Skidmore '67 C20

[SkidmoreGarage]

Originally Posted by MDPotter

I did notice one broken edge spring on the driver side. I was just going to weld it but I read that it would make it brittle so I'll have to rethink that approach.

You will thank yourself for just picking up a replacement. I would not trust a welded spring, but more so that it has been fatigued to its failure point and once you re-foam and re-cover- you will never want to pull the thing apart again.

[SkidmoreGarage]

Slow and steady.

I committed to a rear suspension setup and placed an order with NLE this morning. I have to say they were very helpful over the phone, and very knowledgeable. I ended up with a bit of DIY trailing arm setup. I will share more when the coilovers get here, and I can mock everything up. If you are thinking of giving them a call, please do. They also have great prices and a forum discount.

I also pulled the trailing arm mounts and flipped them today. I also removed this little "frame protector" that is mounted above the axle. This was surprisingly difficult. I swear my truck has the world's strongest rivets. I have a decent air chisel (with new and modified sharp chisel bits), and I have tried cutting an X, gouging with a plasma cutter, and grinding the head off. The head isn't really an issue, even though I struggle four times as hard as anyone I have seen in a youtube video, the heads will come off eventually. I have issues with getting the other side of the rivet out, even with the air chisel. I am just as likely to bend the 1/4" steel that the other end of the rivet is stuck in than to even start to dislodge the head. I don't get it. I still have about 9 to go...

Am I missing something? I spent at least 2 hours getting out 7 rivets and 3 partials. The 3 partials have actually pushed the inner frame brace away (3/16" thick) from the frame creating a 1/8"+ gap. I tried to use some clamps to bring it back together, but I don't have anything strong enough.

I installed a set of energy suspension trailing arm bushings as well. I didn't get any photos of the removal, wire wheel action (couple hours), install of the poly bushing. I am pretty sure all of the rear suspension is/was original. The shocks said Chevrolet and Made in Ohio... I'll get photos of this stuff as it goes back together for the last time.

[68 C10 Driver]

Your project is coming along beautifully! I see you are encountering a lot of the same issues I did with patch panel fitment, but that's why I have a grinder and welder.

I am going to paint mine Medium Green, it had been repainted at one time Dark Green. I like Light Green, but there is already a C10 Fleetside Longley in town that color. I will paint the top White.

Keep up the great work!

[KMC3420]

I have been watching this one, but will follow along now. Curious about your coil over setup. Great job so far. I too struggle with rivets and typically grind the heads off, then use a punch and 4 lb hammer. Those rivets were made to last that’s for sure.

[SkidmoreGarage]

Originally Posted by 68 C10 Driver

Your project is coming along beautifully! I see you are encountering a lot of the same issues I did with patch panel fitment, but that's why I have a grinder and welder.

I am going to paint mine Medium Green, it had been repainted at one time Dark Green. I like Light Green, but there is already a C10 Fleetside Longley in town that color. I will paint the top White.

Keep up the great work!

Thanks! Don't be afraid to go check out samples at your local automotive paint shop. When I went to get my 503 mixed up, they had the book of all the original samples (the exact one you will find scans of online). GM used the same name for different colors for different years. You may find another period correct original color you like, or don't be afraid to pick something similar but different.

[SkidmoreGarage]

Originally Posted by KMC3420

I have been watching this one, but will follow along now. Curious about your coil over setup. Great job so far. I too struggle with rivets and typically grind the heads off, then use a punch and 4 lb hammer. Those rivets were made to last that’s for sure.

Yeah, it is impressive how much abuse they take. I think they must have gotten weaker as the years went on, because all of the info for later stuff seems to indicate that you can just pop it out in 15 seconds. I am going to plasma gouge the rest out, I didn't for the others because the fall air has been making my compressed air VERY wet. You can get the head off in about 5 seconds with the plasma cranked up, but the slag goes everywhere.

[MDPotter]

Some rivets are more stubborn than others. We always cut an X in the head and then pound them out, but sometimes the air chisel does it and other times it just takes a big hammer and a punch.

[TA_C10]

X pattern is easy. I use the air chisel under head of X'd head and it pops right off, then punch tool in air chisel will knock it right out.

