Also... check that your rod seal is OK (#4 in the picture I posted).

 

When I was talking to the mechanic about if I should try it myself and he said it was just four bolts, I said but then there is also that adjustment between the MC and booster and it needs a special tool to do it, too. So that could be beyond me. (I had seen this article that shows the tool and talks about this when searching initially https://techtalk.mpbrakes.com/how-to...r-cylinder-gap It shows the tool and a video using it.)

He very quickly and clearly said, "Nope. Not on Honda's They do not work like that. There is just the one rod that slides out when you take the old one off and you just slide the new one in. It fits right in how it goes."

I said, "Really? Because I saw that you need to get a special tool,etc and even could mess something up in the MC if the length is incorrect."

He said, "Nope. Don't need it." He has a lot of years experience with foreign car specialty. He seemed to be aware of the tool, etc and just saying on a Honda it is different. So the $200 wasn't about that according to that. I said bleeding is also tricky and he said no need to bleed either.

And that is when I considered trying it since now it was just four bolts (albeit under dash and cramped space) and no special adjustments/tools and no bleeding. All things that seem easy to get wrong compared to just bolts.

Now here the info is that adjustment is needed.....so I am confused. If anyone who has actually done the booster swap sees this and could post from actually seeing it off and putting new one on if the adjustment IS needed on a Honda or for some reason not as mechanic said. I'm not sure why he would have said that and as said he has a lot of experience and with foreign cars and has not been dishonest prior. No disregard for what has been posted here at all- it seems like it makes sense. I am just confused why he would say not needed and it prob will determine if I try it or not.

 

What I posted is what I remember from the shop manuals of 1995 Integra and 1998 Accord which are the 2 closest things that I have owned. And I was replacing the master cylinder, not the booster.

I would try it - you've already ordered the booster, right?

If it ends up adjusted wrong, you'll notice it not working properly in some form or another. It won't damage the MC and then you can worry about the adjustment.

It's just about like the first picture at the top of the techtalk link you just posted. The pushrod sticks out from the booster, and fits inside the hollow piston shaft of the MC. But you can't see inside that hollow shaft so you can't tell if the pin has bottomed out and actually beginning to push on the piston shaft. With a helper under the dash and paying attention to how that pushrod feels at the pedal, I think you'll be able to tell.

 

I read in a few places that if the adjustment for the pushrod is wrong it will damage/ruin the Master Cylinder? So just making sure I am not going to damage that and need another part if that's true. This post here said, " you MUST make sure the booster pushrod length is right, if it isn't it can ruin your new master". Will prob give it a try tomorrow- wanted to make sure I am not going to destroy a master cylinder if the length is wrong.

 

Maybe these will be helpful to anyone working on brakes who may read this thread for ideas

https://www.jegs.com/installationins...631010-116.pdf.
https://www.2carpros.com/articles/ho...aster-cylinder
https://www.2carpros.com/questions/brakes-79544546

Both also reference possible damage if pushrod is wrong length.

 

I still don't think there's any immediate damage from an incorrect adjustment. But I can absolutely see long term damage if you get it wrong and keep driving until something actually goes wrong. If you pay attention right away, & then fix the adjustment before driving for hundreds of miles, it'll be OK.

The last link you posted is the best (https://www.2carpros.com/questions/brakes-79544546) because it's actually a Honda. Looks like a 6th or 7th generation Accord. A few pictures in the middle show exactly how to use that gauge-tool. The last picture shows the bleeding sequence for 1998-2002 which is NOT the same as your 1991.

Adjusting the pushrod length is usually not required when replacing the master cylinder, but if you own the tool it's good to check. Seems like it's only needed when replacing the booster. And I don't know if the new booster will come already adjusted or not. When you get it, look whether the adjustment nut is even tightened??

Your best bet is to measure the pushrod sticking out of the old booster, and adjust the new one to match. Then IF(!) the old one hasn't been misadjusted by the previous owner, you'll be OK. But still, I think a helper under the dash can pay attention to the pushrod as you're installing the MC. He can probably tell if the pushrod is too long - it'll lose it's slack at the brake-pedal clevis if it starts to actually push on the MC piston rod.

 

WIas the mechanic correct that I will not need to bleed? If I do ineed to the sequence i see in this thread https://honda-tech.com/forums/honda-...ssure-3338859/ was:
REAR RIGHT
LEFT FRONT
LEFT REAR
FRONT RIGHT

I noticed here it also said damage to the master cylinder possible. I don't know if that is if replacing a master cylinder or bleeding anytime including if needed for booster only. Going to go outside now and look at it now. I found this youtube video to help with removal
Re: Break Pedal has zero pressure
I'll just throw a few things out there that may or may not help:

1) The Accord brake lines need to be bled in a different order than other cars: Rear right, left front, left rear, front right. (I gravity bleed first, and then get a helper to operate the brake pedal while I inspect the fluid. If bubbles keep coming, then air is being introduced somewhere.)

2) Sometimes tiny leaks (which don't result in fluid on the floor) can introduce air into the system. That cage that holds the fuel and brake lines can conceal damage--my own car passed inspection shortly before my brakes failed. My brake lines broke into segments when removing that cage, and there was also a leak to the line that runs over the gas tank. Check the hoses and also check the connections for dampness.

3) When bleeding brakes, make sure there's a block under the brake pedal. If you press the brake pedal too far, you can damage the seal in the master cylinder.

 

#1, yes. I found that on my 99, but then I start with the right rear, then go to the left rear, and so on. On my VW's I start with the right front per Bentley, then LF then RR then LR. But then on my 99 I was replacing the lines, and I didn't have a fitting tight enough.
#2 caused me to have to replace both fuel and brake lines on my wife's 2000 Accord, and brake lines on my 99 Accord. Surprising, I didn't have any issues on my wife's Accord, as it has ABS (my 99 doesn't). Both cars only got the rear lines replaced, and only them were bled.
#3, Never heard that one before, but I suppose it's possible. But then you'd only know it if the master cylinder is blown, as then the pedal would go all the way to the floor (block or no block).

The set up gauge is designed to prevent it. Your mechanic is probably thinking no one has messed with it's settings, which is why he doesn't bother checking. Also, I imagine there's so play designed that would allow everything to function correctly without the set up gauge/tool.

 

Since you're not replacing the master cylinder, I'd leave the steel brake lines connected & just flex the MC out of the way.

If that's not possible; say you can't get the booster out/in without disconnecting those lines, THEN you'll have to bleed the brakes.

And of course, the car is 38 years old. The brake lines might be corroded and replacement will in turn require bleeding.

The bleeding sequence RR - LF - LR - RF like you said sounds correct. Your car doesn't have ABS so it's sequence is pretty standard.

I've heard about the block under the brake pedal. The reason is your normal braking never pushes the piston all the way down the cylinder, so all these years only part of the cylinder gets polished by the piston seals. Now you push it all the way during bleeding & the corrosion on that far end of the MC might damage the seals. I've been pumping it all the way down for years & years (on a bunch of different cars) before hearing that one, and it never caused a problem for me. Still, the reasoning makes sense to me.

 

I agree with you Jim. You're not replacing the master cylinder, although you are unbolting it from the booster. There should be enough room to swing it out of the way to replace the booster though. I would only bleed IF I opened up the system (like replacing an under car line(s) ). Try not to make more work for yourself, than you absolutely have to.
Jim's explaination of using the block does make sense. But if you don't open up the hydraulic part of the system, you shouldn't need the block.