they did not share an equal height. Although I did not get a picture of it, I took them back apart again and I mixed and matched different leaves from one pack to another to get them to have the same relaxed height. However, I do not know what the effective spring rate of each one is. I could probably fixture them in the press and do some simple force vs. displacement math to figure it out, but I didn't feel like it, and it doesn't really matter unless the thing proves to be way too soft once I am driving it. Removing the two leaves from each pack did require that I made new (shorter) center pins. I machined them from some grade 8 fine thread bolts.

[GoSki]

The next step was to put the rear end back under the truck and set it down onto the springs. At this point I had still not narrowed the rear axle, but it was okay because I was only using the right bedside, so I was able to push the axle over to the left side of the truck and let all the extra length stick out that side.

Once I set the truck down onto the tires and stepped back to look at it, I knew right away that I needed a different backspace for the rear wheels. The white wheels you see here are 15x10 with a 5" backspace, so essentially a zero offset wheel. I wanted a wheel with at least 3" of backspace to give me a -50mm offset. The reason I felt this was important was because the rear hubs for the quick change have splined drive plates on the outside face for the axle shaft to engage. This makes the hubs stick out pretty far (much like a full floating rear axle on a 3/4 ton or 1 ton truck) and this rear axle is in fact a full floater like those.

That extra "stick out" of the rear hub made these wheels look "less deep" and I was looking for that deep dish look, especially on the rear.

My solution to this was to order two more wheels in a 15x10 with a 3" backspace. The only downside here was I could not order those wheels already painted white, so I had to get them in grey and handle the color change later.

[GoSki]

Now it was time to start on the front suspension. I knew I was going to have to shorten the front control arms. But before I did that I had to decide which route I was going to take for the spindle.

After thinking about it for awhile, I landed on two different paths, one of them I didn't have too many questions about. I always knew that fabricating my own spindles (uprights or knuckles) was an option because all the late model stock race cars that run these wide five hubs have a fabricated version.

I knew I could do this, but it would require to first capture the correct XYZ pick up point geometry of a stock factory spindle, and then apply the delta offsets for the amount of spindle pin drop I wanted. Then I would have to build a fixture to locate everything, then hand build and machine all the components and weld it up. Being fully aware of how much work that project is, I decided I would try something else first. So I did an experiment using the stock factory spindle off the left front of the truck.

The main difference between the stock factory spindle and a wide five spindle is the diameter of the spindle pin. Racers call it a snout, but the spindle snout diameter on an upright for a wide five hub is much larger than a normal pin. What I kept wondering was if I could just put a wide five snout into a cast OEM spindle, and if I could, then could I set it to the right depth to make the offset for a 1.25" brake rotor to be used with the factory GM brake calipers?

I started with a "donor" fabricated spindle from my friend Pat. This one had been crashed and was no longer good to him, and all I wanted from it was the snout, so I harvested it.













Then it was time to tear down the factory LF spindle assembly so I could machine out the pin bore to accept the wide five snout.











Here you see the bored out spindle and the wide five snout that are about to be married.



So now it was time to mock up a full corner assembly with hub, rotor, and caliper. This was the first "make or break" moment for me, because it let me see enough to know I could make this work. There are some other details I need mention about the press fit between the snout and the spindle, as well as the loss in interference forces between the two parts that happen as a result of doing this, and I do have an excel sheet with the math I did before executing this job. But that will come in another post, for now just check out a wide five hub and rotor mounted to an OEM cast spindle with a factory brake caliper.











This is me checking to see if a 5" backspace wheel will clear the steering arm on this stock height spindle, it did.

[GoSki]

More Tomorrow.....

[GoSki]

So now that I had a spindle assembly that I could mock up, I needed to tackle shortening the control arms on the left side. This would allow me to mock up a complete corner with a tire and wheel, as well as a fender.

Now, let's talk for a minute about the potential downsides to shortening your control arms. The most immediate and obvious one is that you decrease the radius that your arms swing on, and this will increase your camber gain as your suspension travels upward.

In addition to this more aggressive camber gain, any time you starting aimlessly changing things in a double a-arm suspension, you can negatively impact things like your roll center, or the leverage that the the truck has against the coil spring, this would increase wheel rate and make the truck ride more stiff. Depending on what you do, you can also impact caster, bump steer, or the scrub radius, but wheel offset also impacts this, and most of us decide on wheel offset based on looks, not scrub radius. There are more things than what I have listed here, but people are likely already bored with this post.

I did take a little bit of time and scratch out some very simple 2D stuff in CAD to see just what my camber gain would look like. But I didn't worry a lot about it, and here's why.

In order for me to capture the complete picture of kinematic changes I was about to make to the front suspension on the truck, I would have had to measure the XYZ locations of all the suspension and steering points in their stock form, then run the kinematic simulation to get data for the stock suspension. Then I would need to model the shortened arms and do the same study on that model, then compare the two.

There were two ways I could do this, one would have been to set the truck up on some sort of really flat surface (not a concrete floor, like a metal surface plate instead) and take careful measurements of the entire front suspension and steering with plumb bobs, height gauges, string, lasers, micrometer, and a tape measure, to capture all of the XYZ points. I have done this before on a race car, and while it can be done, it is pretty tedious, and you know the whole time you are doing it that it is not going to be exactly right.

The other way to do it would have been to bring the truck to work and put it on the lift and use our CMM equipment to measure all of these points with a Romer arm. This is the right way to do it, but it is too close to an abuse of shop equipment for me to feel comfortable doing it.

Either one of these methods would have given me the starting point I needed to actually model and then understand the stock kinematics, and then how and how much I was about to change them.

I did none of this, and the reason is, this truck is a hot rod, and at the end of the day, I knew for a fact that no matter what the kinematic study told me, I needed to narrow the arms as much as I could get away with to fit the tires inside the fenders. In addition to this, my total front suspension travel was about to decrease down to likely no more than 2-3", and at these travel amounts, the travel deltas for these things are much less.

The one thing that I will end up addressing is bump steer, but that is more of a by product of the steering arm to center link z height than the control arm length. So that was going to happen anyway.

Here is the stock lower arm, I started by removing the bump stop housing.









I fixtured the arm and took some relative ball joint mounting plane angle measurements, then I sectioned out the ball joint ring. My goal was to retain the ball joint angle on the lower control arm, but I had decided I would likely change that angle on the upper arm some. I settled on removing 1.5" from the lower arm








Here is a shot in the middle of it going back together, you can see the heat marks from the welding of the reinforcements on the underside.