[SkidmoreGarage]

Thanks for the commiseration on the rivets. I went back to the plasma and the air chisel. I still have another 4 (or 6?) to go, but got through about 9 yesterday. I swear they are stronger than the average rivet. The grip on the rivet shank is like it is melted to the steel around it.

Get ready for a wall of text!

So I wanted to lay out my plan for the rear suspension now that I have everything ordered, and made all of the hard decisions. I have devoted more effort than I probably needed to, but I think the end result will be worth it. I hadn't planned any of this going in, when I pulled the truck in the garage and restarted this thread a couple months ago, but I ran into major roadblocks that necessitated doing this job now. I have learned a lot planning this all out, and a lot about how to make these old trucks handle (thanks to this forum and others). The biggest thing that I have learned is that if someone else is planning on converting from a C20 long bed to a pro-touring-lite C10, you must REALLY want it. It is better to just start with a C10, as most of the information you find will be C10 specific and all of the aftermarket is geared towards C10s. If the application says "'67-72 Chevy Truck", they really mean 69-72 C10 SWB. The frames, brackets, fittings, mounts, etc. are all different, and the huge wealth of info online is mostly focused on the 1/2 ton trucks.

Starting goal:
Limited slip rear with 3.7+/- ratio and disc brakes

What I decided on:
Currie 9" (63.5" WMS to WMS), 3.5:1 with Eaton Truetrac and Explorer disc brakes. One of the earliest major setbacks in my original plan, was that the QA1 coilover setup required light duty spindles (even with HD brakes) due to the ball joints. No one makes an 8 lug spindle/hub for a 1/2 ton ball joint application. This triggered new wheels, spindles, rotors, etc. This also meant that the rear would need to change as well, oof. I looked at all of the possible fixes before deciding on biting the bullet for the Currie 9":

• New 5x5 wheels to match the old wheels (bought some and sent them back)
• 8 lug wheel adapters for the front (nope), 5 lug adapters for the rear (nope),
• Buying an 8 lug Dana 60 that I thought I could convert (nope, still sitting rebuilt in the backyard waiting to be resold)
• Looking for an old 5x5 12 bolt to rebuild (nope, looked for a month and couldn't find one locally)
• and I'm sure I am forgetting some...

For anyone else who may be doing this, here are the brake lines I ordered from

• Rockauto and Jegs:
• Parking brake cables - RAYBESTOS BC96022
• Outer flex hose - CENTRIC 15066321
• Center Section - Reuse old one for now
• Hardlines - Jegs 555-635822 NiCopp Brake Line [3/16 in. x 20 in.] (3/8" flare fitting)

There is also the need for C20 owners to replace the rear most universal joint with a 1330BC to 1350 conversion (and special 1.125" u-bolts). Strange Engineering makes them, as well as Neapco. I bought the Strange version from Jegs.

Starting Goal:
Drop 3" front and ~5" rear, no C-notch (for now)

What I decided on:
I ended up with the QA1 front adjustable coilovers and 2.5" CPP drop spindles (if you need to replace... always upgrade).

In the rear I went through the following iterations:

• Stock shocks/springs with lowering blocks (what the truck came with, it was all totally blown out)
• New stock shocks with HD 450lb 4" lowering springs (Came to learn that the stock rear shock location doesn't really work for controlling motion)
• DIY shock relocation (was planning to copy/buy the NLE design) with HD 450lb 4" lowering springs (Found that the trailing arm and high unsprung weight of these trucks means that you need a very light spring to keep the tires in contact with the road, and the layback of the shock would mean that you would get a digressive compression at full travel. A shock is meant to control motion in one direction, and is best able to do so when the impact is orthogonal to the shock- it is fine to deviate from this when you can control for the compression and rebound curve across the range of motion- but most the available shocks do not provide this info or design for it. Picking the right shock would always be a guessing game)
• QA1 rear coilover kit (Expensive and single adjustable ($1k), and I had already bought the low roll panhard bar with the rear end)
• NLE trailing arm setup with double adjustable coilovers (Didn't want to replace my trailing arms)

