MGB Semi metallic disk brake - break in

[Boggsy64]

Finally going to get back on the road. The new "Classic Gold Semi Metallic" pads I bought have a fairly detailed break in regime described. There is a lot of braking but not stopping, and then a cool down period but not using the front brakes (instructions say this is to build a "film" on the new rotors). Problem is I will need brakes when I leave my garage because of hills, and there is not a good place to fully speed up and slow down as described. I have replaced disk brakes many times, on other cars, and don't know if all of this process is overkill? If necessary how has anyone handled this coming out of the garage onto city streets, I don't have an abandoned landing strip next door? I can use the handbrake to keep sitting pressure off the front pads until break in done, but it will be difficult to run the whole routine described.

 

[ShawnC_at_Moss]

The procedure is overkill. Bring them up to temp a few times by bringing your car down from speed but not stopping, if you can avoid it, to break-in the pads and rotors together, then go on your way.

Shawn

 

[WillR]

Maclaren pads develop a harsh squeak when driven primarily on the street. Some dealers will tell you thats just the pads and there is nothing you can do. Not true, they are race cars and not meant to putt around in the city. When the sound starts to happen you take it out to this fantasy abandond landing strip speed up to (a number that my mind has decided to forget now that i want it... 60 ... 160?) then drop your speed as fast as you can with out locking the wheels down to 30 mph and again two more times in rapid sucsession. This will heat up the brakes and clean off the "glaze" causing the squeak. For our enthusiast cars with Shawn.

 

[Boggsy64]

One more question on brakes. Should I expect a rock hard pedal, or slightly soft? I have had old cars and the pedal feel is never like modern cars. Don't know if all the old cars I had were brake system defective?

 

[DrEntropy]

If it's "spongy" you either have air in the system someplace or the rear shoes are not adjusted properly.

 

[Sarastro]

The brakes on our cars may not be absolutely rock hard, but shouldn't be really squooshy. If you think they're too soft and you can't get any more air out of them by bleeding, tap on the sides of the wheel cylinders to dislodge bubbles, wait a day (for the remaining bubbles to coalesce into a single void), and bleed them again.

Remember, most modern cars these days have power brakes or, at least, very different brakes from those of 40 years ago, so they won't be exactly the same.

 

[Boggsy64]

Wow finally a victory!! I have always feared bleeding brakes. I have a Mityvac brake bleeder and had success on my BMW motorcycle but no success on the MGB. I kept getting bubbles and wore my arm out pumping the handle. I looked online and found lots of ingenious ways to use a Shopvac as the vacuum source. I made this unit using PVC fittings and some tubing along with a barbed nipple. I used the small vacuum container from the Mityvac unit and let the Shopvac do the rest. Most of the unit is just for convenience (such as an arm and cup to hold the vacuum chamber) and parts cost $15 at Home Depot. The PVC valve was used to regulate the vacuum. The Shopvac is upstream of the valve along with the bleeder vacuum line. The downstream side is open to air to let the vac breathe. As you close the valve it restricts the flow and increases the line vacuum. Worked like a charm. Half an hour and a quart of fluid bled (mostly to insure lines were cleaned out), got in the car and the brake pedal is ROCK SOLID!!!:excitement:

 

[DrEntropy]

Did anyone mention an "Eez-E-Bleed?"

 

[Boggsy64]

I looked the up the Eze bleeder and this is another innovative way to get it done. I did get a lot of crud out of my system, along with old dark fluid, and wonder about pushing it back in (if you are talking about the syringe unit)? I already had the Mityvac unit and just wanted to avoid hand pumping, this did the trick.

 

[Boggsy64]

I had read your post, some time ago, about bleeding your clutch. When I looked up Eez-E-Bleed all I got was EZE bleed, which is a syringe you use to push fluid from the caliper back up into the system. I also found an "EEZI bleed" from Gunson. I think this is more like what you were talking about. In any event there are a million and one devices out there.

 

[DrEntropy]

The Gunson one, yup.