I recently changed my '87 Buick " T " over to vacuum brakes, I used a set-up off an '86 Caprice 10 3/4" booster w/master cyl. All the parts bolted up ok but I had to drill and tap the intake plenum in order to get 16.5-17" vacuum. The pedal is pushed all the way back to it's limit installed. Pedal seems Stiff to push, and is Hard then goes down off panic stops. Will not even lock up front brakes on hard stops. This set-up does not work much better than the Powermaster. Whats going on here???? Any help would be greatly appreciated.
An expert who has achieved level 2 by getting 100 points
An expert that got 5 achievements.
An expert who has written 20 answers of more than 400 characters.
An expert who has answered 20 questions.
Re: Buick Grand National vacuum brake conversion
sounds like the vaccumn canister is not holding vaccumn.( weak or cracked
diaphraim) Also did the swap come with a regulator valve (porposting) to set
rear and front psi? Make double sure the system is bled well.. In addition
the master cylcinder has a shuttle rod that must be centered up in order to
porposition the fluid front and rear.Have a fun day and good luck.
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need. goodluck!
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
Remove Master Cylinder WITHOUT Removing Lines Set it to the Side or Down Below Booster, Go Inside and remove 4 Nuts/Bolts Mounting it Booster Vacuum Hose and Booster Should Pull Right out ...You May Need to Disconnect From Brake Pedal INSIDE VEHICLE ABS May be Difficult to Work Around At Master Cylinder Side But Feasible
These are not rebuild-able, they must be replaced if they leak. One that leaks will hiss while the engine is running. The hiss is vacuum leaking, not pressure leaking out. To possibly check it under the hood, be very suspicious of a leaking vacuum line at or near the booster, not the booster itself. It might be bad, but that is pretty rare. The last one I changed I thought was defective because it hissed when I applied the brakes, but a new one did the same thing! :-( If you decide to replace it, you will be unbolting the master cylinder from the unit under the hood, and also unbolting the unit under the dashboard. Of you are really careful, you might not need to disconnect the master cylinder 's brake lines at all, just gently pull/push it out of the way to change the booster. Be really careful not to kink the brake lines. The unit is bolted to the car with usually 2 bolts through the firewall behind the brake pedal.
When you open the hydraulic brake line air enters. You will have to bleed the air out before there will be any brake pressure.If the master cylinder is empty there will be air in it to, it is a dual cylinder. Remove both lines at the cylinder you will need a bleeder kit (from auto parts store) or make your own, the way to bleed it is to connect a tube to each port on the cyl. then take both tubes to enter the fluid in the top of the cyl.Slowly work the cyl. till all air is out of the cyl.If the vacuum booster has not had the vacuum released you must do that or the master cyl. will be ruined (with air in the cyl. the booster will drive the piston cups to the end and destroy them) After the master has been bled reattach the lines. Use the tool (from parts house) to hold the apportioning valve open. Keeping the master cyl. full at all times,open the bleeder screws on the calipers one at time and bleed all air out.
The brake booster from most of the GM cars of the same size should fit. To change it you need to unbolt the master cylander from the booster be careful not to kink brake lines disconnect vacum hose from booster unbolt booster from fire wall. Now replace in reverse order. Always be careful of the brake lines.
Heres a way to save you a lot of time. remove the two bolts that hold the master cylinder to booster, leave all brake lines connected, pull master away as far as it will go, you may have to pull on the line some, next go inside and remove the pin to remove the rod from brake pedal, you can let brake switch stay, back to booster, remove vacuum line from booster, back inside the car remove the 4 nuts that hold the booster to firewall, make sure rood is clear, go out and pull booster out and remove, install new booster make sure rod hooks to pedal before bolting it up, because sometimes the rod may go in the wrong direction, reverse directions to install, when your done theres no need to bleed brake system. hope this helps.
did you bleed the master cyl. before or during installation? bleed brakes in proper order?RR LR RF LF? does it have a power booster between master cyl.& firewall?check for vacuum to booster.when ABS isn't working you should still have brakes.suspect power booster diaphram.
If you look down under the radiator in the area of the power steering pump, nestled in the crossmember you should see some brake lines going in and out of a rectangular steel block. It should also have a single wire going in the top. That is the proportioning valve which adjusts brake pressure to the wheels. One of these lines is likely the source of your leak. Hope this helps.
I have never worked on a Volvo, but they are pretty much the same as everyone else since they are most likely using the same suppliers. The vacuum brake booster is mounted to the firewall on the driver's side and is usually attached by four bolts, and the brake master cylinder is attached to it by four bolts. Start by unbolting the master cylinder from the booster and gently bend the brake lines so the master cylinder is out of your way. Remove the rod that goes between the brake master cylinder and the brake booster and set it aside. Pull the vacuum line off the brake booster, and unbolt the brake booster. Put the replacement booster in place, bolt it back up, put the rod back in place between the booster and master cylinder, bolt the master cylinder back up to the booster, and reconnect the vacuum line. Take the old booster back to the parts shop to get your core charge, and you should be finished. It is usually not very difficult and should not take more than about an hour using normal hand tools. A DIY job should save you about $100-150 in labor costs, and the part will be much cheaper without the mark-up.
i think if there is a problem it would be if one had A.B.S. and the other did not, otherwise i can't see any problem. just have to look at it and see if everything lines up. i believe the boosters are the same, if they look the same and bolt up the same i don't see any problem. you might want to chk. with a ford dealer just to see if there is a differance in volume on booster.