Four wheel disc brakes on an A - Is it worth the effort?

Hopefully I won't get attacked for this... but I'm working on building a light weight Hot Rod based on a Model A frame. I'll be using the stock A axle with '42 -'45 Ford spindles. I'm thinking of running a Speedway disc brake conversion kit with GM disc brakes up front. Locally I found a 4wd S-10 rearend with disc brakes out of a '99 Blazer that can be had for $125.00 complete with the brake proportioning valve. Is it worth the extra effort to adapt a disc brake rear end or should I keep looking for a drum brake rear end? I've read that getting the brake bias right and finding a master cyclinder that can move enough fluid can be tricky. Any input would be appreciated.
Thanks!

 

As light as a Model "A" is I don't think it would be worth the effort....

 

If the rearend you are looking at is already equipped with discs and it is a width that is good with the bolt pattern you want, then I'd say go for it. On the other hand, I adapted discs to the 8" under my '36 and if I had it to do over again I would have just used the old stock drums. Your front brakes do 75% of your stopping, you want that so that the rears do not lock up first. You might see what others think of the emergency brake set up of the rear discs to make up your mind about that set up. Don't think I am helping you much, just giving you a few cents of my experiences.

 

need less fluid to work because the disc pads are closer to the rotors then conventional shoes are to the drums
i am using the cl***ic
master cly from autozone
they are rebuilt by a large co in canada using a sleeve.....
have good pedal stops great
will use other side master for frt brakes........

 

X2


Poverty leaves an impression

 

I had an "A" with four wheel discs. In my opinion it was unecessary. It would stop great, but it was definitely overkill. I actually resorted to driving that thing with my shoes off and using my big toe for the brakes.

 

Thanks for the replies. I figured it was overkill, but the salvage yards around here don't have anything older than mid 90's or so. I have a friend that has lots of '60's - '70s Ford 8 inch rears, but wants $300.00 a piece for them. I figure add a brake rebuild kit, new bearings, etc. and it'll be a $500.00 rear end. This is a budget build so I've got to think cheap. The car will run some kind of little 4 or 6cyl, so I don't need anything to crazy, just affordable. Anyone got any suggestions?

 

Anyone else got any thoughts on this? I'd like to gather as many opinions as I can.

 

The rear end with discs will likely be lighter than a similar drum equipped one, and lighter in an area that is pretty important. The brakes might be overkill, but, if you use a rear axle, such as one from an 8.8 from an Explorer or 10-bolt from an S-10, the parts will be readily available, which cannot be said for some older drum models.

$125 for a disc brake axle is pretty damned cheap. If you are on a budget, go for it, and the Speedway front kit. Just make sure you order the correct one so the wheel bolt pattern match.

If you get attacked for this, let them attack me too. I like disc brakes.

 

check the replacement cost of rear brake rotors.. many years ago I bought a 8.8 out of a ford because it was cheap and was a disc rear.. all was well until the rear brakes needed a rebuild.. calipers for my application were 125 each.. and rotors were somewhere in the 90 -110 dollar range.. add pads etc and I could have bought another "used" rear..

parts for a drum brake rear are likely less expensive..

 

Personally I want all the brakes I can get. That said, on a '29 it may be overkill. Dics may be a bit lighter or visa versa. Whichever is lighter will cut the unsprung weight and may help the ride.

 

Use the cheaper disc rear, but use an adjustable proportioning valve to dial it in. It's highly unlikely that the factory proportioning valve from the Blazer will give you the correct balance for your lightweight rod.

 

I put 4WDB on my wifes A. It was a sedan. I can't honestly say that it was better. I just did it that way 'cause most high performance cars (even light ones have 4 wheel disks. One thing no one has mentioned with disk brakes is they need power ***ist. I used a front set up close to what you suggest, my rear set up was a Ford 8" with a disk brake kit from some guy in CO. Forgot his name now-kit worked well. One thing the car stopped as straight as an arrow. I think I used a Corvette master cyclider. Depends on where you mount your mastewr cyc. If it's under the floor most GM master will have the connection toward the center of the car where as Fords push fluid out toward the frame. Makes it easier to run lines with the Ford set up.

 

Thanks for the replies. I'm still thinking about it. Anyone else got any ideas?

