Disc brake conversion

[GMCJON]

Allright, I got a few questions on converting my closed knuckle Dana 44 to an open knuckle disc in my 67 GMC. As far as I know the donor axle from a 71 burb is the same length and all of the current axle in my truck. The big question is if I mount a 71 era PS box onto the frame of my 67, doesnt it require some type of shimming to make the box even with the frame? Has anyone out there done this and know the best way to do it? Thanks.

[Beast388]

Send a PM to Pont. He has done this sort of swap on his '67 Chevy.

[breeh]

Several companies sell kits to do this including GMC Paul. I have done it on my 68 and it works fine.

[Scrub]

I have been saving threads off the Chevy board on Power steering conversion, Here it is. It is directed more to a 2wd, but you get the point


From 68 to 72 the steering box is the same for both 2wd and 4wd unless you had a 396 or 400. after 72 there where different boxes for 2WD and 4WD. You will need a 2wd on the later boxes. The Pitman arm on the powerbox has a larger spline than the manual box, so you need a new (or different) pitman arm than what's on your truck now. The piece that attaches the steering-box to the steering column (I call it a flex-disc some call it a rag joint) has a spline on one end (this goes on the steering-box) and 2 bolts on the other end, with a piece of rubber in the middle that looks like it is made out of a cut tire. The spline on this flex-disc is larger for a power-box than a manual box, (sometimes) so you need one of these too. Other than that, everything should fit.
I did this conversion last month on a 70 GMC 2wd, but I used a new steering-box. Evidently some 67 and or 68 frames don't have an indent that causes part of the box to hit the frame so sometimes you must shim the box out with washers or custom shims. Below you will see that chevyman beat on the frame until he had a proper indent.


Jay wrote
I put a 72 C-20 power steering on my 68 C-10. I used the pitman arm from the C-20. I had no shimming or cutting of the frame to make it fit, bolted right on. I also did not run into the problems of the steering gear to column hook up. the column was from a 71 Suburban with manual steering. Also used the front sway-bar from the C-20, holes were already in the frame of my 68. Just make sure you get the mounts, the ones riveted to the donor frame. Hope this helps.
jay

Regarding 67 trucks GMC Paul wrote
None of the car or truck power steering pumps will bolt right on. The frame either needs modified or spacers used, as the frame requires a indentation in order for the gearbox to bolt on, you can use the later models gearboxes by heating frame and pounding a depression into it so that the gearbox will bolt on, or use approx. 1/2-3/4" of spacers between frame and gearbox with grade 8 bolts. The 67 originally used a power assist steering system just like the one used on 63-66 Corvettes. These are still available and use a pump, control valve & hydraulic cylinder in place of just a gearbox. We have both new and used gearboxes available and can put you in contact with a company that will set you up with the original 67 style.
GMCPaul

Tim Christian wrote
Hey Bob I just did this on my 1967 GMC I used a 71 gearbox the pitman arm for a 71 and the bottom half of the rag joint is different you will need one of these from the same year gearbox also. My frame did not have the indention either what I did was made some 180 thousand spacers and used stainless steel bolts that were 1/2 inch longer than normal Good Luck and I hope this Helps
Tim Christian

Chevyman wrote
I just did this myself on a 67 Chevy short box and I used the power steering box and pitman arm off a 1972 GMC 1/2 ton. I also used the column from the same to eliminate the problem of the flex disk where the column mounts to the box. I didn't cut my frame I just took my time to make a dent in the frame till the box fit right. hope this is some help...


TW Scannell wrote
I get some different answers when I ask different people about 2WD vs. 4WD steering boxes. My parts guy says the 67 to 72 boxes are the same for both. I bought an AGR box to do a crossover on a 4x4 and AGR sent me what they called a 2WD box. The answer may be that the original boxes where the same for 2WD and 4WD, and people have put newer 4x4 steering boxes on the older trucks, which I think you can do. Then again, maybe the steering boxes are not consistent. regarding the column spline differences, The manual box I had was off a 2wd half ton Chevy and the power-box was off a 3/4 GMC. This might explain the difference in mating the column splines. Hopefully there is enough info here to give everyone a heads-up on stuff to look for. I sure don't have all the answers, but I can tell you what my experience has been. Thank you to everyone that contributed to this thread.