Brake Drums/disk brakes

[JeffR]

Has anyone converted drums to disk brakes?  I've been looking on-line for a kit or other advise but have not had much success.

[Doug&Deb]

I used a Scarebird kit on my 52 Coronet. Check the search feature on the forum. There are several threads on the subject. 

[Loren]

Before you pick up a wrench, do your homework on this site.

I draw your attention to "Educate me on wheels and tires (Hubs and axles)" by RacerX 20th of November. It's about three pages in.

When you think you can avoid all the potential pitfalls of such a project then race on and report back to us.

Besides I believe you're asking in regards to a pickup, you might want to ask in the pickup forum.

[Merle Coggins]

I used a Rusty Hope kit to convert my front brakes. 

[JeffR]

Thanks for the feed back.....my pic shows the vehicle, but a good point on pickup.....

[bamfordsgarage]

1 hour ago, JeffR said:

Has anyone converted drums to disk brakes? 

Are you having problems with your current setup?

[Sniper]

I am in the middle of a Rusty Hope swap.  Everything is installed, just need to bleed the brakes and test them.

 

Not overly impressed with the swap engineering and especially the instructions. To be honest I really wish I had gone another route myself, see link.

 

 

[JeffR]

Brakes are very weak when I press on the pedal.  I’ve rebuilt the existing system. I may need to try to bleed them again?

[Doug&Deb]

Bleeding them is best done with two people. Also without the proper adjustment tool they don’t always work as well as they should. Properly adjusted these brakes were better than most other cars. 

[Adam H P15 D30]

Rusty Hope kit and remove the check valve from the master cylinder. No problems, no pitfalls. I even used my factory 15” wheels for a while, other kits, not so. 
 

[Sam Buchanan]

2 hours ago, JeffR said:

Brakes are very weak when I press on the pedal.  I’ve rebuilt the existing system. I may need to try to bleed them again?

 

"Very weak" compared to what? Yes, they may feel 'weak' compared to the light touch required with modern power assisted brakes. But properly adjusted (but you have to know the proper technique!) the brakes shouldn't cause any concern if you use a firm foot and drive at speeds our car's engineers intended. 

[JeffR]

Weak.  As in you feel like your not going to stop.  This is from 25 mph and to come to a stop takes great effort on the pedal.  

[Veemoney]

Sounds like you may have some air in the line or the MC. Also make sure you have the rears adjusted out correctly.

[Racer-X-]

Bleeding again may help.  When a car is a problem for me, I will often do a "gravity bleed" which can be done by a single person with a lot of time on their hands.  Top up the reservoir, open the bleed screw on the furthest wheel cylinder (generally right rear), and just let the fluid drip through the hose until you see clear fluid with no air.  Generally, I set a timer on my phone for 10 minutes and come back to it to check then.  Repeat at the other wheel cylinders, and be sure to keep the master cylinder reservoir topped up.

 

Also, did you replace the "residual pressure valve" when you "rebuilt" the system?   Sometimes that's incorporated into a big block called a "combination valve" which also includes a proportioning valve for the rear circuit. If the system isn't holding some residual pressure, the springs will pull the brake shoes back, and you'll have a very long pedal and may not get full braking even at full stroke.

 

Finally, did you turn your drums and use fresh new shoes, fresh out of the box?  That usually results in poor performance.  A lot of times, with front disc/rear drum setups, you don't notice how bad the rear brakes are when you do that.  But with drums on all 4 corners, it becomes evident quickly.  The shoes have to be "arced" to match the drums if the drums have been turned.  The radius of the inside of the drum is measured, and the outer surface of the shoes are machined to match that radius.  Without doing this, the new shoes will make contact with the larger radius at only one small patch instead of along the whole length.  They'll eventually wear in and make full contact, but that can take a while.  And they may glaze where they are making contact and that can cause more problems over time.

 

If you can't find someone to arc the shoes, it's best to just always use new drums with new shoes, and then check that the new shoe makes full contact with the new drum.  If the drum is too tight (too small a radius), the shoe will only contact at the end.  If the drum is too loose (to large a radius), the shoe will only contact at one point, and you can "rock" it back and forth a little and the contact point will move as you rock the shoe, like a rocking chair.

 

If you can deal with a little down time, I find the best results are to send the old shoes and drums to someone who can reline the shoes, machine the drums, and arc the shoes to match.  Any place that relines shoes has to have the equipment to arc them properly.  If they have your drums, they'll be able to make them match exactly.  Or they can match the shoes exactly to new drums they ship you with the shoes.

