Front brake drum, seals, bearings, etc.

[twinboat]

The automatic slack adjuster will continue to advance the S cam.
You can see, with the red lines from the center point of the S cam, that the distance increases as the cam rotates.

The S cam will rotate and expand the shoes until they run off the end of the S.

As far as the drum coming off without backing off the adjustment, if there was no ridge, where there was no shoe contact, or deep groves, inside the drum, it would slide right off.

[CountryB]

Note the the roller advance up the S-cam curve when the brakes are applied. As shown in your picture, the shoes are fully retracted. When the roller reaches the "tip" of the Cam the brake shoes would be at maximum expansion.

Here's a drawing I marked up. I hope this helps explain the operation better. If not google "S-Cam brake operation" and there are plenty of videos on the subject.
Good luck.

[nodine]

Thanks guys. Then it looks like I have a slack adjuster problem and will look into that.

Bob

[CountryB]

Are both front brakes having problems?

It would be unusual (not impossible) for "both" automatic slack adjusters to be bad.

Don't assume the brakes are not adjusted, or working, properly just because the drum slides off without needing to back off the slack adjuster (as Twinboat said).

If just one slack adjuster is not working (and therefore the brake adjustment is bad), and the other side is adjusting correctly, the coach would pull to one side while braking hard.

I don't think you ever described the problem or reason your taking things apart.

if the front brakes just seem to be weak, it could be an adjustment issue (stroke too long), the lack of proper air pressure (not enough air pressure) to front brake chambers, glazed lining, etc. Or maybe just incorrect driver's expectations about brake performance.

[nodine]

Originally Posted by CountryB

Are both front brakes having problems?

It would be unusual (not impossible) for "both" automatic slack adjusters to be bad.

Don't assume the brakes are not adjusted, or working, properly just because the drum slides off without needing to back off the slack adjuster (as Twinboat said).

If just one slack adjuster is not working (and therefore the brake adjustment is bad), and the other side is adjusting correctly, the coach would pull to one side while braking hard.

I don't think you ever described the problem or reason your taking things apart.

if the front brakes just seem to be weak, it could be an adjustment issue (stroke too long), the lack of proper air pressure (not enough air pressure) to front brake chambers, glazed lining, etc. Or maybe just incorrect driver's expectations about brake performance.

Mike,

There are several problems. First the braking ability has declined over the eleven and half years we have owned the coach. The brake pedal is very hard and the coach will make your sphincter muscle draw up if a sudden stop is required.

If a panic stop is made at highway speeds and we have not recently done the pre-trip slack adjuster exercise by applying the brakes hard 5 or more times to the stop with the parking brake released, the coach will pull hard to one side. That is an indication of a slack adjuster not doing its job.

The third problem is a big popping sound on the front when the brakes are applied hard at highway speed. That I believe is a sticking roller or rollers that actuate the brakes when the S-camp pushes against them.

Van, yourself, and Twinboat tell me there are lots of miles left in the linings but since I have things apart I am inclined to replace the linings. I plan to put everything back together and check the stroke on the service chamber after doing the initial setup on the slack adjuster. Will also purge all the old grease out of the slack adjusters and S-cam shaft and get new grease in them. Also going to apply anti seize compound to the axle and seat of the rollers. Not enough that it might get on the brake shoes but just enough to do the job. This is on Van's advice. Have not seen any significant flat spots on the rollers. Going over to Truck Pro in a few minuets to buy shoes and will ask about new rollers. The plan is to put some miles on the coach and then repeat the stoke measurement to see if one of the slack adjusters is not adjusting. If that is the case then I will replace both front slack adjusters since mine are Haldex 10268's which seem to be quite a bit more expensive than others on the market. I assume that is because they are obsolete. To me it is a red flag when you put a part number in Google and most of the hits come up on ebay at three times the cost of normal.

Will wait on doing the rear for now. I need to find out how to cage the service chambers on the rear. They are Haldex and I believe take a large bolt screwed into the rear of the chamber. Do you see any holes in my plan? This may take me a while because I have a son moving and need to help him tomorrow and this weekend. I am retired so no big deal. Don't need to use the coach until June 19.

Bob

[twinboat]

Since the rear shoes do most of the stopping, replacing them will help. They are probably glazed due to light use. Common problem with driving gently and using engine or exhaust brakes.

You could give the MH 3 or 4 hard stops, from 50 MPH, to burnish the shoes. That may improve the stopping power.

If you decide to replace them and don't have the caging bolt. You don't nessesserly need to cage the rear chambers, just back the self adjuster off, while the parking brake is off. ( Chamber is aired up )

Keep backing off until the rod starts to pull out of the chamber. At that point setting the parking brake should not push the shoes against the drum. If it does, just back them off more.

If you locate the caging bolt, install it with the parking brake off. Then it just takes a turn or two on the bolt to hold the springs back.
If you do it with the parking brake applied, it takes a lot more turns and effort to compress the springs.

I'v done hundreds of brake jobs on large vehicle's.

