Thread: Followed Me Home II

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Just to follow up, I talked to Jason at P&J's and he shared that they're no longer doing their chassis' the way mine was done back in '09, and he shared several options for me to consider. We quickly got to the point of power brakes really not being needed on a light coupe/roadster hot rod. Bottom line, I'll be taking off the booster, and if the master can mount direct to the bracket I have and be accessible from a hole in the floor that's the way I'll go. If not I'll be cutting that bracket off and using a different one that shifts the master back about a foot or so, making it accessible for fill.

Roger, with those GM metrics on the front and the big drum brakes on the back, you'll be able to stop on a dime and get a nickel change - even without power brakes.

while you are redoing the master, please remember to consider the pedal leverage ratios. Manual and power systems differ and most disc brake systems do require more pressure because they lack the camming effect of drum brakes

Wilwood claims that their pedal setup, that has a 7:1 leverage ratio master cylinder works as well as most power assisted setups. If you have a lot less leverage, then braking power may be unimpressive.

My under floor setup only has a 3.8:1 ratio, and I've never been impressed with the braking power, even with a 7" dual diaphragm booster and 1" master. I now have a 7/8" Wilwood master coupled to the 7" dual diaphragm booster to gain some more braking force. I barely have room for an 8" master, if needed.

A Wilwood 7/8" master is sold as a manual setup, with a long 3/8" pushrod already attached. The pushrod can be removed, by removing the snap ring that retains the piston, then removing the pushrod, that's retained by a washer in front of the piston. The end of the piston does not have a deep bore, like other models - it's got a shallow cup shape at the end. I found that a 6mm button head bolt works as a pushrod for my booster.

The downside to a Wilwood master mounted under floor is that it makes it necessary to add an access panel, since it uses four 8-32 screw to secure that top cover, rather than bales. Having one under the seat would not be easy to use. Mine's ahead of the seat.

I agree, Jack, and so did Jason at P&J. He said they never put a booster on anything they build, except for a roller chassis where the customer specifically orders a power brake option. Jason also shared that they use the same MC on both power and manual applications, with the difference being that the "cup" on the back side of the piston is a deep recess for the actuating rod on the manual application, while the power application uses the shallow cup since the actuating rod is captive, attached to the diaphragm. The MC's that they stock today are deep recess, with an insert that converts it to the shallow cup, which makes it simple for stocking and replacement. Mine is from 2009, and doesn't have the insert so it will have to change. Another detail, the pedal & MC are both designed for manual brakes, which gives a very light touch if the booster is used.

The good thing is that I found that removing the booster pushes the MC forward enough that I can get the access panel in place in front of the seat. Only needed a simple flat plate adapter to convert from four bolts to two, and to reduce the center hole from ~2.25" down to 1.5". It's already bolted on, just need to swap the MC and bend some new brake lines and it's done.

Roger I have a 7" power booster on my '32 roadster with 4 piston wilwoods, save your money its not needed, I have a buddy who has built a lot of cars and agrees, the power booster is just not needed on that light a car much less that little 7" booster doesn't add to much to the performance, my '37 has the GM calipers and a dual 8" booster and I feel since the car weighs a 1000 lbs more its still probably not needed but it does stop well, if done again I would never fall for the thought a booster is needed on a roadster. I have also cut 2 'glass floor boards out for master cylinder doors, if done again I would use a hole saw and cut a round hole with a round door under a floor mat, easy to do and you only need to be able to get a small funnel through the hole, you can take the bail off from underneath, for some reason I had in my head you have to access the whole dang master cylinder, its not needed just a small hole (1 1/2) is about it, just big enough to see the fluid level through, it looks better and its easier to do.

Originally Posted by Matthyj

......if done again I would use a hole saw and cut a round hole with a round door under a floor mat, easy to do and you only need to be able to get a small funnel through the hole, you can take the bail off from underneath, for some reason I had in my head you have to access the whole dang master cylinder, its not needed just a small hole (1 1/2) is about it, just big enough to see the fluid level through, it looks better and its easier to do.

Matt, at my age laying down under the car and trying to get the bales loose from the MC and then get the lid off, only to crawl back out to lift the carpet panel to access a small, round access port just doesn't compute. Besides, the lid on the MC just barely clears the underside of the floor, so I'm not sure I could get the bales loose and out of the way from underneath. I'll check it tomorrow, but my thought is that trying to pull the lid on this one would be a PITB.
On the '33 I needed access to both clutch & brake MC's so the removable panel is maybe 8"x10". For this one I'll just need a nominal 4" x 6" or so (if I position it accurately). Also, last time I followed a recommendation to cut a piece of flat fiberglass out to form the "lid", using the piece removed from the floor as the "guide", bonded to the underside of the lid. Even with the edges rounded it's 3/16" or more thick. This time I'll cut out the hole using a saber saw with a fine tooth metal blade which takes a very narrow kerf, and will then bond the piece cut out to a piece of 16 gauge sheet metal sized for a nominal 1" rim around the hole for the lid. It will be virtually invisible under the carpet.

Roger, I understand your concerns, my guess is the access panel will be right between your feet (conveniently under a floor mat) as thats where my roadsters ended up with a P&J pedal assembly. I used the cool little aluminum panel that Speedway sells from Doc's Custom, works well but honestly I don't plan on getting in there much but it sure beats my buddies with no access, has to use a squeeze bottle and hose.......did you know in Europe they change the brake fluid once a year, that would make a whole new need for access!

Mine won't be anywhere near my feet - the rod between pedal & mount is ~15" long. The access will be right at the front edge of the seat bottom with the seat all the way back. Even if it were under my feet I wouldn't be concerned...
I'm not sure that the European approach on fluid is not the right way to go. Our DOT 3 & 4 fluid is hygroscopic, absorbing moisture from the air, and it can get pretty nasty if left too long. I had a Jeep GC that was giving me fits so I finally changed the pads. When I pushed the caliper pistons back the fluid coming into the MC was the color of dark molasses, so I bled the brakes and kept pumping until each caliper ran clean, new fluid. Worked fine after getting new fluid in the system....
And just to clarify, the easy way to have solved the problem is to simply buy the remote fill device for the MC like Don suggested and forget about it, but I was never really happy seeing the PB booster hanging there in the first place, with all of the potential issues with vacuum at idle, etc. Once Jason mentioned taking it off I was sold on that approach.

Roger my under the floor resevoir is right under the seat on the edge of a fold in the sheet metal floor pan, I cut an access hole and kept the piece I cut to make a hatch. But years after I did this I still have never made the lid. I think eventually I'll make a screw on access hatch, but run a remote tank set up as you mentioned for the reasons, you mentioned, I'll keep the access hole only for any extensive repairs, later on, but I'd much rather not have to cut the rug up, or get brake fluid spilled inside the car once I'm done!

I'm also running the Dot 5 silicone based stuff to avoid the moisture issues!

Originally Posted by stovens

I'm also running the Dot 5 silicone based stuff to avoid the moisture issues!

Uh Oh.... I think you just kicked the hornets nest!!

Originally Posted by 34_40

Uh Oh.... I think you just kicked the hornets nest!!

Comments, criticisms and advice regarding DOT 5 go here, please - Project Special K

no hornets nests.I am well aware of the mixing issues of Dot 3 or 4 with Dot 5. In my case all lines hoses reservoirs, wheel cylinders and disc cylinders are all new, no fluid So there isn't a contaminant issue that I can think of, i.e. all new parts!

My car could be a semi because there is only air there for brake components.