Converting '67 Chevy C20 Power Brakes to '71 GMC Disk

[DJ_Baar]

Thanks for add to group.
I just picked up a 1967 Chevy C20 LB Camper Special. Only thing not original is 350 replaced 327. Seller provided most everything from '71 GMC front disk brakes he got, (told me same 3/4 ton 8 lug, but 5/8" lugs vice 1/2" and wheels still fit). Anyone do this conversion before or similar & have some constructive advice? And any difference with brake parts other than number of lugs & pattern between C20 & C10? I didn't see any difference in parts catalogs I looked at.

[old Chevy guy]

Studs are actually 9/16 I believe not 5/8. Not sure what parts you have but it will work but you will need different ball joints ,71-72 that should fit your a arms but the stud that goes through the spindle is bigger. You will need to change your flex hoses,master cylinder and brake booster. All need to be 71-72. Also very important is you need to switch the proportioning block to the 71/72 type. The older drum style are distribution blocks newer are proportion blocks. Make sure you have everything before you start.

[old Chevy guy]

Oh and welcome to the forum! Post some pictures of your truck!

[DJ_Baar]

Thank you for feedback old Chevy guy & here are some pictures to include all the parts I got with truck (more were in cab). I also did an intro post this morning to all with more pictures and story.

[notsolo]

Welcome, Good looking truck, in the past I have found a complete front cross member from a donor truck is a good option, 1972 and up would have disk's. Get all of the parts Hub to Hub Booster and MC etc. You may have it all right there, Hard to say what the parts came from unless the PO documented it well. Lay it all out get some more photo's posted and see if you can get some one to chime in on what you have and or need to make it work.

[DJ_Baar]

Going by the Seller's word, but he has been straight with me so far, and he has me for reference on Harley I traded for with him.... I agree, I slide a complete cross member into my '53 Chevy PU, but most is looks here. I am looking for things needed replaced or simply need for conversion now (new ball joints, tie rod ends, proportioning valve, and flex lines). This site had a GREAT reference for the conversion too.

[DJ_Baar]

Ran into problems with tie rod ends & connecting sleeve. Supposed to just use ball joints and outer tie rod ends to match the spindles, but problems with thickness of tie rod ends AND the threads - ended-up with two RH threads and sleaves are RH & LH threads, also one 5/8 & later is 11/16. Friend at AZ actually found post here (http://67-72chevytrucks.com/vboard/s...d.php?t=332740 and http://67-72chevytrucks.com/vboard/s...d.php?t=328438 ) that addresses problem, and hooked me up with parts to fit '73 for inner, outer, & sleeve look like they will work fine.
Any feedback is appreciated.

R/
DJ

[DJ_Baar]

More GREAT links for reference:
http://67-72chevytrucks.com/vboard/s...ad.php?t=13692
http://67-72chevytrucks.com/vboard/s...d.php?t=368382

[DJ_Baar]

I swapped 71 GMC C20 disc brakes onto my 67 w/factory power steering & didn't need tie-rod adapters. Ball joints match year of spindles (71) along with A-arms, and I used post-73 inner/outer tie-rods, drag link, and the stock, original 67 pitman & idler arms. (AutoZone parts: ES409R & ES409L for tie rod ends, and ES2004S for adjustment sleeve.) Pictures to follow after I get 'er all back together with disk brakes in place.

[DJ_Baar]

Problems with Control (A) Arm shaft bushings & ball joints.
Got replacement shafts & bushings from LMC and just not happy with Falcon steering & suspension products. I could NOT get the bushings to seat correctly and galled the A-arms to point I went back to originals I had to include upper A-arm shafts and bushings. (They were low on mileage and STILL better than new parts I received - to include the seals. I just thought I would replace all parts while I did this conversion.)
Then the upper ball joint came with "cheap' hardware, (after getting a miss-boxed wrong ball joint). Sheared the bolts when torqueing to spec per manual. Then used grade eight and found out not same as case hardened and sheared those. So looked-up torque for bolts on internet - and a 5/16 inch bolt is recommended at 20 foot pounds. Manual had me going for 45 - no wonder some sheared at 35! Finally torqued to 25 and used red Locktight. (Bolts replaced the rivets used originally - four each upper ball joint.)
I returned tie rod ends & sleeves I got from LMC and worked-out correct ones from 73 that fit and should work well. More pictures to follow as I get this all back together. Any feedback is constructive appreciated.

