Power Brake Booster Replacement

Justwondering

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87 Chrysler Fifth Avenue

Symptom: engine dies when using the brake at stop sign

History:
After replacing the inner and outer tie rods, tie rod sleeves, and idler arm, I took the car to the mechanic to have him backstop me and check my work. I also gave him the pittman arm to replace as well as described the 'failure to thrive' at stop signs. lol

His verdict echoed those folks on the forum - vacuum leak; however, he checked it over carefully and diagnosed the problem as a brake booster problem.

I ordered the replacement power brake booster and a new check valve.

FIRST MISTAKE:
Replacement brake boosters come with new check valves. Don't buy an extra one.

Now where is that pesky brake booster?
Open the hood. Stand in front of the car and look to the right side fire wall. You'll see a large round, chunky, circular metal bisquit.

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1. Remove the negative lead off the battery.
2. Remove the 2 nuts keeping the master cylinder on the power brake booster.

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Justwondering

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Here is the new brake booster.
IMG_6089.jpg


And here are the service manual directions:
IMG_6090.jpg


The brake booster has 4 threaded studs that go through the firewall.
You have to get the nuts off the studs so you can pull the brake booster off the firewall.

Maybe if you had a hoist, you could get the car up high enough that you could stand and reach your hands up to get to the nuts.

My method was to to open the hood (for light and air flow).
Open the driver's side door for air and light.
Go over to the passenger door, open it and lay down on your back across the seat.

ooch over far enough to take your right leg and hang it over the low area between the seats and bend your knee. You are using this leg to keep you from falling on your head.

Bend to the side and put your head and arms/hands in the floor board below the steering wheel.

you'll now be laying upside down across the seats but you'll be able to look up underneath the dash towards the firewall.

Use a flashlight so you'll be able to see.

MISTAKE 2:
Check to make sure the batteries are fully charged in the flashlight. It is a royal pain to get in just the right position and start removing the first nut only to have the light fail.
 

Justwondering

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I finally settled on a ratchet, my longest (10 inch extender), the adapter that goes at a funky angle, and a deep 1/2 inch socket.
Most of the time I was using my left hand because there are just enough items under there to block your right hand/arm (steering column, lines, brake pedal, etc.).
Yuck.

This is not a hard or complex job.
But due to the location of the nuts back up under the dash, it is not a fun task given how you have to pretzel yourself to get them out.

IMG_6105.jpg

With the nuts off, you can start 'worrying' or rocking the power brake booster out.

BE CAREFUL and mindful of the master cylinder.
You don't want to lose fluid out of the master cylinder, because the fluid feed the brake lines. Air in the brake lines is not good and requires more of your tie to bleed the lines to remove the air.

you don't want to crimp one of the brake lines coming out of the master cylinder.
BE CAREFUL.

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Be persistent, be patient.

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Finally it will release from the firewall.
 

Justwondering

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At this point, I managed to blow through 45 minutes trying various ways to 'rotate' the linkage to get the dang thing out.

Rotate to me is in a circular axis.
There is no amount of 'rotation' that will let this come out.

Pivot to me is in a front and back axis.
You want to be under the dash and pivot the long bar of the linkage towards the back seat.
This will reduce the 'footprint' or 'profile' needed to pull/push it through the hole in firewall.

I had to use a large, long screwdriver to hold the linkage in position.
If I pushed it up high enough to overcome the weight of gravity, the linkage would hang on the backside of the firewall when I tried to pull it through.
If I let it hang down, then the weight of gravity pulled the linkage into too large a profile to feed through the hole.

So I propped it in place with the screwdriver while I went to the engine compartment and finagled it out.
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Linkage position to get it to fit through the firewall. Bar is on top. Remember to pivot.

In this picture you can see the top of the faded orange screwdriver handle.
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Its out!
 
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Justwondering

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Reuse the gasket from the old one.
I wanted to also have some gasket around the studs.

Its closed cell foam and I didn't have anything around here like that... or so I thought.

But closer examination of the electrical box led me to an insert to use around sockets to slow down air flow:
IMG_6120.jpg

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Make an 'x' cut so it will slide over the studs without ripping.
 

