Disc Brake Conversion Pedal Results

[SF-66TC]

For those who have completed a Front Disc Brake Conversion, could you answer the following questions -

Please state whether you did a Factory Spindle Conversion or other ie; Scarebird, ECI, Master Power Brake, SSBC...

1. Was there a difference in brake pedal height (higher, lower, same)?
2. Was there a difference in brake pedal feel (hard, soft, cushion-like)?
3. How far does the pedal depress before brake application?
4. With the pedal fully depressed at its full range, how much space do you have left between floor and pedal bottom?
5. What Master Cylinder did you use?
6. What was the Bore size of the MC?

 

[blackmamba]

Hello! You should give The Ram Man a call!!! This guy KNOWS HIS ****!!! nuff said! He'll get you set up the right way with factory parts! A little bit more than your others, but YOU GET WHAT YOU PAY FOR!

 

[68Bigred]

I did SSBC fronts (4 piston) and single piston rears slotted/drilled all 4. I had to also get dual diaphragm booster. My pedal is pretty much right on top without any unusual travel. However the brakes are bit harder then I like or not as powerful as I like. With out a doubt stop perfectly straight every time but no matter how hard I press they don't lock up but stops quicker then it ever did. I think I need a smaller bore MC but for now they are fine. If my wheels didn't show the brakes I would have just don't the fronts and left drum on the back but love the look of disc all the way around. I went with the smaller disc as well so I can put the stock 14" wheels on it.

 

[thrashingcows]

I'm running the stock 73 C-body set-up on the front, scare bird disc brake system on the rear. I'm using a reman'd 68 Disc brake booster (looks nothing like the proper Bendix unit), and a MC from a 80's M-body. No proportioning valve, run straight off the MC to the fronts, and an adjustable brake valve on the line to the rear.

My system is so touchy you barely need to touch the pedal to make the car start slowing down. And only need to depress the pedal an inch or so to get full lock up. I really think it's TOO much. Have been wanting to swap it over to manual brakes to see if that would give me a better pedal.

 

[68Bigred]

Sorry the hijack the thread...I am running the 70's cbody MC is the M body a smaller bore to increase line pressure? I wondering why is seems thrashingcows has the complete opposite issue I have. Is my MC or my rotors too small? I would assume 4piston calipers would have some gripping power...

 

[saylor]

Please state whether you did a Factory Spindle Conversion or other ie; Scarebird, ECI, Master Power Brake, SSBC...

ECI

1. Was there a difference in brake pedal height?

YES

1. Was there a difference in brake pedal feel (hard, soft, cushion-like)?

maybe a touch softer

1. How far does the pedal depress before brake application?

none - very very small movement if any

1. With the pedal fully depressed at its full range, how much space do you have left between floor and pedal bottom?

never looked, but it is for sure not at the floor. an inch or two off the floor maybe?

i had to adjust the brake light switch at the pedal thingy a little bit.

the MC bore has effect on pedal hardness.

$.02

 

[SF-66TC]

Hello! You should give The Ram Man a call!!! This guy KNOWS HIS ****!!! nuff said! He'll get you set up the right way with factory parts! A little bit more than your others, but YOU GET WHAT YOU PAY FOR!

I had called Wayne before posting, but he's at Carlisle and texted me that he won't be able to call me back until Sunday. I completed my disc conversion and just wanted to compare my results with those who have already done theirs. I was lucky enough to source out a '73 setup and was interested in knowing what those who used the Factory Disc Spindle setups vs the plate setup with Factory Drum Spindles comments were. Of the 4 resposes thus far, all were different, but then again we're not all comparing apples to apples.

It's a FACT that Wayne knows his Mopar brakes, just check out all his YouTube videos - "THERAMMAN01" I've done business with him, but whether you do or not he is more than willing to help anyone with Mopar brake issues - just ask!

 

[SF-66TC]

68Bigred, if you're concerned with how hard your pedal is I'd suggest you get in touch with someone who has done a SSBC setup and see how their setup compares with yours.

My intention for this post was to field out information from those that have done the conversion. The info will help assist those who have done or will do a conversion with what they can expect. The information can also be used to help diagnose whether a problem exists with their installation or if the symptoms experienced are just normal.

