PDA

View Full Version : large volume caliper brakes...booster and master cylinder???



Krash80
05-09-2005, 05:27 AM
Front calipers are F250 big twin pistions, and rears are chevy K20 front calipers....so i need to move lots of fluid!
I got a remanned booster for an '89 XJ, and a MC from a '79 chevy K30. I went w/ the K30 MC over the E350 van one because the chevy one clearly had a larger bore and it mated up perfectly to the booster. The E350 one wouldn't have worked with the XJ booster i got without serious work to the pushrod length.

mounted up the booster, tightened down all the bolts...seems as if the very top/back of the booster is touching the firewall, but i can't tell if it's touching hard enough that it's not mounted flush (all 4 nuts seemed to tighten down the same length on the studs), or it may be sitting perfectly flush against the firewall and top is just barely touching and not affecting anything. Anyone else have that little of clearance to get the thing to fit? Or did i get a weird XJ booster, especially since the E350 MC would certainly not have worked with it and everyone else claims that the two bolt together just fine.

I've gotta get fittings/lines for it tomorrow....should i get an adjustable proportioning valve also, or have you guys had good experiences with just hooking the lines up directly to the MC? Also, which lines go to which hole in the MC? front calipers to front output, rear to rear...or opposite hookup? seems as if the rear of the MC has a larger reservoir, but the front output has a larger diameter hole for the fitting, so i'm not sure which one to hook up to which end.

Obviously all ABS is history...can i pull out the little computer looking thing that's mounted on the inner fender just behind the headlight that's labelled "electronic brake controller" or something...seems like it's useless weight on the dragstrip at this point, or does this thing have another function besides working the ABS?

more questions to follow i'm sure.
BTW...i know squat about brake systems!!! :finga:

-Ron-

Kraqa
05-09-2005, 02:47 PM
You probably didnt' need to get a XJ booster. the Jeep booster actually push quite abit of volume for what its worth. the E350 MC should almost bolt up to the sock ZJ booster and therorecicaly the XJ one two. You need to shave a bit off the MC moutnign surface and oblong the holes. 9/16th drill bit if i recall. The E350 MC is set up for a disk/drum setup the drums use alot less fluid to opperate. the smaller resevoir shoudl be for the rears. one thing about a disk drum MC is that all ford (larger model f150 250 ect) kept a positive pressure on the shoes to the drums. so in actual fact if your using them for disks it will keep a bit of pressure on the rotors and wear out for pads faster.

Drums use more volume and while disks use more pressure. hense the difrence in line sizes on the output. This setup should work alright. If your not in to deep i would suggest lookign into a 1969 corvette MC. it is disk/disk setup and bolts right to the stock MC.


on and run a proportioning valve :finga:

i hope this all works out. take some pics mutha fuuuuka. :weedman:

Krash80
05-09-2005, 05:19 PM
kraqa-

my stock ZJ booster is very different than the XJ booster in a bunch of ways...no way the E350 MC would've bolted up to it and been remotely close to working. However, both the E350 and the K30 MC's both fit perfectly onto the XJ booster, no drilling or grinding necessary at all...exact perfect fit...except the 350 one stuck out more where the pushrod comes in and wouldn't have worked w/ the XJ booster i got.

I think i'm gonna try this setup as long as it's already bolted in...and i'm gonna run all the lines off of it to an adjustable prop valve mounted somewhere inside along the trans tunnel so i can adjust the brakes from inside the jeep.

I'll let ya know what i figure out.

-Ron-

oh yeah...i read the corvette MC wouldn't have enough volume for the huge twin piston calipers up front. I know some vettes had 4 piston calipers, but they were little bitty pistons compared to the F250 twins.

sailbrooks
04-12-2006, 06:09 PM
Any more insight into this anybody? I need to set up my brakes this weekend. I have F-250 twin calipers in the front and eldorado rears. Does anyone have a similar set up? What did you do for m/c or booster? I originally had 4/wheel disks so I would like to keep the double diaphram booster if possible. Anyone know of a MC that bolts up (corvette? year?) I have done the search and there is nothing definative. Kraqa, did you orginally have 4/wheel disks? Frickin pirate blocked the search feature too.

EMTimZJ
04-12-2006, 07:12 PM
You could use a double diaphram XJ booster, they started in 96. You cuold then mate that with the 69 corvette MC for disks at all four corners.

I'm not aware of any different MC's that bolt up to our ZJ boosters.

In the Write-up section follow what Alaska ZJ did except add a proportioning valve and use a corvette MC instead of the E350.

HTH

-Tim

zjeepin
05-28-2006, 10:06 AM
so ron, did you ever come up with a solution? it seems there is still some confusion over what mc to use with the f250 twin piston calipers.