R/
DJ

[DJ_Baar]

Got the disk brakes installed today - working bugs out of steering - will finish tomorrow.

[DJ_Baar]

Got the wheels on, steering all connected.

Still trying to find torque spec for power steering control valve & cylinder ball stud nuts, (another post). And adjustments to routing power steering lines, but have to get this rewired first so I can get the engine running again and bleed power steering.

And still need to install new brake lines and then bleed that system with new CPP master cylinder & booster. But thought time for an update on this project.

(Inner fenders removed because have to take out right side to rebuild heater & HVAC.)

R/
DJ

[projectking]

Where did you get the brake hoses from?

[DJ_Baar]

Got a complete steel brake line kit from Brothers and rubber brake hose set for "71 from LMC.

DJ

[projectking]

Originally Posted by DJ_Baar

Got a complete steel brake line kit from Brothers and rubber brake hose set for "71 from LMC.

DJ

Thanks, lmk how they fit. I'm looking for a set of hoses for my C3500 GMC that I've converted to disk.

[DJ_Baar]

Hope to get them on tomorrow. Will provide more pix as it goes.
(Must have spent an hour looking for 'em --- its been a while since I started & planned this project --- finally found where I looked a few times earlier --- ain't getting old grand?)

DJ

[projectking]

I've read enough about the brake hose choices to be confused, thanks for your help!

[Oregon 1967 GMC]

Looking pretty good there DJ Baar. I'm doing the same and using CPP parts. Wow, original air! That truck has some serious potential. Here's where I'm at and I'll be checking in with you. You gotta love the small window '67s!

[DJ_Baar]

Looking GREAT Oregon 1967 GMC!
I'm a bit stuck with factory power steering (assist). The stud nut thru pitman arm in this picture. It like all other castellated nuts have a cotter pint - but how tight should I make this nut and same for one with power cylinder?
I just replaced all that since leaking in multiple places and having gotten this far, want to get this last couple critical steering attach points installed correctly. (Have a separate post with same question, but no replies.)

[Oregon 1967 GMC]

I use a Haynes repair manual but it's at my friends shop with the truck right now. What I might do is just snug it down and then tighten to fit the cotter pin. I don't recommend but I do a lot of German torque myself "GUTENTEIT!" Just make sure it's not going to come off and if it feels too tight or that it might strip it probably will. If you take it to a shop for alignment etc., you can always ask them to check the torque if you're concerned about it.

[DJ_Baar]

I have both the Factory Chevrolet Truck Chassis Manual & Overhaul Manuals, & Factory Assembly Manual, & Haynes, etc.... Breaks down rebuilding both control valve & cylinder - but only "...reversing the removal procedure" for installation back in truck, WTHO? In one word "Frustrating."

http://tech.corvettecentral.com/.../...2-corvette.../ But only explains "The castellated nut is tightened, with an additional half turn until the cotter pin hole is lined up."

It can't be too much torque, (like tie rod ball stud nuts @ 45 FT LBS). I don't get why I can't find anything more specific to those two critical attach points. There should be some available information more definitive than that for critical steering components (control valve to pitman arm - really)?!

* I'm thinking of tightening castellated nuts in question to point that cotter pins clear, should feel good and snug, but not too tight?

Yes I have the "Goodentight" wrench built into my elbow & forearms too. But also remember breaking things due to over tightening - though I am older (not necessarily wiser) LoL!

[Oregon 1967 GMC]

I hear you DJ and you're right it should be emphasized or at least noted! My haynes has a standard chart for certain sizes, it's too bad it's not noted. I'll be in the same boat within a week so I'll be checking my factory manuals etc when I get out to beautiful Sandy, Orygun. I'll post when I get back if I find out something.

[DJ_Baar]

Nice shop! I have a decent place here in New Orleans area with garage, workshop, & lots of concrete (plus yard for wife to do her thing) - can't complain - it does no good - Ha.

[DJ_Baar]

Have similar issues today - WoW!

http://67-72chevytrucks.com/vboard/s...d.php?t=652234

[projectking]

Sorry to hear that, I'll pick up the set from brothers and report back.