What I decided on:
You can see my thought process in this list as I learned more and began to think through my past MX-5 experiences, and also that my budget isn't huge. I had built a miata as a track car a number of years ago, and I began filtering the big heavy truck plan through that info. If I ever wanted to make this thing handle, I needed to reduce the unsprung weight (#1), have double adjustability for when the bed is empty/full, autocross, or drags, and have as much suspension travel as possible. I ended up with a DIY plan to use the stock arms with poly bushings, stitch weld reinforcements, and a general clean up. For the suspension, I have decided to go with engineering my own lower trailing arm mounts for the NLE spec'ed Viking double adjustable coilovers (C213w shock and 225 lb 12" spring), and use the upper mounts from the kit to piggy-back on the engineering that has already been done. This should work well with the NLE low roll panhard I have, and offer excellent control of the rear end.

Starting Goal:
Simplify and add lightness to gain performance

What I decided on:
So this is the old Lotus mantra, but it holds true. If you want to make something handle, but don't have technology (Camaro ZL-1 can handle and it is neither simple or light), make it lighter and work the best that it can.

Here is the list of lightness mods:

• Flow forged 18" wheels (24lbs) and 275/35/18 (~25lbs) tires Should save at least 30lbs of rotating and unsprung weight.
• Coilover mounted "upside down" to reduce unsprung weight
• Removal of excess brackets and installation of 3/8" - 24 bolts through empty rivet holes
• Changing from HO72 to lightweight (relatively) Currie 9" - I don't have a scale to weigh them, but I would guess over 100lbs difference
• Removal of the original coil springs - plan to add Firestone F9000 airbags to increase bed capacity
• No rear sway bar

[SkidmoreGarage]

Took a bit of a break yesterday and today. I did some "mockup" installation in the rear. Turns out that the 3/4 ton HD trailing arm is too thick for the NLE panhard rod mount by about 3/8".

I whipped the bracket through the band saw to cut it in half and practiced my mig by filling the big 'ol gap. Figured I'd share the pictures.

Also, feel free to offer any constructive feedback on the wall of text in my last post!

[SkidmoreGarage]

I have perfected my rivet removal technique with the plasma cutter! I have also been waiting on 3 wheels, brake lines, and suspension parts for the last week. A bunch of stuff is stuck in shipping limbo. I have one package that has been in transit for 11 days and has made 15 stops, and it has only made it to Nebraska. Another package has made 15 stops and it is still in Montana... I did get some parts though, and I have been keeping busy. I bought a Mr Heater Big Buddy propane heater for the garage. It is a life changer, so much more comfortable to work in the shop when you have heat. I think it will also enable me to paint the frame.

In the meantime, I have been mocking everything that I can. in preparation for mounting the coilovers. After I get everything mocked up, I will pull it all out again for paint.

I removed the extra brackets mounted to the frame, and removed the rear camper step bumper in preparation for the new bumper I bought a while ago. I also drained the 15 gallons of fuel that I left in the old tank, in preparation for removing it from the cab. I also pulled the driveshaft in preparation for a new carrier bearing to be installed.

I installed the rear end, NLE low roll panhard bar, upper coilover mounts, and Boyds Welding tank. Nothing too surprising was discovered during mockup. It was standard "aftermarket parts and c20" issues that needed problem solving. I bought Boyd's mounting kit. It is a quality part, if a little too fancy for the job. I welded the mounting bracket to the frame using some existing hole in the frame. I still need to make a filler. I plan to get a Dorman filler neck from summit and copy TA_C10's bed filler.

I also measured the track width front and rear, and ordered some spacers to square the wheels. I also used my patent-pending cardboard tire to ensure that I wouldn't have any interference. I needed exactly an inch on each side. I bought some billet bolt on spacers.

[1971Stepside]

Those wheels are perfect!

[MDPotter]

I like the approach you're taking with your build so far. Making it mechanically sound, new wheels, repair the rust, freshen up the interior, keep the paint. The seafoam green has really grown on me.

[TA_C10]

Originally Posted by SkidmoreGarage

I also used my patent-pending cardboard tire to ensure that I wouldn't have any interference.

