How to Adjust a Manual Slack Adjuster for your CDL Air Brakes

[@pakky9503]

Im not trying to flatter you Rick, but Im relatively new on here and your videos are so easily explained and understood. You make them super simple by breaking it down and demonstrating how its done. Keep up the great job. And all the best 👍

[@smartdrivetest]

Thank you for being part of the smart driver community my friend. So happy to hear we can help out. Drop us a note if you have questions. All the best, Cheers Rick

[@greysonraasch1686]

Bravo! Finally, a video that clearly shows the slack adjuster and how to adjust. I've been searching for a vid with a clear view of the adjuster and other components. Simple, basic, and easy to understand. Thanks.

[@smartdrivetest]

Hi Greyson Raasch - you are most welcome my friend. All the best, Cheers Rick

[@JohnNorris411]

Most trucks nowadays have automatic adjusters, but many trailers are manual. I drive ag and all the trailers I pull are manual. I am adjusting the brakes on 6 to 10 trailers a day. One thing I would do differently in adjusting them (non test, in the real world) is I would not turn the nut until it stops/full closed position and then back it off and for good reason. The nuts/bolts tend to move easily to tighten and it takes much more torque often to back it off. In my line of work it is very common, especially in older well used trailers that you can adjust the slack to full closed or just further than you wanted to and then when you go to turn the other way, the bolt head strips and you can not back it off, now you got yourself a locked up brake and can not move the trailer, now you have to find something that can turn that stripped bolt head that your wrench will not, like vice grips if you have some handy. I prefer to use my hammer to check the play in the adjuster and tighten the bolt down bit by bit until I get it in the proper range, then go on to the next one. It's never going to full stop. One other thing on trailers, not all adjusters are 9/16". I have to keep with me a 5/16, 7/16, 9/16 and I believe a 12mm, sometimes you will have different size adjustment bolts and style on the same trailer. Some you have to hold a spring loaded locking pin out to be able to back off a bolt, will turn to tighten but will not loosen unless you pull the pin out.

[@bobslate7016]

I drive a 1984 Pete dump truck, I manually adjust the slack adjusters at least twice a week. When doing a lot of mountain driving including off road, I adjust them at the beginning of the day and in the middle of the day, and again at either the end of the day or the next morning. Before I learned how to properly adjust them, I lost my brakes three times. I was very fortunate all three times I was going slow and at the bottom of the grade. I was able to drive at 15 to 20 mph while the brakes cooled off.

[@smartdrivetest]

Hi Bob Slate - thank you for your comment and pertinent information. We're happy to hear that the loss of brakes didn't result in a tragedy and turned out to be a learning opportunity. Where are you in the world that you're still allow to have manual slack adjusters? Most places here in Canada make you retro fit automatic slack adjusters? If there is anything further we can do, drop us a note. Always happy to help. All the best, Cheers Rick

[@isakwilkinson2491]

2023 I'm in a CDL class for a month. Or school. I'm sitting here reading my book for CDL Idaho. And it talks about manual slack adjusters. I'm hoping they're not going to ask that on my permit test but who knows I already took my permit test and failed. But I've only been in my class for one week. I got most of the general knowledge it was just the brakes and combination that I failed on so I have to go back at a later date in retake. There is a lot a lot of information you have to know just to pass your CDL test. I feel a bit overwhelmed but I have friends and family members who are CDL truck drivers and they said just stay at it you will eventually pass it. And some of the questions on the permit are like misleading and try to trip you up. I don't love that. But I'm grateful for getting the opportunity in which to try to get my CDL. And I thank you very much for the video and show me what I'm actually looking at.

[@mrblack61]

Just spent the morning freeing up and adjusting the slack adjusters on my old Saviem SM8, its a 10 ton 4x4 ex military truck. Coming from a car back ground these videos are great to get my head around the basics of air brakes. Its sobering to think that if they are that far out of adjustment the chambers could bottom out, resulting in no brakes. Cheers Duncan (UK)

[@smartdrivetest]

Hi fred bear - Apologies for the late response. Thank you for your comment. We're happy to hear that we could help you understand air brakes and get yours into adjustment. If there is anything further we can do, drop us a note. Always happy to help. All the best, Cheers Rick

[@ogairbender808]

Or rolling the cam over,and no brakes

[@jakestock7685]

Best video on KZbin for slack adjusters. I couldn't find one other video that explains the Locking sleeve. Same setup that's on my 1985 Pete.

