Disk Brake Conversion Discussion

[YellowRose]

Disk Brake Conversion Discussion

I think we have had a terrific discussion here about improving our braking system, with a lot of input. I, for one, want to go the dual MC/Power Booster route and disk brakes. Finding a working bracket for an AC equipped Squarebird seems to be the drawback. They are out there, but some companies don't seem to want to sell you just the mounting bracket. But it looks like we are getting close to finding one that will work for us.

Gary, if you don't mind me asking, whose dual MC/Power Booster system are you going to put on your Tbird? Yours is a '60 Tbird with the original single mc and booster, as I recall. I gather this new dual unit is coming with a new mounting bracket. If so, can you do us all a favor,take and post really good pictures of it in different orientations, and the measurements? If push comes to shove, we might be able to have our own mounting bracket made using yours as the master. We could publish that in the Technical Resource Library for those of us who come after us to use if they want to do this conversion.

[Anders]

These shoes work pretty well.... there are designed for slick surfaces....

Thanks Rusty. They are white walls as well...

Regarding the discussions about brackets; I think it´s quite easy to make one myself if needed. Then spray or chrome it.

[Guest]

Here is a picture of the booster combo I have ordered. It is a MBM 8" dual booster. The 57-72 ford/mercury part # PBUF5772. The reason I ordered this one is because the bracket looks like the old one on my 60 tbird. UPS tracking says I get it monday and I will know then if it fits like I think it will. I ordered it from Carolina Classic Trucks on the web. I considered Old Irish Daves offerings but they all showed 7" dual boosters with an angled bracket. I wanted a straight bracket and 8" dual booster instead of a 7". OID might be able to make up an 8" setup with this straight bracket but since I found this one, I went with it. I don't know if it can be had in chrome or not. This is the same bracket that Simplyconnected has mentioned in an earlier thread so I know it will work. I will have to do some measuring to see if it sits out far enough for an A/C box.
Hope this helps. Gary

[YellowRose]

Disk Brake Conversion Discussion

Thanks, Gary, for posting this and your comments. Also those I received in email. This is a nice looking system, and probably has the mounting bracket us guys with AC needs. I wonder if they will sell just the mounting bracket? We are interested in seeing how well it attaches for you, and whether or not you think the 8" booster would clear our plenum or not.

[simplyconnected]

Just a quick note to draw your attention to the tech specs of MBM brake boosters & M/C's.

Click here

I use the 7" on my Galaxie (because of the Y-Block exh. manifold clearance) and an 8" on my Customline (351W). Both combos from OID, both are the same money, and both use a 1" M/C. There isn't much difference in brakeing, so it's personal preference. Both boosters produce 1,100 lbs of pressure, according to MBM.

I prefer the one-inch M/C over the 1-1/8". If you keep your brake shoes adjusted (or use a residual valve), not much fluid moves, anyway. The 1" actually produces more output psi at the same pedal pressure. (My original manual M/C was 7/8" dia.)

MBM offers an adjustable proportioning valve that I am very interested in:
Part # -- APV1C
This one is chrome. Let's see how much OID wants for it. Maybe he can make it part of a kit. - Dave

[simplyconnected]

Ok, I got an e-mail from OID. He suggests WE DON'T USE the 'Adjustable Prop. Valve' because it 'adjusts line size' like a flow control valve. He advises us to use a 'combination prop valve' because it compensates correctly across the pressure range. Wow! I never thought about it because I'm using an old Mustang combination PV, and haven't run into that. OID said trucks use the adjustable when they carry heavy loads and the driver wants to dial-in more rear brake power.

Other threads expressed concern over the (inside) dash-mounted bellows booster, and how it would affect a firewall-mounted booster conversion.





Notice, the booster assists the pedal. The M/C rod is unaffected and exits the LH side through the firewall. (Easy to see why Ford changed. There's no engineering involved.)

I've heard two suggestions: Just leave the booster there, and the other suggests removing it. I don't know how hard it is to remove, but that's what I would do.

The pedal rod is straight forward with no surprises. Ditch the fender tank (unless you need it for your vacuum wipers) and re-route one vacuum hose to the new booster.

