Yes. . . Another Disk Brake Conversion Question

[michael bustamante]

ok now that rear end has been lowered and bagged (yay!) I started ripping apart my front end to install some 72 disk brake assemblies, (upper and lower control arms with zirk fittings and new bushing and ball joints) ok now I knowI gotta swap out some brake lines but which ones? the rubber ones only or the hard line from the "t" next to the driver side assy or all the way to the prop valve? (which is getting swapped out as well. Disk /drum.
Also I know tie rod ends and sleeves need to be swapped with 73-87 swap but what about in my situation? (1972 disk brakes)
One other thing 73 up lower control arms. . . are they wider? or or the heavy half lca`s wider? The reason Im asking is I was given a set of these and I dont know for sure why the lower control arms are so much wider where they bolt to the crossmember. Should I use these instead?

[michael bustamante]

nobody huh?

[oldblue1968chevy]

hard lines need to be same diameter as 71-72, rubber needs to be swapped out too..

tierods need to be swapped to 71-72 style also, you will need to swap all the steering components (pitman arm to idler arm) its best if you have a whole parts truck.


If you dont understand what im saying, which I may not be using the right terms, somebody else will post up and explain more. I will help all I can though.

[BADPURPLE70CHEVY]

I am doing the same thing right now on my 70 chevy. I am using the front spindles off a 72 chevy and i have the drag link and new upper and lower ball joints. Also have rotors and new calipers. For the rear i got the whole rear end out of a 71 chevy. I am just switching out the axles and drums. Do you have to change the master cylinder out? I dont have a prop valve yet. Is that needed?

[michael bustamante]

yes you need to definatly change the prop valve. other wise the front end wont ever work right.
So you think Id be better off changing out the whole steering rack then?

[oldblue1968chevy]

ive heard you shouldnt switch out just the axles..something about the rearends longer..but if you have the right 70 rearend (2diff. lengths) that it'll work..

so be leary of the rearend

[oldblue1968chevy]

steering rack you mean?...


those bars and all those funny joints,YES thats what i did then i replaced tierod ends (went to the store and bought 71/72 tierod ends

[BADPURPLE70CHEVY]

Do i have to put on a booster? Also i have a prop valve but you say get one for a 71-72. My prop valve is original 70 model.

[john]

Originally Posted by BADPURPLE70CHEVY

Do i have to put on a booster? Also i have a prop valve but you say get one for a 71-72. My prop valve is original 70 model.

The 1970 had a disrtrubition valve for drum brakes. Disc brakes had a prop valve to proportion front disc to rear drum braking.

[bigguy69]

no i dont think you need a booster, but you will need a mc and prop valve for a disc drum truck. if you keep drums on the back.

[BADPURPLE70CHEVY]

Thanks, one more thing. I was told all i would need is the drag link for the front besides what i have which includes rotors,new pads,new upper and lower ball joints,my 72 spindles. Is that it?

[oldblue1968chevy]

you need top/bottom balljoints

i put new rotors pads bearings on also...used orig. calipers..

I do not know what a 'drag link' is, so i cannot answer that ?

[michael bustamante]

its the center link i think is what hes talking about. From what Ive read if you keep the center link you need to order the sleeves inbetween the center link and the tie rod ends from cpp. (2 different threads I guess) ok once again for brake lines. do I replace everything in the front brake lines from the prop valve down or fust from the "t"?

[SCOTI]

The lines are slightly different between disc & drum set-ups so you will need the right disc brake lines from the master to the crossmeber 't' union (don't forget rubber flex lines while you're swapping in fresh stuff). As was mentioned, you also need the correct disc brake prop valve vs. re-using the old drum distribution valve.

[lolife99]

You need to get your new M/C and porportioning valve first, Then I believe you will have to adapt the rear line to fit, and change the line down to the "T" on the crossmember. It's mainly a "make it fit" requirement,... not a disc/drum necessity.
The disc porportioning valve is "plumbed" differently than the distribution block on your drum brake set up.
I would also purchase new rubber brake hoses.

Look at member 72BlckButy's Project "Blank Slate",... for the before and after pics of his disc brake swap.

[lolife99]

Man,... SCOTI,... I type too slow.
Sorry for the duplicate post.

[MikeB]

The attached file may help a little. The 69 column should read 67-70.

Center link is different. Pitman arm and idler arms are the same, at least that's true on the 69 and 71-72 power steering trucks. However, manual steering trucks used a smaller Pitman arm than power steering trucks.

[SCOTI]

Hey MikeB.... Haven't seen you on in a while. Hope the world is treating you well neighbor.

[MikeB]

Originally Posted by SCOTI

Hey MikeB.... Haven't seen you on in a while. Hope the world is treating you well neighbor.

I hate to admit it's been so long that I don't remember you or your truck. Then again, I'm over 60 now!

[michael bustamante]

whod`a thunk a simple conversion would be so complex! Ok well I converted to power steering a long time ago (changed pitman) so Ill need to swap out the center link, tie rod ends, and sleeves to accept the 72 hubs and upper and lower control arms. got it.
swap front lines and retrofit the rear lines to the new prop valve, got it. ok guys any other tips?
oh and scoti, Great thread about modifying the rear shock brackets. I followed your instructions and they worked great.

[SCOTI]

Easy as cake no? And you now have $70 extra toward that disc brake swap!

[C20-67_N_MO]

WOW!

You guys are very detailed explaining these things.

As I will be doing a total swap on my braking system with 1-ton drum cylinders on mine and discs on the front-end.

Thanks,

-Scott-

[profe56]

are the pitman and idler arm 67-72 the same for c10 w/power stering?
and 73-87 are the same for 67-72?because I did disc brake conversion in a C10 69 from a 73-87 but the iner tie rod is 5/8 and outer tie rod is 11/16, I know there are custom sleeves but if I change the center link from a 73-87, ider and pitman arm will fit on it.

[michael bustamante]

ok I dont get it now. I did the conversion to my 72 hubs and control arms over the weekend and my tie rod ends went right into the hubs. I think the tie rods will have to adjusted a little out, and of course I havent driven it yet but I cant see why the steering rack has to be replaced. The pitman was already replaced when I converted to power steeering but other than that???

[texanidiot25]

Are the tie rod ends correct? They'll go into the spindle, but the taper of the end won't fit tight.

You can run the drump distrubution block just fine. Haven't had the down time needed to swap the MC and redo my hard lines. but on the drum MC and block, The truck stops damn hard. My job is driving the truck (delivery), and there is no shortage of stopping power in any event. Better brakes than what I had in my '90 Firebird by far.

Not saying it's right, but it ain't weak or terrible by any means. The only tendency it has is to lock the rears if you simply stomp hard. But gradual braking and this truck hunkers to a stop with no drama.