Brake Booster Checkout

[Zedyone_kenobi]

UPDATE:

I picked up my new (rebuilt) brake booster today. I am going to paint it semigloss when the weather is not as crappy and then get on with the swap. I also picked up a "new" decal for it from MSA today. Yippe. I went ahead and added the rear wheel bearings, seal, and nut while I was at it.

There I go again, with the While I was at It's. haha

FastWoman, thanks for the advice. I will do that. they are only offering me 20 bucks for the core. But I guess that is better than nothing. I am looking forward to seeing how they compare.

[Zedyone_kenobi]

I do have a question though. Behind the master cylinder is diamond shaped bracket. Their are seals between the booster and that bracket and the bracket and the MC. Nobody seems to offer those anymore. Where can I get those?

[ZCurves]

I do have a question though. Behind the master cylinder is diamond shaped bracket. Their are seals between the booster and that bracket and the bracket and the MC. Nobody seems to offer those anymore. Where can I get those?

You could use some gasket material from the parts store and cut out your own, this is assuming the originals were paper (I cannot remember which). You can use RTV to seal.

If they were rubber, you could probably still get by with gasket material and RTV or your could try an new bicycle inner tube sliced open and laid flat -then cut out to shape.

Either way it will never be seen once it is installed. I know that you are a purist;), which I admire -so consider this as "as a last resort" advice.

[Zedyone_kenobi]

That is great advice. I think I may have some gasket material around here somewhere! But if not RTV may work fine as well. We will see. I have time to work on it. I finished painting my booster tonight a nice shade of semi gloss. I think it is going to clean up well.

[Zedyone_kenobi]

UPDATE:

Here is my new brake booster painted and with the decal applied. It looks so happy!

I found a little rust on the firewall where the steering rack comes out, so I have to take care of that before I install the MC. I think I will take a shot at shining up the mounting bracket attached to the old booster as well.

I am going to take careful measurements of the length of the fork rod, the amount the push rod sticks out of the old booster, and match it perfectly to the new one. The more measurements the better.

Advice for the new mechanics out there. Anytime you have a old part removed in tack, take lots of measurements and write them down in your car Journal. They can be used for reference later. THe more you measure on a part that was working the better chance you have to duplicate it with the adjustments on the new part.

[Zedyone_kenobi]

I polished up the mounting bracket and moved it from the old unit to the new unit. I did have an issue though. The pushrod that pushes on the master cylinder on the new booster cannot be adjusted to the exact same length as the one I am taking off. I think I am close, say 1/16" to 1/8" close, but It bugs me that it is not the same. I am pretty sure I have enough pedal travel to make it up, but I would have liked it to be identical.

Also, I think the gasket between the mounting bracket and the master cylinder is a dust barrier, and nothing more. There is no seal between the bracket and the booster body. I will probably RTV it up and not worry about it.

[Zedyone_kenobi]

Well there she is. Installed and ready to go. All I can say is WOW. My 2 year old could press the brakes in the car now. It is astonishing what a difference and how easy it is to press the pedal. What a wonderful upgrade. For everybody who has an old booster, this is one hell of a worth while upgrade.

Now the caveats.

There is a little plunger/pushrod that sticks out of the booster that presses into the master cylinder. I took careful measurements of how far this was suppose to stick up past the shiny mounting plate I used as a datum. The threads supplied on the refurbished booster were too short to adjust all the way out where the stock booster was. So I was left about 0.100" short of where I use to be. This would be pedal travel I would have to make up before ANYTHING happens, and since it is so close to the pivot, that 0.100" feel more like 1.5" at the pedal before I get any resistance. But when I do, boy do they come on well.

Also, make sure when you buy a refurbished booster that you make sure the pin that goes through the brake pedal and the fork of the booster will fit. I got mine mounted and spent 10 minutes try to get that damn thing in and low and behold it was too small. I had to drill it out. Just make sure it fits before and save your back some anguish.

Cliff Notes: Was this mod worth doing? Absolutely!!! The cars brakes feel eager to do the task of braking, instead of being mashed into submission. I will look to get some all thread or maybe a bolt and a rounded nut to replace the one I have to get the right distance. But as it is now, I can lock up the rears then the fronts with easily half the effort of before.

Some work we do is not flashy and glorious, but it is the little things that add up to make these car feel like their old selves again!

Edited January 27, 2011 by Zedyone_kenobi

[d240zx2]

92.8% Done...

[LeonV]

But as it is now, I can lock up the rears then the fronts with easily half the effort of before.

If I read that right, your rear wheels lock before your fronts do. This is not good for braking stability nor for maximum braking performance. Your brake balance is off. The fronts should lock first in the highest grip situation that you plan on driving in (dry pavement, stickies tires you will use). Then they will definitely lock first in lower grip situations.

Just FYI...

[Zedyone_kenobi]

Humm, I may need to check into that. It could be that since my pushrod is not going far enough into the master cylinder that I am not getting enough fluid to my front brakes.

I will check this out. Good words of warning.

[Zedyone_kenobi]

92.8% Done...

nah, still 90.5%, but I did redo some door weather stripping while I was add it. You just never know where the next project will come from! THat is why I love older cars!:stupid:

[Zedyone_kenobi]

QUESTION..

According to the factor service manual below:

The pushrod is suppose to be 0.1377" to 0.1575" recessed down form the flange of of the brake booster. Mine was sticking out beyond the flange! I wonder if I am compressing the plunger constantly! I am going to take a mold impression of how much space I have between the push rod and the master cylinder piston! I may have been doing this wrong for a long time. When I took off the previous brake booster, it was sticking out past the flange surface.

The picture in the FSM shows it is suppose to be recessed as well... This is curious.

The pushrod in this pic #2 is not past the flange.

This is what I am going to do.

I am going to remove my Master cylinder.

Insert some modeling clay in hole where the MC piston is. Then I am going to reattach the MC. I will then take it off again and see if the pushrod is actually touching the MC piston at all. This is an interesting problem. I look forward to getting this right!