[@smartdrivetest]

Hi @jakestock7685 - And you are most welcome. We're happy to hear we could help out. If there is anything further we can do, drop us a note. Always happy to help. All the best, Cheers Rick

[@timcountryman961]

Thank you. I finally understand what the manual was attempting to describe.

[@smartdrivetest]

Hi Tim Countryman - We're happy to hear we could help out. If there is anything further we can do, drop us a note. Always happy to help. All the best, Cheers Rick

[@Israfil-RF]

Hello Rick, It's very informative video and very nice explanations! Appreciate all you do! Best regards from beautiful country of Tajikistan!

[@smartdrivetest]

Hi Rustam Isrofilov - And you are most welcome. We're happy to hear we could help out. If there is anything further we can do, drop us a note. Always happy to help. All the best, Cheers Rick

[@patb9375]

Thank you for the video. I am always amazed at how people do not listen and ask questions you have answered at least 2-3 times in the video, or in this video do not comprehend this is an example of a system they will not see but need to have basic understanding. Scary that they will be driving. Ask a tow driver how often the air tank has smugh in them and you can tell no has ever drained wet tank. Awesome video good commentary and teaching.

[@smartdrivetest]

Hi Pat B - Thank you for your comment. Yes, it happens that people will ask questions without finishing the video - it happens. On older trucks there was a lot of sludge in air tanks, but on the newer ones, this isn't so much a problem because the air dryers are really good. See this video: kzbin.info/www/bejne/r3PMXmmbisibZtk All the best, Cheers Rick

[@shane1648]

I thought i recognized you lol. Whoop shout out from coldstream, great video. I hadnt done this in 7 years, video saved my butt

[@smartdrivetest]

Thank you my friend. We're so happy to hear that we could help out there in Coldstream. All the very best, Cheers Rick

[@kathydurante]

Thank you, Rick for your excellent videos! I'm writing the ICBC air brakes test this week in order to operate our fire trucks.

[@smartdrivetest]

Hi Kathy Durante - We're happy to hear we could help out. If there is anything further we can do, drop us a note. Good luck on your test! Be sure to let us know how it goes. All the best, Cheers Rick

[@kathydurante]

@@smartdrivetest Thank you ☺️

[@smartdrivetest]

🖖

[@kathydurante]

@@smartdrivetest Officially air brakes endorsed! Keep up the great vids - they are super helpful.

[@Anonymous..VQ3.5Lg35]

Thank you the direction is what i was looking for to loosen slack adjuster

[@zyxnix]

I used to adjust my brakes all the time on our company trailers back in the day. I just needed a refresher on how to do it. I think the trailer I'm running now needs tightened up a bit.

[@smartdrivetest]

Odd that in 2024 you have a trailer that has manual slack adjusters my friend. See this video for adjusting automatic slack adjusters: kzbin.info/www/bejne/ZqXbineFlNqoa7M Drop us a note if we can help further. All the best, Cheers Rick

[@g41thomas]

Excellent video Things every driver should now

[@smartdrivetest]

Hi GETREAL! - not really my friend! If you're going for an Air Brake test, yes. But in the industry, it is very, very unlikely that you're going to encounter manual slack adjusters. All the very best, Cheers Rick

[@slraines71]

very informative and straight to the point. Thanks for posting.

[@smartdrivetest]

Hi Shelley Raines - Thank you for your comment. And you are most welcome. We're happy to hear we could help out. If there is anything further we can do, drop us a note. Always happy to help. All the best, Cheers Rick

[@dougbanks7548]

I drive a 94 bluebird limo coach .At inspection slack adjustor needed adjusting. They did .but was done wrong and smoked my new brakes and hub. Was able to back it off. Now going to test drive. If it happens again will need to install new slack adjustor.

