late model 14 bolt brake questions

[88bigburb]

Ok, I know the disk swap thing has been covered before, and maybe even this exact situation, but I only have my phone as access, and get tired of searching relatively quickly, so if anybody can point me to a thread thatd be awesome.

Im intending to swap in a 2005 14 bolt, with factory disk brakes into my 91 k5, im wondering what kinda master Cylinder I will need to run, im thinking it would be good to swap the front to the bigger piston calipers, as in the high gvw burbs and whatnot, not intending to swap to hydro assist, but its not out of the question. My 91 k5 has some way different brake lines than my 88 burb in the master cylinder area, so not sure if its gonna be as simple as different master and adjustable proportioning valve or not. So if anybody has done this particular swap and knows of a thread detailing it thatd be awesome or part numbers or really any help at all, id be greatly appreciative. And if you know anything about the cables I need thatd be great too, thanks in advance... Dom

 

[dremu]

My 91 k5 has some way different brake lines than my 88 burb in the master cylinder area

This is probably because the 90-91 trucks had rear-wheel-only ABS, so your '91 would have a valve thing for the ABS (and an electronics module, likely says "KH" for Kelsey-Hayes.) FYI, many folks find that it doesn't work for crap and just unplug the fuse.

If you really want to (and bleeding might be easier this way), you could remove the ABS module and valve, and run a new hardline from the master to the combo valve. There's a reference as to what is what on the combo valve if you don't like to trace the lines in this thread: http://coloradok5.com/forums/showpost.php?p=3265965&postcount=18

Anyway, as for your swap:

Front calipers for the Burbs are either 1/2 ton or 3/4 ton, and should be the same physical size. Only the piston is different between the two. Assuming you're going to have 8-lug wheels front and rear, you may already have 3/4 ton stuff up front. IIRC the 3/4 rotors are larger diameter and so have different backing plates -- for your Blazer, I'd just swap in an entire set of 8-lug outer from a later Dana 44 or any 10-bolt.

Lots of folks, myself included, have had perfectly good results with the stock master cylinder and proportioning (actually, "combination") valve on disc conversions.

Conversely, I've had all kinds of trouble on the one truck on which I did "upgrade" the master and combo valve. In the end I'm pulling out all the fancy "upgrades" and going back to stock parts.

If it ain't broke, don't go fixing it. Get the axle in and the brakes working, and if you find the back locks up way before the front or has other trouble, then -- and only then -- work on the issues you find.

As for hydroboost, you could consider that after you get the axle in and the truck stopping with the existing master/booster. If you change the entire system all at once, diagnosing the trouble will make you crazy, believe you me, so change one thing, or as few things as possible, at once.

-- A