Brake question??

[SoCal'75]

I am switching the vacuum brakes for hydroboost on my '75 K10. I have read conflicting info on the brake pedals. Do I or dont I have to change it?
I have a 4spd in the 4x4 and the hydro set-up is coming from an automagic truck('79 C30). I can cut the pedal pad down if need be,but I'm confused about what I have read. Thanks for any input.
-Lance

 

[Mike D]

I am not an expert but if you remove the master cylinder, and vacuum brake booster, there should be a rod that activates the the brake booster from the brake pedle. Disconnect and compare this rod to the one used with hydroboost.If there is any difference swap the rods and mount the boost unit and master cylinder. I would check with at least two auto parts stores to verify if the master cylinders were the same or different. It was my understanding that the hydroboost generated noticeably greater braking assist than a vacuum setup. If the auto parts stores are no help just hookup your current MC. Bleed and test drive. The brakes may or maynot be too touchy.

 

[SoCal'75]

sorry, maybe I didnt say it right. I need to know if I have to change the brake pedal also? And if so will an automagic pedal work in a 4spd truck?(I know I will have to trim the pedal pad)
Thanks
-Lance

 

[Mike D]

I converted my 81 K20 from 4sp to automatic. The hinge pivot used on the brake peddle for a truck that is automatic is wider than the one used for a standard trans. The brakes don't care which peddle is used. The worst case senario is you connect the new actuation rod to the old peddle.