The Stovebolt Site Forums The Shop Area Driveline disc brake set up

I figured that i would start a new thread since i can't find what i am looking for and I don't want to interrupt a previous thread.

I was planning on using Disc brakes in the front of my 1951 3100 to help with stopping and keep the drum brakes in the rear. I was also planning on keeping the stock (new) master cylinder. Is this going to cause an issue? Is it required that i change to a dual master cylinder system? I was told that i can not use a the disc/drum proportioning (sp?) valve.

Thanks for any help with figuring this out. I still need to but all the new brake lines, etc.

Chris

The stock master cylinder absolutely will NOT work with disk brakes. So, you have two choices: 1. Unassisted dual master cylinder, or 2. Power assisted dual master cylinder. Both will require a proportioning valve.

Even if the stock master cylinder would work, there is no sense in adding the safety of the disk brakes only to stay with the single circuit master cylinder (weak link).

so if i go with the unassisted dual master cylinder, would that require me to do a ton of modifications? Can i keep it under the floor boards?

just found what i was looking for! minimal changes (minor line change)

http://www.classicperform.com/Store/1947_59_Trucks/4754BBD.htm

thanks guys!

Yep, that's the one I used. I moved the proportioning valve to the frame rail because with power assist, the valve interfered with the transmission cross member.

photo

Your link shows the vacuum assisted version. If you do so, it WILL require cross member modification to fit even if you relocate the proportioning valve. Hard to see in my photo above, but the cross member is notched to clear the master cylinder.

thanks, i put the wrong one onto the link... there were a bunch of them that i was looking at.

The picture helped me visualize it a little better!

Why would the original not work with the addition of a proportioning valve on the rear?

after looking at the valve, it has 2 different inlets and 2 outlets so it would require a dual master cylinder. Look at David's photo, you will see what i mean.

I know that but you can buy a proportioning valve that has a single in and out. I guess I was wondering if the discs needed a larger stroke volume than the old drum setup.

Sorry, i thought that is what you were asking. I am not sure.

on the CPP website, i just found a manual master cylinder for disc/drum. Is that just a non vacuum assisted master cylinder? I can't figure it out.
Part number is listed below

4756MMK-2 1947-54, disc/drum, kit

I see several posts about notching the rear trans xmember. I'm doing a 49 3100 with disc/drum and dual m/c. No power assist. My cross member needed to be move back a min of 5 inches to fit m/c even if I relocated the proportioning valve. I cut it off moved it back 9 inches on m/c side to have excess room. Put a new brace (front to back) parallel to frame attached to both ends of cut x member with gussets for strength.

Is my fix overly radical compared to other "notching"?

You can look at my setup in More Pix in the Bolt Bucket in my signature below. I didnt go with power assist because it would require modifying my crossmember. I set it up with the proper prop valve and res valves and it all came out great. In the end, I have no modifications to the crossmember at all. It all fit just right.

The ONLY thing that may give you pause is that the floor hole is round, and not in the same place and you cant use it very well for filling your MC. Nothing a piece of tubing cant fix, just sayin. I found a nice square stainless door at Brothers, and modified my cab, so I can fill it fine. Most people dont go to all that trouble.

Enjoyed your input. There is just no doubt that the new m/c would not have fit with the trans rear cross member in place!! Adjusting everything as far forward as possible - even trimming the m/c plunger length to minimize overall length, the m/c is covering the mounting position of the cross member. The m/c bracket is mounted in orig m/c mounting holes, the proportioning valve is moved to the inside of the m/c between the m/c and frame rail.

I'll post a photo of the modified cross member before I reinstall it. Due to changes I have to drop the exhaust to put it back in. Hope I can figure out to post a photo.

This forum is great. Have learned so much!

TX if you are convinced your MC wouldnt fit without modifying the crossmember, you must have the powerbooster kit version. Without it, I was able to accomodate not just an OD transmission, but this crazy elaborate floor shifter with room to ummm.. spare? The exhaust system just went right in. But, I do not have power assist, so I get to stomp harder.

Oh, and forgot to mention I'm installing a remote reservoir so I dont have to worry or crawl under truck to check m/c fluid level. Splurged on a billet dual reservoir to made it look better than plastic. Won't work any better I'm sure.

Thought about the door for floorboard access but seems I'd have to modify trans cover in floor. Just seemed easier....

Not, no booster. I can only think I have mounted the m/c too far rearward. I used the original mounting holes. I guess I could have drilled a hole further forward and used it as the forward mounting, using the original forward mounting hole as the rear mount. I could have eliminated the spacer between the m/c plunger and the helm joint. Would have saved 5 or so inches and probably had no crossmember interference. Live and learn...

Seems our interests may be similar. My trans is an original three speed on column and recently rebuilt. It works just fine for me but have wondered if it could be converted to a floor shift. Browsing this site I see you had some correspondence about this some time back. Has this conversion been accomplished and can you tell me how or where to fully understand. I'd like to change to open driveline - doable with orig trans? - and Maybe change rear ratios. I just putt around town with this truck. 45 - 50 mph is about max I drive. Maybe another 10 mph would be nice without blowing anything up or over revving. I have a late 235 ci installed.

If you look at the pictures in "More pix in the bolt bucket" below my signature (turn signatures on in options) you can see what I have done so far. Lots more to do. The floor shifter is almost ready for testing.

WOW! I'm very impressed with all you've done. You obviously have some fantastic welding and fabrication skills - plus engineering and "vision" well beyond most.

I'm sure my setup is different than yours. My m/c mounting brackets are significantly further rearward than yours. Plus your m/c looks overall shorter but that may just be the photos. Mine is now in and "I'm over it". Next time...

The floor shift looks great. It would be great if you had it drawn up so others could fab or you or a fab shop could make and sell to folks like me. Hint hint. Seems there is interest on this forum.

Envious of your shop too. I'm a novice at all of this. Little old in the game and a little short in the wallet to achieve what you've accomplished. I'll just have to stick to buy and install. I can generally do that with great instructions!

Really, TX it isnt anything to do with me, other than I just found a kit that I felt good about. CPP sells a nice kit that bolts right in. I got it through Brothers, but alot of times, its just about knowing the vendors well. I suggest get all of their catalogs and do some research. Doesnt matter what we are talking about. Before going to the trouble of reinventing the wheel, check to see if they have done it. The floor shift is a new, never been done before product, so is the hitch assembly, but everything else was someone elses idea. There are many people out there who have really amazing ideas. Just have to find them.