The Stovebolt Site Forums The Parking Lot Big Bolts Under floor master cylinder for 1.5 tons

Howdy All --- given that it looks like there will be no room left in my engine compartment, I'm curious to hear what if any underfloor systems folks here have tried/applied. I'm going with large disk brakes all around on this beastie and the the master needs to be properly sized. I'm guessing an adjustable proportioning valve will handle balancing front and rear as long as I am moving something close to the right volume of fluid. The rear disks came with the Dana 80 axle ('98 Chevy C3500HD) and the front will be similar...so, what are the thoughts here on using something similar but underfloor to the C3500?

Ive seen places like Zig's offer 7" and 9" floor mount power MC's. They can be proportioned to drum/disc or disc/disc. Its the direction I was looking into. they have a model for early Chevy trucks- about 300 bucks if I remember correctly.

Yeah,they have drum/disc,disc/disc under-floor units available,for 1/2-1-tons. My friend installed one, (half-cocked,didn't do any research),and the M.C. bore doesn't deliver enough volume to begin to stop his (2-ton) bus. There may be one available out there somewhere,but I looked,and cannot find one. There's a "Fellow 'Bolter",in Indiana,that fabbed his own. All disc brakes,on a '46 2-ton.I can't remember if he used hydro-boost,(power steering pump),or vacuum. If you send him a P.M. ,he may be able to help. RDomeck,(user Name).E-Mail:randy@indianapolisfabrications.com. Hope this helps.

I would look into a hydroboost set up that will use the power steering pump for added boost, then the correct master cylinder for the hydroboost your using. You should be able to mount it under the floor on your bus. It will help if you can determine what the bus will weigh so you can size things to handle your load.

I was thinking with 11" discs up front, and drums in the rear, that it would be enough stopping power. Perhaps, more research is needed. Im not building a 2 ton bus tho. LOL.
Still a sizable truck in any regard. thanks for the input WW5757.

I would and have used a hydrobooster and master cylinder from either of your donor trucks (disc brakes front and rear). That way you have a complete brake system from a factory vehicle, use the proportioning valve from the same and there will be no guessing about it. Only thing you might need are some 2lb residual pressure valves if not already incorporated as part of MC or proportioning valve.

Mount the assembly under the cab wherever it fits and where you can get a long push rod from the stock brake pedal to reach it.

Grigg

Thanks Grigg & All --- Since I have to hang new pedals anyway, the C3500 setup seemed to make the most sense to me as well. They can be had as mostly new parts for not that much money. A fully re-manned Hydroboost from Cardone is only about $200 bucks and a brand new MC can be had new for less than a hundred. Seems fair for basically a new system. Just have to work out the hangers & such. And given that the C3500 is rated at 9000#'s gross and my bus should come in just under that, it should make for a reasonable match.

Being new at this full build thing, I really appreciate feedback from you guys that have been there. Thanks again.

Hey,Tango,I don't mean to burst your bubble,but,your say your bus will NET,(Empty weight),just under 9,000#. if you plan on installing a sink,holding tanks,stove,furnace,generator,etc,etc,you'll be adding some substantial weight,so you may want to take these factors into consideration. Just to be on the Safe Side.

Negatory WW...I am estimating GROSS on my finished bus wet to come in under 9000. Closer to 8000 actually. It is a tiny shell of a thing (Shorty...21' bumper to bumper) that only weighs in about 3700 as she sits now.

And the C3500HD's total GVW is actually 15,000 so I should have plenty of Lagnappe.

Cool! That's GOOD news! Closer to 1-ton G.V.W. Cheaper parts,to boot!!