That said, it would be helpful if anyone else replying to this post will answer the questions in the posted format.

"Saylor" did exactly that and viewing his reply gives the reader a quick answer to the posted questions. After answering the questions in the requested format, additional information can be added to which viewers can then chime in and offer their experience and knowledge.

LOVE YOUR WHEELS BY THE WAY - DISC BRAKES PEERING THROUGH THE WHEELS ARE BADASS!!

 

[SF-66TC]

HERE'S MY INFO & PEDAL RESULTS

I have a '66 TC and just completed my disc brake conversion -

1. What type of conversion was used?

'73 Spindles used for my conversion

2. Was there a difference in brake pedal height?

Had Booster rebuilt by Booster Dewey. Upon installation Brake Pedal height was lower by 1/2". I had to re-adjust the brake light switch.
Spoke to Booster Dewey and he said it's possible booster is not 100% flush against fire-wall. I told him it was and he really didn't have an answer.
He stated same original parte (both pedal & MC rods) were used so really didn't have an answer....

3. Was there a difference in brake pedal feel (hard, soft, cushion-like)?

Brake pedal feels cushion-like/spongy for first 1" to 1-1/2" until brake application is felt then it' becomes firm. Confident there is NO air in system.
Will check rear wheel cylinders. Read write-up regarding wheel cylinders mfg prior to 20years ago had tendency to leak in air., will need to diagnose.

4. How far does the pedal depress before application?

Pedal depresses about 1" to 1-1/2" before application

5. How far is pedal from floor after full depression of pedal?

I'd say roughly 1-1/2" from floor bottom

6. What Master Cylinder was used?

I believe it was from a '67-'68 with disc brakes (need to confirm with Wayne Brown)

7. What was MC bore size?

I believe the bore size is 1-1/32" (need to confirm with Wayne Brown)


THINGS TO CHECK:

A. Need to check the adjustment for the MC rod, might not be adjusted correctly.
B. Will plug MC line ports to test if sponginess remains. If sponginess still present may have issue with MC. If sponginess disappears then cause will be downstream past the MC. Perhaps rear wheel cylinders do not have "expanders" in them thus allowing air to sneak into system.

Other than the low and spongy feeling pedal, car stops on a dime. Rear Prop valve adjusted to barely lock rear brakes upon hard braking. Using rebuilt Midland Ross drum brake booster. I know a Dual Diaphragm booster is recommended, but this single works fine even under various panic stops so I'll stick with it for now. I attribute a lot of my stopping power to the Kelsey Hayes 2.75" Single Piston calipers and 11.75" rotors I'm running.

 

[saylor]

directly from my man ralph @ ECI: "a dual MC disc/drum model from a mid-late 70s chrysler that fits, with 1 1/32 bore"

M1633. http://www.autozone.com/brakes-and-...ake-system-/227207_0_0/?CJPID=4142120cmpid=cj

 

[SF-66TC]

I'm running the stock 73 C-body set-up on the front, scare bird disc brake system on the rear. I'm using a reman'd 68 Disc brake booster (looks nothing like the proper Bendix unit), and a MC from a 80's M-body. No proportioning valve, run straight off the MC to the fronts, and an adjustable brake valve on the line to the rear.

My system is so touchy you barely need to touch the pedal to make the car start slowing down. And only need to depress the pedal an inch or so to get full lock up. I really think it's TOO much. Have been wanting to swap it over to manual brakes to see if that would give me a better pedal.

Don't know anything about your rear brake setup, but I would venture to say your symptoms have something to do with the MC you're using combined with the rear disc system. How do you have the rear discs dialed in with the adjusting valve? Maybe you need to reduce the pressure to the rear discs. Try reducing the pressure 100% and try it.

Today I got everything with my brakes dialed in and I couldn't be happier. Initially I had 1-3/4" travel before the brakes would apply, but now I have about 1" without the sponginess I initially reported. The pedal is soft and it doesn't take much additional pressure to stop the car. I'd say everything is spot on = soft application, press a bit harder and the booster takes over and the car stops 100% better. I previously stated the car stopped on a dime before I dialed it in, but now it's 100% better than that which makes it 200% better than the drum brakes! I'm quite surprised and impressed with how everything has turned out. Felt disc brakes would be better, but I wasn't expecting them to perform this well.

