My '75 K10 still has the D44 and 12blt axles in it. Can I put a hydroboost brake set-up(off a '79 C30) on stock half ton axles/brakes without trouble? I have "searched" and found conflicting info. This is a daily driven truck. Thanks for any help
-Lance
Yep. Be sure to change to the hydroboost master cylinder, as they are different.
Some other observations on doing the swap in your case, as I put hydroboost on my '74 C20, originally equipped with vacuum boost:
You'll also want to get the brake pedal from the donor vehicle as those are different. In fact, if you can, get the pedal, the booster proper with its attached plunger rod, the master, the hoses to the steering pump, and the pump itself.
Which brings up that your '75 would presumably have the compression-fitting hoses and connections on the steering pump and steering box. '82+ vehicles have the other O-ring style connection. This means that the hydro booster is different for the different years.
One option would be to get parts for a 73-81 hydroboost truck, either from a donor or at the parts counter. You'll still need new hoses (there are three now instead of two) but you can use your existing steering box.
The other option is to convert to the new style. (Well, you *could* mix-n-match and have custom hoses made, but that can be costly, plus if you need a replacement you can't just get one off-the-shelf.)
Then you switch the pedal, master, booster and pump and hoses AND the box. I don't mean to dissuade you from it -- I love my hydroboost! -- but it can snowball quickly.
One more observation: You *can* mix-n-match parts for the steering pump. The biggest different between a hydroboost steering pump and the other one is that the hydro has two return lines. This is just an extra fitting on the reservoir; the pump itself is the same. (The factory ones may have had different tuning, i.e. pressure or flow, but the aftermarket ones have the same part number of the bare pump for either hydro or vacuum brakes.)
You could braze an extra fitting onto the reservoir, and some folks have put a tee into the return line and made it work. I just took the reservoir off the donor truck, replaced the O-ring around the pump unit, and called it good. And you can convert an O-ring style pump to compression or vice versa just by changing the orifice in the back. Again, the pump unit itself is the same (by "pump" I mean the cylindrical mechanism that unbolts out of the reservoir can.)
Anyway, that's prolly WAY more than you wanted to know ... but it may prove helpful to you or the next guy.
-- A
