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Drum to disc brakes

5K views 26 replies 10 participants last post by  Beechkid 
#1 ·
I recently purchased a 67 Mustang with 289HP and C4 transmission. There has been no modifications done to this vehicles with the exception of replacing the original master cylinder to two chambers and a power boost system installed by the previous owner
Have replaced most common wear things including all fluids and filters. Found the brake system,as expected, to need a lot of work. Brakes were relatively new but I am guessing the guy who did those brakes did not delve far enough into the system. The self-adjustments did not work. Wheel cylinders were leaking and pistons full of crud and moisture. All have been replaced.
Brake lines inspected and in good condition. Replaced all cylinders including hoses and the tee block for the rear are new. Manually adjusted all 4 brakes and then got the self-adjusters working.
Brakes are firm with no leak down after stopping. Brake shoes like new and it didn't appear the the rears were engaging at all when I opened it up. Emergency brake handle would pull all the way out without an resistance so I know they did not work.
Now that everything has been replaced I would like to begin upgrading the brakes and start with replacing the front drum with discs.
Researched a lot on line and find 3 things that confuse me. Some kits come with a proportioning valve and some come with new distribution blocks. Some come without either.
I understand how each work and that the front brakes delivery a larger portion of of the braking.. Will the existing distribution block work on a front disc conversion. I have not changed the distribution block but that is on my list of things to do.
Thanks for the help and sorry if I posted in the wrong area of the forum.
 
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#3 ·
Thanks for the response but I have not bought a front conversion yet. My question was whether I would need a separate proportioning valve to adjust pressures or will a combination proportioning/distribution block work?
I do not need a power booster/master cylinder as a new one was installed before I bought the Mustang
 
#6 ·
With regards to changing out the master brake cylinder with a drum/drum to disc/drum swap....yes and yes you need a proportioning valve assuming you are not using a factory system. but IMHO, the best and least expensive system to use for this (and was the very common one to do) is the 1974 ford maverick master brake cylinder....available in drum/drum, disc/drum & and power disc/drum versions, it's specific for that chassis and works excellent.
 
#8 ·
Thank you for the helpful response Beechkid. :)


According to rockauto, the Maverick part looks something like this for manual front discs
https://www.rockauto.com/en/moreinfo.php?pk=1615884&cc=1132210&jsn=14375


Yes!!!!! This was a very popular upgrade up through the late 70's when the aftermarket started making "kits" with what I considered for the most part to be assembled pieces of anything they could find (for many of the aftermarket companies) or one off components which can't be replaced....and you should be able to get oem disc assembly replacement parts for everything else very easily.....mustangsteve is an excellent resource!!!!!!


https://www.mustangsteve.com/product-category/front-disc-brake-conversion-brackets/
 
#9 ·
I’m running 4 wheel disc brakes (Wilwood) with the stock master cylinder and stock distribution block. I’m not having any issues but the car originally came with front discs ... so it has a dual reservoir mc. I don’t know if the distribution blocks were different from disc vs drums. I’m assuming you wouldn’t need to replace the distribution block. If you do replace, then I would just go with an aftermarket proportioning valve. The proportions valve does the same thing as a metering block so you don’t need both. It’s one or the other. A proportioning valve is far better than the distribution block... especially when you start mixing parts that were never on the car to begin with. As far as brakes go... I’m very happy with Wilwood. I think they offer the best bang for the buck. I feel like the car (69 Mach 1) stops like a modern car now. I did the rear disc conversion but not sure if it was really worth it. The front was definitely worth it.
 
#11 ·
MCC351 I'm glad to hear you're happy with them, as I don't know anyone who has used them and I just ordered the 12" Wilwood rear kit to compliment the no name front disc kit that was in the car when I got it. I pulled the rears apart to find the pads barely worn but everything rusted to pieces and full of cobwebs. I'm assuming this means the car either doesn't have a properly adjusted proportioning valve so the fronts have been doing all the work, which might explain why it feels like I have manual brakes. Booster and dual reservoir look new-ish and appear to be in working order. Did you have to remove the proportioning valve when you added the disc rear? I'm assuming that the pressures would be incorrect if not?
I drove my car 4 times before I ripped it apart (3 years ago) to address numerous issues, then life happened. Finally trying to get back at it.
 
#10 · (Edited)
Wilwood (and some other aftermarket brakes) are excellent, but I always worry about whether I'll be able to get parts for them in the years to come.



Given the choice, I plan to stick with factory-type Ford brakes, but since I am still running 15" rims, I think that makes the most sense anyway.
 
#12 ·
Have been under the hood trying to get this done in addition to shocks and springs.


The master cylinder that I bought off Rockauto, THIS ONE, doesn't fit the compression fittings on the brake lines. They're actually reversed so I'm either going to have to source new brake lines or cut the lines, swap the fittings and flare the ends.


Anyone deal with this and have an easier solution?


Thanks,
Bart
 
#17 ·
One of the lines can be done with only one adapter so I'm going to do that for that one. The other (Going from the 9/16" line fitting to the 7/16" port) can't be done with one adapter so I'm going to cut that one and replace the fitting with the correct size.


no worries
 
#18 ·
if anyone is considering doing this, you might as well plan on changing the brake line that runs from the engine bay to the rear axle. it's $49 in stainless from Classic Tube. mine was rusted through in a couple of spots which made it impossible to bleed the brakes. the brake line is held up by metal clips with no rubber insulator, my brake line has the metal clips fused to it and it's all rusty.


once the brake line gets here I'll be a few days from having it done finally.
 
#19 ·
In case anyone was wondering, it is possible to snake a new front-to-rear brake line in from the engine compartment without removing anything. :)


That was the good news.


Bad news is, I still can't get pressure into the rear brakes and have officially tried everything. I'm wondering if the pushrod from the pedal to the master cylinder is slightly longer with the Maverick cylinder so it isn't returning the piston to it's proper resting place while I'm trying to bleed the brakes. Or the master cylinder is defective, either way I've ordered another so we'll see.


The new fronts on the left side are working well so there's that. :)
 
#21 ·
If you are going to mess with brake systems you need to get a decent flaring tool and learn to use it.

Disk brakes require higher line pressure than drums to get the same deceleration force. That is why power became standard with disks.

You may or may not need a proportioning valve. If you find it is too easy to lock the rears then do something to reduce the pressure. That can also be done with wheel cylinder diameter selection.
 
#23 ·
Hi raydav, thanks for the reply.


I got the new master cylinder in with the original pushrod and the brakes are bled and working again. The forward line got a new flare fitting the first time around and since I had to take it all apart again I put the correct flare nut on the aft line also.


Are you saying that it's going to be hard to stop without power brakes now that there are manual discs on the front?
 
#24 ·
Your car will take more effort at the pedal, but should be easy to modulate, and will have good stopping power, with manual discs. Drums are self-energizing; the pads 'brace' against the spinning drum and help aid whatever hydraulic pressure you give them. Disc brakes self-clean, which makes stops more consistent, keeps braking force more equal from side to side even on cars that do not get regular maintenance. Rust and crud in the drum will never be an issue, and even if they get wet, they don't have problems. However, they take more force to achieve the same braking power.


That's why the manufacturers went to power disc brakes, and typically didn't offer manual ones.
 
#27 ·
In short to what Grim is saying, as long as you provide regular maintenance, you should have no issues with either drum or disc brake systems....non-power systems do take a little more pedal pressure to actuate the brakes but it's nothing that isn't easily learned/recognized and you will get use to very quickly...no different than getting into a Geo from a F150...… it's just a different vehicle with a different brake system and a different feel.
 
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