1956 Thunderbird power brake problem
 

I recently purchased a 1956 Thunderbird that had a frame off restoration finished in 1995. It only had 15k miles since restoration and had been kept in a climate controlled place. I have gone through pretty much the whole car doing maintenance to get to good driving capability. I’m having difficulty with the power brake system. It had a disc front kit upgrade with dual master cylinder and upgrade rear drum cylinders. It doesn’t seem to have any power assist. All four wheels lock up with hard pressure, but there is no lowering of the pedal when starting car. It takes hard pressure on a hard pedal for stopping. It is plumbed correctly according to a diagram I found which has the power only to the front discs. The power system will hold a vacuum overnight. It has a regular brake light switch and no proportion valve.

Does anyone have ideas on what could be wrong? Or what to check. Thank you.

Re: 1956 Thunderbird power brake problem
 

Welcome to my world, I have a 64 and it has the same issues Hopefully we can both learn a lot, thanks for posting

Re: 1956 Thunderbird power brake problem
 

Those old systems are different. The remote booster is probably a Midland, and with a disc conversion only boosts pressure to the front disc. That’s it, it’s how they worked.

There’s no easy way to put a modern booster on an early bird. The hood latches don’t clear. Move the battery to the trunk and the brake pedal over where the clutch would be. Not much help on a manual transmission.

I’m using a hydroboost off the power steering. It’s way light, I wouldn’t recommend it. But I ran a set up probably like yours for years. It’s just how it is.

No idea on a 64. Different style booster, but here’s a link for that

Here’s a link on that question. Read down a bit.


https://forums.fordthunderbirdforum....ter-woes.9893/

https://forums.fordthunderbirdforum....booster.14855/

Re: 1956 Thunderbird power brake problem
 

Thanks for the info and first link. It is a midland and has silicone fluid that I assume has been in since converting to disc. The fluid is purple and very clean in the MC. I’ll make sure that vacuum is sufficient and see if I can hear the diaphragm moving. Should the pedal still drop a little when starting if it’s working? Thanks for any more info. Here’s a photo of the unit.

Re: 1956 Thunderbird power brake problem
 

Hello If you are a member of CTCI club might research it there. Lots of info on early birds. That may be where Miker referred you to.

Re: 1956 Thunderbird power brake problem
 

Find a hill with no one around. Slow the car to 15 mph or so, put it in neutral and shut the engine off. Pump the brakes to use up the vacuum in the booster. Then with the brakes on and the car rolling restart the engine. You’ll feel the boost come in. On my hydro unit it puts you thru the windshield. On the Midland, not so bad.

I learned this by accident pushing the manual choke in too early and leaving my neighborhood down a long hill. Obviously you need to be out there alone, no traffic.

Good call on CTCI, my links just came up at random.

Re: 1956 Thunderbird power brake problem
 

Thanks for the info. Seriously hard to find a hill in the plains of ND. lol.

I’m really interested hearing from someone with a similar set up as me to know how the system reacts when working.

Re: 1956 Thunderbird power brake problem
 

I missed your location. My wife was from Glen Ulin, west of Bismarck. Try coasting down from 60 or so. If you ever drive that slow,

When I had the front disc, Midland, rear drum combo from a major tbird supplier it never felt like a power booster. Not like the big firewall mounted ones.

The one thing I remember is you had to have the rear brakes properly adjusted, or the pedal travel and stopping was terrible. When 1 click on the handbrake helped the braking it was time to crawl under and adjust them.

Re: 1956 Thunderbird power brake problem
 

lol. I live in the Red River valley (really flat). Interesting you mention the hand brake. When I got the car it didn’t do much. All new everything in the drums. So I adjusted them to work great. After about 100 miles they don’t do much. Not sure what the story is there. I’ll continue to mess with the power and see what I come up with. I do all my own work. Have built quite a few cars. Was just hoping someone had some good info on these.

Re: 1956 Thunderbird power brake problem
 

They used to “arc” the shoes to fit the drums. Pretty hard to find anyone who still has that equipped today. But if they aren’t done then your initial adjustment is a small point of contact. It’ll wear off in 100 miles, so it needs another adjustment. It gets more complicated when you turn the drums, etc. But you might ask around, where you are people are less inclined to throw things away. If I’m telling so something you already know, my apologies.

I’d tighten them back up, see what happens. There’s a link here somewhere on the parts to buy to retrofit 57 self adjusters to the rear drums. That really helps.

Re: 1956 Thunderbird power brake problem
 

Thanks for the info. Even at 76 I learn something every day. Keeps a guy going.

Re: 1956 Thunderbird power brake problem
 

Well, I’m 76 also, and I’ve had this bird for 27 years. Most of what I learn seems to come from doing it wrong the first 2 or 3 times. Just trying to save others from my slow learning curve.

Re: 1956 Thunderbird power brake problem
 

I installed disc brakes hoping that would solve the amount of leg pressure needed to stop the car. The discs did not solve the problem they need more pressure than drums. I upgraded my brake booster to a C490. It has a larger vacuum can and the piston is smaller with a longer throw resulting in more pressure.


The C490 was used on trucks (Dodge?), it's very rare and I paid $1,000 for it on eBay.


Expensive but now when I am coming to a stop, I don't have to press the pedal as hard. It works VERY well. Doesn't feel like a modern disc brake but I feel it was worth the cost.