All prior posts still stand. - Dave

[YellowRose]

Disk Brake Conversion Discussion

Hi Dave,

This confirms what OID told me in a phone call with him last week. That we did not need an adjustable prop valve, just the combination one would do the job. He also told me, as I recall, that it was not necessary to remove the under-dash mounted bellows booster. He said he has a Lincoln with one of his engine compartment mounted dual MC/Power Booster systems on it. He hooked it up through the firewall to the under-dash bellows booster and runs it like that with no problems...

[simplyconnected]

This confirms what OID told me... it was not necessary to remove the under-dash mounted bellows booster. ...He hooked it up through the firewall to the under-dash bellows booster and runs it like that with no problems...

Well... I'm looking at a big spring that your foot must overcome. If this booster doesn't assist, then I must believe it hinders (but I don't know for sure). I suppose If I paid someone to do the retrofit, I might tell him to leave it.

I would remove it just to give myself more real estate under the already crowded dash. I guess it boils down to personal preference.

Watch for combination valves designed for cars about the size of your Thunderbirds. Bone yards must have a zillion of them from cars like Crown Vic's, Marquis's, full-sized Chevy, Buick, Olds, crossovers and minivans. Any of them will work just fine if freshly pulled from a closed system.

The best and easiest proceedure is to use diagonal wire cutters. Snip the wires and brake lines, leaving the nuts and connector in the valve. (Diagonals cut steel brake lines, easily.) When you get home, clamp the valve in a vise and unscrew the nuts with a box-end wrench. If they look good, no reason why you can't re-use them on newly flared brake lines. - Dave

[Howard Prout]

My first reaction is why not just put a tee in the vacuum line and run with both boosters? Or is that likely to make the brakes too sensitive?

I need some help understanding the implications of the current discussion. Am I right that if we just change the booster/mc, that we not only don't need any valves but that we should not install a proportioning valve for possible use later with disc brakes?

If we convert to disc brakes we need a combination valve, right? Are all combination valves created equal? Are all combination valves non-adjustable? My understanding is that a combination valve marries a proportioning valve and a metering valve. And the purpose of the metering valve, sometimes called a hold back valve, is to engage the rear brakes slightly before the front brakes. So could we use a proportioning valve if we also installed a metering valve? Does the proportioning valve have to be nonadjustable?

There are a lot of proportioning valves on the market but little mention is made of metering valves. This appears to be rather dangerous because I am sure there are others like me who would have installed a proportioning valve and not a metering valve and ended up with an unsafe vehicle.

Now what about something like the SSBC Prop-Block, A0730P? I know it is a proportioning valve and a distribution block but is it also a metering valve?

Where are these combination valves located on vehicles? Are they located where they can be easily removed? When I go to the wreckers how do I know what to look for? Am I right that they will be close to the MC?

Sorry to have so many questions.

[simplyconnected]

Howard, I think you are asking the same questions a lot of members want to know the answers to. If I were doing this for the first time, I would want to know, too.
Let's start with FAQ about combination, metering, and proportioning valves:
http://www.mbmbrakeboosters.com/F.A.Q.-S/FAQs-Proportioning-Valves.html

Next, let me aver that all the big car companies use non-adjustable combination valves (in non-ABS disk/drum systems).

I don't know how much boost your bellows actually delivers. Having said that, if your bellows works, you can certainly add it to your outside booster. (I mean, why not? If it doesn't work out, disconnect it.)

If you boost all-drum brakes, you don't need any valves. According to OID, you should not install a proportioning valve for future changes. (I agree. Read on.)

If you convert to disk/drum, you will need a combination valve. Yes, it meters, proportions, and usually has an electrical switch that will drive a warning light (indicating you have lost half your brake pressure).


The important part is, it ties the front and rear pressures into a ratio. I also read, if you rupture a line, it shifts to the side closing off the leak, and delivers full pressure to the 'good' circuit while conserving brake fluid loss.

I have not seen any combination valves that are adjustable. Since they meter, your rear brakes will stop first. This gives stability. Then, the fronts operate with proportioning through the range of pressure (which can be 1,100-2,000-psi).

I emphasized getting a valve off a disk/drum car that is about the same weight as your car. My valve is off a '90 Mustang that is quite a bit lighter than my Galaxie, but it works just fine. They are usually held by one or two bolts. Use a pair of diagonals for cutting the electrical wires and brake lines.

Non-adjustable combination valves are usually mounted on or just below the master cylinder. Just follow the two lines from the M/C.

