Power/Manual Brakes?

-
MuuMuu101

MuuMuu101

Well-Known Member
Joined
Jul 6, 2012
Messages
1,919
Reaction score
312
Location
MidWest
I'm stuck on the fence on what I should put in my 1968 Dart GT with Kelsey Hayes discs in the front and 10" drums in the rear. I used to have a GM aftermarket PB unit on there but took it out because it was a cobbled up mess. Now trying to fix the problem I have half my friends telling me to go power and the other half telling me to go manual. I currently have a new NAPA MC for a 1980 Dodge Aspen in my possession and was thinking about just fabbing mounts to throw that in there. However, an old auto tech from work is telling me to just go back to power brakes (more pricey) and fix it close to stock. I do plan on going to front and read discs within the next year or two. I need some more input from the specialists. Thank you! :D
 
I don't think you can go four wheel dics without going power but I might be wrong.
 
Power just makes the pedal easier to push. You will need a different mc when you convert to 4 wheel disc, so do the bare minimum to get by for now.
 
manual brakes with the KH front disks work just fine. personally i always pull the booster. i like the peddle feel better and one less place to get a vacume leak

1968dartman said:
I don't think you can go four wheel dics without going power but I might be wrong.
Click to expand...
yes you can

5.7 hemi said:
...You will need a different mc when you convert to 4 wheel disc...
Click to expand...
no you don't. you need to remove the residual valve from the disc/drum MC and you'll be happier with an adjustable portioning valve. the stock one won't have very good bias under hard braking. of course brake size, pad material, tires and suspension all affect how well it all works :yawinkle:

good luck
 
The thing is, it is the diameter of the bore in the MC that determines the pedal effort -- a larger bore makes a stiffer pedal with shorter stroke, a smaller bore makes for less effort but a longer stroke. The weird thing is, on A-bodies, Mopar supplied a smaller bore MC with power brakes (15/16), and a bigger bore MC (1-1/16, IIRC) with manual brakes -- the opposite of what you might think would be logical. So the factory manual disk brakes require pretty hefty pedal effort, but the feel is great. If you just remove the vacuum unit from the power brake MC, it works fine, and is still less pedal effort than the factory manual setup -- many people recommend this MC for that reason.
 
I don't have any studs to deal with to use a converter. With regards to bore. They should roughly be the same. The Kelsey Hayes bore was 1" per the service manual and this one is 1.03". My old MC on the aftermarket unit was leaking and hacked up a little like the rest of the car so I'd rather not use it.

Here's what I'm dealing with regarding to the firewall...
IMAG0995_zps0ee6f500.jpg
 
Why not get some steel plate to re-inforce that opening and make it stronger if you cannot get a new piece welded in.
 
srduster340 said:
Why not get some steel plate to re-inforce that opening and make it stronger if you cannot get a new piece welded in.
Click to expand...

That's what a friend and I were thinkingon doing essentially. Just reinforcing that spot and fabbing some new mounting studs for the MC I already have to sit on.

Here's Dr. Diff's panel...
7420378-IMG_1872Medium.jpg


I believe he sells the panel and an aluminum MC for $90.

If I go manual, I need to get the pushrod from him anyways, but I'm just thinking that I should work with what I've got for now, assuming the MC would cooperate with the brakes.
 
I recently rebuilt manual KH disks and 10 rear drums on my 1967 Dart. They feel great, and stop the car well without a lot of effort. I wouldn’t add a power booster, it is not needed in these light cars.

I can tell you this; if a few pistons are stuck in KH disk brakes, the pedal becomes real hard requiring a lot of effort and loooong stopping distances.
 
wjajr said:
I recently rebuilt manual KH disks and 10 rear drums on my 1967 Dart. They feel great, and stop the car well without a lot of effort. I wouldn’t add a power booster, it is not needed in these light cars.

I can tell you this; if a few pistons are stuck in KH disk brakes, the pedal becomes real hard requiring a lot of effort and loooong stopping distances.
Click to expand...

I haven't even taken the wheel off to check the front discs yet. However, I took apart my rear drums. Shoes look great and I'm in the process of replacing wheel cylinders.

But just checking to make sure, the I have MC should be good, right?
 