I'm running the 73 C-body setup (w/ceramic pads) and rear brake drums w/Bendix shoes, the original DRUM Midland Ross single diaphragm brake booster (rebuilt by Dewey), a '67 MC with 1-1/32 bore (straight to front discs) and a Mopar Performance/Wilwood adjustable valve (Mopar #P5249088) inline from the MC to the rear drums. While it's advised that disc brakes require the extra boost of a dual diaphragm booster, I was informed that my original booster would work just fine AND IT DOES! Took the car out on the freeway at 70mph and brakes worked flawlessly.

 

[blackmamba]

Sounds great. Guess I'll jump in too! lol!I'm restoring a 1968 Polara Coupe and I just finished installing the Front Disc Brake Package from a 1970 Plymouth Fury III. I'm going Rear Disc package also with the Max Assist Bendix Booster from The Ram Man.

 

[SF-66TC]

EDITED - Got My Brakes Dialed In And Couldn't Be Happier! ink banana:


HERE'S MY INFO & PEDAL RESULTS

I have a '66 TC and just completed my disc brake conversion -

1. What type of conversion was used?

'73 Spindles used for my conversion

2. Was there a difference in brake pedal height?

Had Booster rebuilt by Booster Dewey. Upon installation Brake Pedal height was lower by 1/2". I had to re-adjust the brake light switch. Spoke to Booster Dewey and he said it's possible booster is not 100% flush against fire-wall. I told him it was - He stated the same original parts (Pedal Rod & MC Rod) were used in the rebuild, but really didn't have an answer as to why my pedal would have dropped and I needed to adjust my brake light switch. He did say however that people have had to make adjustments as I, but then again couldn't say why.

3. Was there a difference in brake pedal feel (hard, soft, cushion-like)?

Brake pedal feels cushion-like/spongy for first 1-3/4" until brake application is felt then it' becomes firm. Confident there is NO air in system. Will check rear wheel cylinders. Read write-up regarding wheel cylinders mfg prior to 20years ago had tendency to leak in air., will need to diagnose.

4. How far does the pedal depress before application?

Pedal depresses about 1-3/4" before application - Update - Pedal depression is now 1" before application

5. How far is pedal from floor after full depression of pedal?

I'd say roughly 1-1/2" from floor bottom - Update - I now have 2" of space from floor bottom

6. What Master Cylinder was used?

I believe it was from a '67-'68 with disc brakes

7. What was MC bore size?

I believe the bore size is 1-1/32"


THINGS TO CHECK:

A. Need to check the adjustment for the MC rod, might not be adjusted correctly.
B. Will plug MC line ports to test if sponginess remains. If sponginess still present may have issue with MC. If sponginess disappears then cause will be downstream past the MC. Perhaps rear wheel cylinders do not have "expanders" in them thus allowing air to sneak into system.

Other than the low and spongy feeling pedal, car stops on a dime. Rear Prop valve adjusted to barely lock rear brakes upon hard braking. Using rebuilt Midland Ross drum brake booster. I know a Dual Diaphragm booster is recommended, but this single works fine even under various panic stops so I'll stick with it for now. I attribute a lot of my stopping power to the Kelsey Hayes 2.75" Single Piston calipers and 11.75" rotors I'm running.

UPDATE: Brakes feel FANTASTIC and I'm 100%+ satisfied with this conversion. Proper REAR brake adjustment was key to resolving my spongy pedal.

This is the Adjustment Procedure I used (for rear drum brakes). You will need to remove all load to both wheels and axle during adjusting.

1. Remove the wheel and drum from opposite side you are adjusting.
2. Make your adjustment and test by spinning the wheel - it should stop within 1.5 revolutions.
3. Once 1st side is adjusted, you must remove its wheel and drum.
4. Reinstall drum and wheel on new side to be tested.
5. Make your adjustment and test by spinning the wheel - it should stop within 1.5 revolutions.
6. Once BOTH sides have been adjusted, re-install drum and wheel and torque lugs