Apologies if this has been discussed too much already, but a forum search didn't find much to answer my question. What is available for a 55-59 3800 trucks for either power brakes and/or dual circuit systems? I see a lot of power brake conversions available for 3100 trucks, but all appear to have a 1" master cylinder. I believe a 3800 has a 1.125 bore for master cylinder. Thanks for the help!
1959 Chevrolet 3800 Pickup 1937 Chevrolet GC Panel Can you still call it a barn find if it's your barn?
I'm going to guess that all conversion kits are for half ton trucks. Given that, your larger wheel cylinders require a larger volume of fluid. If you used the available boosters, you'll have a lot more pedal travel than you're used to. If you convert to a tandem master cylinder, then that will theoretically make up for the loss of volume, as you have 2 pistons moving fluid. As far as effort, a boosted 1" bore will likely still require less pedal effort than the manual 1.25 inch bore. There are factory one ton boosters out there, and at the last I knew, still at least one outfit in L.A. rebuilding them.
We use quite a few Hydraboost units that work off the power steering pump. Very good pedal feel, less bulky that the vacuum assist, and fluid volume per stroke is not a problem. Should work great for your app.
Interesting. Would you happen to have a picture of that kind of setup? I'm familiar with the hydraboost on a square body truck. Power steering pump off the back of the generator? Thanks.
1959 Chevrolet 3800 Pickup 1937 Chevrolet GC Panel Can you still call it a barn find if it's your barn?
If you opt for the bolt-on CPP unit, the direct bolt-on using your original pedal is a drum/disc set-up with proportioning valve. The drum/drum unit without the valve is NOT available utilizing your original pedal. The only difference between the two is a small adaptor that changes the center of rotation for the pedal, and CPP will not offer that, nor will they offer the drum/drum with original pedal configuration. (And they're quite adamant about it too!) Should you go that route, get the disc/drum boosted tandem master cylinder for original pedal utilization and chuck the proportioning valve. As well as a Hydraboost works, there's a whole lot more involved. Whichever way you choose, replace your hoses!
I did a google search and came up with this drum-drum unit on Classic Industries website. Claims to use the original pedal but may have to modify the transmission mount. Is this different from the CPP unit mentioned in EI's post? Would really like to use the original brake pedal and read some bad reviews of another unit that came with a pedal.
1959 Chevrolet 3800 Pickup 1937 Chevrolet GC Panel Can you still call it a barn find if it's your barn?
They must have succumbed to market pressure! My conversation with CPP (5 years or better) became rather heated. I was surprised he didn't hang up on me after questioning the logic of not providing something that a lot of guys (in my view) would just like to have power brakes for a relatively low price and ease of installation! I would have bought 2! As it stands I robbed the link form one to build the other. Now I need to take it back off so I can copy that link so I can get the other one back to operational! I have a video on installation on YouTube. It's in the "Project Whitey" playlist. youtube.com/user/elderlyiron Click "playlists". I would supply the video link, but YouTube has locked me out of my account on this machine. They keep sending a text to my landline to verify my account, and support keeps telling me to log into my account to change the settings! Brilliant...
I think that this version has an 8 inch vacuum assist as compared to 7 inch on some models, so that would be better for 1-ton application. I might give this one a try. Thanks for the info.
1959 Chevrolet 3800 Pickup 1937 Chevrolet GC Panel Can you still call it a barn find if it's your barn?
In my 55.2 I installed a hydro boost unit with a firewall mount linkage from CPP I believe, poor workmanship, took apart and reconfigured unit to move brake pedal left of steering column, works well. Need to brace firewall for brake pedal force.
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires. '47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle. '54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed. '55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
This is my opinion, on this matter. My 3800 has the stock master cylinder, although rebuilt, still in use. The ol girl has had plenty of weight in her bed and stopped just fine. Brake wheel cylinders and all components have been overhauled. I never had any issues of bring her to a safe stop even during panic braking. She has a 235cu in, power plant. I could see upgrading if the suspension components were transplanted to a newer disc assembly. Just my 2 cents Jim
