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Old 08-17-2023, 04:50 PM   #1
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Question Identifying airbrakes on 1979 Crown Coach

Hey all,
New to the forum so glad this place exists! Jumping right in then.

We have a 1979 Crown Coach that we are in the process of converting. The airbrakes are cracked, and my mechanic is not able to tell the exact parts that are on the bus without having to go under and take them apart.

To save on time and labor cost, I am hoping to identify what type of brakes would be suitable as replacements beforehand so we can order them and get it all done in one go.

So my question: Does anyone know what parts I should buy as replacements for:
4x small airbags on the very rear tires
2x large airbags on the front tires
2x valves that supply airbags with air on rear axel

Thank you so much in advance for any information, or even a direction to search for the information.

Orion

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Old 08-17-2023, 11:11 PM   #2
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Join Date: Jun 2016
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Posts: 1,381
Year: 1990
Coachwork: Crown, integral. (With 2kW of tiltable solar)
Chassis: Crown Supercoach II (rear engine)
Engine: Detroit 6V92TAC, DDEC 2, Jake brake, Allison HT740
Rated Cap: 37,400 lbs GVWR
What do you mean "The airbrakes are cracked" and "I am hoping to identify what type of brakes would be suitable..." when you appear to be asking about air bags for the suspension? I'm confused! The Crown Coach Junkies forum on Facebook has members who would probably know the answer(s) to your question(s).

John
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Old 08-18-2023, 12:27 PM   #3
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Quote:
Originally Posted by Iceni John View Post
What do you mean "The airbrakes are cracked" and "I am hoping to identify what type of brakes would be suitable..." when you appear to be asking about air bags for the suspension? I'm confused! The Crown Coach Junkies forum on Facebook has members who would probably know the answer(s) to your question(s).

John
Hey John, thanks for your reply and your question. Sorry if I was not clear. I am asking about air bags for the air brakes (not sure if that includes the suspension). I am not the most mechanically minded, so I may be confusing things. The air brakes are leaking air.

Thanks for the tip about the Facebook group! I will reach out to them now.
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Old 08-18-2023, 12:33 PM   #4
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Air bags are your "springs" holding up the bus, air chambers are what actuate the shoes to make the bus stop. They are in the same neighborhood but do completely different things. I bet you could find lots of information about air bags on the internet.
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Old 08-18-2023, 12:43 PM   #5
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Hi Orion,

As others have mentioned, you're pretty clearly talking about the air bags (properly called Air Springs) which are part of the suspension and not in any way related to the braking system, except that they both use air...which might be the point of confusion.

The valves you're referring to are called Leveling Valves and they're almost universal and any truck shop...or even my local NAPA...has those on the shelf. As far as the air bags go, they'll have numbers on the sides which you or your mechanic can see pretty easily. Yes, you or he/she will have to crawl under the bus...but nothing needs to be taken apart to see the numbers molded into the sides of the bags. One important safety note - never, ever get under a bus if the air springs are inflated without blocking up the bus body or knowing, for sure, that if an air spring failed there's enough clearance with the bus settled down that you won't get crushed. It is a real risk.

Crown built buses to order, so even buses from the same year may be configured differently. Some had rear engines, some had mid engines...and that might change the air bags they used. So, really, the only way to know what you need is to look at the bags. They'll have a brand (Firestone or Goodyear, probably) and a number. Usually the brand is on two sides and the number is only embossed on one side...so if you don't see a number, look at the other side. Again, nothing needs to be taken apart to find these.

And...since you're new to the air brakes...this video might help you out a bit on understanding those:

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Old 08-18-2023, 01:22 PM   #6
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Hi again, Orion. In the hope that it helps explain what you are looking for, I just took pics of 3 different air springs (air bags) I had on the shelf here...to show you what the numbers look like.

