Break slack
 

Break slack

Started by solardude, June 09, 2018, 09:29:31 PM

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solardude

I have finished all the rear radius rod bushings, and all other associated repairs, I am now preparing to remount the wheels. However in the process of removing the drums, I backed off all the breaks to make drum removal easy. I have been told the proper adjustment of the breaks is to tighten slack adjuster till breaks are locked up, then back off 180 degrees. So I counted the "clicks" 180 degrees was 38 clicks.
So I plan to do that to all 4 of the rear wheels in hopes of even breaking.

Does that sound correct?
What is your method for slack adjustment?

SD
Jeff
1993 MCI 102C3
Cummins L10/Allison ATEC
Twin Cities, MN.

eagle19952

Are you talking auto slacks...?
Donald PH
1978 Model 05 Eagle w/Torsilastic Suspension,8V71 N, DD, Allison on 24.5's 12kw Kubota.

solardude

Not auto slacks, manual.
When in doubt: read the manual. The manual says to tighten and back off two clicks in front and three in back. Answered my own question.

SD
Jeff
1993 MCI 102C3
Cummins L10/Allison ATEC
Twin Cities, MN.

richard5933

You've got to be careful to follow the proper front-to-back recommendations. When the shop working on our 4106 first did the brake adjustment, the tech followed what he thought was the right way and set them all the same. Problem was that the bus designed for something else. Front brakes were being asked to carry too much of the braking load and quickly overheated, causing a near-disaster on the way home. I turned around, had them crack the manual (and call Luke for confirmation) and then readjust. No problem after that. This is not something that should be done based on what seems right, but rather strictly by the book.
Richard
1974 GMC P8M4108a-125 Custom Coach "Land Cruiser" (Sold)
1964 GM PD4106-2412 (Former Bus)
1994 Airstream Excella 25-ft w/ 1999 Suburban 2500
Located in beautiful Wisconsin

Utahclaimjumper

 If you keep "breaking" your slacks, its going to get expensive. >>>Dan
Utclmjmpr  (rufcmpn)
EX 4106 (presently SOB)
Cedar City, Ut.
72 VW Baja towed

chessie4905

Before reattaching the wheels, check for bearing looseness at rear hubs. Loose bearings can cause drum drag when putting coach back down on the wheels.
GMC h8h 649#028 (4905)
Pennsylvania-central

brmax

Make sure all air tanks are full when taking on this job. This is very important on spring brakes and a good pattern with the others as well.
I was taught the wheel needs to be off the ground when checking and adjusting. I still like to follow this method for a rolling sound check for scraping and or misalignment of shoes and somtimes winter weather shoe issues.
The cdl brake visual check should be a step in this adjustment and followed. I found a wood handle wedged in place for brake applications work well as theres not always another helper around. :)


Good day

Floyd
1992 MC9
6V92
Allison

buswarrior

The entire sorry history of slack adjusters must be observed and respected, when we start tossing "advice" about brake adjustment.

You may have already damaged certain slack adjusters, by your methods.

A busnut MUST identify the particular brand and model of slack adjuster that some previous owner may have installed, compare that to what the coach manufacturer installed, and RESEARCH the correct methods for their install, ongoing maintenance and how to both back them off, and re-adjust.

No kidding, there have been auto slacks that using "traditional methods" breaks their internals.

The consequences of doing this wrong are setting the coach on fire, via a dragging brake setting the tires on fire... or, stepping on the brake pedal and the coach not stopping as you want it to...

One size does NOT fit all, as we approach the mid point of 2018, and busnuts are deep into the variety of auto slacks that came out back 25 plus years ago, some for only a brief and convoluted time.

PLEASE be SMART, then you will be SAFE!!!

Happy coaching!
Buswarrior
Frozen North, Greater Toronto Area
new project: 1995 MCI 102D3, Cat 3176b, Eaton Autoshift

windtrader

great advice, buswarrior! Some may take comfort having a manual and following the instructions which were written for OEM equipment while in fact what is installed after 30-50+ years can be something different.
Don F
1976 MCI/TMC MC-8 #1286
Fully converted
Bought 2017

eagle19952

No kidding, there have been auto slacks that using "traditional methods" breaks their internals.

personally i think these should be illegal.

getting under your bus and snooping around should b a regular deal'

Owning a bus and not able or willing to adjust your own brakes is  fools game.

Back in my gravel hauling field mechanic days...I handed drivers 9/16" wrenches and a tutoring moment.

or a pink slip and a check.
Donald PH
1978 Model 05 Eagle w/Torsilastic Suspension,8V71 N, DD, Allison on 24.5's 12kw Kubota.

TomC

Always adjusted the brakes down to stop then back off 1/3 turn. I've never heard that adjusting brakes differently from front to back made a difference-after all, these are air brakes. Compared to hydraulic brakes that do move in direct proportion to how much pressure is applied. Good Luck, TomC
Tom & Donna Christman. 1985 Kenworth 40ft Super C with garage. '77 AMGeneral 10240B; 8V-71TATAIC V730.

richard5933

Quote from: TomC on June 10, 2018, 11:21:12 AM
Always adjusted the brakes down to stop then back off 1/3 turn. I've never heard that adjusting brakes differently from front to back made a difference-after all, these are air brakes. Compared to hydraulic brakes that do move in direct proportion to how much pressure is applied. Good Luck, TomC

Makes a huge difference to some coaches - the 4106 is has different sized drums front and rear, and obviously the larger ones are designed to do more of the braking. Setting them the same front to rear is what caused the smaller drums to heat up faster than they should and fade quickly. The way it was explained to me is that the larger drums should engage first and carry more of the weight when stopping. I'm no brake expert, but I followed Luke's advice on the 4106 and now on the 4108 and stopping is much better.
Richard
1974 GMC P8M4108a-125 Custom Coach "Land Cruiser" (Sold)
1964 GM PD4106-2412 (Former Bus)
1994 Airstream Excella 25-ft w/ 1999 Suburban 2500
Located in beautiful Wisconsin

luvrbus

Quote from: TomC on June 10, 2018, 11:21:12 AM
Always adjusted the brakes down to stop then back off 1/3 turn. I've never heard that adjusting brakes differently from front to back made a difference-after all, these are air brakes. Compared to hydraulic brakes that do move in direct proportion to how much pressure is applied. Good Luck, TomC

Must be a GM thing TomC,how in the hell would a automatic slack adjuster adjust to that ? maybe GM's don't have propositioning valve
Life is short drink the good wine first

eagle19952

on ice..front brakes can/will hurt you.
many (in the Arctic off road) are disabled.
Donald PH
1978 Model 05 Eagle w/Torsilastic Suspension,8V71 N, DD, Allison on 24.5's 12kw Kubota.

luvrbus

Quote from: eagle19952 on June 10, 2018, 12:26:04 PM
on ice..front brakes can/will hurt you.
many (in the Arctic off road) are disabled.

For years tandem trucks never had brakes on the front axle,some older buses had a valve to disable the front brakes or reduce the air pressure
Life is short drink the good wine first