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Clutch Brake Adjustment


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Anyone have a detailed explanation/directions on how to adjust the clutch brake? The last two times I've had the truck in for unrelated service, I've asked that it be done. But for whatever reason, they seem to avoid it like the plague.

It's bad. And I'm tired of grinding the Hell out of it to get it in gear.

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FlatWork

Gudday m8

Wot we do is clunk the gear lever into 1st gear (the biggest badest gear in the box)

th@ slows the gears down to stop spinn n then push cog selector into desired gear

we do this also to engage G/Box PTO

cya

§wishy

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1 hour ago, Swishy said:

FlatWork

Gudday m8

Wot we do is clunk the gear lever into 1st gear (the biggest badest gear in the box)

th@ slows the gears down to stop spinn n then push cog selector into desired gear

we do this also to engage G/Box PTO

cya

§wishy

I have noticed that dropping into 1st does slow it down.

And yeah, for me, the pto is also another reason I want it adjusted. On a normal day, I engage it at least half a dozen times.

What I've been doing with the truck recently is hauling asphalt millings. Loading directly under the mill in parking lots. So I'm running in 1st quite often. But I'm doing a lot of city driving too. It just needs to be correctly adjusted. I've watched a couple of blurry youtube videos. Hopefully I can figure it out.

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8 hours ago, fjh said:

Make and model of truck?

for (most) normal trucks this is a linkage adjustment?

'04 Mack CX 613. !0 speed Eaton Fuller.  AC 427.

I've never looked at it before. But I'm hoping when I do, that it's pretty clear how it works. I just won't know what's considered "properly adjusted".

 

I'm also going to check the trans oil. It's a little (not much) wet around the output housing. If I need to add any, I've been told the correct oil is synthetic SAE 50 manual transmission oil. Is that right?

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For a fuller trans yup!

On the mack they provide an adjustment on the lever if that has become seized  ( Likely Why no one wants to adjust it for you ) you can remove the clevis pin and wind the clevis in several turns that will shorten the cable in turn that will give you more clutch brake and less free pedal!

once you got the brake where you need it  then you can set the free pedal  with the adjustment  provided on the clutch  itself . IF its not a solo clutch!

Edited by fjh
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1 hour ago, fjh said:

For a fuller trans yup!

On the mack they provide an adjustment on the lever if that has become seized  ( Likely Why no one wants to adjust it for you ) you can remove the clevis pin and wind the clevis in several turns that will shorten the cable in turn that will give you more clutch brake and less free pedal!

once you got the brake where you need it  then you can set the free pedal  with the adjustment  provided on the clutch  itself . IF its not a solo clutch!

Thank you! Now we're getting somewhere.

It would seem to me, if there was a problem with the adjustment lever, someone would have said something. But, as I have found out the hard way- truck and hydraulic service based companies in Lansing, MI, absolutely suck. You go in, tell them what you need, don't complain about their prices or wait times- and they start looking for reasons not to serve you.

I guess they've got enough work servicing fleets.

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Alright. I crawled underneath it. What I saw is this:

 

The clutch cable comes down, and connects to a lever with a clevis. At the top of that lever, there appears to be something for making an adjustment. There's a bolt that rides thru a slot and locks. And a set screw opposite of that. The set screw/jamb nut, looks like it only has a couple of threads left before it's bottomed out.

I took the inspection cover off and looked up in there really quickly. It has an electrical wire connected to it. It looked like there was quite a bit clutch dust caked on. I just did this really quickly outside the shop on the concrete slab. I've got a project to get out of the way before I can pull the tractor in and get underneath it.

 

Any suggestions how to move forward from here?

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So first take the cover off check that that the clutch brake is not just spinning on the shaft if it is you need to replace it! If it is still splined to the shaft Proceed as follows

because the arm set is maxed out PLAN B  I would loosen the jam nut behind the clevis at the arm back it back 1 or 2 turns then remove the clevis pin and turn the clevis back to meet the nut you just loosened now re fit the pin into the clevis and arm and try the clutch brake!

if you run out of thread on the clevis  PLAN  C  loosen the Rear most nut on the clutch cable Sheath two turns or so Then tighten the front nut!The objective here is to make the fork closer to the throw out bearing assuming you still have free pedal! once that's done and once you achieve clutch brake you will need to reset the clutch with the winder on the face of the pressure plate so you have a 1/2 inch gap between the clutch brake and the bearing face to achieve your 1 1/2 free pedal that you should be used to having by having a properly adjusted clutch! There is a plan D AND E how ever  Last resort! Don't want to go there unless forced too! :rolleyes:

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Adjust internally first to get  1/2 inch to 9/16  inch between clutch brake and throw out bearing,if this doesn't bring your brake into adjustment and corect free pedal make linkage adjustment,you can adjust at the lever if u want by turning the Clevis,I was just having a problem and found the Clevis pin worn out and needed a bushing in the clutch arm,good luck

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Quite honestly guys if you think about  It really don't mater which order  you do them the end result will be the same how ever linkage first you will avoid doing the internal one twice! The fact is the the linkage governs  the clutch brake squeeze as stated by Glenn!