[@smartdrivetest]

Hi Doug Banks - Thank you for your comment. And we're happy that we could help out. Let us know if you get the problem sorted. If there is anything further we can do, drop us a note. Always happy to help. All the best, Cheers Rick

[@bigryanm7083]

im not sure if my Dads Peterbilt that he is fixing, is or has a manual slack adjuster, i have to check it out when, he tries to start it up, this is a good video Sir Rick thank u..

[@ThomasJoseph315]

Crystal clear explanation! Thank you very much!

[@smartdrivetest]

Hi Thomas Joseph - you are most welcome my friend. All the best, Cheers Rick

[@anthonyrobinson6448]

Great video, thank you! This helped me understand much better!

[@smartdrivetest]

Hi Anthony Robinson - you are most welcome my friend. If we can help further, drop us a note. All the best, Cheers Rick

[@rajgill3482]

thank you for making such an important video. ❤

[@smartdrivetest]

Hi raj gill - you are most welcome my friend. Drop us a note if we can help further my friend. All the best, Cheers Rick

[@jasonmiller8167]

Do you have a video on doing the maintenance on brakes, particularly greasing them?

[@BalwinderSinghDeol]

Such a great video. Thanks for all your videos. They are so good and informative..

[@smartdrivetest]

Hi Balwinder Deol - you are most welcome my friend. All the best, Cheers Rick

[@allenfullerton6693]

Excellent video !

[@jerrysturgeon8784]

Have to do it all the time mine has manual slack adjusters on it run a dump truck and do asphalt work on the highway brakes have to work properly have to use them to stay in the machine

[@brodyfillmore2973]

Extremely helpful! Thanks

[@alejandrogamboa615]

Thank you. Very informative.

[@smartdrivetest]

Hi Alejandro Gamboa - you are most welcome my friend. Have a look at this vid too: kzbin.info/www/bejne/mn7bmp-Xqbljp9k Drop us a note if we can help further my friend. All the best, Cheers Rick

[@Velavelly]

For the newer technitions out here trying to figure out why they have never seen a manual slack its because their not used in the industry anymore. you will commonly find automatic slack adjusters on the roads today, automatic slack adjusters dont have to be adjusted regularly but must be checked on a routine basis, an out of adjustment automatic slack is usually due to a faulty slack

[@buncherman2412]

Thank you for the help

[@smartdrivetest]

Hi buncher man - you are most welcome my friend. Drop us a note if we can help further my friend. All the best, Cheers Rick

[@therischow]

Thank you for posting. Very helpful

[@smartdrivetest]

Hi therischow - Thank you for your comment. And you are most welcome. We're happy to hear we could help out. If there is anything further we can do, drop us a note. Always happy to help. All the best, Cheers Rick

[@Stevenfrijol]

I just retired, I always carried a 9 16 wrench, leatherman multi tool, small cresent wrench, flashlight, wire and some duct tape.

[@pvthowell1]

I run a 2013 Pete with manual slack adjusters.

[@SuperTransmission]

Forget the bar , don't get me wrong u still can check with a bar but it is not necessary Tighten your slack slowly back it off Tap the drum with a small hammer When the drum rings you are done U can back off & repeat a few times Follow this procedure on all wheels tractor & trailer your brakes will all be equal u will be amazed how this works

[@smartdrivetest]

Hi FINALDRIVEGUY - Thank you for your comment. Owing to the fact that the drum is cast iron, I would strongly recommend NOT hitting it with a hammer - even a small one. And especially in the winter when the drum is cold. You could crack or break the drum. Fortunately, almost all manual slack adjusters have gone the way of the dodo bird and it is unlikely that drivers are going to encounter manual slack adjusters. If there is anything further we can do, drop us a note. Always happy to help. All the best, Cheers Rick

[@SuperTransmission]

You are not cracking a brake drum tapping on it with a small hammer its not made out of GLASS Its heat-conductive and wear-resistant cast iron alloy You would have a hell of a time cracking it with a 20 pound sledge hammer. Oh & one more thing running in the rain in cold weather & you park overnight & your brake shoes freeze to the drums what do you do release the brakes & beat the drums with a hammer to break them loose I would recommend chocking your wheels first SO YOU DON'T GET RUN OVER. I think a canadian could prolly even figure that out, Or maybe you can wait till the spring thaw.

