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John E Davies

Brakes - Auto-adjust vs Manual-adjust, what are the differences?

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I have been chasing a grabby brake problem, and my Auto-adjust brakes never did self adjust correctly, regardless of how many brake applications there were... I learned about some important differences. I thought that I could remove the self-adjusting hardware and install an adjuster and spring from a manual adjust brake, and then all would be well. It is not so simple.

 

Auto vs Manual:

 

IMG_6560.thumb.jpg.036aa6b3282b747603b41c8889f6dca3.jpg

 

The shoes are shaped and drilled differently, and the spring for the adjuster rides outside the screw, not around it. This is critical since you can't just swap them.

 

IMG_5152.thumb.jpg.7cbc4f6301abedfb2549be8d1e33fe67.jpg

 

I tried... here is the manual spring and its adjuster attached to the Auto shoes:

 

IMG_5150.thumb.jpg.94ed413ce1b618abf78824a293a7e6a4.jpg

 

When the adjuster is turned, the teeth drag the spring up and bang it hard into the magnet. Ooops.

 

IMG_5151.thumb.jpg.90874807a16a7826e48909b6423875d1.jpg

 

So.... if you are having issues with the Auto adjusters not, uhmmm, auto adjusting, as I was having, can you just manually adjust these brakes? Yes, you can. MAYBE. You can simply reach in through the oval hole with a small screwdriver and lift the adjuster arm up and let it drop repeatedly until it no longer turns the screw. It's easy and quick. But there is a problem. Here is the adjuster cable, looped over the pulley, under spring pressure:

 

IMG_5159.thumb.jpg.22c67a03cee148c6053c20e6e6156cc8.jpg

 

Here it is with the arm lifted up:

 

IMG_5160.thumb.jpg.3e6128d24539ada4630d3138ee5138a2.jpg

 

The cable raises up out of the pulley groove (there is no retainer). I was not able to get it to fall out, but the possibility is high if your cable and pulley is not well lubricated and moving freely. Which is a common problem. Mine were dry and dragging before I serviced them. If the cable falls out of the groove, you will have problems and have to disassemble the brake. Here is a look at the entire Auto-adjust mechanism:

 

[attachment file=IMG_5121 copy.jpg]

 

IMG_5116.thumb.jpg.20c46287874ab28caefd5ca5fccc85d4.jpg

 

The top of the cable hooks to a sheet metal arm that sits under the magnet bearing. This area must be well lubricated or it will bind.

 

IMG_5117.thumb.jpg.0ef36265768715acb3953de25d073cea.jpg

 

These brakes are a real pain to keep operating correctly. Here is a tip to make removing the hold down springs simple, for either version:

 

IMG_5155.thumb.jpg.8350204a73e4f689ad6848e4664d3d85.jpg

 

Make sure the slot in the spring cap is aligned with the jaws, so it will be easier to “stab” it over the matching tab of the hold down pin... you can’t easily see how things are aligned.

 

IMG_5156.thumb.jpg.b7ecf9f3945df9aab24c2b119f20ae6c.jpg

 

The Auto adjusting mechanism is problematic, adds a lot of extra drag to the system (three additional pivot points), requiring heavier and more springs for the shoes to function. The Auto brakes are much MUCH more difficult to reassemble after they are taken apart for a repair or service. I swapped out my goofy front brakes for a pair of Dexter Manual Adjust ones, cost was $110 from eTrailer. Generic ones are a little cheaper.

 

In this particular case, simpler is way better. Disc brakes are still in my future.

 

John Davies

 

Spokane WA

 

 

 

 

 

 

IMG_5121-copy.thumb.jpg.9550decfdf6f716fcfd583e12231945e.jpg


"Mouse":  2017 Legacy Elite II NARV (Not An RV) Two Beds, Hull Number 218, See my HOW TO threads: https://olivertraveltrailers.com/topic/john-e-davies-how-to-threads-and-tech-articles-links/

 

Tow Vehicle: 2013 Land Cruiser 200, 33" LT tires, airbags.

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Thanks for documenting this potential problem.  I'm monitoring wheel temperatures with the type of infrared thermometer that you recommended and so far (8000 miles) have only had one unrelated problem.  I'll be thoroughly going over the brake adjusters when I repack the wheel bearings in another 2000 miles, likely in October.

 

Bob G.


Bob G

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