Disk brake upgarde

[GMCRanchTruck]

Hey all, I need some help understanding something. I want to add front disk brakes to my 1970 C20, but I want to keep the 8 lug bolt pattern on the rotors. I can find spindles for the C20 that fit a 71, but not for a 70. Is there any reason the 71 spindle would not simply bolt on my 70 C20?

Keep in mind, everything I am seeing for the 1970 disk brake is a conversion kit to bring it to a 5 or 6 lug bolt pattern.

Thanks for any help with this.

[lolife99]

The 71-72 balljoints and outer tie rods are larger.
That's why its not a direct bolt on.

[k2rm]

This is the kit I used for my C20
https://www.performanceonline.com/19...-8-Lug-Deluxe/

[rpmerf]

I'm working on this currently. 70 C20. I'll share the info later tonight. Basically the same as a c10, but c20s use larger spindles, and are harder to find.

[rpmerf]

You have a couple options.

The easiest options would be to talk to one of the vendors and get a conversion kit.

The next options would be to piece everything together. This is going to be the option I am going to be going into detail on.

I found a 1982 C20 with no engine or transmission to pull the front suspension from.

I am using rock auto for as many replacement parts as possible. You can get everything here except spindles, center link or conversion spindles, and the prop valve.

Spindles
The main piece you need is the spindles. Everything centers around these. They will need to come form a 71-87 pickup. I think this goes up to 91 for suburbans. You have a couple of different options here.
Junkyard. Not fun, you can get them for cheap.
Parts truck.
CPP - $275 for the pair. http://www.classicperform.com/Chevy-Truck.htm#11

Ball joints
You need to match the ball joints to the spindles. You need to use the 71-87 ball joints. These will fit in your control arms. I would do the control arm bushings at the same time.

Tie Rods
The outers will match the knuckle. 71-87. The thread on these tie rods is different so you will have to make a choice here. Use your 70 center link with 70 inner tie rods, and conversion sleeves OR use a 71-87 center link and inner tie rods

Pitman Arm
your 70 pitman arm will bolt up to a 71-87 tie rod end, if you wish to go that route.

Idler arm
Idler arm was the same 67-82. It changed in 83. Match your idler arm to the center link.

Rotors, Pad, Calipers, Master
71-80 they used 1 system (I believe). In 81 they switched to 2 systems. JB6 and JB7. JB7 was the heavy duty system. It is easy to identify because of the metal master cylinder. I can't remember all of the detail. The truck I got everything from had JB7 stuff so that is what I am using. I am not sure if you can use the JB7 parts on 71-79 spindles. I believe you can, but I haven't looked into it. Either way, I would order all of the parts for the same year to make sure they are compatible.

Got to pick up the kid from the bus stop. Will post more info later.

[GMCRanchTruck]

Thank you guys for all the quick info. I had planned on replacing the ball joints and tie rods anyway with the newer 73 and up version, so it sounds like I should not have an issue with the 71 spindle at all. Thanks for all the quick detailed responses.

rpmerf I still would like to hear how things went when you are all done.

[rpmerf]

Part 2.

While you are in there, you might want to switch to a 73-87 steering box as they will be 3.5 turns vs the stock 4.5 turns. Might be a good time to do your sway bar bushings and shocks too.

control arms
Control arms should be the same 67-87 from what I've heard.

wheel bearings
Match the spindle. Might do the washer, nut, and cover also.

prop valve and brake lines
Not sure if it was the same through all of 71-87. My 82 had the prop valve in front of the engine. Flex lines went through the frame in front of the control arms. Line to the back went down the passenger side of the frame. I plan to copy this setup with all new lines.

booster
I am using my 1970 dual diaphram booster. Just replaced it about a year ago, so that helped my descision. You can use the 73-87 booster, but the bracketry and linkage is different.

I wanted everything to be as factory as possible. The knuckles, ball joints, tie rod ends, idler arm, center link, calipers, pads, rotors, bearings, flex lines, prop valve, hard lines will all be the same as what came on that 82 truck. No conversion parts or part numbers to remember. The only oddball will be the 1970 pitman arm on a Lars 3 turn steering box.

You might have you done before me. I got the parts off the 82, but still need to order all the wear items from Rock Auto.

If you are using 71 knuckles, I would try to order everything for a 71 to keep it consistent.

Be aware of brake line sizes. It is a bit different for at least my 82. I will have to check my notes. The 70 has a tee for the front brakes. The 82 has separate lines for left and right.

[Steeveedee]

If you can find a later model truck in a wrecking yard, you can just gank all the parts you need for the entire swap. You'll get everything you need in one shot. You might need to rebuild or replace the master cylinder,or maybe rebuild or replace the calipers. If you've never been into a truck this deeply, that would be a problem.