Stewart warner brakes

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On the local old car club tour this weekend, I found that the brakes would not lock up when I pressed the brake pedal hard. I had just readjusted the brakes by turning the adjusting nut in until I could just be turned the tires by hand and then backing it off 10 clicks as it says in the service bulletin 1974 no. 1 for 1933-1935 models, looks like a reprint of the stewart warner bulletin. I had the shoes relined and the friction disc is just ok. I had to use one out of a 1934 pierce, as the original was warn down to the rivets. I plan on sending the original in to be relined. Is there some adjustment I am overlooking? Thanks again, Doug

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Hi Doug, all the braking action is from the friction of the disc. I had to replace my friction disc on my 836 when it got down to the rivets. It would not apply enough friction to force the brake shoes to do their job..

Take your car out for a drive and using the hand [parking] brake, see if it stops better than with the foot pedal.. if so, it’s the friction disc. the hand brake operates on all 4 wheels on these models. I had to use the hand brake to augment my foot brakes when the friction disc was worn out.

Make sure your pedal adjustment and friction disc adjustments are allowing the disc to do it’s job.

Hope this helps.

Greg L

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Thanks Greg, I will try the hand brake test as the friction disc I put in was ok to poor. There do I send the disc to be recovered. Is it the Ft. Wayne clutch company listed under services ? What do they charge? Doug

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Took it out for a test drive and pulled the hand brake all the way back. There was no difference between it and the foot brake. I tried the adjusting nut on each wheel and found them to be as tight as they could go without any drag . So do I tighten the cables more? Thanks again Doug

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What type of brake lining was used to reline the brake shoes?? These brakes need a soft, high friction lining material.. not the hard material used in modern drum brakes..

The high friction material is woven, it looks like thick Heavy Duty burlap. Modern lining looks like formica or hardboard.

Greg L

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Thanks again Greg, Thinking back to when I redid the brakes I believe I ordered the right material and had a local friend install it on the brake shoes. When you take ten years to restore a car your memory starts to fall off the back end. Since I’m now 60 , I had better do the next car a little faster. Doug

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Hi Doug, Let’s not talk about our ages.. and failing memories.. that discussion would go on forever..

This next check of the brake system is hard to describe.. but I’ll try.

When you apply the brake pedal, it clamps the driveshaft driven disc agains the movable pressure plate or ‘reaction plate’.. I don’t know what else to call it. this plate rotates in the housing, which causes the output shaft on the right side of the brake unit to rotate.. the lever on the shaft is connected to the cables and rods that pull on the brakes. This brake lever has only a certain amount of travel, if the brake linkage is too loose, most of this travel will be used-up taking up slack and excess clearances, before actual braking action can take place.

Since you have adjusted the brake shoes, so that they have minimum clearance, the next area is to see if the brake unit’s shaft and lever isn’t traveling so far that it is near the end of it’s travel. This would limit the braking action at the wheels..

I’d check the amount of travel that the brake unit’s output arm and levers have to make before braking action is applied at each wheel.. if the travel is excessive, adjust the cables and rod connections to have the brakes apply earlier.

If you have minimal play and clearances, and the brake unit levers only have to move, say 1/2 of their available travel before braking action starts,, then the only remaining item to cause poor braking is the friction disc. I’d get it relined.

Hope this makes sense..

Greg L

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Thanks again Greg, I will check out those cables, etc. Have you or anyone eles used Ft. Wayne clutch for friction disc work? And how did it turn out ? Thanks Doug

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On the cars with the Stewart-Warner power brake units, use only straight mineral gear oil in the transmission and brake unit. Do not repeat not use gear oil with a hypoid additive. This may not be associated with your current discussion, however, I pass it on for your information.

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That’s a good point Paul.. make sure you are using the same gear oil in the transmission and powr barke unit that you use in the rear differential with the worm drive gears. Staight gear oli without any sulphur additives.. the sulphur eats up the bronze and brass gears, shims and bushings.

Greg L

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Yes, I used the straight mineral gear oil. Doug

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Fort Wayne Clutch istalled new lining material on the friction disk for my 1933 PA 1236 sedan. This material was designed to operate in gear oil. Removal and installation of the friction disk in the power unit was a relaively easy task. Rich L

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