Brake booster problems

I JUST went through this! My car had a very hard pedal and would not stop no matter how hard I pushed. The problem pretty much has to be the hose or check valve (you may be getting suction but is it enough? I think it requires about 14 lbs). A quick test for this is to buy a length of hose that will reach from the plenum to the booster OUTSIDE the car. Tie the the partially open (just enough to let the hose out) engine cover down to the bumper and run the hose along the driver's side door and into the front hood. Then road test. If that doesn't fix it then the bad news is that the problem is the booster or the master cylinder. The good news is that you won't have to replace the hose which runs through the door sill and is a true PITA to get done. You don't mention if you're handy enough to do the work yourself but if so, you need to remove the booster and the master cylinder for rebuild/inspection. An independant Ferrari shop will probably charge 5-6 hours of labor to remove and replace so you're looking at about $800 in labor plus a markup on the rebuild which they will subcontract to a rebuilder. You DONT want to get new parts from an OEM supplier unless you're willing to spend $1200 - $2000 for OEM parts. Brakes is brakes and there's nothing magic about 4 wheel disks even if the're on a Ferrari. I ran a thread in this (do a search) when my problem started and another F-chatter recommended Power Brake Exchange in San Jose. I don't have their info handy but just call 411 for the number. Ask for Martine - he knows me. If I recall correctly their cost was just over $200 to rebuild the booster and another $90 or so if the master needs to be honed. If the master is really bad it may need to be sleeved but their price is still quite reasonable. You might want to ask them to test the booster before they rebuild it as otherwise they may just assume it is bad and go straight into rebuilding. It is almost certainly bad but its good to get some baseline numbers to see how much vacuum it will hold, if any. Feel free to PM me if I can give you any other help.

Steve

 

Don't fear the hose replacement, it's almost a 'rite of passage' for 308 owners and is eventually needed for the decaying accompanying heater hose as well.

Take pictures as you go (& GL) with the brakes.

 

You didn't mention the year/model of your car. Mine is an 85 QV with over 100K miles so its no surprise that the rubber diaphram failed as all rubber does on a 26 year old F-car. I don't see where adjusting the master cyl. ball/rod will change anything. I'm still certain its the booster but I did not stay in a Holiday Inn last night and I can be pretty stupid about mechanical stuff no matter where I spend the night.

 

it is the calipers, front or the rear seized up, remove the brake pads & squeeze the calipers
with a C-LAMP make sure they are moving in & out, bleeding them alone is not sufficent
they have to be working, going in & out several times,or you have to rebuild them

make sure you are looking @ them moving in & out
sometimes its the small flexible hose to the calipere blocked up

 

good

 

I respect John's opinion - he may well be right but my money's still on the booster. It seems unlikely to me that BOTH front (or rear) calipers would fail at the same time. I think that if one got stuck the car would swerve under braking. The OP doesn't give a lot of detail about the symtoms. In my case the pedal was super hard (no booster assist) and there was a lack of braking, especially when rolling up to a stop sign or light at low revs, at all four corners. If it turns out to be the calipers then bravo John and you can check out Birdman's site for DIY rebuilding instructions. Not difficult to do if you're fairly handy with a wrench - say about a 4 on a scale of 1 to 10.

 

This line says it all. No change in pedal feel from engine-off to engine-on points directly at the booster, NOT seized calipers.

 

Mr, MNExotics,,,,,

Hey I have an Extra,, from a low mile 328.
( I just wanted the 25mm master unit, but this came with it.)
for sale cheep,, but not free.
Needs a spit shine.
PM me.

Edwardo

all proceeds get donated to my Monie Pit,, I mean Mondial.
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