If it is designed for front disk/rear drum, and mounts on four studs your good to go. The later master cylinders have larger fluid capacity than the early dual circuit master cylinders. Be sure to beef up the fire wall where MC mounts.


If the new MC you have is an aluminum two bolt, plastic fluid tank type, you will need to fab up something to hang it off the fire wall. There are four to two bolt adapter plates for sale, but you may as well just fab up something where the four studs are missing.
 
wjajr said:
If it is designed for front disk/rear drum, and mounts on four studs your good to go. The later master cylinders have larger fluid capacity than the early dual circuit master cylinders. Be sure to beef up the fire wall where MC mounts.


If the new MC you have is an aluminum two bolt, plastic fluid tank type, you will need to fab up something to hang it off the fire wall. There are four to two bolt adapter plates for sale, but you may as well just fab up something where the four studs are missing.
Click to expand...

I'm leaning more towards just fabbing something up but if I decide to get Dr. Diff plate I'd use the adapter.

It's a two bolt and I found the mount this morning. http://arengineering.com/products/master-cylinder-adapter-no-studs/
 
It looks like you already have 2 holes drilled for a later 2-hole aluminum MC. That is what I did for a manual MC in my 64 Valiant. I just used a big washer to cover the opening. I wouldn't fool with welding a plate to the firewall. Just wirewheel the rust off and paint. The pedal load is mostly taken by the brake bracket under the dash. If you use DOT 5 brake fluid (silicone), your paint won't disappear again.
 
BillGrissom said:
It looks like you already have 2 holes drilled for a later 2-hole aluminum MC. That is what I did for a manual MC in my 64 Valiant. I just used a big washer to cover the opening. I wouldn't fool with welding a plate to the firewall. Just wirewheel the rust off and paint. The pedal load is mostly taken by the brake bracket under the dash. If you use DOT 5 brake fluid (silicone), your paint won't disappear again.
Click to expand...

Which reminds me... This is how the brake pedal bracket looks... :banghead: Would you still say it has enough structural integrity?

IMAG1003_zps97915d5b.jpg
 
Mc size is dependent on the wheel cylinder size and caliper bore size/amount of pistons. So if you use a 6 piston caliper in front and 4 in the rear, mc bore size will be different than a single cylinder front and drum brake cylinder in the rear.....double check if ya need to with dr. diff, wilwood, etc.
 
I think with a 4 wheel disc setup a larger bore mc may be needed. I would check with wilwood and see what they say.
 
5.7 hemi said:
I think with a 4 wheel disc setup a larger bore mc may be needed. I would check with wilwood and see what they say.
Click to expand...

I'm not at the point for 4 wheel discs just yet. I just want to make sure my MC will work with the KH discs and 10" drums I've currently got. The MC will be replaced when I got to 4 wheel discs.
 
That will work just fine.
 
I see no mention of Pedal Ratio.Cars with manual brakes have a larger PR then power brake cars.


As for the 4-2 bolt adapter, I always cut the mounting pad of an old MC, grind it flush, enlarge the center hole and drill two extra holes in the plate. Use the new MC as a template.
 
BigBlockMopar said:
I see no mention of Pedal Ratio.Cars with manual brakes have a larger PR then power brake cars.


As for the 4-2 bolt adapter, I always cut the mounting pad of an old MC, grind it flush, enlarge the center hole and drill two extra holes in the plate. Use the new MC as a template.
Click to expand...

Well, did Dodge offer a longer pedal for manual disc cars back then? All the larger pedal ratio will due in my case is make it easier to push the brake pedal down (essentially applying less force), correct?
 
MuuMuu101 said:
Which reminds me... This is how the brake pedal bracket looks... :banghead: Would you still say it has enough structural integrity?
Click to expand...
Doesn't look bad to me. You should see what some from the rusty north look like. I would remove it and paint it, as I did with all mine, since the factory didn't appear to bother with paint. Given the cuts, I would add a backer plate to the MC bolts. It looks like the existing 2 holes aren't quite centered but might be close enough. You could drill new ones or rat-tail file them. 2 to 4 bolt adapter plates cost ~$45, but I recall that some people had to fab a longer push-rod for those, but maybe that was because they were using a power brake push-rod.
 
You must log in or register to reply here.
-

Back
Top