Hi all, I am concerned about adjusting the brakes on my Truck. Ok, I know about the mechanicals (All stripped and renewed where necessary), the thing is..... When I adjust smaller car brakes I spin the wheel to assess the 'clearance'. I cannot spin these Huge heavy truck wheels to know if the clearance is adequate. How do other folks do it?
My normal procedure is:
Jack up wheel
adjust each shoe to make contact
spin wheel... adjust until wheel will not spin
Back of adjuster a couple of 'clicks'
Spin wheel (if still binding, back of another click.)
Lower Wheel.
Any tips? Thank you.
Adjusting Brakes
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mudflap
- First Lieutenant
- Posts: 138
- Joined: Sat Jul 07, 2012 12:45 am
- Location: Macomb Twp, MI
Re: Adjusting Brakes
Hi Roland,
The procedure that you describe is pretty much how it goes on the CCKW...
Here is a passage from TM 9-801, paragraph 181:
"Front Brake Shoe Adjustment (fig. 165). Always check hub bearing adjustment (par. 199). A satisfactory brake adjustment cannot be obtained unless the hub bearings are in proper adjustment.
ON BANJO TYPE AXLES ONLY. Remove two adjusting hole covers on backing plate, one at each side of hydraulic flexible line connection. Insert screw driver through hole in plate until screw driver engages notches on wheel cylinder adjusting cap (fig. 165). Turn adjusting cap in clockwise direction (when looking at end of cylinder) until there is a slight drag as wheel is turned by hand. Back off adjusting cap four notches to provide running clearance between brake lining and brake drum. Repeat this procedure at rearward shoe. Make adjustment at both front wheels, and make
Rear Brake Shoe Adjustment. Rear brake shoes are adjusted the same on both split and banjo type axles. Install wrench on hex head of one adjusting pinion shaft. Turn adjuster in clockwise direction as indicated by arrows on figure 166 until there is a slight drag as wheel is revolved by hand. Back off adjuster three-quarters of a turn, which will provide proper running clearance between brake lining and brake drum. Repeat the procedure on the opposite adjuster. Make certain that all brake shoes on each axle are adjusted as uniformly as possible."
From my limited experience, during initial setup - i.e. when you have had everything apart, and you are pretty much starting from scratch the following works well:
On the fronts, I have found it helpful to remove the drive flanges. It makes it easier to spin the wheels and feel the level of contact between the shoes and the drum without having to turn the gears in the differential.
For the rears, ideally you can pop the axle shafts loose. This again gives you a good feel on each wheel independent of the other wheels or the driveline. When I reassembled the brake system on my truck after totally overhauling it, I left the rear axles out before adjusting the brakes, which made it much, much easier.
I suppose, that you could also lower the driveshafts, which would at least decouple the wheels on each side, but you still would have to contend with the gears inside the differential.
For normal maintenance type adjustments, I think that you can get away with a lot less disassembly, as your starting point is a little more consistent, and you shouldn't have to move the wheels and/or crank on the adjusters as much.
One other thing I noticed on my truck was that it is important to have the wheels on, and torqued down prior to adjustment. A couple of my drums did not quite sit perfectly flat on the hubs using just the three mounting screws. This increased the drum run-out to the point where it was impossible to get a consistent adjustment around the entire circumference of the drum. Once the wheel was on and tightened down, they spun perfectly true. Not sure if this is something unique to my truck, or is common with CCKW brakes.
Best Regards,
Bob.
The procedure that you describe is pretty much how it goes on the CCKW...
Here is a passage from TM 9-801, paragraph 181:
"Front Brake Shoe Adjustment (fig. 165). Always check hub bearing adjustment (par. 199). A satisfactory brake adjustment cannot be obtained unless the hub bearings are in proper adjustment.