LOL, I'm sure this will be accepted in no time by the patent office

Which dorman filler are you planning? Did you see my update on filler, it works! I'm happy with it going down between the bedsides, but just for FYI you could always get a filler neck that 90's so you could just go straight through the floor instead which might be easier.

[SkidmoreGarage]

I haven't picked a specific filler yet. Summit has some Dorman fillers that are obviously used by the aftermarket, even though they are vehicle specific. It is surprising how difficult it is to find the dimensions for oem parts. I went to my local Auto part stores to see what they had, they looked at me like I was crazy. They don't stock anything but 1000 of the wrong size belts, over priced batteries, and air fresheners. It's only a matter of time before everyone just orders from Rock Auto. The parts stores are happy to order things in, but if I have to wait and it will be overpriced and probably wrong, I'll just cut out the middle man and make the mistakes myself.

https://www.summitracing.com/parts/r...-243?rrec=true
https://www.summitracing.com/parts/rnb-577-948
https://www.summitracing.com/parts/oer-k94764

I'm really interested in finding one that is 45* bend right after the filler neck and then has an extension that is 2". I plan to use a locking modern gas cap, like a Jeep, and no filler door. Hopefully that makes sense. I will bolt it through the filler panel like what TA_c10 made (which I looked through your build thread and couldn't find, maybe the pictures got eaten? Stupid question, but do you still have a paper template to scan?

I also got my shocks in the mail. I spent part of this evening offering them up to design a bracket. Things are looking good. I'll need to get the coils on though to make sure they clear the tires, and then I'll start prototyping and welding. Trying not to overthink it...

[TA_C10]

Cool, maybe I can help then. Check out https://www.fillernecksupply.com/

They have it all. Any angle, and many styles. I ordered mine 2 years ago when I had a different plan, but I was determined not to waste money and use it . So if I had it to do over, a 45 degree straight down through floor would have made it a little easier. But, then you have to cut through bed support rails so take your pick on those designs.

But cool thing is they have the stock style with vent already attached and you can just pick a really nice cap from any place you want. And if you want recessed with stock style, you can't get their recessed 45 degree panel. Lots of options.

And last, I got all my gates hose and aluminum straight pipes from Amazon.

I look forward to seeing what you end up with!

[SkidmoreGarage]

Thanks for the link. I haven't made much movement on the filler setup, but I have done some more research, I haven't found anything that is exactly what I want and not overpriced. I may order the handful of stock fuel fillers I am thinking of to the local auto parts place to try out. I also may just hack something together with an old filler neck and some parts in the spares box in the meantime. The leading contender is this from a 70's FJ40.

I finally got all of the parts delivered (but my wheels are backordered until 1/15/21 , Jegs said that they would be shipped 12/15.. but they didn't process my order right away and I missed it. I will order from Summit from now on, way faster shipping). I was hoping to have it back on the ground before new years, oh well...

I mounted up one of my tires (275/35r18) and mocked up ride height on the front and the back, it looks good but I will go with a 285/40r18 next time. It really needs more sidewall. The tires I got were a good value and a place to start. I wanted to Continental ECS tires, but they are almost triple the cost. I got these NS-25s for $110/tire. So $1140/set versus $440/set.

The 1" spacers I ordered were perfect to make the tires square, and make the tires fit in the wheel well.

Also, the OEM brake parts I listed above fit the Currie 9" and stock C10 perfectly, so if anyone else reads this in the future- you can order those from rockauto. You (I) will need a new brake tee fitting to adapt from the 7/16 stock line to the 3/8 - 24 for the flex lines.The parking brake cables also slotted in perfectly to the C10 parking brake cable junction. The housing may be 2" too long, but I have a plan to route it out of the way.

[SkidmoreGarage]

As part of mocking everything up, I went to measure the pinion angle with the flipped trailing arm brackets and the lowered ride height... I was expecting it to be perfect. It was off by 4*! I cursed and started researching shims, but reason prevailed and I pulled everything apart.