 

i like the idea of having the most brake i can afford. go with the disc brake rear end. like the others have said, just make sure that it isn't worn out already.

-danny

 

If you think its too much brake, or too grabby, You could adjust your
pedal ratio to acount for the better brakes. I think Most are in the 7 to 1 range but
if you go to 10 to 1 the pedal will move more thereby becoming less touchy.

This might not be ideal but its something to think about.

Jeff

 

Why not if you like disc brakes and you are already hanging them on the front why not put them on the back.

Go fast cars need stop fast brakes.

As for master cylinder just get one for an S-10 if it had 4 wheel discs it should be all the master cylinder you need.

 

I took my 29 roadster to the west coast last year. By the time I got to Calgary Alberta I had an axle seal that was screwed in a 40 Ford banjo. Calgary is a BIG city and we couldn't find a seal for it. We finally cobbled a seal with the axle ID and the old shell for the OD and epoxied them together. I finally found seals and a cage bearing in Vancouver.

In the mountains, I had a couple of "**** Clench" moments due to braking , or lack of it. The car had 40 rear drums and buick drums and 40 backing plates up front. When I got home the banjo came out, the front drums came off. I want this thing to STOP when I want it to Stop. I used a Speedway caliper bracket for the 11 3/4in ford pickup discs up front and bought rotors, calipers, and pads from a supply house. I hung a Ford 8in under the *** and used 96/02 Crown Vic rear discs which are pretty much a bolt on to the 8in. All that is required is a 1/4in spacer, the dia. of the bearing , between the bearing and the retainer plate. So I have about $300 in front and rear disc brakes
Now I can get parts, front and rear, pretty much anywhere.
Like I said I want this thing to stop when I say WHOOOOAAAA?

 

Thanks for the replies. I think I'm going with the S-10 rear as it is already removed from the vehicle as well which saves me a lot of trouble. What have you guys done for parking brake setups?

 

nobody ever almost rear ended an SUV with their hot rod and said,
"i wish i had less brakes and totaled my car just now, it would have been so traditional."

 

I am using 4 wheel disc on my 31 A pick up , I am running 75 monte carlo rotors on ford spindles up front
S-10 rotors w/Speedway brackets on a 8.875 BOP rear, and a dual mastercylinder setup
with balance bar that they use in dirt track cars. not finished yet but all the racers i talked to said it should be good. No propotioning valve , balance bar takes care of that.

 

What's a balance bar? I've never heard of one before.

 

Well said! I've put off going to disks on my car, because I just didn't want to change it. But after a few near miss's, I'm rethinking it and should be making a change to the front. If you just are putting around town, that's one thing, but if you are driving on the freeway there are just too many people that won't give you the room to stop.

 

I have a 98 explorer rearend in mine fits great.........

 

I would definitely go with the disk brakes all around. I don't know where Sazall buys his parts but I paid $32 each for the new rear rotors on my Explorer rear end and the caliper rebuild kits were less than $20.

They stop better and on a light car like your Model A you should get at least 50K before needing attention. Since it is a new build you will be buying it all anyhow so there isn't any additional cost going with a universal type 1" master cylinder and a small 7" booster.

 

A balance bar is a set up where you run two master cylinders, one for the front brakes and one for the rear brakes. The balance bar goes between the pedal and the push rods of the two masters and is adjustable as to how much pressure goes to each master cylinder when you step on the pedal.
Here are a couple of examples. The second one has a cable attached to it so the driver can adjust the brakes bias as he drives - very common in race cars.

 

Parking brakes can be a h***el with disks. You might get everything you can from the donar car. If that doesn't work try "Control Cables" Google them. They have instructions on how to measure everything and will make you up a kit. Not to expensive last time I used them. I forgot to mention in my first post that I have 4WPD on my coupe as well. I used a Versialls rear. Works great and is 9".

 

I was wondering that too. I am reading one to go under a Plymouth. I paid about the same prices.

 

after a near death experience with my family in a fad T (no rear brakes) in the 70's I have had four wheel disc's on all my cars or plans to do so. I have since been rear ended by street cars in my hot rod but my cars STOP.

 

To my way of thinking you can never have too much power or too much brake. That said, on my sedan I use a 9" with the big van drums and discs on the front. I think the S10 brakes would serve you just fine.