70 C30 disk brake conversion

[JennCat]

I could use some advise, (probably lots of it) concerning the disk brake conversion on this truck.[IMG][/IMG]

I bought this truck from an owner in Oklahoma and had it towed to Kansas. After fussing with it for a while I gave up, sold it to my friend and left for a while. Upon returning (months later) he still had it sitting where it was last parked, doing nothing. So, I'm going to try again. I bought it back from him (he hadn't even transferred the title) and with a new outlook, I am going to go forward with a build.

Some history.
This truck belonged to a fire company (hence the decals) and once hauled a supplemental reservoir. For most of its life it has sat inside a bay at the fire station waiting for something to happen. Consequently, it has very little rust. That was my main objective for finding a project truck, little or no rust. This is it.
Additionally it has a 350/4bbl which starts and runs with no trouble whatsoever. I have every reason to believe the truck is entirely stock with the exception of the flat bed. I also have every reason to believe that because of its life at the station, the odometer has not been tripped, though I don't know how to confirm that.

Another reason I think the odometer hasn't been tripped is that it still has the SM465 which as you all know, doesn't allow one to put alotta miles on a truck very quickly. Had the transmission been an automatic, I might question that.

However, after years of sitting indoors at the station, it was eventually auctioned and served as a farm truck, hauling hay and miscellaneous items, rarely leaving the field. Again, this old truck is in great condition considering the circumstances. The circumstance I am referring to is the fact that this truck had been sitting in a field when a brush fire swept over it.

And though it may not be clear in the picture, it did sustain some superficial damage. Wiring harnesses are partially melted, hoses, rubber and plastic show signs of heat and inside the cab was coated with blackened residue. Also, the windshield is cracked from the heat. So that was when it was sold and I acquired in that condition.

These things are minor (from my own POV) as there is very little rust and it runs great.

However as you all know, a 1970 stock C30 is not easily streetable unless daddy owns stock in the Exxon/Mobile Corporation. Mine doesn't.

So there are many things needing done. The body parts and engine I have under control. But drive train and suspension are a mystery to me. I am planning on putting an NV4500 into it and changing out the drums to disk.
This is where I will have a ton of questions. Though I have read through the forums here and elsewhere, there are many differing opinions and various methods of accomplishing the things I plan to do. In fact, there is so much varied info that it’s difficult to sort into a unified collection of data pertinent to my specific application.

So here’s where I am presently. I have the body work and engine under control for now. And I might even manage the trans swap with a little guidance. But information on the disk brake conversion is driving me nutz.

Questions on the conversion:
1) I have read that a full front end from any 73-87 Suburban is pretty much a direct bolt on. Is this correct?

2) My truck is a dually. I have recently replaced the 2 piece rims with one piece steel wheels. While the front wheels were off, I took note of the drum configuration and the extension which has the 8 lug studs. Since the Suburban is not a dually, is it the case that I will have to order new rotors (for the disk brake conversion) which have the extension for accepting the dually rims?

3) I am (once again) in quest of a donor truck. Am I restricted to a Suburban for the disk brake conversion or is it possible to use something like a 72, ¾ ton pick-up?

I have many more questions concerning this but to keep the information straight, I am limiting my questions to these.
Thank you for any advice offered. It is appreciated.

[airdale94]

I think what you want is a 73-87 1 ton dually front end not a Sub. or a C20.

[71Dually]

Greetings JennCat,

Great looking hauler you got there, welcome to the 1-Ton Fun Club. Please share some more details and pics, love to hear more.

As airdale94 says if you want to retain dually front hubs stay away from the Suburbans and C20's. I'm putting together something for you that's pretty extensive regarding donor vehicles and what parts to use for your front disc brake conversion.

Meanwhile, heres a link to an interesting writeup on an upgrade to your obsolete Eaton rear brakes you may also want to consider. Those parts can be found on the same vehicles that have your front brakes.

http://67-72chevytrucks.com/vboard/s...d.php?t=536119

There are lots of write ups for disc brake conversions in the forum you may want to read. I've read many of them and they helped tremendously to garner the knowledge I have today regarding the JB8 brake swap. Lots of GMPartswiki catalog parts cross reference research helped too. I want to do one on my '71 C30 and I'm currently gathering the parts for it.

Search for them in the search box above. I believe with your 1970 you need to swap upper and lower control arms to 1971 and later arms in order to use the later disc brake spindles due to ball joint size differences so look for some of that info also.

I'll post a proper reply regarding the 67-72 C30 dually specific JB8 conversion (including front discs) posted later this afternoon. With the exception of the control arm swap it hopefully will cover everything you ever wanted to know about the bolt in factory part conversion.

Here's a opportunistic plug of my big little beast with a couple recent pics from August 1st.
We were out picking up new lumber to redo the stake bed floor.

No prefab LMC kit available here folks, we had to visit the real lumber yard for our bed wood.

[JennCat]

Wow, thanks for the information. And 71Dually: nice one ton. I do hope to retain the dually front suspension and also have been wondering about the differential. At this point I'm guessing Eaton;
I'll post more pics when I get my truck back, its getting new glass right now. Hope to have it back soon.
I'm going to have to rebuild (at least) the front brakes until I find a donor then I think transmission is next. Meanwhile I plan on gutting the cab and cleanin' it up a bit. Probably be a little while before any noticeable cosmetic work get done . Right now, I just want 'er back on the road. Hope I posted this in the right place. I'll have a look at the link. Thanks again.

[Junkpyl]

Any updates on the Jb8 conversion? I started this on my 72 C30 dually with some Bell tech drop spindles but my new calipers don't fit. I sourced jb8 calipers for an 82 Chevy so they should have worked??? Problem is the retainer and spring clip that go between the slide surface and the caliper would not fit. Any suggestions? Returned the calipers and will order another set from a different supplier.

[Aruba1]

I used the front end and rear end of a 1989 C3500. It fit like a glove but I had to reposition the leaf spring perches and also replaced the front driver side hard brake line. For some reason it was not the same thread size as the C3500-specific soft line. And while at it I also upgraded the HD/longer front springs and added SuperSprings on the rear. Of course she wears 19.5" all around. The truck is a beast and rides great, loaded or unloaded.

[SCOTI]

Originally Posted by Aruba1

I used the front end and rear end of a 1989 C3500. It fit like a glove but I had to reposition the leaf spring perches and also replaced the front driver side hard brake line. For some reason it was not the same thread size as the C3500-specific soft line. And while at it I also upgraded the HD/longer front springs and added SuperSprings on the rear. Of course she wears 19.5" all around. The truck is a beast and rides great, loaded or unloaded.

Crew cab '89 C3500? There's a difference just to make sure others are aware.

[Aruba1]

Originally Posted by SCOTI

Crew cab '89 C3500? There's a difference just to make sure others are aware.

Yes, it was a crew cab!

[SCOTI]

Originally Posted by Aruba1

Yes, it was a crew cab!

Yep..... 73-87 1-ton or thru 91 'if' it's a crew-cab. 73-80 are a closer match if one wants to avoid the metric hardware.