Foretravel Owners' Forum

Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: pthurman48 on June 09, 2020, 04:49:24 pm

Title: Brake Air Cambers and Proportioning Values
Post by: pthurman48 on June 09, 2020, 04:49:24 pm
Hi Group,
  I have been to a air brake mechanic.  I need help with part numbers for the brake air cambers at each wheel.  I would also need to replace the proportioning values.  The mechanic said that it was tied to the VIN Number.  FT will not give info to me or others about the parts.
Title: Re: Brake Air Cambers and Proportioning Values
Post by: dans96u295ft on June 09, 2020, 05:10:48 pm
my brake rotors and pads were the cheapest at ft. they should give your mechanic the numbers, just not you. they did mine
Title: Re: Brake Air Cambers and Proportioning Values
Post by: wolfe10 on June 09, 2020, 05:23:42 pm
The U225 and U240 have air wedge drum brakes-- no resemblance to the air disk brakes on other models.  Work very well, but parts and and servicing are unrelated.
Title: Re: Brake Air Cambers and Proportioning Values
Post by: pthurman48 on June 09, 2020, 08:39:40 pm
ForeTravel does not have any of my brake parts.  Just FYI

95 U240 36'
Meritor Rear Service Brake Air Chambers x673276L12  &  z333276L12  Type 12

        Front Service Brake Air Chamber v353276p16    Type 16

Hope to get some and get them changed out tomorrow.

Pat,
Title: Re: Brake Air Cambers and Proportioning Values
Post by: dans96u295ft on June 09, 2020, 09:03:35 pm
WOW! They did for my 96. Guess you never know for sure. I've had good luck with them so I always promote them. Thanks for letting me know. I was told in 96, FT and fire trucks were the main users of our air-disc brake systems
Title: Re: Brake Air Cambers and Proportioning Values
Post by: Old Toolmaker on June 09, 2020, 10:06:38 pm
The U225 and U240 have air wedge drum brakes-- no resemblance to the air disk brakes on other models.  Work very well, but parts and and servicing are unrelated.
And I would use caution when choosing a mechanic to service your wedge brakes.  It's not that they are overly complicated only that they are different.

FWIW, the braking force is determined by the taper on the wedge that applies the air chamber force to the shoes.
It may be that your brake mechanic doesn't want your work.
Title: Re: Brake Air Cambers and Proportioning Values
Post by: dans96u295ft on June 09, 2020, 11:47:11 pm
Yep. Same on the air-disc brakes. My shop didn't bleed the grease out of the calipers and one hung up in 200 miles. You all sent me the service bulletin and I hand carried to him and they fixed the problem at my expense!
Title: Re: Brake Air Cambers and Proportioning Values
Post by: Old Toolmaker on June 10, 2020, 12:32:57 pm
I asked some questions then started reading so that I'd understand the operation of the most important system on my RV.  No where did I see proportioning valves as are found on hydraulic systems.  I may be wrong but for the time being any mechanic that tells me that I have a problem with proportioning valves will cause me to take a step back.
Title: Re: Brake Air Cambers and Proportioning Values
Post by: Olde English on June 10, 2020, 02:23:27 pm
I had a hydro brake proportioning valve on a piece of highway maintenance equipment, so I know they existed. It was on a chipper, as in seal and chip road repair, it had Rockwell axles all round and a 555 cumins motor.
Title: Re: Brake Air Cambers and Proportioning Values
Post by: pthurman48 on June 11, 2020, 12:32:15 pm
as an Update:
  I now have new numbers from Meritor
Meritor Rear Brake Air X673276L12 Obsolete 
                                    Z333276L12 -> M243276L12  Type 12
                                    R63276T20 inActive                  Type 20

Meritor Front Brake Air V353276p16 inActive              Type 16

I am confused,  FT OEM #Z333276L12 updates to  M243276L12 , going by the axle tag the number should be R63276T20.  The first number is a type 12 chamber and the second is a type 20???  On top of that can't get the chambers due to lack of sales.  So I sent pics to a local truck repair place(they will not work on MH) and they said that the chamber is a common 30 30 with round connection ports. 
Why would FT have put a smaller chamber on rather than follow what Meritor recommends??  Why now does the MH have a 30 30 which is bigger than the OEM??  Only help FT gives is the old part numbers nothing else.

Pat,
Title: Re: Brake Air Cambers and Proportioning Values
Post by: craneman on June 11, 2020, 12:36:58 pm
Be glad as the 30/30 can be found anywhere. I still have 4 new ones from the crane business I bought for spares.
Title: Re: Brake Air Cambers and Proportioning Values
Post by: pthurman48 on July 03, 2020, 12:23:32 pm
Update:
  Some of the air leak issues was the air control valve (brake release knob).  I replaced all the brake air chambers, front new type 16 and type 24/20 on the rear.  On the way to Port Aransas, TX (Surfside RV Park), we noticed a thump under our feet when the MH hit large bumps.  Well when I checked this morning, guess what I found, the new brake air chambers on the front are hitting the frame/body of the MH.  Check out the pics.  The new ones are larger.

Holding 40 psi after 15 hrs.
Pat,
Title: Re: Brake Air Cambers and Proportioning Values
Post by: Pamela & Mike on July 03, 2020, 12:41:52 pm
Is it just the chamber clamp bolt hitting?  If so it can be indexed 45* from where it is now.  With this being the front you can swivel it around just don't do nothing but loosen just enough to move clamp..  The rear contain a wild cat and isn't a DIY.

Mike
Title: Re: Brake Air Cambers and Proportioning Values
Post by: pthurman48 on July 08, 2020, 10:17:30 am
Update:
  I did loosen the nuts on the band on the air chamber.  I moved the band around some.  It was not enought, on the way home I heard it hit the frame.  The other side was not hitting the bolt, it was the band.  I went back to the shop that did the work and got the old chambers.  After looking very close and finding on the rear, I found "midland t-16".  I looked this text up on inet and found the same chambers I have.  I bought 2 of the 6 on ebay site for $45.00 each plus $20.00 each shipping.  With this information I also now know that some FORD trucks use the same chambers, NaviStar trucks also use them.  I also now know that I do not understand why a type 16 chamber from one company/application is different from another???..?  In other words I have 2 type 16 chambers that are different from 2  MIDLAND T-16/N36216/NAVISTAR 593401C9 and FORD number.  I know they are different size and shape, bolt pattern and size are different.  Why?
Title: Re: Brake Air Cambers and Proportioning Values
Post by: pthurman48 on July 08, 2020, 10:25:42 am
Here is another pic>
Title: Re: Brake Air Cambers and Proportioning Values
Post by: SteveB on July 08, 2020, 01:19:08 pm
There are standard stroke chambers and long stroke chambers. Looking at the Midland/Haldex specs the outside dimensions are about the same. The major difference is the long stroke chambers have a wider mounting stud spacing.