I'm considering installing rear wheel disk brakes on my 31 Ford ( 8" Ford rear end ) I'm currently running 9" Mustang 11 disks on the front. Will the conversion dramatically improve the stopping distance. Is it worth the expense ?
The single biggest factor thats going to affect stoping distance is your tires. As long as your currant setup isn't doing anything funky and the bias is correct changing from drum to disk Is a waste of time on the rear
If you were just building it and don't have brakes that are operational then yes put the disk on it (SPEEDWAY System) but if you already have brakes that work thats a different
thing.
I had the same front and rear brakes with no problem.
If you are having problems maybe your M/C isn't sized properly.
96/ 02 crown Vic are almost bolt on You need a spacer 1/4 by 3 in behind the retainer in front of the axle bearing. Get ecrything form the rear end in a yard. Hoses etc.
We tried a couple of bore sizes because I haven't be happy with the brakes. Everything is new. I originally installed them and later had an experienced rodder/mechanic work on them. They passed the Safety. I would like to drive across the 401 to the Plunket t event but wouldn't dream of driving it on the highway through Toronto the way it is.
I thought about changing the front disks to 11" rotors but that would require I change the 14" rims and wheels and tires etc.etc..
The brake bias is adjustable with Wilwood adjuster, and has been set and reset, as well.
what size drums on the back now , pinto size ?? 8 inches ??. I always like to compare the weights of the donor car to the project car
passing safety generally means nothing fell off when it was on the hoist .
when you say it doesn,t stop , what are the symptoms . ie soft pedal / hard pedal and wont stop .
all the hot rods or drag cars I,ve been involved with using donor car brakes . I look at comparing the size an weight of the vehicles . then look at bore sizes compared to mastercyl calipers an cylinders . and also pedal ratio .
personally I wouldn,t use a pinto M 2 set up on anything , too small imo . but i have a guy i know running low 11,s in a pinto an it stops well at the track
Myself i wouldn,t use any thing smaller then a mid size gm front disc , an a 10 inch rear drum on a hot rod
my 50 chebby truck has 10.5 inch amc bendix / ford style disc on front an mid size gm 10 inch drums on back stops great . on a pacer or hornet gremlin , that disc set up is behind a 14 x 6 steel rim
but note . our 86 trans am with 4 wheel disc , hands down stops better then our 87 T am with drums on the back
and our grand cherokee at 4446 lbs with 4 wheels disc brakes stops better , easier then the 50 at 3600 lbs with disc an drum ..77.
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I,m as cool as Milner , but axeually a bit more like Beckwith
We tried a couple of bore sizes because I haven't be happy with the brakes. Everything is new. I originally installed them and later had an experienced rodder/mechanic work on them. They passed the Safety. I would like to drive across the 401 to the Plunket t event but wouldn't dream of driving it on the highway through Toronto the way it is.
I thought about changing the front disks to 11" rotors but that would require I change the 14" rims and wheels and tires etc.etc..
The brake bias is adjustable with Wilwood adjuster, and has been set and reset, as well.
Everyone has their own opinion on brakes (remember the tube size debates,, all of them).
Not saying one is better or worse. Just saying this worked real good for me!!
Don't those adjustable valves just restrict the rear??
I had a mid '30's car with power everything on it for options as far as weight goes.
I had the small MII 5 stud rotors on the front and just the drums on the back that are stock on a 8" maverick rear.
I had a master cyl.,,booster and proportioning valve off of a '91'ish fox body mustang.
No manual adjuster. I made sure the ports on the valve all went to the proper wheel (which doesn't make sense when you look at it on the fox)..
That car always stopped good at any speed. IMO I would use the same system again without any hesitation..
I never considered changing anything on it other then the Must.II "anti-rattle" clips but thats another issue.
the weight of your car and how hard the brakes will work.
It's physics...... brakes "absorb" energy (actually convert it to heat through friction) If your car weighs 1,500 lbs, in normal driving it will only work 1/2 as hard as it was designed for. Yet if you lead the cops on chases you may work the brakes to full potential.
