Drum pedal feel?

I am not accustomed to the feel of drum brakes. The system is basically all new. I bled the MC and the brakes. adjusted the shoes so they drag and the pedal still goes down 3/4 of travel before firming up. Is this normal. The car is a '53 Ford bus. coupe.

 

Bleed your brakes again. you might also check your balance bar (it pushes your master cylinder), if its adjustable you might lengthen it a bit.

 

Is it possible that you used too large of a line, and the M/C has to move too much volume before making good pressure?

 

Three quarters of pedal travel sounds like a bit too much. Did you replace the master cylinder and the wheel cylinders? A "new" master can be bad. But, it will want to "drift" down once pedal pressure is applied. If it stays firm, but needs alot of travel to get there, you may have the wrong size wheel cylinders. When they are too big, the master cylinder has to supply more fluid to them to make them actuate the shoes.
If you have already confirmed there are no leaks and the master cylinder is good, you may want to recheck the wheel cylinder sizes. A Chilton's/Motor's repair manual or factory repair manual will list the wheel cylinder and master cylinder specs.
Hope this helps!

 

If you can pump the pedal once or twice and it gets better, then you have air in the lines. You didn't say if you changed to a different master cylinder or it is an original. If you did upgrade to a newer one, check the push rod, it should have about 1/16'' of play at the cylinder, and if that is ok check the bore size of the cylinder. If you have too small of a bore,(like under 1'',) it will take more pedal travel to make things happen.You should have also bench bled the cylinder before installing it.

 

I did bench bleed the mc and it was a factory type replacement. The wheel cyl's were also factory part replacements. The lines seem to be all standard size. The pedal does not firm up nor get worse. I bled the system using the same method I used on our racecars so I am 95% sure all the air is out of the system. I drove it this way last year so I guess I'll just do the same this year.
Thanks
Chris

 

You may need to make an adjustment to the actuator push rod at the master cylinder. If it is too short the travel will be exagerated.
3/4 play sounds like way too much to me.
With what everyone else mentioned and you explained, I don't think that there is air in the system.
If the car was like this prior to the replacement of the master cylinder, wheel cylinders, etc. I would think that the push rod needs to be adjusted. That is the first place I would start.
Good luck.

 

That would make sense, but I don't remeber seeing any adjustment capabilities. I will definetely double check though , or take a look in my manual.
Thanks Chris

 

Just had a brain fart. Look closely at your flex hoses. If you haven't changed them you might want to think about it. Old hoses can expand under load and give you the feel you are encountering. You can try squeezing off each hose with vice grips to see if you can isolate the problem. Put something under the teeth so you don't damage the hose. As it was also put earlier, if the shoes don't have the same arc as the drum, you could also have a similar problem. It is fairly difficult to find a shop with a shoe grinder, but it is really worth the effort to have it done. You won't believe the difference it can make.

 

Yeah I'll check into that Thanks

 

Large brake lines won't make any difference. If the M/C moves say 1/20th of a pint on a full depression, that same amount - 1/20th of a pint - will show up at the other end. Provided all the air is out.

I'm guessing the arc of the shoes don't quite match the arc of the brake drum.

Tighten the brake adjusters on each wheel to the point where you can't rotate the wheel/drum assembly by hand.

Back off 10 clicks.

Easy to do on a standard 53 drum brake setup. If you have self-adusters you'll have to hold the adjuster gizmo down with a small screwdriver so you can back off the brake adjusters star wheel.

An old trick told me by an old brake shop guy.

3/4" play sounds like it should be right on the edge of, "too much", but within reason.

Aside from the potential differing arcs problem, old brake hoses that expand sounds like it could also be the cause.

 

have you tried Ludwig?

 

ha.... I thought for a while there I was the only one with a warped sense of humor.

I was gonna suggest DW or Gibralter for a good kick drum pedal feel.....

 

If the pedal is firm, and the pedal travel is too long, then I would first check the brake adjustment, as C9 suggests. That's the most likely cause.

 

I'm with C9 on this one. Check yer brake shoes adjustment. The fact that you said pumping the pedal doesn't make it higher/harder makes your shoe adjustment sound real suspicious.

 

I already tightened them down and backed em off. Shouldn't they center when I apply the brakes anyhoo?

 

Try adjusting them again. Some adjusters only need to be backed off about 7 clicks from the setting where the wheel is hard to turn.

The brakes should not drag when they are not engaged, but they should not have lots of free play either.

 

does your car's anchor pin have an adjustment?

what i mean is,for those who don't know,the anchor pin up top will have a hex nut that you loosen,and another smaller bolt inside that that rotates the shoes.

the outside edge of the drum will have a small slot to insert a feeler blade,so you can check that the shoes make contact on the UPPER side of the drum,not just the bottom,where the star wheel adjuster is.

 

I always preferred Slingerland..maybe HotRodDrummer has his own preference???

 

I don't think so but I will check.

Thanks

 

I drove the car, hit the brakes a few times and readjusted the front shoes (put a few more clicks on each. The pdeal feels a lot better. Also, the bolt connecting the pedal to the mc is eccentric to take up some play. I am going to check that also.

Thanks Chris

 

Chris...When you adjust the push rod make sure the pedal isn't exerting constant pressure on the m/c...you'll drag the brakes for sure...I always adjust the brakes pretty tight for the first miles...helps "arc" the shoes to the drum...I learned to do brakes at a service station (remember those?) when I was 14...we had the only shoe arc attachment in the area..it really made our job a lot easier...great brakes the first time...

 

10-4 , thank you!