[@geoffroybrabant-vincent9526]

@@smartdrivetest got to hit the drum with a hammer, yes. most of the time it's the only way to get them off...

[@eatshitful]

@@smartdrivetest Just watch some ice road truckers they wack the crap out of drums when it is -50 out haha Usually to unfreeze the brakes.

[@kentkirkpatrick7953]

I just spent 3 hours freeing stuck brakes on an old truck. I beat the piss out of them with a 10lb sledge. No cracks, no brakes. Worked like a charm. This guy is a saying you'll break them needs a reality check... And hair.

[@PaulGarcia-p1q]

Thx you for the info. You’re awesome. GOD bless

[@smartdrivetest]

You are so welcome! This resource may help too: www.smartdrivetest.com/airbrakes-cdl-rv/air-brakes-explained-simply Drop us a note if you have questions. Cheers Rick

[@rclbranch160barons4]

Going to start driving a Western Star Batch mixer cement truck (4 axle - 2 front 2 rear) sometime soon. Any advice available out there?

[@smartdrivetest]

Hi RCLBranch160 Barons - Thank you for your question. Know that the truck is going to have a turning radius bigger than a football field. So for the first little bit, know that the slower you go, the sharper it's going to turn. If you're in the least little doubt about where your vehicle is in space and place, get out and look. Secure the vehicle first of course. ;o) Brake early and maintain a 5 second following distance. If there is anything further we can do, drop us a note. Always happy to help. All the best, Cheers Rick

[@crashedking1931]

Just what I needed. thanks

[@leyunew]

Tnx a lot for that clear explanation, but me.. I have never adjust manually even if am CDL driver for 4+ years

[@drewmurphy2796]

When did they start using auto slack adjusters?

[@JonathanBruins]

Amazing video.

[@smartdrivetest]

Hi @user-vb2gk9ij9w - We're happy to hear we could help out. If there is anything further we can do, drop us a note. All the best, Cheers Rick

[@jb-ik8sj]

So there will be 4 slack adjusters on a 10 wheel tractor and 4 slack adjusters on the trailer as well if total wheels are 18?

[@Bendigo1]

2 per axle. 3 axles(10wheeler) 6 slack adjusters, 5 axles(18wheeler), 10 slack adjusters.

[@Lone_Wolf_91]

WOW! Thank You Sir! Ive got test in next week and I was thinking the best way would be to tight it fully to the end as we applied brakes and release by some measure like You said 1/4 to 1/2 turn. Eazy if you use brain and understand basic mechanics ;) Take care all!

[@smartdrivetest]

Glad it helped! Good luck on your test next week my friend. All the best, Cheers Rick

[@blakewilliams9584]

@@smartdrivetest Lp

[@ogairbender808]

Never had to adjust the slack adjusters,but I'm confused,you said it's the width of a thumb nail,I thought it about a half an inch.

[@stayhooked9499]

Very informative thanks

[@roadwarrior4773]

Thanks!

[@smartdrivetest]

Hi Ammar Alfatlawe - you are most welcome my friend. Drop us a note if we can help further my friend. All the best, Cheers Rick

[@gpguy2749]

Great vids, thanks. What is meant by “pedal reserve” ?

[@Bendigo1]

It means the amount of pedal you have left if you need to brake harder. You should be able to stop with less than a quarter of the full travel of the pedal. You want the extra so that if brakes wear, you have more brake to apply. If you can press the pedal all the way to the floor and still not stop, that is VERY bad.

[@bubbahyde322]

So worm screw on that adjuster rod? Isn't the s cam splined?

[@smartdrivetest]

Hi Bubba Hyde - I don't understand your question my friend? Please reword. All the best, Cheers Rick

[@bubbahyde322]

@@smartdrivetest I believe the splined end of the s cam goes into a ratcheting sprocket that is geared on the outside and adjusted by the 9/16 worm screw. I had originally not understood the ratcheting and outside gears on the sprocket. Thanks for your checking back! Awesome work!