The factory "differential" valve is calibrated for front and rear axle weights.
So if your combo matches the Mustang ll weights you will be fine.
Also mentioned above if you drive sane and you have a hard pedal try different pads. I have found that organic pads grab well cold but are not made for sustained high speed stops like metalic/ceramics
Larger or "better" rear brakes require caution, with a manual "metering/proportioning valve" on dry roads you may dial in your brakes to maximise rear brake work but in low traction situations you could find your self pulling 180's and going backwards at scary speeds.
My favourite observation........"the factory spends millions getting it right, few can do better" ( except turd world cars, only way to improve them is a blast furance)
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Fords Rule ! If it ain't designed and manufactured in North America it sucks ! I don't do rice, pasta, fish and chips, sauerkraut, Ikea or other third world motor vehicle !
For a light 31 that rear end should be more the enough to stop in a reasonable distance. Questions that need answered. Boosted ? pedal ratio ? master bore diameter ?calliper bore? Tire's ? Good tires wear out fast and are soft enough to easily poke your thumb nail into.If you bolt Hockey pucks to the axle the best brake system will suck.
Regretably the brakes are not boosted.
The car is built on a TCI frame, and I purchased the brake pedal assembly ( pedal ratio ), bracket for master cylinder, calipers , rotors etc. from a cataloque hoping that it would be a good working system. We have since changed out the master cylinder to increase the pressure, which helped. Prior to that I couldn't even get the brakes to lockup even on our dirt road.
Can the car lock up all four wheels on a panic stop? If not, you have a pressure/volume issue unless your pads are race style pads that need heat in them to work. I would start off with a cheap organic pad since they tend to have good initial bite when cold.
What size is your master, and what is the original application? What size are your wheel cylinders? Do you have a standard prop valve in line with the adjustable wilwood - you should as it has a delay built into, and the adjustable bias valve goes in the rear line. Do you have residual pressure valves plumbed in your lines?
Some things that are often missed when building a brake system from scratch:
Make sure that your linkage gives enough pushrod travel so that you have adequate stroke for the master cylinder. You want to be able to adjust it so that it just bottoms out, them back it off a couple of turns. This will give you the full master cylinder capacity.
Unless your master cylinder has internal residual pressure valves, you need them in line. A 2lb one for disk brakes, and a 10lb one for drums.
A lot of factory proportioning valves have the residual pressure valve built into them, if its not in the master cylinder.
When running disks/drums - the drums are supposed to activate a split second before the disks. Factory prop valves have a delay built into them to activate rear drums to a split second before the front disks. This is done for stability reasons. An adjustable prop valve just lowers the pressure to the rear drums to lessen how hard they engage.
You can tune the action of the rear brakes by changing the wheel cylinder size if the adjustable prop valve does not give enough range. Generally you go smaller if you don't have enough adjustment on the valve.
Check the pedal ratio, and make sure that is is a manual brake ratio - generally around 5-6:1. Power brakes are generally 3.5-5:1 pedal ratios (it can be dependent on the booster diaphram size compared to the master cylinder bore size). More ratio will give a better feel but a longer pedal throw.
There is no air left in the brake lines, right? Pedal is high and hard?
We won't get into a dicussion of brake line sizing since that has already been discussed to death...
I talked to Wilwood and ordered a 4 piston 11"rotor replacement kit. We replaced the 15/16" master cylinder with a 7/8" as recommended. Replaced the braided lines with longer ones. Replaced the 14" wheels and tires with new 15's. Shortened the brake pedal arm about an 1 1/2".They also adjusted the brake bias.
I had this done at a professional shop, and when I picked it up the brakes thumped, and were not consistant. I thought they had some air in the lines. As I hadn't cut the pedal arm down yet I decided to pass on going to Syracuse with sketchy brakes
When I took it back in, they turned the new rotor because it was warped, and the pedal seems more consistant. The car doesn't stop as well as my Ford Ranger but is better than before.
