Using an open end wrench is not going to work that well in the real world. You would be much better off with a 5/16" 8 point socket. Also...even on the newer trucks in our fleet that are well maintained will require a brake adjust on 1 to 2 slacks per truck that are automatics. On older trucks with a lot of miles on them usually 4 or 5 will need adjustment, and really should be replaced(especially the haldex...those do not last all that long).

 

on tractor drive axles, the socket/ratchet assembly often will not fit... the point was the fact that it requires a great deal of torque to damage a meritor slack while trying to adjust the brake.

 

Right, it turns easy in the tightening direction but will not turn in the loosening direction unless the pawl is lifted. The trouble is the other slacks (Haldex, Bendix, etc.) have no pawl and simply require brute force to turn backwards so some of the grease monkeys don't know the difference and will break a Meritor slack that way.

Birken

 

ahhhh, it's all come clear to me now!

never even thought of the fact that many guys may have only worked with slacks that use one-way clutch mechanisms!

oh, don't forget that backing these slacks off regularly destroys the clutches... one of the selling features of the A-M slacks.

i was weened on the A-M slacks as i worked in a navistar shop, so i just always compared everyone else's slack to theirs... excuse my ignorance.

 

Good information to know.

The selling feature of the other slacks is the fact that they use one way clutches instead of teeth, hence they have infinite adjustments and will adjust a little bit each time rather than waiting until they click over a tooth like a Meritor one. Whether it makes any practical difference is unknown to me....

I tend to prefer the Meritor ones but I have found that in retrofitting strange and ancient trucks for automatics that Haldex has a much, much broader selection for different applications, as does Bendix but not as much....

Birken

 

as long as the applied stroke remains decent (nowhere near the stroke limit), you're ok. I've always told my customers to occassionally make a hard brake application while idling across a parking lot (force a full chamber stroke to occur); normal brake applications might not be enough to keep them well adjusted.

 

***when you are requested to adjust the brakes on a vehicle with auto slacks... the intention is to inspect the stroke, and adjust accordingly***

 

This talk about backing them off against the clutch teeth, I always took a bar under there with me and pulled on the slack while I turned the adjustment. Pull turn pull turn pull turn- just that quick you're done and there's no backing off involved. And I got to see what the actual stroke was (sort of, anyway), which you don't see if you're doing the back-off method.

 

never ever thought of that before, instead of backing off. you're measuring the stroke travel, and then tightening down the adjustment only until it's right!!!

thanks for that thought!

isn't it funny how that for years we can overlook the obvious because we've already been taught/shown the "proper" method?

thanks joeyb

...... still can't believe I've overlooked something so obvious for all those years ........... ;0)

 

I have manual slacks on one of my flat decks. Although is is permissible to swap manuals with auto's, you cannot swap auto's with manuals. If caught, it could very likely lead to an out of service ticket.

If maintained properly I believe Auto's are superior to manuals.

Although everyone should be trained how to adjust and maintain both types.