I just slapped a 60 under the front of my rig combined with a 14 bolt rear with disc.

My brakes just got super not buildy pressure.

I don't know a better term for it. But when the vacuum assist is helping I can easily get my pedal to the floor and it doesn't stop very well.

I assume that I just need a larger master cylinder from some sort of chevy 1 ton application.. Any tips or tricks on installing and making this work?

Wow, I had thought to have a response already. =).

Who has done a Master Cylinder switch? I think that Rob Gorell did one.. anyone else?

me, MichaelW, Matt... are the ones i can think of.

pics (including the p/n i used) are all on my site: brake upgrade

-Rob

Search:

http://www.4x4wire.com/forums/showflat.php?Cat=&Number=252217
http://www.4x4wire.com/forums/showflat.php?Cat=&Number=325166


The common one is a chevy MC. To be an upgrade though, you have to measure piston diameter to make sure. Stock Isuzu is 15/16" IIRC (see Rob's pics). I'm using an OEM Chrysler/Willwood style MC with a 1 1/32" bore. I think a "1-ton" chevy MC can be as big as 1 1/8".

With your calipers, I'd say the bigger the better, but if going chevy, I'd go for a later model AL MC vs the older, cast iron monsters.

Edit: My Chrylser/Willwood style:




--Dan

The traffic on the whole site was way down the last few days. I suspect that it had something to do with the three-day weekend.

Yeah, I like the idea of the newer master cylinder because the older guys have that silly sealing mechanism with that gasket that likes to go out. The newer design also seems like it would like to be upside down better.

Any idea of a model/year to try and reference?

I remember low to mid 80's Chevy 1-ton (C30, K30, etc.), but I think there are even multiple options in that category. I have the NAPA/Carquest part number in my pictures, you could work backwards off that to find the application.

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another interesting consideration if you're up for a challenge... you could always look at a hydroboost setup. this would negate trying to matching a m/c to the stock booster, but you would have to match up to the linkage... and then there's the plumbing. but hydroboost setups are awesome, there ton's of articles floating around out there about chevy guys doing such a swap. probably not your easiest or cheapest solution by a long shot, but would be cool for sure and offer you more pedal than you'd ever need.

-Rob

Hydroboost sound interesting, but I dunno if it is wise on my stock isuzu power steering pump which is already trying to play with the hydroassist steering .

I've got the same MC as Dan (thanks to his guidance)...also available in 1 1/8" bore for '81 Dodge D150. Works great, except for leaking MC caps (aftermarket crap...). I think a '98 Cirrus reservoir will fit, I'll know hopefully after hitting the junkyard.

BTW, how big are the caliper bores on your 60/14bolt? What size MC did the donor vehicle have (rear drums probably, no?)?

Service manual lists the factory Isuzu MC at 1"...not a huge difference from 15/16", but it may effect your calculations.

uhh... the donor vehicle ... yeah that was a yeah...


basically I have 3/4 ton calipers on the rear of my chevy 14 bolt and 1 ton from some early 80s 1 ton chevy truck. Definently drum on the original vehicle.