slack adjusters: manual vs auto

[dondiesel444]

My old Int'l had manual slack adjusters, and now my Mack has automatic. I don't think one of the rear is working, can I change the auto's to manuals? I don't see why not. I kinda like knowing that the brakes are adjusted properly. I can see where auto's are better on tri-axle trucks pulling tri-axle trailers, thats a lot of adjusters to keep an eye on. but my truck is a single axle and I don't mind crawling under there and adjusting them.

 

[PackRat]

A lot of old timers like manuals, rather than autos.

We have autos on everything. Rarely have any trouble. Some have been DOT'd out on the road, and almost never parked for an out of adjustment.

When we overhauled trailers last summer, some acted like the ratchet was bad, but were still working properly.

You can still check the autos and re-adjust manually, if they make you nervous. Nice, not having to worry about it, especially in bad weather.

Guess it boils down to personal preference.

 

[rubberfish]

I don't know what the laws are where you are,
but here in B.C. if the truck came with auto's, you're not allowed to convert to manuals.
I drive a '97 midliner (mack) and the auto's sit at 1 7/8ths. 2" is considered "out".
I ratchet them up to 3/4" manually and it stops quite well.

 

[dondiesel444]

I wonder how anyone would know what the truck originally came with? I tried to manually adjust the one that isn't working, and it doesn't turn. it will loosen up, but not tighten. I'm not sure if I'm doing it right, there is a little spring loaded button I hold out it a screwdriver, than turn the square head on the blot on the top of the adjuster, it doesn't turn to tighten, only to loosen.

there maybe something else wrong with the brakes, but I think it's the adjuster. when i step on the pedal, it does move, but only a little, not as much as the other side which I know is working.

oh yeah, when I apply the parking brake, only the one side holds, the side I think is bad doesn't lock up......any ideas?????

 

[Truckie]

Personally I like the manual slack adjusters I think they hold better and stay adjusted longer than the automatic slack adjusters I have on my Mack. I Keep them greased up pretty good but they don't adjust for $hit infact the only one that dose work the way I like it is the right front steer. The drive axles got the type slack adjuster that you have to back off a nut with spring clip and then adjust it, and then retighten the nut and spring clip. Next time IM due for a brake job IM going to replace the four rear slack adjusters. I got a 1979 Fruehauf trailer with a 1997 JHM body on it, and that trailer has manual slack adjusters on it and I like the way they work.

Mike

 

[Copper]

I don't like 'em either, but autos do seem to work okay, if they're in good shape. Most aren't, though, that I've run across.

The ones I've got on some older IH's have got a plug in the side, with a little spring and a plunger with some little ratchet teeth on it. I'd bet if you can back yours off and not tighten them, the ratchet is in backwards, or something like that. The ones of mine work the opposite, you can set them up, but you can't back them off unless you screw out the plug and disable the ratchet.

Last I looked, I could get rebuild kits from Bendix for them, and they were pretty cheap - you might look into doing that if you don't want to change adjusters.

 

[dondiesel444]

mine have that little spring and plunger too. if I hold the plunger out with a screwdriver, I can't turn the adjuster, it just won't tighten. however, if I back off the adjuster, it does turn.

the brakes are so far off on the one side, I can look throguht the inspection hole and the lining is a half inch from the drum. even after I apply the parking brake, it's still that far away, and only the other side is holding the truck (scary). I think I should just get a new adjuster and see if that helps. I was looking and I think to put manuals in there the whole arm that goes in to the brake chamber would have to be changed too....

 

[Ak HDM]

slack adjusters

I would replace that slack adjuster,& set it up the way the manufacturer says to. as long as the s-cam & bushings & the air can push rod are good, it should keep the brakes adjusted.
the maximum push rod travel on a type 30 chamber is 2", so you want a lot less than that for the brakes to work the best.

hope this helps you

Mike

 

[Duke]

WELCOME to the site!!!!


Please come back often!

 

[Ak HDM]

Duke, thanks for the welcome! This is a great site. I will be here often!
Mike

 

[Duke]

Post new topics & threads. Don't lay back in the shadows. The only way to attract more members & get the ball rolling is to keep this place jumpin'!!

 

[dondiesel444]

I went ahead and bought 4 manual slack adjusters today. I'm gonna install them tomorrow and see how it works. it's too scary driving around with only 3 brakes which are not adjusted right and one that doesn't work at all....

 

[Duke]

Don,

Is it warmin up enough up there to get anything done?
I'm so sick of the cold.

 

[dondiesel444]

Duke, yeah if I put enough layers of clothes on I can work outside for a few hours, but it sux....

 

[Pacific]

The problem with auto slacks is nobody gives them hard enough brake applications to ratchet them up. I don't think the auto slacks were standard issue on your Mack.

I prefer manual slacks myself but it is nice not to have to crawl under the truck to adjust the brakes when its pouring down rain when you have autoslacks.

With the DOT here being strict on brakes guys with auto slacks get nailed for out of adjusted brakes because they never check them.

When you have manual slacks you crawl under the truck your doing a visual inspection day so you spot problems with your truck before you have major problems.

Your rear brakes are the main stopping power so you want both of them to work properly.