Skip to main content ↑ ↓
Topic: Re: Air brake spring chamber- New ????? (Read 1384 times) previous topic - next topic

Re: Air brake spring chamber- New ?????

I want to replace the rear air brake spring chambers.

I can buy from;
NAPA (there own brand TW HD3030) In stock local, $47
 Ryder (MGM brand) have to order, $75
OReilly  BrakeBest , 3030 Intrxx ,a Bendix branded product. can get in a few days. $93

I don't see many specs published to be able to compare one to the other.

Has anybody changed there's, and what brands have proven there worth?

I have one rear Spring chamber that is a long stroke, all others are normal stroke (rear and front air chambers). I thought this was strange until I read a post where somebody stated that they too had this setup in the rear, along with a slightly different rear caliper (from the factory). The author had stated that they were going to investigate why this was done during manufacture.I'm unable to find that post again. If that is your setup please contact me or post your findings.

Thanks for your advice!
1995 U320C SE 40'
Jeep 4x4 Commander - Limited - Hemi
"The Pack"  Yogi and Diesel our Airedales -  Charlie our Boxer/Akita mix. Gone but NEVER forgotten Jake our yellow Lab.
NRA Law Enforcement Firearms instructor - Handgun/shotgun
Regional Firearms instructor for national Armored Transp. Co.

Re: Air brake spring chamber

Reply #1 –
Lon all of mine are the same calipers and brake chambers. While diffrent brands are ok, I would not mix componets on an axle. I know on all of our air brake trucks all componets are the same (Chamber size and stroke, slack adjusters, and brake hardware), per axle. While mix and match componets on an axle may work , it might create a brake balance problem and uneven brake ware. I might would talk to ForeTravel or Arvin Meritor and find out what parts belong on it. As Far as NAPA Chambers are concerned they are as good as anyones, rebuilt is fine as well there is nothing in them but rubber pancakes and springs, also a word of CAUTION do not dissemble the air brake chambers themselves the springs inside are under a lot of compression.
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: Air brake spring chamber

Reply #2 –
Bruce makes a good point about how dangerous the chambers can be. If the clamp is loosened, the spring pressure WILL violently separate the chamber into two flying parts and can maim anyone close by. Here is a video showing how to "cage" the spring so the chamber can be separated. Not many parts inside and very easy to rebuild by a DIYer.

Here is a video on how the chamber works and how to cage it: Truck trailer bus motorhome spring brake release caging bolt

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Air brake spring chamber

Reply #3 –
Also, back a few years ago when I thought I had blown a pancake seal for a chamber I was told that the model our older coaches used was obsolete. The part had to be ordered with a couple day wait. If not 'readily' available would it be worthwhile to upgrade to newer ones where parts are 'Truck Stop' available?
The selected media item is not currently available. Dave Head & Megan Westbrook
Titusville, FL - The Great Outdoors
'98 270 buying this month
Toad is a 2018 F150 XLT

Re: Air brake spring chamber

Reply #4 –
I have purchased from NAPA both professionally and privately over the years and have always found them to be reliable.

I will echo the above advise.  Never, ever disassemble the chambers without caging both the service AND parking brake springs.  If you have not been trained on this by a competent person don't do it.

Below is a diagram showing the service brake with the parking (spring) brake chamber attached.  It's the spring, which applies the parking brake, that is the most dangerous as it is highly compressed and will let go when the clamp band is released.  On some older chambers such as the older Wagner units corrosion can cause the bands not to release.  People had thought that the spring has failed and have then been injured by releasing the spring and hitting the clamp to release it.  Newer units have welded bands to prevent one from releasing the bands.

Just replace the complete unit with the correct size.  Take the old unit with you when you go to the parts store.

It also obvious but I will say it anyway:  Release the air pressure before doing any work on the brake chambers.


Keith
Keith, Joyce & Smokey the Australian Cattle Dog
1995 U320 SE Extreme 40' WTBI Build # 4780, with a Honda CR-V hopefully still following behind.
Motorcade # 17030
FMCA # F422159

Re: Air brake spring chamber

Reply #5 –
Pierce, thanks for posting the video. Until I watched it I almost understood it.
Dick, '03 U320 40' Tag, 2 slides, Coach #6075
Full Timers
2009 Honda CR-V

Re: Air brake spring chamber

Reply #6 –
I have no plans of taking the chambers apart.
It would be foolish to rebuild a $50 part that has been exposed under the.motorhome for almost 20years.