Right now he just wants his clutch brake Back and Have offered  several solutions! :thumb:

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Not arguing but,if adjust the linkage first then internally you will be moving the bearing witch will change the linkage adjustment you just made,thoughts ?

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Also I wanted to say the reason for the internal adjustment is to get 1/2 inch to 9/16 inch between the brake and throw out. Bearing witch they say you must maintain for full clutch release.

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3 hours ago, MACKS said:

Not arguing but,if adjust the linkage first then internally you will be moving the bearing witch will change the linkage adjustment you just made,thoughts ?

Your not  arguing because thats the way be learn about trucks.But the lever does not set the position of the brg.Only the clutch pressure plate adjustment sets the postion of the brg.The linkage only sets the position of the fork.You may have the brg setting close to the pressure plate and the fork just pressing on the brake disc.Now go in there and adjust the brg and the fork will not move away from the brake disc or get closer.The reason i say adjust the brake disc first is i had alot of studens work under me at the dealership and i learn long time ago to make it simple as can be for them and like said set the brake disc first and in most cases the rest of the clutches life which could be 500000 miles the clutch brake is not reset maybe over two times and thats due to wear on the disc or fork.Now if the clutch is set to were the clutch disc is not releasing then the brake disc is going to wear out fast or is some one mashes the clutch down against the brake went moving many times then the brake will wear fast.I know you can watch videos of adjusting the clutch but just make it simple and you will find it is so easy to under stand.

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glenn akers

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16 hours ago, MACKS said:

Ok I got ya now,just had it in my head the internal adjustment would move the linkage also,thanks for the clarification..

The only time this doesn't apply is with a unit with hydraulically operated clutch fork  If you adjust the internal on these they will for the most part preposition automatically after a few pushes of the pedal ! 

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Thank you for the good info, guys. I learned a lot. I'm going to see what I can do with it. But more than likely the entire clutch is going to need replacing. It's got several inches of free play in the pedal, and almost no room for adjustments in the places talked about. It's not slipping or anything. It still grabs nice and firm.

I spend a lot of my time in parking lots and city streets doing bump and go under an asphalt mill. Stop, move 25 feet, stop, move 25 feet, stop. Over and over. It's hell on a clutch. AND your clutch leg!!

How much (just a rough figure) can I plan on paying for a clutch job? Material and labor. I plan on using all new parts. No reman. parts.

Edited by Flat Work
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18 hours ago, Flat Work said:

Thank you for the good info, guys. I learned a lot. I'm going to see what I can do with it. But more than likely the entire clutch is going to need replacing. It's got several inches of free play in the pedal, and almost no room for adjustments in the places talked about. It's not slipping or anything. It still grabs nice and firm.

I spend a lot of my time in parking lots and city streets doing bump and go under an asphalt mill. Stop, move 25 feet, stop, move 25 feet, stop. Over and over. It's hell on a clutch. AND your clutch leg!!

How much (just a rough figure) can I plan on paying for a clutch job? Material and labor. I plan on using all new parts. No reman. parts.

Bud 

By what your describing throws up  a red flag  in my mind Either the clutch cable is stretching OR 

If it has several inches of free play  and no clutch brake  and it  is engaging near the top then I think  your shop of choice has be messing with external adjustment!!!!!and calling it A CLUTCH ADJUSTMENT ! !  NOT!

Take the time to do what we have been saying here. and you may save yourself a thousand bucks or two changing out a clutch that is perfectly OK just ill adjusted! OR get them to do it with the instructions here!

JUST SAYIN!

Edited by fjh
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  • 2 years later...

So, the Mack I have has the solo clutch,  the indicator shows it at about half way between new and replace.  My problem is similar to what you described, the pedal has to be on the floor to get into gear and the truck starts to move with the clutch less then 2" from the floor.  The clearance on the throwout bearing is right at 1/2".  there is practically no freeplay at the pedal. how do I properly adjust?  

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The way to reset a solo is remove it from the truck and then you clamp it. if you do make sure you put bolts in before you remove it. You can take all the free play out witch is not the right way but might help. If your fork was not replaced it could be the problem. Talking about the clutch fork, They get eaten up on even the bushings and two shafts that go to the fork. If some one familiar with clutches changed it they inspected and replaced what was needed. If not a little slop anywhere makes a bigger problem later. If all is good the solo does also cause this problem. 

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2 hours ago, 1965 said:

If you have a solo clutch, best thing to do is R&R it with an easy pedal clutch first time you have a problem with the solo clutch.

Yup Agreed! Have seen way to many of these fail in the same way! best solution is the above ! I wish they would go back to the old style notch adjuster on the easy pedal platform! Don't early see any advantage to the wrench winder!

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the clutch brake adjustment itself is in the linkage but set the clutch first then adjust the linkage, check and make sure your clutch brake is not damaged and replace it if necessary. 

Edited by Ezrider
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