[@bobhunt3197]

They didn't have auto slacks when I started driving, and I prefer manual slacks to this day, if I get a choice.

[@renatoruiz3609]

I like your videos 👍🏻👍🏻👍🏻👍🏻👍🏻

[@manjeetdhillon5013]

very helpful.Thanks for uploading it.

[@smartdrivetest]

Hi Manjeet Singh - Thank you for your comment. And you are most welcome. If there is anything further we can do, drop us a note. Always happy to help. All the best, Cheers Rick

[@dennissutton4860]

I'm here because this manual slack adjusting question came up in the Texas CDL permit test for air brakes. I have to be honest. I guess I need to see a different angle or something to understand the physics. I'm still lost with this explanation. No thumbs down though. It helped others.

[@smartdrivetest]

Hi Dennis Sutton - what is it that you're not understanding my friend? Can you send us the questions in the TX CDL manual that you were asked? This might help too: www.smartdrivetest.com/cdl-air-brakes/air-brake-manual-adjustment-pry-bar-method Drop us a note if we can help further. All the best, Cheers Rick

[@MAYURGUPTA9]

Thanks for information

[@ralphjacques7618]

Thank you for this

[@smartdrivetest]

Hi Ralph Jacques - you are most welcome my friend. Drop us a note if we can help further my friend. All the best, Cheers Rick

[@jhoefernandez976]

Thank you sir, is MELTS also teach and demonstrate how to adjust the slack adjuster air brake.tnx

[@jimmyb6842]

This vid explained it best

[@smartdrivetest]

Hi Jimmy B - Thank you for your comment and compliment. And you are most welcome. If there is anything further we can do, drop us a note. Always happy to help. All the best, Cheers Rick

[@roberthoraker5494]

I have adjusted my brakes a time or two

[@Peashoot88]

thank you sir!!

[@christophercudia8354]

what is the measurement

[@smartdrivetest]

Pry bar or applied stroke method? Cheers

[@jasonjohnson4170]

Thank you.

[@smartdrivetest]

Hi Jason Johnson - Thank you for your comment. And you are most welcome. If there is anything further we can do, drop us a note. Always happy to help. All the best, Cheers Rick

[@PTHLO666]

👐🏻like as obviously 👍🏻

[@smartdrivetest]

Hi Valerii Miazdrikov - thank you for your comment and compliment. Take care my friend. I'm going to get some equipment next weekend and see if I can get the CDL road test up for you. All the best, Cheers Rick

[@robertcollins7515]

Is 6pack actually necessary. Wouldn't you just pump the brakes just the same?

[@smartdrivetest]

Hi Robert Collins - Thank you for your comment and query. Once a month or so it's important to do a 6 pack because during normal brake applications, you're just not depressing the brakes hard enough for these to crank over to the next position on the ratchet. If there is anything further we can do, drop us a note. Always happy to help. All the best, Cheers Rick

[@robertcollins7515]

Great info. What a difference in the 2 system. Our would be better if maintained. What are the drawbacks of not putting the cover on the brake chamber.

[@theburningred01]

What can cause the locking sleeve not want to come out? It pushes in fine but doesn't want to come back out. It's a new manual bendix

[@Bendigo1]

Not enough grease, or dirt in the gap.

[@jamesklee9980]

No grease

[@bubbahyde322]

What causes this to come loose?

[@smartdrivetest]

Hi Bubba Hyde - it doesn't come loose my friend. The brake pads wear and your adjusting how close the pads are to the shoes. All the best, Cheers Rick

[@bubbahyde322]

@@smartdrivetest good good, in an inch and a half of push rod travel how much outward movement of the pads at the cam? How much expansion away from the pads could a heated from conceivably move? Thanks Rick!

[@tonyalejandro6309]

What does it mean when I have to adjusting the driver side slack adjuster atleast 3 times a day

[@georgeatkinson1023]

IIf you’re adjusting your brakes that often you have bad slack adjusters

[@tonyalejandro6309]

George Atkinson yes sir that’s exactly what it was thank you

[@smartdrivetest]

Thanks, Cheers.

