putting 71-72 brakes on a 68?

[gcburdic]

68....asked this question awhile back....see if this thread helps any....http://67-72chevytrucks.com/vboard/s...d.php?t=381785

[sixtyeightchevykid]

ok so i would also have to get new ball joints for a 73+. now all i have to do is find a 73 and up parts to do this

[seekhunt]

I put the complete crossmember from a 76 1/2 ton onto my 67 1/2 ton. I used the master and proportioning valve from the 76. You need to increase the bore of the rear wheel brake cylinders to the 1 1/16 variety or your rear tires when braking will lock up too easy in the wet. The inner tie rod end is from an 89 3/4 ton. Have the machine shop knock about 1 1/4 inches of thread off (That'll leave you with about 5 inches to the good).
So that being said, now you have 5 bolt lugnut pattern up front and 6 bolts on the rear. So for the rear I used a 3 series diff housing from the mid 70's or 80's so I dont have to run around with 2 spare tires. Weld new spring purchases in new locations. Pete

[SCOTI]

Originally Posted by seekhunt

I put the complete crossmember from a 76 1/2 ton onto my 67 1/2 ton. I used the master and proportioning valve from the 76. You need to increase the bore of the rear wheel brake cylinders to the 1 1/16 variety or your rear tires when braking will lock up too easy in the wet. The inner tie rod end is from an 89 3/4 ton. Have the machine shop knock about 1 1/4 inches of thread off (That'll leave you with about 5 inches to the good).
So that being said, now you have 5 bolt lugnut pattern up front and 6 bolts on the rear. So for the rear I used a 3 series diff housing from the mid 70's or 80's so I dont have to run around with 2 spare tires. Weld new spring purchases in new locations. Pete

It's not an absolute on the rear brake cylinder size. Larger diameter wheel/tire combo's possibly won't see the same issue. I did the post-73 suspension/brake swap to my 68 (using the original 68 c.member) & did not have issues w/lock-up using 29" tall tires. I used a master cyl & power booster for a 71-72. All the brake lines were post-73 up to the OE union under the pass side of the cab. From that union back it was OE 68 lines/cylinders.

[seekhunt]

Thats a good point. Its totally dependent on your situation, and as with anything, do a lot of reading and research so you dont have to completely reinvent the wheel every time you come up with something you'd like to do. Us older guys have been through many projects, and its important to just take it all in, and then just do what you were going to do anyway!

[63chevyll]

Originally Posted by cpetersen

Nah, I wouldn't. Just replace the wore out stuff. Makes a big differance changing the balljoints. I just had something funny happen, the only thing I didn't replace was the steering gear, i took it off and cleaned and painted it. Guess what now it is leaking. lol. I suppose I will get one of those quick ratio boxes.

who makes Quick ratio boxes for these trucks?

[63chevyll]

humm, i thought the frames were narowwer on the 72-older trucks.

And ive been using the orig crossmembers from 72

[SCOTI]

Originally Posted by 63chevyll

who makes Quick ratio boxes for these trucks?

Google AGR or try Flaming River.

thought the frames were narowwer on the 72-older trucks.

And ive been using the orig crossmembers from 72

Same frame width & basic orientation from 63-73. Front c.members will swap from 63-87.

[SIXT8LOU]

Originally Posted by cpetersen

Also make sure you use the 72 centerlink. You will also need to move the brake hose hold downs to the otherside of the subframe. I also used the master, pro valve and booster off of the 72. You will also need to change all of the front brake hardlines also. Its always a goodtime to change them since it is all apart. I think you will need to change the tie-rod ends too. When i converted mine. I rebuilt the whole frontend. I parted my 72 and put all the mechanicals into the 68.Attachment 582075

how do you change the hold downs for the brake lines??? iam doing the same swap,,,,, move them from back(68) to front(72)...... and do i have to change the hard lines?? or are they different size???thanks...

[cpetersen]

I drilled the weld hole out and bolted it on to the otherside. If i remember right the hole was already there. Yes you will need to change the lines they are larger. I just bought a set from LMC. I had to redo the passenger side line. It was to far inside the frame rail i couldn't use my headers. It would have boiled the brake fluid. So i ran the new line in front of the motor mount. Then run it over the sub. I'm getting ready to run rear disc next.

[sixtyeightchevykid]

again sorry its been a while, i found a 73 what i and going to get the parts off of tomorrow if it doesnt rain, i got the spindles and rotors the other day and cleaned them up and painted the spindles, going to grab the calipers, master cylinder, booster, proportioning valve, hard lines, tie rods ends, center link, and maybe the rims,.
im going to get new ball joints and wheel bearings, ill try tokeep you guys updated a little beter from now on, also im getting a rearend out of a 71 or 72, so that i can keep the rear coils and go with the matching 5 lug, and something a little better than 4.11 gears lol