1957 rough idle when applying the brakes

[Mike Geary]

Hi gang, here's another one for you, my 57 runs smoothly and idles well but when I apply the power brakes, the idle raises several hundred rpms and the engine runs a little rough. I would guess it has to do with vacuum but there doesn't appear to be any vacuum leak. Any suggestions out there? Mike

This page contains affiliate links for which I may be compensated. As an eBay Partner, and Amazon Associate I may be compensated if you make a purchase at no cost to you.

 

[Dick Rupp]

Hi gang, here's another one for you, my 57 runs smoothly and idles well but when I apply the power brakes, the idle raises several hundred rpms and the engine runs a little ruff. I would guess it has to do with vacuum but there doesn't appear to be any vacuum leak. Any suggestions out there? Mike

Mike, if you have power brakes check the power brake booster and hose. Listen for an air leak when you push the brake pedal

 

[Wilding]

Air is leaking thru the booster canister and into your intake manifold, leaning out the mixture, thus the RPM increase and rough idle. It's probably the seal that closes off the vacuum to the atmospheric side but it could also be a leak in the main diaphragm. Should be an easy fix once you find the source.

 

[Mike Geary]

Air is leaking thru the booster canister and into your intake manifold, leaning out the mixture, thus the RPM increase and rough idle. It's probably the seal that closes off the vacuum to the atmospheric side but it could also be a leak in the main diaphragm. Should be an easy fix once you find the source.

I'm a little lost, are there rebuild kits for the boosters? Could you elaborate a little more on that please? Mike

 

[Wilding]

Yes, you can buy rebuild kits and in some cases individual parts to fix a problem. Take the booster apart and see what parts you'll need. If the main diaphragm is bad you can tell right away. If it's not then replace the seals (they'll be part of a rebuild kit) and any other parts that look tired and you should be good to go. No need to replace to whole unit unless it's worn out, or if you don't want to rebuild it yourself you can get a rebuilt unit on an exchange basis.

 

[Mike Geary]

Yes, you can buy rebuild kits and in some cases individual parts to fix a problem. Take the booster apart and see what parts you'll need. If the main diaphragm is bad you can tell right away. If it's not then replace the seals (they'll be part of a rebuild kit) and any other parts that look tired and you should be good to go. No need to replace to whole unit unless it's worn out, or if you don't want to rebuild it yourself you can get a rebuilt unit on an exchange basis.

One last question, who sells the rebuild kits? I've only had this Thunderbird for several months and it's entirely a learning experience for me. Thanks, Mike

 

[Wilding]

Casco or Hills Thunderbird Center have kits, parts and complete units.

 

[Mike Geary]

One last question, who sells the rebuild kits? I've only had this Thunderbird for several months and it's entirely a learning experience for me. Thanks, Mike

Okay, thank you both forgetting me going in the right direction. Mike

 

[richsfords]

Hi gang, here's another one for you, my 57 runs smoothly and idles well but when I apply the power brakes, the idle raises several hundred rpms and the engine runs a little rough. I would guess it has to do with vacuum but there doesn't appear to be any vacuum leak. Any suggestions out there? Mike

YOU got the answer by now but i would have bet it was something like this. IN MY 1957

 

[OhioTbird]

Mike


In your pic. Please tell us Santa didn't run over Rudolph!

 

[Ward 57]

Mike


In your pic. Please tell us Santa didn't run over Rudolph!

LOL. I can still count the times my shop and me had some expletive's. hopefully not too many more. Glad he caught it. Mine is still original rubber and it's finally giving up. An ongoing process ....

 

[Bob611]

So my two cents, if not hose or check valve that plugs into power booster. Then it would be internal diaphragm, like in Richsfords picture. Again imho I would not attempt rebuilding myself. I just went through this ordeal and used http://boosterdeweyexchange.com for rebuild. No plug, but great workmanship, but be prepared to wait six weeks. Could find videos of his work on YouTube.

 

[cliffcostello]

Mike, I have the same exact problem in the 1957 Thunderbird I recently bought. Was told by my mechanic that it was most likely the booster. What avenue did you pursue with your booster? Did you rebuild yourself, send it out (if so, who and what kind of job did they do?), or did you buy a remanufactured booster?

Since our cruising season is basically over here in upstate NY, this will be one of my Winter projects for this car. Thanks for any info on your experience. Cliff

 

[vernz]

Mike, I have the same exact problem in the 1957 Thunderbird I recently bought. Was told by my mechanic that it was most likely the booster. What avenue did you pursue with your booster? Did you rebuild yourself, send it out (if so, who and what kind of job did they do?), or did you buy a remanufactured booster?

Since our cruising season is basically over here in upstate NY, this will be one of my Winter projects for this car. Thanks for any info on your experience. Cliff

Cliff, Did you ever get your booster sorted out? I just finished rebuilding mine and the (as yet untested) process was pretty easy. BTW, I'm in upstate NY too. Near Saratoga Springs. Vern

 

[Ward 57]

Bought the parts and had a local Classic Mustang shop rebuild my booster & M/C. They also rebuilt my fuel pump. They have a fellow who is a genius. It came out as 1/2 the cost of sending it out.