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Topic: Slack adjuster adjustment (Read 1557 times) previous topic - next topic

Slack adjuster adjustment

I final got under the coach to inspect the brakes.
Heres what I found:

Rotors good no scoring or cracks, some rusting.

Pads seem like new, about 1/2" shows on the end of the slide pin.

Calipers stuck on slide pins. I hit the pins with penetrating oil and gave them a few good whacks, they are now free ( I will use brake cleaner later to help remove oil from pins).

I did notice on the rear that the right rear has a different caliper assembly than the others. It did NOT have a grease fitting and a relief valve. It only had a plug. I removed the plug inserted a grease fitting, put the clay based grease in, then removed the grease fitting and ran the slack adjuster all the way forward then back. then forward again during the slack adjuster adjustment.

All the other calipers had two grease fittings and a plug for the relief.
Clay based grease has been put in all calipers.

I'm not exactly clear on the slack adjuster final adjustment.
I thought I read the brake manual and understood that he rod from the air chamber should have about 3/4" of travel, Is this right?
I watched several U tube videos that showed to run the caliper piston up to the rotor than back off 1/2 turn. This was NOT directed to Air Disc brakes but to air drum brakes.

I also have one rear air chamber(#30) that has a different rod than the others. It has a longer throw, and has a area on it that is painted red.

Any tips on the final slack adjustment?

Thanks

Re: Slack adjuster adjustment

Reply #1 –
Morning Lon,

I think the Meritor manual has you back off 1/2 turn.
Do you have that manual? Mine is out in the coach.
I'm not real comfortable with different parts in there.
Will all wheels brake the the same?
You may be able to find out from Meritor if those parts can be used as exchange parts.

Re: Slack adjuster adjustment

Reply #2 –
Thanks John.
I downloaded the manual. but I'm not 100% clear on the adjustment. I also seem to have one "odd ball" caliper and a one air chamber that's different (same size but a different stroke) these parts are on different rear wheels.

I just want to be sure its adjusted correctly.

Re: Slack adjuster adjustment

Reply #3 –
Quote from: Lon and Cheryl –
I just want to be sure its adjusted correctly.
I am confident that my brakes are properly lubricated and adjusted. How did I do it and why am I confident that the work was done properly? About $140 at FOT ... yesterday. This thread prompted me to have the brakes checked during our current service event. That mechanic said all was good, but they were in need of proper lubrication. My instructions were to "check the brakes." He adjusted them and lubricated them.

Re: Slack adjuster adjustment

Reply #4 –
Just remember that you have to ask to get the brakes lubed at FOT. If you just ask for a lube job, they lube only the chassis and don't include the breaks or ask you if you want the breaks done.

Is Billy Jack back at work yet? How is his son?

Re: Slack adjuster adjustment

Reply #5 –
Quote from: Kent Speers –
Just remember that you have to ask to get the brakes lubed at FOT. If you just ask for a lube job, they lube only the chassis and don't include the breaks or ask you if you want the breaks done.

And the Meritor brakes can/should only be lubed a couple of times over their life.  I think it's twice.

Re: Slack adjuster adjustment

Reply #6 –
I included checking the brakes on the order. The specific item was:

Complaint: C8000 Check, Lube, and Adjust brakes
Cause: Checked, lubed, and adjusted brakes
Labor: C08049 Lube and expel excess grease
Parts: 1 ea Grease, brake, Rockwell

I asked mechanic about the work he did. He said he adjusted brakes, and they were very dry and in need of lubrication. We show about 86,000 miles on the coach. It is about 15 years old. Don't know what was done on the coach prior to about two years ago.

Re: Slack adjuster adjustment

Reply #7 –
I ended up calling Foretravel and talked to the service dept.
 He stated that they use the gauges from Meritor to adjust the brakes. Unfortunately I don't have the gauges. I guess its not as easy as turning in then turning out, the adjustment is from the push rod length. He said in a pinch you could use a ruler.

I also called a local tire place and asked if they could do the adjustment, he told me that they did not have a certified brake person to adjust slack adjusters. Only a certified brake mechanic can legally adjust the brakes.

Re: Slack adjuster adjustment

Reply #8 –
Quote from: Lon and Cheryl –
I final got under the coach to inspect the brakes.
Heres what I found:

Rotors good no scoring or cracks, some rusting.

Pads seem like new, about 1/2" shows on the end of the slide pin.

Calipers stuck on slide pins. I hit the pins with penetrating oil and gave them a few good whacks, they are now free ( I will use brake cleaner later to help remove oil from pins).

I did notice on the rear that the right rear has a different caliper assembly than the others. It did NOT have a grease fitting and a relief valve. It only had a plug. I removed the plug inserted a grease fitting, put the clay based grease in, then removed the grease fitting and ran the slack adjuster all the way forward then back. then forward again during the slack adjuster adjustment.

All the other calipers had two grease fittings and a plug for the relief.
Clay based grease has been put in all calipers.

I'm not exactly clear on the slack adjuster final adjustment.
I thought I read the brake manual and understood that he rod from the air chamber should have about 3/4" of travel, Is this right?
I watched several U tube videos that showed to run the caliper piston up to the rotor than back off 1/2 turn. This was NOT directed to Air Disc brakes but to air drum brakes.

I also have one rear air chamber(#30) that has a different rod than the others. It has a longer throw, and has a area on it that is painted red.

Any tips on the final slack adjustment?

Thanks
Lon,
My 1995 U300SE has a different RR caliper and brake can also. I thought it was replaced when the previous owner had the rear brakes completely redone but now I wonder. I did look into it and believe that the odd caliper is an earlier version, can't remember completely but I seem to remember that the casting numbers verified my suspision. I'm not worried about it. I did replace the plug with a Meritor relief valve purchased at the local truck stop. It poses no issue for me as long as the slack adjuster is properly adjusted. The slack adjusters are also automatic so after a few cycles you can check again to see if all is OK. I had no need for special gages for slack adjustment straight ruler or tape measure is OK if you are a decent mechanic. Read the manual and apply your best mechanical skills. Search some of my previous posts on either brake lube or helper springs to see if there is more info there. Also, don't forget the suggestion that if you need Meritor brake service help, check with the local fire dept to see who they use for brake service as many of the heavy fire trucks use Meritor disc brakes.
Good luck,
Rick
 

Re: Slack adjuster adjustment

Reply #9 –
Thanks Rick,

You pulled this post back from the dead. With spring here and temps rising my thoughts lead to crawling under the coach and adjusting the slack adjusters and changing filters and fluids.
30 years ago my thoughts would have had anouther direction.