Allis Chalmers brakes not working

[Bergz22]

Just put on new shoes and machined the drum surface. The brakes still barely work. They have the slide bar adjuster. Anyone know how this is supposed to be adjusted?

 

[BillG]

Well first off a model number would be a great start, pneumatic or cushion tires. As far as the adjustment, use an inside and outside caliper to get the drum size and set the shoes to approx. 1/16 smaller and equal. The bar nut should be tightened to 22 in/lbs, if my memory serves

 

[Bergz22]

Well first off a model number would be a great start, pneumatic or cushion tires. As far as the adjustment, use an inside and outside caliper to get the drum size and set the shoes to approx. 1/16 smaller and equal. The bar nut should be tightened to 22 in/lbs, if my memory serves

So the sliding bar is used to set the shoe spacing in place of a star adjuster wheel? It has pneumatic tires.

It is a ACP50K

 

[BillG]

Yup, that is the reason for the specific torque. As the shoes wear the bar slips on the screw and nut. Clean and dry when you assemble the bar.

 

[Bergz22]

Yup, that is the reason for the specific torque. As the shoes wear the bar slips on the screw and nut. Clean and dry when you assemble the bar.

So if I leave the shoes set in, shouldn’t they self adjust as the pedal is pumped?

 

[BillG]

As long as the link does not slip and drop back. Back in the day we would replace the link as a normal part of a brake job. Easier than doing it twice as the link was the weak part.

 

[Bergz22]

As long as the link does not slip and drop back. Back in the day we would replace the link as a normal part of a brake job. Easier than doing it twice as the link was the weak part.

Thank you. I’ve never done on of these before.

 

[Bergz22]

As long as the link does not slip and drop back. Back in the day we would replace the link as a normal part of a brake job. Easier than doing it twice as the link was the weak part.

I should clarify that the brake pedal is soft, but gets hard after it is pumped a few times.

 

[Oxbow]

I should clarify that the brake pedal is soft, but gets hard after it is pumped a few times.

Sounds like they need bled perhaps?

 

[Bergz22]

Sounds like they need bled perhaps?

I bled both sides twice today. I didn’t see any air.

 

[BillG]

If the problem was air they would never get hard no matter what. The problem is as you pump, the flow does not have enough time to fully return, so once you reach the point where the fluid is blocked the pedal will be hard. Either you need to readjust the link or the drums are oversize for the shoes and the link is reaching full extension. This is where an inside and outside calipers are valuable, it's much easier to get them set before installing the drum and you can be sure of the setting. They use to make brake setting calipers for this purpose, don't know if they still do.

 

[Bergz22]

If the problem was air they would never get hard no matter what. The problem is as you pump, the flow does not have enough time to fully return, so once you reach the point where the fluid is blocked the pedal will be hard. Either you need to readjust the link or the drums are oversize for the shoes and the link is reaching full extension. This is where an inside and outside calipers are valuable, it's much easier to get them set before installing the drum and you can be sure of the setting. They use to make brake setting calipers for this purpose, don't know if they still do.

Will look into it. Thank you.