I had to move the battery back an inch or two. Hood clearance using the original bracket was fine

Re: 1956 Thunderbird power brake problem
 

“Rare and expensive”. Maybe so, but the best solution I’ve heard in all the years of living with and reading these complaints. And probably better and cheaper than the hydro boost I ended up with. Nice job.

Re: 1956 Thunderbird power brake problem
 

FYI, the rule of thumb when installing a power brake system (most cars) is that the booster requires at least 16 " of vacuum on a warm engine at idle in gear.

Cars in general:
*a soft pedal squishy, or goes to floor is a bad master cylinder
*a hard pedal is a bad booster

Was this car equipped with power brakes when it left the factory?

Re: 1956 Thunderbird power brake problem
 

jakesbackyard, where did you find this car? 35 years ago baby birds were reasonably priced. Then they went outta sight price wise. Now they are moderating in price A LOT ! I like the 55s the best. I got a shirt for Christmas and it says "just one more car - I promise" Yeah right! LOL

Re: 1956 Thunderbird power brake problem
 

I am following along as my Wife's Christmas Present was a 57 that someone converted the front to disc & while driving on Christmas morning she stated that she would have to work out a bit more as she was having some issues with pushing the pedal down. Unfortunately she had spine surgery due to stage 4 breast cancer that had metastasized to her spine, so she has to work even harder than most to push the pedal!

God Bless
Bill
https://www.jalopyjournal.com/forum/...closed.614419/

Re: 1956 Thunderbird power brake problem
 

jakesbackyard, here a couple links from CTCI about front disc brakes.
Unfortunately they haven't been updated in about 10 years so some of the info and sources for parts may no longer apply.

https://www.ctci.org/gilsgarage/disc-brake-conversion/

https://www.ctci.org/gilsgarage/disc-brake-performance/

Here are three more links.
Casco, Hills and Prestige all specialize in '55/'57 T-Birds with replacement, used original, new reproduction parts and in-house restorations.
Also free phone Tech Support.

https://www.classictbird.com/

https://hillsresto.com/

https://prestigethunderbird.com/

.

Re: 1956 Thunderbird power brake problem
 

This car was a consignment at GR Auto in Michigan. I had sold a custom 49 Ford I had built from scratch and driven for a few years. At 76 I didn’t want to build another car. I wanted a mostly done car to just personalize. Had always wanted a Baby Bird…preferably a 56. This one was the correct everything that I wanted, except I didn’t want the spare and a few other things. I’m pretty much a hot rodder at heart so I wanted to “personalize” it to me yet keep all the goodies for someone down the line to return it to stock if they like. And that I did.

Here’s a link to what I brought home… https://www.grautogallery.com/vehicl...rd-thunderbird

And here’s what it looks like when I took it for its first cruise about a month ago. I know some will cringe at what I did, but it can be put back in about 4 hours.

Re: 1956 Thunderbird power brake problem
 

Do I have to be a member of CTCI in order to see anything. I have tried to go to their sites but they won’t even load.

Re: 1956 Thunderbird power brake problem
 

When I got this car everything had been either replaced or rebuilt when frame off restored on ‘93-‘95. I got 7 totes of used and new parts that were replaced, rebuilt or upgraded. In those parts were a brand new unused large booster vacuum diaphram, a small diaphram and other used rebuild booster parts. It had been converted to dot 5 fluid which is clean and nice. I have 45” vacuum on the main line to the booster. So right now I’m thinking I may just take it apart, look it over, put in new diaphragms and see what happens. The kit to rebuild is crazy priced.

Re: 1956 Thunderbird power brake problem
 

Nice ride. I’ve lays thought the 56 with the Connie kit gone and the dagmar’s was the best look. So I’m no cringing.

Is the 45” a typo? I’m think 15 would be closer.

Re: 1956 Thunderbird power brake problem
 

Haha…a senior moment. Read the wrong side of gauge. It has 18” vacuum.

Has anyone used a VH44 booster which is available real reasonable?

Re: 1956 Thunderbird power brake problem
 

Here’s an old link to the HAMB. I don’t write off stuff just because it’s from overseas. You can read it and draw your own conclusions. But if you’ve got it on hand and can check it out first, worth a shot.

https://www.jalopyjournal.com/forum/...sters.1216131/

Re: 1956 Thunderbird power brake problem
 

Here’s the one I’m trying to find a little more info on…

Re: 1956 Thunderbird power brake problem
 

That’s mentioned in post #4. It appears they’re Chinese replacements for an Australian company no longer making them. Used on factory cars down under. So quality control is always under question. Also some old price comparisons to domestic products.

The real answer is to compare the line pressure from the master to the booster, and then from the booster to the brakes. But that requires a set of gauge and at least a couple t fittings to do it right. Or just dead head it one at a time at full leg pressure. But either way then you get to re bleed everything.

Best of my knowledge Ford didn’t use 2 different pivot ratios off the pedal for power/non power. And there’s no easy way to change that on a bird-no second hole drilled, or much room for it.

Way back when I put a similar system (probably identical) on my bird it didn’t balance very well front/rear. Turned out the front pads were the hard “guaranteed for life” cheap replacements. A softer pad in the front disc made a noticeable difference. More stopping for less pressure. And as I think I mentioned, the rears had to be kept in adjustment.

Re: 1956 Thunderbird power brake problem
 

I see you are using dot 5, I am also on my 64. Could that be the problem

Re: 1956 Thunderbird power brake problem
 

Some say dot 5 is firmer, some say softer. Companies say it should be softer because 5 contains more oxygen. Some say not much difference. It’s anybody’s guess.