Thanks for that video link!
1995 U320C SE 40'
Jeep 4x4 Commander - Limited - Hemi
"The Pack"  Yogi and Diesel our Airedales -  Charlie our Boxer/Akita mix. Gone but NEVER forgotten Jake our yellow Lab.
NRA Law Enforcement Firearms instructor - Handgun/shotgun
Regional Firearms instructor for national Armored Transp. Co.

Re: Air brake spring chamber

Reply #7 –
I  bought a new one from NAPA, less than $50.
Sure looks nice, all black and gold, too bad it has to hide under the Foretravel were nobody can see it.
I will put it on this weekend then do the other side.
Turned out the lug nuts were 38mm but the BUDD studs were 13/16". 3/4" impact did a fine job removing lugs and studs.
1995 U320C SE 40'
Jeep 4x4 Commander - Limited - Hemi
"The Pack"  Yogi and Diesel our Airedales -  Charlie our Boxer/Akita mix. Gone but NEVER forgotten Jake our yellow Lab.
NRA Law Enforcement Firearms instructor - Handgun/shotgun
Regional Firearms instructor for national Armored Transp. Co.

Re: Air brake spring chamber- New ?????

Reply #8 –
I pulled the left rear spring/air chamber and was shocked to see it was a 24/30 spring chamber. I believe the other rear is the same, but I have not gotten to that side yet to confirm.

I have never heard anybody comment they had anything but #30 air chambers or 30/30 rear chambers.

I'm thinking that the previous owner or his mechanic, for some reason, replaced the chambers at some point with the 24/30. The front are #30.

Does anybody have a 24/30 air chamber on the rear of their coach?

I have never been impressed with the breaking, maybe this is why.
1995 U320C SE 40'
Jeep 4x4 Commander - Limited - Hemi
"The Pack"  Yogi and Diesel our Airedales -  Charlie our Boxer/Akita mix. Gone but NEVER forgotten Jake our yellow Lab.
NRA Law Enforcement Firearms instructor - Handgun/shotgun
Regional Firearms instructor for national Armored Transp. Co.

Re: Re: Air brake spring chamber- New ?????

Reply #9 –
Quote from: Lon and Cheryl –
I'm thinking that the previous owner or his mechanic, for some reason, replaced the chambers at some point with the 24/30. The front are #30.
I would think a phone call to Foretravel, you should be able to find out what came on the coach
1994 U225
build #4514

Re: Air brake spring chamber- New ?????

Reply #10 –
Quote from: Lon and Cheryl –
I pulled the left rear spring/air chamber and was shocked to see it was a 24/30 spring chamber. I believe the other rear is the same, but I have not gotten to that side yet to confirm.

I have never heard anybody comment they had anything but #30 air chambers or 30/30 rear chambers.

I'm thinking that the previous owner or his mechanic, for some reason, replaced the chambers at some point with the 24/30. The front are #30.

Does anybody have a 24/30 air chamber on the rear of their coach?

I have never been impressed with the breaking, maybe this is why.

No idea on the chamber numbers but increasing my normal chassis air pressure by replacing the main air governor valve raised my air pressure from 90-105 to 110-130 range.  Brakes work better IMO 
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Re: Air brake spring chamber- New ?????

Reply #11 –
Think Lon may possibly have the wrong can. We have a 30 (30 square inches) on the rear on ours. A 24 sq. incher seems small for the rear. You can find the size stamped on the rear facing can. 4 different can manufactures so may be marked differently. I have the Rockwell/Meritor Dura-Master shop manual and will make a PDF document if anyone is interested. Mal adjusted slack adjuster may be part of the problem. Suggest contacting closest fire department shop mechanic for tips as fire apparatus use a lot of this product.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Air brake spring chamber- New ?????

Reply #12 –
Thanks, Pierce for posting the link to that video on YouTube. The warning about the damage that gators can do and the sudden potential consequences is new information for me, a relatively new and inexperienced DP driver. Knowledge is power!

Are the spring brakes only on the rear wheels? I wonder about sudden loss of control if the front brakes were suddenly applied. Thanks.
Royce & Denise, MC #17410
'01 U320 4220 ISM450 Build #5895 SOLD
Toad: '10 Honda CR-V

Travel makes one modest. You see what a tiny place you occupy in the world. - Gustave Flaubert

Re: Air brake spring chamber- New ?????

Reply #13 –
Quote from: BamaFan –
Thanks, Pierce for posting the link to that video on YouTube. The warning about the damage that gators can do and the sudden potential consequences is new information for me, a relatively new and inexperienced DP driver. Knowledge is power!

