70 power brake booster help

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bsbeck
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70 power brake booster help

#1

Post by bsbeck » 24 Sep 2018, 09:13

Hey everyone. I got the carb back from my builder (he rebuilt it) but I'm still bogging on take off. I don't think the power brake booster is even working, feels like manual brakes and it's making a loud sucking noise at times. I've traced down all vacuum lines and they are good but the sound comes and goes, especially when hitting the brake pedal.

So, is that part of my bogging issue, cause the brake booster is creating a vacuum leak? I've never replaced a power brake booster so tell me how bad, what to do and not to do and give me all the tips you can.

Also are aftermarket brake booster ok or should I send the original off to get rebuilt? I'm scheduled to go to my first car show in about 3 weeks, so I'm really in a pinch to ship it off for 4 to 6 weeks.
Scott B.

1970 Cougar Eliminator (Competition Blue / Black Comfortweave)
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67429merc
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Re: 70 power brake booster help

#2

Post by 67429merc » 24 Sep 2018, 09:30

You need a booster for sure! Give WCCC a call! They might have one rebuilt and ready ship back to you.The aftermarket boosters a junk! Stock motorcraft carb?
67 standard(my first car) 428 4 speed
68 xr7
69 eliminator
70 eliminator
65 f100
70 mustang convertible
67 vw convertible

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Don Rush
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Re: 70 power brake booster help

#3

Post by Don Rush » 24 Sep 2018, 12:49

Stay away from one time use, Chinese boosters and DO NOT give up your original BENDIX core for a rebuilt until you confirm your are getting a correct booster in exchange. We have economy and premium in stock.

https://secure.cougarpartscatalog.com/s ... booster%20

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bsbeck
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Re: 70 power brake booster help

#4

Post by bsbeck » 24 Sep 2018, 19:34

My stock carb got replaced sometime long ago by someone else. It's an Edelbrock 1407 750 cfm now. I had it rebuilt (off the car) and I'm going to take the car to the guy and let him tune it on the car this week but I'm just wondering the the brake booster is creating a leak that's causing my poor performance? I had someone suggest cap off the vacuum to the brake booster and see if it runs any better. I guess that wouldn't hurt the brakes anymore than they are now. They just feel like manual brakes now.
Scott B.

1970 Cougar Eliminator (Competition Blue / Black Comfortweave)
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bsbeck
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Re: 70 power brake booster help

#5

Post by bsbeck » 24 Sep 2018, 20:36

I looked through about 8 pages of Repairs on here after searching brake booster but don't see any guides or tips. Anybody want to share any????
Scott B.

1970 Cougar Eliminator (Competition Blue / Black Comfortweave)
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hanver
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Re: 70 power brake booster help

#6

Post by hanver » 25 Sep 2018, 04:40

I would advice against driving your car with the vacuumhose to your booster capped off. I had my old booster blow a hole and almost had a crash since the damn brakes were so hard I could not get the car to stop, even with 2 feet on the pedal.
The pedal is much harder to press on a powerbrake car (if the booster fails) than on one with manual brakes
Unless you have a nice wide stretch of road with no traffic, then you might give it a go at your own risk ofcourse :)

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Don Rush
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Re: 70 power brake booster help

#7

Post by Don Rush » 25 Sep 2018, 12:17

One easy test is run your car for a minute, shut it off and return hours later and pull the plastic check valve out. It should give significant resistance and you should hear a loud "whoosh" sound when pulled. If it cannot hold vacuum after parked you have a bad diaphragm.

https://secure.cougarpartscatalog.com/6 ... attribs=87

waterlife
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Location: Marlboro, NJ

Re: 70 power brake booster help

#8

Post by waterlife » 25 Sep 2018, 14:21

Its a tough job, all day and maybe into 2nd day. Pull drivers seat and console out, get a pillow and get cumffy
1970 COUGAR M CODE

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Don Rush
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Re: 70 power brake booster help

#9

Post by Don Rush » 25 Sep 2018, 16:31

Actually... Should be about 3 hours unless things are really rusty. Just know that this bracket is double nutted and will cause grief if you do not know.

https://secure.cougarpartscatalog.com/c ... attribs=87

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bsbeck
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Re: 70 power brake booster help

#10

Post by bsbeck » 25 Sep 2018, 18:04

Seriously? Full day into the 2nd???? I see one screw head on the engine bay side. Can someone outline the steps on a 70? I thought I should see 4 bolts all on the engine bay side and then just unhook from the pedal on the inside....and of course the brake lines. Should I replace the master cylinder too?
Scott B.

1970 Cougar Eliminator (Competition Blue / Black Comfortweave)
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