rixter

ok, it appears as though the vacuum issue in my 87 is a ruptured diaghram in the brake booster
I perused the procedure and talked to the guys here at the shop who all cringed at the mention of the job
realistically, on a scale of 1-10 how difficult and PITA is this?
TIA

Jim bailey - 928 International

It is necessary to make the tool to hold the booster compressed or the rod which goes to the brake pedal will stick too far inside the car to get the booster out. Even then you will think that there is just not enough room BUT it will come out ! We of course remove the engine FIRST I did however change the one on the old very brown 1980 but that is a two valve.

Mrmerlin

its an easy job if the engine is out...............That said you probably have the car with the engine installed option..........so remove the master cylinder, and air cleaner housings, then figure out the holding device for the rod and remove the 4 booster hold downs nuts use some thick towels or other things to protect the painted surfaces, and then its a rubics cube to figure out the removal process

FlyingDog

It's one of those jobs where you have to find the exact right combination of George Carlin's 7 dirty words and strange facial contortions to find the right angle for getting between the engine and fender. Once found, it's not hard (on a 16V).

Visegrips work well for the rod, just clamp down very tight and don't bump them when removing/installing.

Lizard928

I have done it on a 16V engine, but that was with dead motor mounts and the use of a 2x4 to get just enough clearance.

I would pull the engine first before I did it on a 32V car though.

928ntslow

Hey Rixter...I think I may have the same issue. 15 bars vacuum and the brake pedal hisses when applied and held in the stop position. Until vacuum is built up at warm up, the brakes don't do the best job of stopping the car. I make sure the car is well warmed up before traveling.

Do you have the same symptoms?

borland

What Jim B said, plus .... a half-moon wrench works best on the MBC inside bolt.

rixter

my symptoms right now are,
spongy brakes till warm, high idle all the time, climate control screwy, cruise screwy, ac screwy, essentially anything vacuum operated is messed up... when I turn the car off there is this huge air release right in around the booster that I can't quite put a finger on, it's NOT coming from any of the lines
adding all these factors together leads me to believe the booster is shot

worf928

Booster removal is not that bad. Other than standing on your head under the pedals and getting stuck under them with your arms in pretzel shapes there's only one real trick and that's getting the booster out once it's loose. Here's how I've done it:

All the vacuum lines and hard lines are out of the way or tied back. Air box is out and of course the brake res and MC are out. Once the booster is loose you pull it out of the firewall to clear the studs. Then you tilt the top of the booster towards the middle of the engine and lower the booster while you're tilting. You can then carefully wiggle the rest of the back-side rod out of the hole in the firewall.

There is one 'gotcha': The '87 and newer boosters are internally very weak. When you have the front-side rod for the booster clamped be very careful that you don't put any more 'pulling' pressure on it. Pay special attention to this when you are engaging or disengaging the back-side rod with the brake pedal linkage or getting the back-side rod in or out of its hole in the firewall. If you pull more than a little bit on the back-side rod while the front-side rod is clamped the front rod may break loose. The front-side rod is peened on in two places to an internal ring fixed to the diaphragm. It doesn't take a lot of force in addition to that necessary to compress the internal spring to pull the rod out of its home. OTOH, the '86 and older booster are built like brick $hi+ houses.

While you have the booster out replace the clutch master cylinder. Waaaay easier with the booster out.

JHowell37

I think Porsche actually sat the brake booster in a jig, and then proceeded to build the rest of the car around it. When I had the spare body (that you sold me) last year, I found that cutting the car into quarters was the best way to facilitate removal.

shmark

Too funny... not I'm in the middle of pulling mine right now too. And I just found out that unbolting it prior to clamping the pushrod is a big no no. Now I get to bolt it back down again before I can get it out. Crap. Good luck rixter.

shmark

Stupid question time. The manual says basically to clamp the rod and then remove the booster. Helpful. So I have the engine-side rod clamped now and the nuts inside the car removed...still won't move much and I don't want to pull too hard and damage the diaphragm. Does the inside rod come out with the booster (in other words, detach it from the pedal)? Or do I detach the rod from the booster leaving it inside the car? If so, what do I detach?

...and yes my car has the engine-in option.

(sorry for the hijack rixter)

cold_beer839

Richard,

I have had 2 brake boosters go bad on my Mustang over the years. The way I tested them to make sure they were bad before removal, was to pull the vacum line off the booster then plug it. If the engine smoothed out and other vacum dependent accessories started to work, then I knew the booster was bad.

shmark

Any hints on detaching the interior rod? From the booster or the pedal? I just don't want to cause myself yet another problem.

TAREK

Rixter, there is what seems to be a grommet filled access hole in the inner fender that seems to be made just to slide through a long socket for accessing the master cylinder inner bolt. This may save you some aggravation
Good Luck
Tarek