I don't know if the (SSBC Prop-Block, A0730P) is a combination valve or not. That's why I like to stick close to OEM parts. You may have to call Stainless for your answer.

You can do the booster & M/C and keep your drums. But I suggest you do the whole power disk brake job at once. Mount your components, plumb, and bleed, one time. If you do it piecemeal, you will end-up doing the job at least twice with a lot of unions and unnecessary flared ends because your plumbing will change if you add/delete tees and valves, and you will need to remove your M/C and booster to get to the plumbing.

[Howard Prout]

I just had a look at the master cylinder in my 1992 F150 - front discs, rear drums, rear ABS. The brake lines lead directly from the master cylinder to the axles (see pic.). But what is that bump on the side of the master cylinder that feeds the line to the front brakes (the line closest to the firewall)? Does the master cylinder include a combination valve? I thought I was going to be able to replicate the system on the truck but that doesn't seem to be the case. Does the rear ABS make a difference - my guess is that it does.

[protourbird]

Hi Dave,

This confirms what OID told me in a phone call with him last week. That we did not need an adjustable prop valve, just the combination one would do the job. He also told me, as I recall, that it was not necessary to remove the under-dash mounted bellows booster. He said he has a Lincoln with one of his engine compartment mounted dual MC/Power Booster systems on it. He hooked it up through the firewall to the under-dash bellows booster and runs it like that with no problems...

The adjustable proportioning valve is a must do to the differing weight of the vehicles. The combination valve is designed for a specific weight. BE SAFE USE THE CORRECT PROP VALVE!.
Also when you remove the under dash bellows you need to be aware that you will get substantial firewall flex (I learned this the hard way) which will give you a soft pedal feel no matter what you do.

[Guest]

Booster update.

Hi everyone; I received the booster and bracket pictured and this particular MBM bracket will not work on my 1960 straight stick. There is not enough rise from firewall to the booster in the bracket to clear the steering column reverse shift lever and the backup light switch bracket and switch. The original bracket has more rise from the firewall to the booster. It cleared the shift lever and backup light switch by about an inch.
I am going to use my original bracket on the new booster. I have it bolted up with a little modification and I think it will work fine. I will try to get some pictures when I'm satisfied with the instillation.
For all of you who need one for an A/C equipped bird, this MBM bracket and the stock Ford brackets will NOT work. They do not set the booster out far enough to clear the A/C box. I finally saw some pictures and the A/C box almost goes to the back of the engine. Farther than I thought. I sure would like to see a few pictures of a straight stick bird with A/C to see what ford used.

The MBM Bracket # MBMF5772BPR is 3 5/8" deep with a 1" rise front to back. The front being the firewall end and the back being the booster end.
The factory ford bracket is 4" deep and the rise is about 2" front to rear.
The 5 1/2 " bracket mentioned in another post would probably work with A/C if the rise is enough to clear the stuff on the steering column. There is about an inch more room where the booster bolts to the bracket because of the booster design. 7" or 8" boosters should work. It sure would be nice to have a bunch of different brackets to play with just to get a real idea of what combination works with what since no supplier seems to know for sure.
I hope this helps.
Have a good turkey day, Gary

Here is a picture of the booster combo I have ordered. It is a MBM 8" dual booster. The 57-72 ford/mercury part # PBUF5772. The reason I ordered this one is because the bracket looks like the old one on my 60 tbird. UPS tracking says I get it monday and I will know then if it fits like I think it will. I ordered it from Carolina Classic Trucks on the web. I considered Old Irish Daves offerings but they all showed 7" dual boosters with an angled bracket. I wanted a straight bracket and 8" dual booster instead of a 7". OID might be able to make up an 8" setup with this straight bracket but since I found this one, I went with it. I don't know if it can be had in chrome or not. This is the same bracket that Simplyconnected has mentioned in an earlier thread so I know it will work. I will have to do some measuring to see if it sits out far enough for an A/C box.
Hope this helps. Gary

[ParTaxer]

Is there anyway to flip the bracket to gain the necessary height?

[YellowRose]

Disk Brake Conversion Discussion

ParTaxer has a good thought! Can the bracket be flipped?

Gary, thanks for the post regarding your installation. Ya'll might call Old Irish Dave 575-544-4729 or email him at:
shamrock_dave@yahoo.com

I know he is working on this bracket problem. He has a lot of different brackets. He might have found one that will work.