Justwondering

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MISTAKE 3:
Pay attention to the orientation of the linkage before you put it back in the hole in the firewall. I didn't. So the long bar of the linkage was hanging down rather than being on top.
Once that happens, there is not enough room between the bracket and the brake pedal to reorient it.
You have to pull the booster out again and reorient the linkage and then put it back through.

MISTAKE 4:
DO NOT RUN THE NUTS DOWN ON THE STUDS until you check to see if the linkage is in proper alignment.
I ran the bolts down and then realized I couldn't reorient things without taking all 4 nuts loose again. My arms were tired, my back was tired, and I was totally disgusted with myself.

At this point, I simply laid back and took in a pretty, calming view.
IMG_6127.jpg
 

Justwondering

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Different linkage orientation.
This is the correct orientation. Bar on top. You'll can 'pivot' the bar towards the brake booster or like it is shown 'away' from the booster. But the bar is 'on top'
IMG_6132.jpg


This is the WRONG orientation. The bar is on the bottom. Bar needs to be on the top for this to line up with the hole/pin in the brake pedal.
IMG_6130.jpg
 

Justwondering

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Very pretty when its all done.

MISTAKE 5.
Don't forget to put the bracket back on the left side of the stud before you run down the nut on the master cylinder.
I'll have to go out tomorrow morning and do that. Dang it.

Putting everything back is just the reverse order of taking it off.
I did replace the metal clip holding the bigger vacuum line -- just used a screw clamp.

MISTAKE 6.
Do not let the metal clip (which held the smaller pin), don't let that metal clip lay on the floorboard while your head/hair is on the floor. In my case (long hair), somehow the clip managed to get in my hair, I didn't notice it and wasted another 20 minutes looking for it.
Finally, I went over to ask my husband to see if he could find it for me.
He smiled and said sure, reached up and gently pulled it out of my hair.
He's a great guy, waited to bust out laughing until I was back in the car. lol

In general, the project took me a long time because the directions said rotate and I wasn't creative enough to realize what they meant. Pivot would definitely made more sense to me.
I also didn't 'test' my work as I went before I commited to tightening things.
Generally that meant I did things at least twice.

But, it is doable and I learned a lot. :)
 

jasperjacko

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Of all the work I've done on my car, r&r the booster was one of my least favorites. I removed the seat to make room for 200 and none of your business pounds.
 

brotherGood

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Yeah, I left my seat in..that royally sucked. But I was so pumped about what I paid for my booster and master cylinder, I got over it.
 

Master M

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That is one heck of a beautiful watermelon. Besides that scrumptious watermelon, you take extremely nice pictures and outline a lot of do's and don'ts. Great Job !!
 

BudW

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There is three things I might have done differently.

First, is to remove the plastic knee booster.
It makes seeing what you are doing a lot easier. It won’t make the wrenching much easier but at least seeing what you are doing makes it mentally easier.

Second, is to give the (what appears to be) bare metal booster a paint job first. In a few years, it might not have the same patina as it has today.

Third is to get a cheap magnetic dish to put your fasteners into. It keeps them from growing legs as well as all together in one location. I have one that will stick to the metal floor board and works great.
Dish.jpg


Great job and pictures. I’m proud of you!
(Except for not sharing the watermelon . . .)

Edit: I would like to see this moved and sticked to the "Chassis, Suspension and Wheel’s” section.
 

Justwondering

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Bud --
I appreciate your kind words!

What would you have painted it with? I have no experience with painting metal, only painting fiberglass.

The knee bolster removal - smack my head Doh! Great Idea.

I definitely need to get the magnetic tray.
 

BudW

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I would have gotten a cheap can of gloss black rattle can paint and given it a quick coat or two.

Note: I purchased a pair of new brake boosters, for my big block conversions.
The large diameter booster you have fits into the same spot the engine wants go into, so you have to either toss the booster, or get a smaller diameter one.

I have a small diameter booster that looks like came from same company (looks identical to yours, except smaller).
Also I purchased another booster that I’m not happy about for other car. It is the orange/gold metal coating color to it and I just don’t like the way it looks (not the color (which I can paint over), but the overall design of it. It just doesn’t look factory.
 

Justwondering

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Whats inside one of these boosters?
I'm sending my old one in to get the core money or I'd take it apart.
 

Justwondering

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Also,
On the old booster there were to spigots for the check valve.
On the new booster there are three.
I hooked up the two hoses and just left the cap that came with it on the third spigot.
 
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