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08-01-2014, 11:39 PM
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#1
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Senior Member
Winnebago Owners Club Workhorse Chassis Owner
Join Date: Nov 2010
Location: Surrey, B.C.
Posts: 201
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Park Brake system failure on a W24 chassis
I think other W24 chassis owners might like to hear about what happens when the PARK BRAKE PUMP ASSEMBLY fails while driving.
I have a 2007 Itasca, W24, 60000 miles. Returning from a trip one month ago, I experienced a Park Brake failure. I was accelerating onto the freeway when the motorhome suddenly slowed down. At first I thought the engine quit but then I realized that the brakes had activated then released. I drove for another 60 miles, slowed down for an exit, when suddenly the brakes deployed and released again. I made it home, unloaded the RV, started the engine to move the coach but it would not move. The brake was seized on. The following morning, a workhorse mechanic attended and managed to get the park brake drum on the driveshaft to release. I was able to drive it to the Workhorse shop where it stayed for three weeks. It turns out that I had a park brake pump assembly (PPK) failure. When it failed, it caused the park brake prop shaft brake to apply, twice. These two applications destroyed the entire brake unit on the back of the transmission. I had to wait while the two, separate park brake components were ordered from Workhorse. I searched the internet for a more reasonably priced supplier, but no joy. My extended maintenance insurance expired 6 months ago so it turned out to be a very expensive repair, $7400.
I have since used the motorhome and the park brake system seems to be working properly. I was very concerned about a future PPK failure so I added a fail safe unit made by Brazel's RV Performance in Centralia, Wa. It is called the "Ultra Save Park Brake valve". If the PPK, located under the hood, fails, it will not allow the prop shaft brake to activate while the motorhome is in motion. The only glitch at the moment is that I cannot lower my jacks when the key is in the accessory position. They work fine when the key is in the run position only. This was not the case prior to the park brake failure.
Knightly
__________________
Knightly
2007 Itasca Sunrise 35A, W24 Chassis, Blue Ox, Toad-HHR. Retired
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08-01-2014, 11:51 PM
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#2
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Registered User
Join Date: Aug 2014
Posts: 608
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Wow is all I can say it is about 3 hours labor to replace the system. A second option is to add a hand parking brake control and scrap the system I have done that on a couple of units. The unit is not getting signal when in Accy so that was wired wrong when they did the repair.
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08-02-2014, 12:28 AM
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#3
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Registered User
Join Date: Jul 2013
Location: Somerset, Ky
Posts: 256
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1mainiac
Have you done this for the newer J72 system or only on the older J71 system?
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08-02-2014, 08:23 AM
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#4
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Senior Member
Tiffin Owners Club
Join Date: Jul 2011
Location: Cape Cod
Posts: 360
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I had the J72 APP. You can remove it and install a hand brake but I have been told by Freightliner that would not hold (my RV is a 34' FRED) and that I would also have to a a parking pawl to the transmission. That is what has been done. I would inquire as to the weight limits of just the hand brake system and the weight of your coach to see if it would work. This is also why I carry wheel chocks, just in case.
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08-02-2014, 08:55 AM
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#5
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Senior Member
Join Date: Oct 2002
Location: Madison, MS
Posts: 10,521
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Quote:
Originally Posted by mrv8outboard
I had the J72 APP. You can remove it and install a hand brake but I have been told by Freightliner that would not hold (my RV is a 34' FRED) and that I would also have to a a parking pawl to the transmission. That is what has been done. I would inquire as to the weight limits of just the hand brake system and the weight of your coach to see if it would work. This is also why I carry wheel chocks, just in case.
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This is the first time I've ever heard that the J72 AAPB was used by FCCC.
Where did you have a PP added to your Allison???
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08-03-2014, 11:34 PM
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#6
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Senior Member
Winnebago Owners Club Workhorse Chassis Owner
Join Date: Nov 2010
Location: Surrey, B.C.
Posts: 201
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Auto Park Brake failure
Quote:
Originally Posted by ktoutoor
1mainiac
Have you done this for the newer J72 system or only on the older J71 system?
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Yes, my rig uses the J72 system.
__________________
Knightly
2007 Itasca Sunrise 35A, W24 Chassis, Blue Ox, Toad-HHR. Retired
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08-03-2014, 11:37 PM
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#7
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Senior Member
Winnebago Owners Club Workhorse Chassis Owner
Join Date: Nov 2010
Location: Surrey, B.C.
Posts: 201
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Quote:
Originally Posted by edgray
This is the first time I've ever heard that the J72 AAPB was used by FCCC.
Where did you have a PP added to your Allison???
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I did not add a PP to my Allison. I replaced the Park Brake Pump assembly plus module so my park brake is now working normally.
__________________
Knightly
2007 Itasca Sunrise 35A, W24 Chassis, Blue Ox, Toad-HHR. Retired
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08-04-2014, 07:19 AM
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#8
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Senior Member
Tiffin Owners Club
Join Date: Jul 2011
Location: Cape Cod
Posts: 360
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My J72 APP failed (applied at 65 mph) on a trip to SC. When these units do this the mechanical unit is toast (it may seem to function but can not hold on incline) and replacement. This started a long process, but to keep it short for now, FCCC in Gaffney had Allison install a park pawl system in the transmission and change out the control pad to accommodate the upgrade. Then FCCC removed the J72 APP and installed a foot activated, shoe drum type parking brake.
This was what I pushed for as the some of the parts for the J72 system are NLA. If you can find them (they are out there) are expensive as well as FCCC told me it would happen again, so why rely on a faulty system.
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08-04-2014, 07:49 AM
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#9
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Senior Member
Join Date: Oct 2002
Location: Madison, MS
Posts: 10,521
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Quote:
Originally Posted by mrv8outboard
My J72 APP failed (applied at 65 mph) on a trip to SC. When these units do this the mechanical unit is toast (it may seem to function but can not hold on incline) and replacement. This started a long process, but to keep it short for now, FCCC in Gaffney had Allison install a park pawl system in the transmission and change out the control pad to accommodate the upgrade. Then FCCC removed the J72 APP and installed a foot activated, shoe drum type parking brake.
This was what I pushed for as the some of the parts for the J72 system are NLA. If you can find them (they are out there) are expensive as well as FCCC told me it would happen again, so why rely on a faulty system.
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Good to know it CAN be done ! Glad you were able to "convince" FCCC that this modification to their original design was a better solution to the AAPB problem you experienced.
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08-04-2014, 12:35 PM
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#10
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Senior Member
Tiffin Owners Club
Join Date: Jul 2011
Location: Cape Cod
Posts: 360
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It was recommended by them and then I pushed to have it done rather than try to repair. This was also out of warranty by the time this occurred. I read in Roughing It Smoothly of person with the same issue and resolution paid up to 7500.00 to have it done. Fortunately I was able to have mine done at no charge.
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