Brake booster question

[monaco]

Quick question guys
I have a 66 monaco that has had a brake booster installed, not sure what it was off of. How do I know if it's the correct one? Also when I hit the brakes there's nothing until you get to the end of the pedal then the brakes slam on. Would that be the booster or master cylinder problem?

 

[C Body Bob]

Quick question guys
I have a 66 monaco that has had a brake booster installed, not sure what it was off of. How do I know if it's the correct one? Also when I hit the brakes there's nothing until you get to the end of the pedal then the brakes slam on. Would that be the booster or master cylinder problem?

Couple of things. You do have it connected to a proper vacumn source. And are you sure the booster is working. Have you properly bleed the master & THEN the entire brake system starting at the right rear working forward to the closest cylinder. And I assume you have the correct push rod & travel. Also you do have good brake linings and the drums are adjusted correctly. Too loose & you want have much feel to the pedal

 

[Ross Wooldridge]

Pictures would help.

Drums or disc/drum?

 

[Davea Lux]

Sounds line the travel rod is set too short or the brakes are very far out of adjustment. Start by checking the brake adjustment on all four wheels. If you are satisfied that they are adjusted properly and that the brakes are properly bled, next check the travel rod adjustment. Your brake pedal should have about 5/8 to 3/4 inch free play before the brakes start to engage. If you have more than this, remove the master cylinder and lengthen the travel rod until that level proper level of free play is obtained. Note that sticking wheel cylinders can also cause the type of erratic braking you have described. A cylinder that is sticking in the deployed position will usually result in a shoe that is stuck to the drum or dragging.

Dave

 

[Yatzee]

Quick question guys
I have a 66 monaco that has had a brake booster installed, not sure what it was off of. How do I know if it's the correct one? Also when I hit the brakes there's nothing until you get to the end of the pedal then the brakes slam on. Would that be the booster or master cylinder problem?

If you have "brake drop" it may well be that you have a damaged pressure cup in the master, usually for the rears. If you don't have enough clearance between the booster and master your brakes will bind naturally, if too much clearance you will get what appears to be "pedal drop". Vacuum should be a total manifold source ( base of carb) with nothing else attached to that source line, 18 Hg minimum for proper operation. If you've run out of travel at the pedal arm perhaps this was an aftermarket install and you've got the wrong pedal ratio which results from a manual arm used on a power system. These and other things mentioned above need to be investigated but I surely wouldn't drive it the way it is.