[Sniper]

In order to do a gravity bleed your master cylinder has to be about the wheel cylinders, something not applicable to the stock braking system.

 

All drum brake systems do not use proportioning valves and in the case of the residual pressure valve, it's part of the master cylinder in the stock braking system.

[ratfinkxxx]

I just received my kit from TSM Mfg. Have not started the install. These kits use the original hubs.

https://www.tsmmfg.net/

[greg g]

Do you have the proper amount of free play in the brake pedal at thr top of its stroke?  If I recall it's around 1 1/2 inch.

[blucarsdn]

I really wonder if there is any advantage (s) to converting a vintage vehicle brake system to disk brakes in lieu of a properly maintained drum brake system? I have two vehicles, a '37 GMC 1/2 ton and my '39 Plym conv coupe. In both cases the brake conversions were done as part of a total upgrade to the vehicle suspension, power-train and engine.

I converted my 37 GMC to a large late model 150 hp 6 cylinder with a automatic trans, rack/pinion steering was a must. My '39 Plym conv was a Montana car that had been pounded across rural gravel roads, the frame and front cross member that broken and been repaired twice. I wanted a safe reliable highway car that could cruise at modern speeds, so I did a Rest-O-Mod on the car adding power rack-pinion steering, disk brakes, AC, Cruise, PW's etc.

I recently purchased a '53 Olds Super 88, an unmolested car that needs a lot of TLC. The '53 Olds super 88's were very fast reliable vehicles. I had one from 1954-58, that is why I bought the '53 i have now. We just finished doing a complete brake job, new stock cooling system. The only deviation from stock was the addition of an HEI ignition. The Oldsmobiles of the  '50's were well engineered, reliable cars, they would run all day long at 90 plus with no problems. If it ain't broke don't fix it.

The people that I have known that attempted to convert their brakes to disk, started off a whole chain of events that resulted in a vehicle that was unreliable and unsafe. Wm

[Sniper]

there is a reason no one uses front drum brakes anymore. 

 

 

[Doug&Deb]

There are many reasons owners convert to discs. In my case an out of round drum at the limit of being cut and the price of an NOS one. I prefer originality but financially it was cheaper to convert. 

[Bryan]

1 hour ago, Doug&Deb said:

There are many reasons owners convert to discs. In my case an out of round drum at the limit of being cut and the price of an NOS one. I prefer originality but financially it was cheaper to convert. 

That's what happened to me when I popped my exhaust manifold in half. Would love to keep it original, but Ebay prices for another possibly weak manifold turned me off.  Spend another $100 and get a new part.  

[OUTFXD]

a

Edited December 11, 2021 by OUTFXD

[soth122003]

IMHO the 2 biggest reasons to convert to disk brakes were and are speed and terrain and weather and terrain. With the advent of faster cars the drum effectiveness were reduced by lack of heat dissapation. Add in hilly or mountainess terrain and accidents happen. Same for wet brakes. Drum brakes when wet don't work very well. The disk brakes were a solution to both problems. They bleed of heat very well and the water does not negatively impact the brake pads and disks vs the brake shoes and drums which kinda trap the water.

 

Now if you  want to drive your vintage car at modern speeds in all kinds of terrain, more power to you, and switch to disks. But as we age most of us tend to slow down and enjoy the drive. These cars were designed during the era of 40-50 mph speeds as well as two lane black top and the drum brakes work great for that. 60-80 mph with the cell phone whackos on the road get the disks.

 

Joe Lee

[kencombs]

First let me say, I will be installing disks on the front.  At least that is my intention as of this minute. 

 

But, remembering the time when my truck (56 Dodge, low bed side, 230) was in use the non-interstate speeds where not much different than today.  55 nighttime, 65 daytime on almost all state highways.  Lower on county and city of course.   The only difference now is that some state roads are 70mph and many more vehicles.  And the roads without exception are much better that back then.  Wider smoother, less grade change, more gradual curves, actual shoulders available almost everywhere.  I live just a few hundred feet off of the original rt66 and in some places nearby I can see and drive on the 30s concrete.  Barely enough room for two modern pickups to pass.

 

So, IMO, originals would be perfectly adequate for everything but interstates or high speed urban traffic.  But, it is cheaper for me to put disks on the front with a modern master cylinder than find drums, get shoes relined and do the needed master and wheel cylinder repairs. 

 

Since I'll be using the original rear end, with an A833OD, I'll need to solve the hand brake issue.

[sidevalvepete]

On 12/12/2021 at 8:13 AM, blucarsdn said:

 

 

Edited December 13, 2021 by sidevalvepete