Some have larger numbers, but some like that Firestone 20C are smaller and harder to read. But they will all have a number. And with that number and brand, you can find an exact match or a cross-reference from another brand. While not the cheapest place, I have bought lots from truckspring.com and here's an example of a listing when I searched for Firestone 20C.

https://www.truckspring.com/products...-358-6900.aspx

That's probably not the bag you need...just an example of what you'll find when you search for your bags.

Here are the pics of what to look for:

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Old 08-20-2023, 04:27 PM   #7
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Year: 1989
Coachwork: Crown Coach
Chassis: 40ft 3-axle 10spd O/D, Factory A/C
Engine: 300hp Cummins 855
Rated Cap: 91
What Ross and John said. It would help to know what your Crown is more precisely. 1979 Crown Coach is like saying 1979 Ford. It could be several things and will definitely determine how to provide the info you are looking for. Details matter a great deal.

For instance, is it a yellow school bus body? Where's the engine? Amidship under the floor? Rear mounted behind the rear axle? With no info at all my guess is it may be a Crown II with a rear mounted engine and the squared off body front and rear. They were available with air suspension either Rear air/front sprung, or full air all around on both axles. They also had one of three different engine options. Detroit Diesel 6V92, 8.3 Cummins, or the V8 Cat 3208. Most all had an Allison auto transmission, even though I've been reliably informed that there were a handful built for a school district with 5spd manual transmissions. Real Unicorns.

In any case what Ross says about the Air Springs is totally true, and the leveling valves are indeed common as grass. If by chance you have a Crown Supercoach (the rounded body style since forever) with air ride suspension and a mid engine then you have a truly special Crown. There were also about 50 Supercoaches with the rounded body ordered by a San Diego area school district with rear mounted 8.3 Cummins engines. These were not air-ride equipped as far as I know. All the ones I've seen were typical spring suspension. There were some others ordered by other districts or commercial customers but not many.

Another possibility is that it is NOT a school bus but one of the rare special Tour/Custom Coach builds for various operators for whatever reason they required it. Some commercial operators, some Colleges, and even some Industry customers ordered these in some form or another for their needs.

Just as an aside. It's also very easy to find and replace the running gear components on a Crown including the Brakes and air system parts. These are all basically off the shelf and still in production today. Crown used commonly available standard industry components, except as custom specified in special cases by the Customer, but still off the shelf. This is one of the prime reasons Crowns are still on the road today (those that survive) and able to keep in good repair limited only by the owners $$ resources. But they are still way cheaper to keep repaired than any highway coach.

As soon as you can manage to post pics we'd all love to see what you have.

In the mean time please take the time to describe in detail what you have, Engine, transmission, overall length, number of axles, and where you got it from is also helpful in many cases. Without more info it's hard to be much help. Where you're based/living is also helpful.
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Old 08-22-2023, 12:10 PM   #8
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Quote:
Originally Posted by sportyrick View Post
Air bags are your "springs" holding up the bus, air chambers are what actuate the shoes to make the bus stop. They are in the same neighborhood but do completely different things. I bet you could find lots of information about air bags on the internet.
Thank you for the info! I am starting to learn the difference
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Old 08-22-2023, 12:15 PM   #9
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Quote:
Originally Posted by rossvtaylor View Post
Hi again, Orion. In the hope that it helps explain what you are looking for, I just took pics of 3 different air springs (air bags) I had on the shelf here...to show you what the numbers look like.

Some have larger numbers, but some like that Firestone 20C are smaller and harder to read. But they will all have a number. And with that number and brand, you can find an exact match or a cross-reference from another brand. While not the cheapest place, I have bought lots from truckspring.com and here's an example of a listing when I searched for Firestone 20C.

https://www.truckspring.com/products...-358-6900.aspx

That's probably not the bag you need...just an example of what you'll find when you search for your bags.