[@bigmoneyboss7898]

Hello, Rick! I am having trouble with curves they are so hard the ones by my house are 45mph but I can't seem to do 30mph around them any tips on how to get the hang of it? They scare me so much!

[@smartdrivetest]

Hey - is this the newly licensed driver?? 80) Do 30mph! A significant number of roads have speed limits according to the highway designation and not according to the physical properties of the roadway. You need to do what you comfortable with that allows you to maintain control of the vehicle. If you're comfortable with 30mph - do 30. Also, make sure that you're looking through the curve and down the road. The car will go where you're looking. In other words, don't be looking at the end of the hood - pick you gaze up to look through the curve. All the best, Cheers Rick

[@bigmoneyboss7898]

Thanks!

[@smartdrivetest]

You are most welcome my friend!

[@gonzalesjr89]

My 2015 kenworth has those slack adjusters weird

[@theawfultruth9136]

The new dmv manual says is 1 inch of free-play

[@ahmedamuhammed8920]

Why do we need to be tested on manual slack adjusted which we dont have it in our trucking industrail!!!!!!! Mcarithium

[@gregorysias6090]

what ?? you think that is tough..??? plumbers still have to prove they can work with lead pipe and solder lead pipe.. we havent used lead pipe regular since 1935. but its all over for repairs and they have always tested for it.. maybe 1935 is not correct.. but you get the meaning....and you dont use cast iron much .. but you still got to prove you can work with it to get your journey level card in plumbing. as well as threading pipe.. which is usually reserved to pipe fitters.. but occasionaly a plumber will install gas lines with black pipe and need to thread it themselves.. and once in a blue moon.. you just might run into a slack adjuster... and you need to know what to do...

[@eatshitful]

@@gregorysias6090 To bad the repair industry didn't keep up that well. Most mechanics now have no idea what a carburetor is!

[@bobh6728]

At think a lot of trailers still have manual adjusters.

[@mrwonderful2142]

I'm here because my front adjusters were 6 whole turns out of whack 🤣

[@Greenbearls]

These container chassis are so old they still use tube tires. Pretty sure they still have manuals because they are always so far out of adjustment.

[@tylerpatterson1267]

Why do all these videos from multiple different people say you need to know this for a CDL test? Never once did I have to do anything even remotely like this on my test. There wouldn’t even be time to do this. You had to complete the entire pre trip, skills/parking test, and road test in less than 1 hour. 1 hour time limit and then you were done. Complete or not

[@cheeze_man]

If we will not adjust manually a slack adjuster WHY is this question on the DMV test? Those DMV guys what is in their minds to put on the list this question?

[@Alan_42219]

95 international is manual 94 fraught liner is manual

[@theawfultruth9136]

I can't stop wondering why DMV ask for this slack adjuster test for 70s 80s trucks ....they just want you to fail by overwhelming you with unnecessary study material

[@sam3d]

California is phasing out all trucks older than 2010

[@smartdrivetest]

And how are they going about doing that? Cheers Rick

[@jamesklee9980]

@@smartdrivetest and that should SUPRISE you?

[@marktempleton-ky8tr]

Bull crap on adjusting automatic adjusters and in states not legal for drivers to adjust breaks without being break certified

[@smartdrivetest]

Since few if any trucks have manual slacks, it's a mute point. Here's the video for the auto slacks: kzbin.info/www/bejne/ZqXbineFlNqoa7M Drop us a note if we can help further. All the best, Cheers Rick

[@johnmartinelli5511]

You talk to fast!! Slow down-----

[@smartdrivetest]

You can slow down the video in the KZbin settings. And turn on the closed captions as well. If you have further questions, drop us a note. Cheers Rick

[@cuddy90210]

Thank you.

[@smartdrivetest]

Hi Cuddy-2M - Thank you for your comment. And you are most welcome. We're happy to hear we could help out. If there is anything further we can do, drop us a note. Always happy to help. All the best, Cheers Rick