...not drivable, pedal too soft and vehicle does not stop. From 30 to zero takes about 1/4 mile.
So how do I go about troubleshooting the individual components? How do I test hydraulic pressure?
I'm hoping for someone to give me a systematic approach to resolve this and get this working.
Yes, I have spoke with Manny and I really don't think any of the calipers are defective.
Thanks Neil Fonville
1975 GMC II
I hold off on answering when I think the answers you will get from others will be more helpful. Not working on this thread so let me say this: It will stop better than that with the fronts only. So you got a master cylinder problem or air in the lines/calipers, even the fronts.
So get the fronts working. You don't have to rotate the calipers to get the bleeder at the top of the bubble like you do the rears. You should keep the push rod on the combination valve pushed in when bleeding the fronts.
I say again, get the fronts working and we will come back to the rears after a positive report on the fronts. Note that the combination valve will reduce the fluid pressure to the fronts for anything but full application of pressure at the pedal. That is supposedly to give the shoes time to move out and start engaging the rears before the front disks engage, preserving stopping stability.
The Maintenance Manual has the systematic approach, but that is for OEM configurations. Yours is not stock, but the procedures should prove helpful. It also discusses the function of the combination valve, so read that. The pressure delay function of the combination valve is not required on a 6 disk system.
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