B1Fa brake drums

[Stumpy(NH)]

Has anyone got a solution to reapir or replacment of oversize drums on a B1FA? I haven't taken it apart, but have adjusted the brakes out to max and still need a double pump on the pedal to get a solid feel.

I have no idea....spary weld and turn back to spec? I can see in the drum through the inspection window that there is alot of brake lining in there.

Thanks for the help

[MBF]

Stumpy-when you say you've adjusted them did you do the "major" and "minor" adjustments? By adjusting the concentrics on the bottom you may be able to move the shoe out enough to solve your problem. Have you bled the entire system? Mike

[NiftyFifty]

Spray welding drums seems like a very bad idea... 2 different metals heating and cooling at different rates in a major system like the brakes doesn't seem to be a good plan... I take it no replacements possible??

[Stumpy(NH)]

Stumpy-when you say you've adjusted them did you do the "major" and "minor" adjustments? By adjusting the concentrics on the bottom you may be able to move the shoe out enough to solve your problem. Have you bled the entire system? Mike

Oh boy, can you expand on the major and minor? See, I learn something everyday.

I did adjust the concentrics at the bottom...is there another adjustment?

[Stumpy(NH)]

Spray welding drums seems like a very bad idea... 2 different metals heating and cooling at different rates in a major system like the brakes doesn't seem to be a good plan... I take it no replacements possible??

I don't know if there are replacements available. I don't know about the spray welding either. Was just a question. I did have a piston for a one lunger spray welded to build it up and match an overbored cylinder....I realize that is not a brake system and the heat issue is most likey lower where it is watercooled...just a thought.

Any idea for a parts source?

[MBF]

Stumpy, the major adjustment is the concentric at the bottom of each shoe. The "minor" adjustments are the large nuts on the back of each backing plate at the 3 and 9 o'clock positions. The brakes on these trucks aren't self energising. The minor adjustment controls how far the shoe retracts away from the drum when the brake pedal is released. To adjust properly you need a special tool that matches the setting of the brake shoes to the actual diameter of the drum on each wheel. Note: making either the major or minor adjustment will effect the other respecitve adjustment. Do a search on brake adjustment on the forum. I thought of a couple of other possibilities to consider. Does your truck have a vacuum booster, and has that been bled prior to bleeding your system? Does your truck have two cylinders per wheel? Are you getting the correct throw on your master cylinder plunger from your brake pedal? Mike

[Stumpy(NH)]

Stumpy, the major adjustment is the concentric at the bottom of each shoe. The "minor" adjustments are the large nuts on the back of each backing plate at the 3 and 9 o'clock positions. The brakes on these trucks aren't self energising. The minor adjustment controls how far the shoe retracts away from the drum when the brake pedal is released. To adjust properly you need a special tool that matches the setting of the brake shoes to the actual diameter of the drum on each wheel. Note: making either the major or minor adjustment will effect the other respecitve adjustment. Do a search on brake adjustment on the forum. I thought of a couple of other possibilities to consider. Does your truck have a vacuum booster, and has that been bled prior to bleeding your system? Does your truck have two cylinders per wheel? Are you getting the correct throw on your master cylinder plunger from your brake pedal? Mike

I'll check on the Booster. It is currently not hooked up due to a leak in the diaphram. I am sure the system has been bled, but will bleed it again as a check.

The throw on the master cylinder is a good question. Not really sure there.

The minor adjustments on my truck are both at the 6 oclock position on my truck.

looking in the archives now.

[wallytoo]

The minor adjustments on my truck are both at the 6 oclock position on my truck.

they shouldn't be. the two at the 6 o'clock position are for the major adjustment, and move the bottom of the shoes closer to the drum. these have a hex head nut with a rectangular head bolt through the center of them. the minor adjustment cams are located partway up the backing plate, maybe at 9:30 and 2:30, and have hex heads with a shoulder at the base. these move the shoe a little closer or farther from the drum.

you also have just one wheel cylinder for each drum, unlike the smaller trucks (1/2 and 3/4 ton) which have two wheel cylinders per drum in the rear.

your symptoms sound more like air in the system to me.