Here are the pics of what to look for:

Attachment 73434
Attachment 73435
Attachment 73436
Thanks for this reply and the previous one. I'm understanding what it looks like and how to find the part numbers now. The bus is in Orem, UT and we are in St George, UT. Its a few hours away from where we live so we don't have everyday access to it yet, hence the blind searching on the internet haha. I'll post pictures to the bus shortly when I can get the pics from my wife.

We're going to get it in safe driving condition and drive it back home to be more accessible to work on.

I will watch the video and get more familiar with how it all works!
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Old 08-22-2023, 12:30 PM   #10
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Quote:
Originally Posted by Crown_Guy View Post
What Ross and John said. It would help to know what your Crown is more precisely. 1979 Crown Coach is like saying 1979 Ford. It could be several things and will definitely determine how to provide the info you are looking for. Details matter a great deal.

For instance, is it a yellow school bus body? Where's the engine? Amidship under the floor? Rear mounted behind the rear axle? With no info at all my guess is it may be a Crown II with a rear mounted engine and the squared off body front and rear. They were available with air suspension either Rear air/front sprung, or full air all around on both axles. They also had one of three different engine options. Detroit Diesel 6V92, 8.3 Cummins, or the V8 Cat 3208. Most all had an Allison auto transmission, even though I've been reliably informed that there were a handful built for a school district with 5spd manual transmissions. Real Unicorns.

In any case what Ross says about the Air Springs is totally true, and the leveling valves are indeed common as grass. If by chance you have a Crown Supercoach (the rounded body style since forever) with air ride suspension and a mid engine then you have a truly special Crown. There were also about 50 Supercoaches with the rounded body ordered by a San Diego area school district with rear mounted 8.3 Cummins engines. These were not air-ride equipped as far as I know. All the ones I've seen were typical spring suspension. There were some others ordered by other districts or commercial customers but not many.

Another possibility is that it is NOT a school bus but one of the rare special Tour/Custom Coach builds for various operators for whatever reason they required it. Some commercial operators, some Colleges, and even some Industry customers ordered these in some form or another for their needs.

Just as an aside. It's also very easy to find and replace the running gear components on a Crown including the Brakes and air system parts. These are all basically off the shelf and still in production today. Crown used commonly available standard industry components, except as custom specified in special cases by the Customer, but still off the shelf. This is one of the prime reasons Crowns are still on the road today (those that survive) and able to keep in good repair limited only by the owners $$ resources. But they are still way cheaper to keep repaired than any highway coach.

As soon as you can manage to post pics we'd all love to see what you have.

In the mean time please take the time to describe in detail what you have, Engine, transmission, overall length, number of axles, and where you got it from is also helpful in many cases. Without more info it's hard to be much help. Where you're based/living is also helpful.
Indeed it seems we may have the unicorn you described? Ours is a 40 ft 1979 Crown Charter Coach Bus with a rear engine Detroit 8V71 Two Stroke and a 5spd manual standard transmission in reverse. I found some of the specs from the guy we bought it from and one of the pictures, but my wife has the others, so I'll get her to send me some and post them. It's an orange and white body with metal on the sides, cargo compartments on the right side.


We bought it on eBay it from a guy in Severy, Kansas. It had come from a school in Idaho, and had been driving regularly 2 years before it retired and became ours.

I'm glad to hear it can be easy to replace parts. Come to think of it, that was one of the reasons we bought a Crown . My wife did a lot of research before choosing this bus - I am now catching up a bit with my own discoveries in being more involved with the project.
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Old 08-22-2023, 02:54 PM   #11
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Rated Cap: 91
There you go. It's whats commonly called a Crown Atomic because they were made for the Atomic Energy Commission for use in transporting employees back and forth to work on the restricted location. There were others bought by Charter Companies too.

There's a guy on this site who knows a lot about these and he'll be along shortly I'm sure. I've only driven them occasionally through the years in commercial service but he's up close and personal with one. It's a Crown but you still have your work cut out for you.
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Old 08-22-2023, 04:00 PM   #12
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Quote:
Originally Posted by Crown_Guy View Post
There you go. It's whats commonly called a Crown Atomic because they were made for the Atomic Energy Commission for use in transporting employees back and forth to work on the restricted location. There were others bought by Charter Companies too.

