Rear disc conversion with hydroboost system

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Squarebody1985

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Hey all, I have done a rear disc conversion on my 86 1ton 4x4 single wheel. Was told by several people that it was a simple install it and forget it. Said that I did'nt have to worry about the proportioning valve or anything that has to be done with vacuum booster system. Really wanting to get advice and info from the ones that have already been down this road. I do indeed have brakes but not impressed at all with the pedal position or the feel of it. Thanks in advance for any help!!!!!!!!!
 

Strick

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Run it!

HS
 

Frankenchevy

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@Frankenchevy has a rear disc set up on his truck. Maybe he can provide some input.
I have hydroboost, but my brakes feel good. The parking brake setup with my eldorado calipers isn’t great though.

@Squarebody1985 , I’d try to rebleed the system really well. That’s the closest to free you can try first. Before you do, maybe ditch the LSPV. If that doesn’t work, a disc/disc prop valve may be worth a try.
 

Frankenchevy

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I missed the title, just read your post after Craig tagged me and thought you had vacuum boost. I still say try bleeding first. Also, sounds silly, but make sure your calipers aren’t installed upside down(on the wrong sides). IIRC, it’s possible to install either way if you use k10 front calipers on the 14ff adapter brackets.
 

mxer147

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How about a few pics of the rear brakes, please?
 

Squarebody1985

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@Frankenchevy has a rear disc set up on his truck. Maybe he can provide some input.
Thanks Craig 85....... I again want to thank you for the help on the AC. Works great and everything you recommended and told me was spot on!!!!!!
 

Squarebody1985

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Squarebody1985

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F-64

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Curious as to your front/rear brake bias now due to your wheel cylinder size change.
Lock your brakes at 50mph. Does it stop straight or does the rear of the truck start to swing around?

Don't do too much testing or you will flat spot your tires.
 

vr1967

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What master cylinder do you have? If original, will the port for the wheel cylinders supply enough fluid for the rear disc calipers?
 

Squarebody1985

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What master cylinder do you have? If original, will the port for the wheel cylinders supply enough fluid for the rear disc calipers?
Yes it's original..... before I decided to do it I read quite a few posts that said they didn't change anything with their hydroboost system that's the only reason I went ahead and did it lol. Like I said I have good brakes but I guess it will just take getting used to the pedal
 

wlwarnke

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When I did my K5 with caddy calipers. I used this master.

Dorman M39052 Brake Master... https://www.amazon.com/dp/B001PYNXLI/

Direct bolt on to the hydroboost.

Went back later and swapped to the PV4 combo valve (disc/disc) after a few drives in the rain and the rears locked up prematurely.

This master makes bleeding a breeze. You can fit a syringe in the port and push fluid down to the calipers easy peasy. No pedal pumping required.

When swapping Combo valves you introduce a ton of air. Once I started getting clean fresh fluid out of the calipers, I started recycling it back through.

Another thing to look at is the parking brake adjustment (caddy calipers). If not adjusted properly, you’ll have a soft pedal.

They’re supposed to auto adjust by simply using them. Sometimes they do, sometimes they don’t. Mine have been pretty trouble free e for a few years now and will stop 35s amazingly.
 

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