Disk Brake conversion not working

[jd2ksilver]

The question that is going on here is.... "disk brake conversion not working" ...if you review the picture (s) supplied with the original question, you will note that the fellow is trying to use a stock type, single chambered master cylinder with what looks like shade tree engineering to upgrade his braking system.
Bill

Bill;
I did not see any pictures supplied with the original question. The only pictures I see are the ones I posted in response to the original question. I guess I must be the fellow using the stock type original single chambered master cylinder installed with what looks like shade tree enginnering. However I must state that my disc brakes work well (much better than the originals in my opinion) and have worked well sense the day I installed them over two years ago. First thing I did once the disc conversion was completed was a front end alignment and everything alignment wise is well within spec. Aside from the safety improvements this upgrade acomplished I can now go into any bubble pack auto parts store and purchase any components required to make repairs on the road. I am currently working about 250 miles from home on a two week temporary assignment in Atlanta, Georgia. I drove my Plymouth and feel comfortable driving in the Atlanta traffic. I know, understand, and respect that this POC forum is dedicated to the original preservation of the Plymouth automobile. But I feel that any safety upgrades to make these cars more drivable as daily transportation (as they were originally designed) should be a fair topic of discussion on this forum.
Don Coatney

I have front disc brakes with the original master cylinder also.  They work great.  The brakes improve the drivability of my car at least. 

[48ply]

52PLYM, Don't know whose conversion you are using or what your knowledge of the braking system is, but you?might find some interesting reading at this site.
http://www.ecihotrodbrakes.com/brake_facts.html

[Don Coatney]

The question that is going on here is.... "disk brake conversion not working" ...if you review the picture (s) supplied with the original question, you will note that the fellow is trying to use a stock type, single chambered master cylinder with what looks like shade tree engineering to upgrade his braking system.
Bill

Bill;
I did not see any pictures supplied with the original question. The only pictures I see are the ones I posted in response to the original question. I guess I must be the fellow using the stock type original single chambered master cylinder installed with what looks like shade tree enginnering. However I must state that my disc brakes work well (much better than the originals in my opinion) and have worked well sense the day I installed them over two years ago. First thing I did once the disc conversion was completed was a front end alignment and everything alignment wise is well within spec. Aside from the safety improvements this upgrade acomplished I can now go into any bubble pack auto parts store and purchase any components required to make repairs on the road. I am currently working about 250 miles from home on a two week temporary assignment in Atlanta, Georgia. I drove my Plymouth and feel comfortable driving in the Atlanta traffic. I know, understand, and respect that this POC forum is dedicated to the original preservation of the Plymouth automobile. But I feel that any safety upgrades to make these cars more drivable as daily transportation (as they were originally designed) should be a fair topic of discussion on this forum.
Don Coatney

[32cabrio]

Hi Bill, Please expand on your comment re: needing to change the castor/camber on some cars when changing to disc brake system. I've done two of these conversions so far, albeit on Fords, but have never had to alter the castor/camber settings and never had a problem with handling, braking or tire wear. I'm not saying you're not correct, I just haven't heard of this before. Thanks.

[Wm Steed]

It maybe true that disk brakes in some applications don't need a power assit, however, what/when was the last facory  application you have seen that did not have power assit.
The question that is going on here is.... "disk brake conversion not working" ...if you review the picture (s) supplied with the original question, you will note that the fellow is trying to use a stock type, single chambered master cylinder with what looks like shade tree engineering to upgrade his braking system.

There is another point to a disk brake conversion problem that most people overlook. The geometry for a disk brake front end is different from a drum brake. I can't remember the exact numbers for the caster/camber differences, I guess I could look it up, but not just right now, in any case corrections have to be made, which can not be made on some fixed point front ends....Bill

[tedsweet]

disc brakes do not require a power assist.

[Wm Steed]

I think you are going to find that you have several problems why your disk brake conversion is not working correctly.
For starters..... disk brakes require a power assist and a larger master cyliinder with a proportioning  valve to equalize the pressure between the drum and disk brakes. If the master cylinder is mounted low on the frame a residual valve must be used in the system to stop the fluid from draining back from the disk brakes on the front into the master cylinder.

Upgrading any mechanical component on old cars usually sets off a whole chain of events which the average shade three mechanic is not prepared to deal with, that is why it is wise to convert  the whole system, be it an engine for more power or the brakes to stop the thing.

Think about this before you modify your vehicle...
If you are involved in an accident and there is bodily injury, will your shade tree engineering stand up to the legal onslot that will follow the accident?  Hmmmm ??? ....Bill

[Don Coatney]

I recently installed disk brakes on the front of my '52 Belv.? After careful bleeding, adjusting, etc., my pedal travels to within an inch of the floor before the brakes are applied.? According to info from others, the problem is that the "juice" is not being applied correctly with the disks in front and the drums in rear.? I do not want to redo the braking system ie. master cylinder etc.

Apparently, I need a proportioning valve, but I can't find one to fit the old master cylinder system.? Does anyone have any suggestions ?

Please email me.

Suggest you post your question on the P-15, D-24 forum at

http://merc583.addr.com/cgi-bin/webbbs/webbbs_config.pl?#151200

First fill out a profile on that forum so everyone knows a bit about you and your car. Several folks that frequent that forum have done the conversion. You need to install residual valves in your brake lines as has been mentioned. The original master cylinder will work well once you do this. I have installed disc brakes on my P-15 and I recommend this up-grade. This up-grade can be completed for less money than the eBay cost of the Ammco brake adjusting tool that is required to correctly adjust the factory brakes.
Don Coatney

[Joel Nystrom]

In my experience,  a proportioning valve does not affect pedal travel. It affects the front to rear brake bias.

I do not know if you swapped master cylinders or not, but when swapping from drums to discs you normally use a MC with a larger bore.

Good luck. :)

[jd2ksilver]

I have front discs also.  I have the red, and blue valves, but to be honest, I am not sure which goes where.  I can take a pic later and post it, but you should be able to google it.  Mine were from Plydo.  And you should be able to cut into the lines no problem.

[52plym]

I recently installed disk brakes on the front of my '52 Belv.? After careful bleeding, adjusting, etc., my pedal travels to within an inch of the floor before the brakes are applied.? According to info from others, the problem is that the "juice" is not being applied correctly with the disks in front and the drums in rear.? I do not want to redo the braking system ie. master cylinder etc.

Apparently, I need a proportioning valve, but I can't find one to fit the old master cylinder system.? Does anyone have any suggestions ?

Please email me.