[nodine]

The left front went back together without any problems. Set the pads against the drum and backed off slightly. Then applied the brakes a few times to seat the shoes. Then went back and reset the S-cam. Travel on the service chamber plunger is 3/16 of an inch. Now will do the other side. Discovered that when the wheel is off is a great time to lube the kingpin, slack adjuster, and S-cam shaft. So much easier to get to things and wipe off the excess grease.

Bob

[CountryB]

From your posts it sounds like you are thinking that the roller moves in the "opposite" direction of how it actually moves.

Sorry if I have mistaken your posting or underestimated your knowledge on this.

With the brakes released (not applied) the roller is near the base circle of the S-Cam (about where the marks in your photo are).

When you step on the brakes, the roller moves away from base circle toward the tip of the S-Cam.

BTW - did you end getting new Slack Adjusters?

[nodine]

Originally Posted by CountryB

From your posts it sounds like you are thinking that the roller moves in the "opposite" direction of how it actually moves.

Sorry if I have mistaken your posting or underestimated your knowledge on this.

With the brakes released (not applied) the roller is near the base circle of the S-Cam (about where the marks in your photo are).

When you step on the brakes, the roller moves away from base circle toward the tip of the S-Cam.

BTW - did you end getting new Slack Adjusters?

Mike,

No I am going to put some miles on the coach and then re-check the plunger travel of the service chamber on each front wheel. If there is a significant imbalance then I will replace both front slack adjusters. We have a lot going on until the end of June. I plan to check the rear then. Could have a grease seal leaking so plan to pull the rears and check them out.

Bob

[nodine]

As luck would have the pressure switch failed on my air compressor. I have a new one on order. My 1500 foot lb 1" air wrench had a difficult time removing the lug nuts on the left front wheel. They must have been torqued to 1000 lbs. I understand that 22.5 inch wheel lug nuts with the backing washer should only be torqued to 450 to 500 ft lbs. When going back together with the left front I used my torque wrench set to 160 lbs attached to a 3 to 1 torque multiplier I have. That comes out to 480 ft lbs which is within the recommended range. Now that the air compressor is down I used that same torque multiplier and a breaker bar with a 36 inch pipe to get the lug nuts loose. Worked nicely. When I get done with the brakes all the lug nuts will be torqued to the proper range. The way those tire shops get happy with the 1 inch air wrench its no wonder everyone is not driving around with broken lug nut studs.

I am not a big man (163 lbs) and will be 73 next month so need all the help I can get. In addition to the torque multiplier I purchase a wheel dolly from Harbor Freight to help getting the wheels off and out of the way. It works quite well and there is no need for the crowbar under the tire when going back with the tire. I may have to purchase a second dolly when doing the rear.

Also discovered that it is much easier to polish the wheels while the tire is removed from the hub. Did the left front before putting the wheel back on.

Bob

[CountryB]

That dolly idea is really smart.

BTW - can you provide the part numbers for the brake shoes (and wheels bearings/seals if you did those) and whatever else you bought?

Of course to be useful, we will need to know "model/type" of brake assembly (such As "Bendix XXX brake system" - so others with the same setup will have a parts list without needed to disassemble first.

For example, my front brakes are "Bendix ESD-225" (disc brakes). What do you have?

[nodine]

Originally Posted by CountryB

That dolly idea is really smart.

BTW - can you provide the part numbers for the brake shoes (and wheels bearings/seals if you did those) and whatever else you bought?

Of course to be useful, we will need to know "model/type" of brake assembly (such As "Bendix XXX brake system" - so others with the same setup will have a parts list without needed to disassemble first.

For example, my front brakes are "Bendix ESD-225" (disc brakes). What do you have?

Good morning Mike,

The front shoes on my coach had a sticker that read Spicer 4130. I took a pair of the old shoes with me to TruckPro and the guy at the counter took one look and did not even need to look up a part number. Came back in a few minutes with two brake kits complete with new springs and rollers. $44.74 each and total with tax $97.76. The brake kits are Van Horn L1308E. I found the shoes, rollers, and springs online but the cost was about the same at TruckPro and did not have to pay shipping. Here are the links:

https://tinyurl.com/y5j83ygl

https://tinyurl.com/y54mw9r6

I did not need to do seals or bearings. The S-cam shafts did not have any end play and moved freely so they were not pulled down.

Bob

[CountryB]

For anyone else that comes along looking for info...
This is the brake setup (front drum) for your coach and most others of that vintage and weight.

It's the Bendix (Spicer) EB-150-4L or ES-150-4L
EB = Standard, ES = Extended Service

[nodine]

Took a trip up to Crossville for a few days and got back yesterday. Some good hills on I-40 between Knoxville and Crossville to test the brakes. Could diffidently notice an improvement in braking and can't wait to do the rear brakes. Since we tow a heavy full size truck we decided to make sure the brakes there were working as they should. Made an adapter to hook my air compressor up to the air input for the BrakeMaster. Put the BrakeMaster on the truck and jacked up the left front wheel. Made sure the wheel moved freely with the BrakeMaster installed and then applied 10 lbs of air pressure. The brake shoes were touching but the wheel could be turned with a little effort. Then increased the pressure to 20 PSI and could not turn the wheel. That leads me to believe the toad brakes are doing their job when the coach brakes are applied.

Bob