ON BANJO TYPE AXLES ONLY. Remove two adjusting hole covers on backing plate, one at each side of hydraulic flexible line connection. Insert screw driver through hole in plate until screw driver engages notches on wheel cylinder adjusting cap (fig. 165). Turn adjusting cap in clockwise direction (when looking at end of cylinder) until there is a slight drag as wheel is turned by hand. Back off adjusting cap four notches to provide running clearance between brake lining and brake drum. Repeat this procedure at rearward shoe. Make adjustment at both front wheels, and make
Rear Brake Shoe Adjustment. Rear brake shoes are adjusted the same on both split and banjo type axles. Install wrench on hex head of one adjusting pinion shaft. Turn adjuster in clockwise direction as indicated by arrows on figure 166 until there is a slight drag as wheel is revolved by hand. Back off adjuster three-quarters of a turn, which will provide proper running clearance between brake lining and brake drum. Repeat the procedure on the opposite adjuster. Make certain that all brake shoes on each axle are adjusted as uniformly as possible."
From my limited experience, during initial setup - i.e. when you have had everything apart, and you are pretty much starting from scratch the following works well:
On the fronts, I have found it helpful to remove the drive flanges. It makes it easier to spin the wheels and feel the level of contact between the shoes and the drum without having to turn the gears in the differential.
For the rears, ideally you can pop the axle shafts loose. This again gives you a good feel on each wheel independent of the other wheels or the driveline. When I reassembled the brake system on my truck after totally overhauling it, I left the rear axles out before adjusting the brakes, which made it much, much easier.
I suppose, that you could also lower the driveshafts, which would at least decouple the wheels on each side, but you still would have to contend with the gears inside the differential.
For normal maintenance type adjustments, I think that you can get away with a lot less disassembly, as your starting point is a little more consistent, and you shouldn't have to move the wheels and/or crank on the adjusters as much.
One other thing I noticed on my truck was that it is important to have the wheels on, and torqued down prior to adjustment. A couple of my drums did not quite sit perfectly flat on the hubs using just the three mounting screws. This increased the drum run-out to the point where it was impossible to get a consistent adjustment around the entire circumference of the drum. Once the wheel was on and tightened down, they spun perfectly true. Not sure if this is something unique to my truck, or is common with CCKW brakes.
Best Regards,
Bob.
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RolandRat
- Sergeant
- Posts: 22
- Joined: Wed Nov 08, 2017 9:04 am
Re: Adjusting Brakes
Hi Bob, many thanks. Removing the hub drive/ axles is somewhat obvious...why did I not think of that !!
Yes, I always fit the road wheel. The 3 drum screws I have replaced with new Stainless, hub 'cleaned' so they should fit snug.
a strange thing is occurring while bleeding the brakes. The front nearside will not bleed, that is, no air OR fluid comes out !
In chasing the issue through, I have found fluid as far as the end of the flexi hose, so now just the wheel cylinder/bleed screw to sort out. The job for today.
Regards Roland
Yes, I always fit the road wheel. The 3 drum screws I have replaced with new Stainless, hub 'cleaned' so they should fit snug.
a strange thing is occurring while bleeding the brakes. The front nearside will not bleed, that is, no air OR fluid comes out !
In chasing the issue through, I have found fluid as far as the end of the flexi hose, so now just the wheel cylinder/bleed screw to sort out. The job for today.
Regards Roland
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Motto
- First Lieutenant
- Posts: 80
- Joined: Sat Jul 13, 2013 5:42 pm
- Location: Woodend. 3442. 75 km outside Melbourne, Australia.
Re: Adjusting Brakes
Which end of the flex hose do you have fluid at? The inboard (frame end) or the outboard (wheel cylinder end)?
If the inboard end then you may have a blocked hose. Old brake hoses are prone to swelling internally and blocking the bore whilst looking quite ok on the outside.Usually applying the brakes can force fluid through them but the return spring on the shoes can't push it back so the brake remains on.
If fluid is running through the hose then the only thing left is as you say, the bleed screw.
David
If the inboard end then you may have a blocked hose. Old brake hoses are prone to swelling internally and blocking the bore whilst looking quite ok on the outside.Usually applying the brakes can force fluid through them but the return spring on the shoes can't push it back so the brake remains on.
If fluid is running through the hose then the only thing left is as you say, the bleed screw.
David
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RolandRat
- Sergeant
- Posts: 22
- Joined: Wed Nov 08, 2017 9:04 am
Re: Adjusting Brakes
The problem was quite simply rectified !! I poked a wire down the bleedscrew hole. It was blocked, but I don't know why. It was clear when I fitted it.
Brakes all done now.
Brakes all done now.