I flipped the trailing arm brackets back to the stock orientation, and found that the pinion angle is perfect that way. Currie must make these axles assuming that people drop their trucks. Crisis averted, but I wasted the effort of removing the rivets, flipping the brackets, and then taking everything out twice. Oh well, all's well that ends well.

As part of pulling the driveshaft to check the pinion angle, I also planned to replace the carrier bearing and clean the U-joints. I have the old style stud mount. I saw a lot of discussion about switching to a one-piece or the later "girdle" type carrier bearing. Both of these required a new driveshaft. I'll wait for an LS swap before worrying about a new driveshaft. The replacement Timken bearing carrier was only $17. I gave it a shot of hammertone paint to hopefully delay the crust-ification. I haven't installed it yet, but the old parts came apart really easily considering they are probably original. If you are doing this job, remember to mark all of the matching ends with a paint pen to assemble it the same orientation for balancing. I also got my new 1350 to 1330BC U-joint to install before going back in.

[SkidmoreGarage]

Now for the DIY rear coilover setup. I finally finished my rear coilover mounts for the Viking coilovers I ordered.

Here are the details for anyone who may be interested:
I wanted to use an adjustable lower mount as a frame "Z" may be in my future (I will not C-notch the frame, I measured and I would get at most .5-1" of additional travel before hitting the bed- so it isn't worth the hassle). I also wanted to be able to adjust my drop without using only the coilover spring preload.

I looked into what I thought may work and settled on a design that would mount the lower mount in double shear, rather than single shear, and have adjustability up or down if I ever need to make a change (or I get it wrong the first time!). This is my first C10 rodeo...

For the design, I would use .250 wall 4" box section to box the trailing arm, and weld on a universal axle tube bracket for the lower coilover mounts:
Like this


The tricky part was that there are a lot of angles involved in getting the mount, trailing arm, and coilover to not bind and not have interference while maximizing shock travel (I managed 10" of axle travel). I spent a lot of time measuring at all of the possible ride heights and throughout full articulation, checking for tire clearance, eyeballing shock angles, test fitting, and starting over. It all ended up working really well, but there are some compound angles and tight clearances required to make it all work. The c-channel is level, the shock mount has a 30* layback and a 5* tilt. The first mount took a day of fiddling, the second took an afternoon including finish welding both parts. .250 wall steel is no joke, it takes a lot of time to cut and shape. I was very thankful for my little bandsaw to make the major cuts. For welding, I used a MIG and I did a root pass and a finish pass on my welds to give the bracket as much strength as possible.

Fun fact, a lot of folks will tell you that the trailing arm setup doesn't twist due to the solid axle and the panhard bar. They use this to justify why you don't need any flex in your trailing arm bushings. I measured the rotation of each trailing arm at +/- 4* before binding. This doesn't sound like a lot, but it is significant.

I have tacked the mounts into place, but it is late and I want to do it right, which means cutting the tacks off to use some weld-through primer under the mounts before finish welding. I'll get the final pictures of the welded mounts tomorrow. The ones here are just the root pass.

[SkidmoreGarage]

More Pictures

[MDPotter]

I can tell that you've got a lot of time invested into the rear end of this truck. It will definitely be a solid performance rear end when you're done!

[TA_C10]

Coilovers will be nice. When you measured the flex in trailing arm are you running rubber or poly bushings? Would this make much difference?

[SkidmoreGarage]

@mdpotter, thanks. It has taken longer than I expected but it finally has some momentum. I just have to make up the rear brake lines and I can take it all apart again for clean up and paint.

@TA I was using poly bushings. I can imagine that rubber could flex more, but there may be some mechanical interference that stops articulation beyond what I measured.

I didn't make it into the garage yesterday and I'm heading out of town until Thursday, so progress updates will wait for xmas. Something annoying I've discovered is that the Currie axle has the brake line brackets too high up on the axle tube. This causes the brake line and fitting to contact the frame at full compression. The tabs are welded at the exact same angle, so I think their jig must be off. I am really not excited to cut them off and reweld.

[Wiekser]

I like the way u used that bracket. Looks great.

btw. what is the wheel brand/type u are using?

[SkidmoreGarage]

Wheels are American Racing vn510 18x10 0 offset (5.5" backspace).