Are the spring brakes only on the rear wheels? I wonder about sudden loss of control if the front brakes were suddenly applied. Thanks.

Rear only
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Re: Air brake spring chamber- New ?????

Reply #14 –
Front brakes: Air applied.

Rear brakes: BOTH air applied (first chamber)-- same as fronts AND spring applied, air released for emergency/parking brake.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Air brake spring chamber

Reply #15 –
Quote from: Dave Head –
Also, back a few years ago when I thought I had blown a pancake seal for a chamber I was told that the model our older coaches used was obsolete. The part had to be ordered with a couple day wait. If not 'readily' available would it be worthwhile to upgrade to newer ones where parts are 'Truck Stop' available?

This mirrors the conversion I had with the Foretravel parts dept today.
The parts guy could not tell me the size of the rear chambers, he could only give me the part number. The part is a Meritor/MGM part. My research was unable to get me the specs of the part.
Strangely he has a different part number for the left and right side.
RIGHT= K93276 X24
LEFT= K83276 X24
It would appear from the end of the part number that the chambers are #24 in size.

I don't understand why there would be a different part number for one side vs the other.
I think as Dave mentioned,  a update from the old parts might be beneficial should a road side emergency require a Chamber replacement with a readily available part.

I'm also surprised that the larger #30 chamber is not installed considering the weight and the duty the rear brakes have to perform.

Does anybody have any pictures of the rear underside of there 90's Foretravel that shows the rear air chambers? If I can see the chamber, I can ID it based on the size of the front part of the chamber vs the rear spring part.
 
1995 U320C SE 40'
Jeep 4x4 Commander - Limited - Hemi
"The Pack"  Yogi and Diesel our Airedales -  Charlie our Boxer/Akita mix. Gone but NEVER forgotten Jake our yellow Lab.
NRA Law Enforcement Firearms instructor - Handgun/shotgun
Regional Firearms instructor for national Armored Transp. Co.

Re: Re: Air brake spring chamber- New ?????

Reply #16 –
Royce,

The cans with springs are in the rear only. Reaching back a long way in my memory, when the parking brake is applied, the spring is equivalent to 50 lbs air pressure. Every owner should apply the parking brake while driving 20 mph or so away from traffic. Too many expect to be thrown through the windshield when the effect is much less. The parking brake should not be counted on to keep the vehicle stationary on anything but flat ground and even then the wheels should be chocked.

Here is a video that shows how effective (or ineffective) the parking brake is compared to the service brake.
Bus Parking Brake vs. Service Brake application

Lon, just read your post. Will try and upload a photo tomorrow. Ours are MGM 30. The number reflects the square inches of diaphragm area. The only reason I can think of would be because of complaints of the rear locking up first in rain or snow with the 24 square inch providing less breaking effort. Just a guess.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Air brake spring chamber- New ?????

Reply #17 –
UPDATE:

I got up from behind the keyboard and went out and crawled around under the money pit.

The front air service chambers are #20.

The rears (both) ARE 24/30 chambers. The different part numbers must be because the air inlets are flopped one side to the other. It would appear that you could use the same standard part by using a 90 fitting on the right side to attach the 2 air hoses.

I'm still surprised that the larger chambers were not used. The effective braking power would be much stronger. I would be tempted to put the larger rear chambers on, but I must conclude that Foretravel engineers that designed the coach picked these parts and specs for a reason.
 
1995 U320C SE 40'
Jeep 4x4 Commander - Limited - Hemi
"The Pack"  Yogi and Diesel our Airedales -  Charlie our Boxer/Akita mix. Gone but NEVER forgotten Jake our yellow Lab.
NRA Law Enforcement Firearms instructor - Handgun/shotgun
Regional Firearms instructor for national Armored Transp. Co.
 

Re: Air brake spring chamber- New ?????

Reply #18 –
Quote from: Lon and Cheryl –
UPDATE:

I got up from behind the keyboard and went out and crawled around under the money pit.

The front air service chambers are #20.

The rears (both) ARE 24/30 chambers. The different part numbers must be because the air inlets are flopped one side to the other. It would appear that you could use the same standard part by using a 90 fitting on the right side to attach the 2 air hoses.

I'm still surprised that the larger chambers were not used. The effective braking power would be much stronger. I would be tempted to put the larger rear chambers on, but I must conclude that Foretravel engineers that designed the coach picked these parts and specs for a reason.

Snow and ice lockup?

Bob
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4