There's a guy on this site who knows a lot about these and he'll be along shortly I'm sure. I've only driven them occasionally through the years in commercial service but he's up close and personal with one. It's a Crown but you still have your work cut out for you.
Thanks, Mike, for the tag! And yes, Orion, I have one also. Mine is a 1974. Since we have similar buses, I can get you the air bag numbers off mine and they might very well be the same as yours. I'll send you a message with my cell number.

If you want to see how resilient these buses and the great Detroit 2-stroke diesels are, you might be interested in my "rescue" story:



And here's a video I did of some maintenance items:

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Old 08-23-2023, 02:23 AM   #13
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Originally Posted by rossvtaylor View Post
Thanks, Mike, for the tag! And yes, Orion, I have one also. Mine is a 1974. Since we have similar buses, I can get you the air bag numbers off mine and they might very well be the same as yours. I'll send you a message with my cell number.

If you want to see how resilient these buses and the great Detroit 2-stroke diesels are, you might be interested in my "rescue" story:



And here's a video I did of some maintenance items:

Great to meet you Ross! Wow that is so cool, we really do have similar busses. Yes the air bag numbers would be super helpful if you would share them. I'll shoot you a text tomorrow (or I guess later today at this point in the night).

We are definitely on a journey with this bus and it is exciting to meet another who has experience with this model!

I will watch your video as well when time allows. I am interested to see your story.
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Old 08-23-2023, 12:36 PM   #14
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Thanks so much everyone!

I just want to say how much I appreciate everyone's responses. I am reading through them and finding great insight and wisdom in the replies.

It may take me awhile to respond to everyone, as I work quite a bit (multiple jobs almost every day of the week).

Just don't want you all to think I've ghosted on ya.
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Old 08-29-2023, 01:32 AM   #15
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Good looking Atomic! More pictures please!!
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Old 08-29-2023, 08:00 AM   #16
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I did air up my Crown "Atomic" and get the numbers off my air spring bellows for Orion and I'm sharing those pics here, for the archives.

The drive axle air bags are Firestone 1T15M-4 and that's a normal/common numbering convention.

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The tag axle bags are more problematic, though. They are also Firestones but the number doesn't match anything in the Firestone list. It looks like 21.1 to me...but if you look closely at the photo, it almost looks like there's possibly a 2 beneath the last digit 1? I cannot find these on the Firestone site and an email to Firestone has, so far, gone unanswered. These are reversible sleeve bellows with an (approx.) 6" top plate.

Click image for larger version

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Old 08-30-2023, 01:49 AM   #17
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Chassis: 40ft 3-axle 10spd O/D, Factory A/C
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Damn, Ross. It seems there's always something, even for the items that should be easy. I've run across this kind of stuff too with Crowns. Some stuff seems to just vanish for no apparent reason. Off the shelf doesn't seem to mean as much as it used to back in the day. Good luck with getting one, and you know you're going to want to find it now for sure before the need.
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Old 08-30-2023, 02:11 AM   #18
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Rated Cap: 20? five rows of 4?
old parts and paper catalogs

I went searching for air springs for a 1988 bluebird all american last year. I ended up looking by dimensions, style of bellows, style of mounting, style of airline connections and internal or non internal bump stops. In the case of this bus, I found a very good close substitute. I bet I spent 16 hours looking at drawings and comparing numbers.

william
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Old 10-05-2023, 02:19 AM   #19
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Hi all, sorry for the radio silence. On the grind paving the road to the skoolie dream.

Update: Ross Taylor was of paramount help in assisting us in getting the correct parts. Shout out to Ross!

We have ordered the parts and are planning for late October repairs, and will be bringing the bus home!

Thanks again everyone! Excited to chat with and get to know you all more as time goes on.
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