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Old 12-24-2021, 12:47 AM   #1
tdangle
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Last step in Disc Brake Conversion

I've run into multiple problems with this conversion. First of all the required front end rebuild did not go too smooth. I had all the parts but just the actual rebuilding was nothing short of a huge pain in the ass. Now the front wheels have to much camber (its visible) with almost no shims in place. Need to talk to a alignment shop about this.

I purchased a 71/72 C20 master cylinder and booster unit to replace my dual 8" booster and have the correct MC. The booster won't bolt up as it needs a deeper firewall mounting bracket. In my research, I found the brake calibers are the same on a C10 and C20, just the rotor is a little larger. Back brake wheel cylinders are 1 1/8 vs 1" bore, so I figured I could pretend its a C10 and use my 8" dual booster and a C10 MC (difference is 1 1/4 bore vs 1 1/8 for for the C10). Should work. New AC Delco MC, PV2 proportioning valve. Just finished the lines, need to bench bleed MC and bleed entire system. I'll let you know how it turns out.
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1970 Custom Camper/C20 , GM Crate 350/7004R, Dana 60, factory AC
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Old 12-24-2021, 01:30 AM   #2
Slingus
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Re: Last step in Disc Brake Conversion

A good alignment shop should be able to take care of that, and have shims. I converted my 67 C20 to front disk, with 2" lower front springs, and with rebuilt/new everything - brakes, balljoints, adjustable tierods, etc. And truck has a much heavier big block in it now. So needless to say the camber was pretty screwy. But an alignment shop fixed all that no problem, and the truck drives better than ever now.

Ive also heard that later model disk front ends would give different offset and camber to the wheels when used on a earlier model conversion, but I could be wrong about that.
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Old 12-24-2021, 01:14 PM   #3
May70
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Re: Last step in Disc Brake Conversion

Following this. I purchased POL tie rods and their adjusting sleeves for a 70 to 73-8X for my 70 c20. I did this a while back and haven't had time to go back however I recall thinking there was not nearly enough threads engaged on the sleeves. Seems like they need to be adjusted out because the tires look inset but again I dont think there is any room to go out... I also wondered where im going to take this to get it aligned once I'm ready..

I haven't mounted calipers either. Still need to run all lines, figure out which master cylinder to buy etc. A lot too it.
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Old 12-24-2021, 03:30 PM   #4
tdangle
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Re: Last step in Disc Brake Conversion

POL is where I got my stuff from. I bought the entire C20 disc conversion kit less master cylinder, booster, lines and PV. That part went fine. I had to pick up new lower control arm bushing/shaft as once I got everything apart there was a lot of play that I couldn't see with everything together. That was a ***** to say the least. The loaner tool lower ball joint press setup did not work out well for me either. Had it been a C10, I think everything would have been fine, the C20 lower ball joints are just a little bigger complicating things. I had already replaced the upper control arm bushing/shafts so that was already done.

What to use for m/c and booster setup was an issue. the C20 booster for 71/72 has a longer arm in the back than the 70 drum booster setup. I was unable to source a new deeper bracket setup so I stayed with my original booster. I did change to a 71/72 mc. I was actually able to get the hard lines hooked up to the new pv and then made lines from the mc to the pv.

The reason I used a C10 mc was the 71/72 C20 mc has a 1 1/4 bore with a dual 11" booster. I didn't think the dual 8" booster would give me enough assist with the 1 1/4 bore mc so I went with the C10 mc at 1 1/8 bore. Remains to be seen if it works OK for me.
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