Parts Prices 1624 Brake chambers.

[Jon Wehrenberg]

I am involved in replacing my brake chambers.

I know that our #30 (about $37) chambers in the front and the #3036 (about $122) chambers on the drive are available from local truck parts suppliers.

On certain of our coaches, especially XLVs with tag axle emergency brakes the chambers are #1624 which is not common or readily available. For anyone contemplating having the tag axle brake chambers replaced be aware that Prevost can supply them but at about $412 apiece. There are two ways to reduce that cost significantly.

All parts suppliers can get a piggy back #1624, which is essentially the rear or emergency brake portion of the brake chamber. To that you need to add the parts for the service brake portion by buying a #16 brake chamber and using the plunger, diaphragm, spring, clamps, and non pressure can. That will yield a #1624 for a cost of about $150 to $175, a savings of at least $237 per side or $474 for the bus.

But I also found a source for the complete #1624 from Buy Rite Parts and Supply, Hopkinsville KY (270-886-3976) for $95.55 each a savings of $632 per bus.

I have not ordered from Buy Rite because they just emailed me with the prices and I went with the piggyback unit listed above so I cannot tell you of their shipping costs or turn around time, but if you have any idea you are replacing your brake chambers this is something you definitely want to look into.

From experience I have decided to change my brake chambers every five years regardless of their condition. If you are running with old or original equipment brake chambers at least have a plan for how you will be able to keep traveling with a bad brake chamber (possible, not recommended) until you can get one replaced. It might not be a bad idea to at least carry one #1624 because of their lack of ready availability. (Ditto for air bags, but that is another subject)

[ajducote]

Jon,

The online NAPA catlog list a LOT of brake chambers.

is this the complete 1624 we need for the tag? Or is this just part of it?

http://www.napaonline.com/Search/Detail.aspx?R=MBIGP1624_0006424816

I have a local NAPA dealer that carries a lot of truck parts. It looks like they may be a good source for brake chambers.

[michaeldterry]

Jon,

The online NAPA catlog list a LOT of brake chambers.

is this the complete 1624 we need for the tag? Or is this just part of it?

http://www.napaonline.com/Search/Detail.aspx?R=MBIGP1624_0006424816

I have a local NAPA dealer that carries a lot of truck parts. It looks like they may be a good source for brake chambers.

Andre - this appears to be a piggy back unit like Jon described from Buy Rite Parts. If that's the case, you would still need to buy a #16 chamber (http://www.napaonline.com/Search/Detail.aspx?R=MBISC16_0215351707), too and use the parts Jon outlined in his post above.

[Jon Wehrenberg]

I went through the NAPA catalog. Maybe it is my zip code that is the problem but no matter what search words I used "no match" came up for 16/24. I went though their listings (550 came up) and see that they can be a source on the drive and steer axle brake chambers. I have been frustrated at what I think are excessive prices from Prevost on tag axle chambers which has prompted my search. NAPA never came up in my search efforts, but I see now they could be source of common parts and chambers.

As I indicated above there are three ways I now know of to obtain replacement 16/24 brake chambers (spring brakes). Buy from Prevost, buy a piggyback and a 16 brake chamber and make a 16/24 from the parts, or order from BuyRite.

BTW, I know a lot of owners will have Prevost or a converter do routine maintenance, and I think Prevost lists levels of work. I can say that I do not often get to pull my wheels and get my head under the bus from the street or curb side so now that I am able to do that I am giving a highly detailed inspection of everything now visible. I have already found a hub seal leaking, apparently it started leaking on our recent trip to Frozen Florida. I am also finding a repeat of what I found when I bought the bus and that is the steer axle brake pads are not wearing uniformly. The outer pad on both sides on the steer is wearing most and the inner pads are at or near their original thickness. The tag axle brake pads are wearing equally on both inner and outer pads. No big deal, but something is not right and I cannot figure out what. My point is I actually give a damn about my coach and its condition. I wonder how many techs are going beyond the list of things to do and are poking their nose everywhere looking for potential problems. BTW, if you are using a shop regularly, and are satisfied, stick with them, but record every little detail so with each visit they can monitor things such as my uneven brake pad wear.

[Jon Wehrenberg]

One thing I forgot to mention, and am not recommending, but it has made me do some thinking.

With the exception of the push rod, it appears a 20/24 is dimensionally the same as a 16/24 so the two can be interchangeable. The 20/24 push rod is 5/8" instead of the 1/2 found on the 16/24 so you would have to purchase a larger clevis with 5/8 threads because you cannot use the one currently installed.

However, the service brake which is the 16 has 16 square inches of area and at 100 PSI exerts a 1600 pound force on the slack adjuster arm. The 20 has 20 square inches and it will exert 2000 pounds of force at 100 PSI. It may not seem like a big deal, but I am sure the bus designers selected the brake chamber size and brake pad or brake shoe sizes based on balancing the braking forces so no axle locks up prematurely. ABS was added to further prevent lockup. Because of my inability to do all the analysis necessary before taking on the responsibility of changing what the engineers decided was best I am reluctant to switch my 16/24s to 20/24s.

[Jon Wehrenberg]

I ended up using a 1624 piggyback and adding a 16 brake chamber (minus the back) to create the 1624 I needed for the tag axle.

7777

This is the piggyback and the 16 brake chamber

7778

And this is the old brake chamber and the newly assembled replacement. The only part not used is the back shown between the two. I could have saved some money by buying the entire assembly, but by the time I learned the whole 1624 was available and for $95, I had already ordered the piggyback and the 16. As it was I still saved $250 per side or $500 compared to Prevost's costs for 1624 brake chambers.

[Jon Wehrenberg]

I am posting this just to give everyone something to think about.

When I finished replacing my brake chambers I connected the clevis on the push rod to the slack adjuster arm. Our slack adjusters on all but early coaches (prior to somewhere in the early 90's) are automatic slack adjusters. Older slack adjusters had to be adjusted frequently (not a difficult task), but with the change to automatic slack adjusters the clearance between the pads or shoes and the drims or discs is maintained automatically, or at least that is what is supposed to happen.

My coach has 235,000 miles on it and everything always appeared OK. I say appeared OK because it is stressed that automatic slack adjusters are not to be manually adjusted. When I finished hooking the clevis to the slack adjuster arm I brought the adjustment manually into range. I noticed on my RH drive axle that the adjustment wasn't smooth like on the LH side. My point is if you have any brake work or do have an occasion to adjust the spacing be alert to how your slack adjusters feel and if they are functioning properly.

The adjustment of our brakes is critical. The adjusters maintain a stroke length that is designed to minimize rod travel and motion on the brake chamber diaphragm optimizing the efficiency of the brakes and keeping the wear on the diaphragm to a minimum.

So how do you know if the brake adjusters are doing their job? With the brakes (emergency and service) off measure the distance the push rod extends from the chamber. Apply the brakes. If the travel of the push rod with the brakes applied is less than 1.5 inches (or as a rule of thumb 1/2 of the total maximum travel which is either 2.5 inches or 2.25 inches depending on chamber size) then the brakes are properly adjusted. I have not been measuring travel during my normal maintenance work, but I will be doing so from now on.

I don't know if this is part of the Prevost maintenance schedule, but if not I would suggest you add it to the list of things to be done. When brakes go out of adjustment it happens so gradually that we are not aware something has gone wrong. This is a good way to prevent that from happening.