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Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: 1985 on January 14, 2018, 10:49:21 pm

Title: 1985 35 oshkosh
Post by: 1985 on January 14, 2018, 10:49:21 pm
Does anyone know the part numbers for rear brake chamber on a 1985 35' Oshkosh cat 3208t it has Rockwell stamped on it and it is leaking.
Thanks in advance
Title: Re: 1985 35 oshkosh
Post by: stump on January 15, 2018, 08:44:45 am
You can measure the diameter and use this chart.
Once you know what size Truck Pro Fleet Pride etc should be able to supply it to you. Get a new clevis also old ones can be a pain to get off the shaft. It will probably be a 24/24 or 30/30 if it has 2 air lines to it.
http://aemstatic-ww1.azureedge.net/content/dam/etc/medialib/new-lib/Fire_Apparatus/print-articles/volume15/issue8/27936.res/_jcr_content/renditions/pennwell.web.288.166.jpg
Title: Re: 1985 35 oshkosh
Post by: Old phart phred on January 15, 2018, 10:41:53 am
Do not attempt to take the chamber apart if it is spring loaded, could be FATAL!
Title: Re: 1985 35 oshkosh
Post by: stump on January 15, 2018, 11:13:08 am
Do not attempt to take the chamber apart if it is spring loaded, could be FATAL!
YES YES YES DO NOT ATTEMPT TO TAKE THE OLD ONE APART !!!! If you are not sure how to replace these I suggest you pay a shop to do it for you. Also do both sides usually the other ones are not far behind the first.
Title: Re: 1985 35 oshkosh
Post by: 1985 on January 15, 2018, 06:15:35 pm
Do I need to take the wheels off it does not look like a regular big truck setup. Looks like the dual chamber is bolted directly to the backing plate not sure yet. But thanks for the help.
Title: Re: 1985 35 oshkosh
Post by: craneman on January 15, 2018, 08:05:02 pm
That would be a wedge brake system. I have them on the front of my crane. Does it only have one chamber? A pic would help.
Title: Re: 1985 35 oshkosh
Post by: red tractor on January 15, 2018, 08:09:17 pm
It should be a double chamber on the rear of the vehicle as that is the park brake and service brakes. And yes it does have the wedge brakes. I don't remember how to get the chamber off and a new one installed. I think the wheels have to come off.
Title: Re: 1985 35 oshkosh
Post by: craneman on January 15, 2018, 08:14:30 pm
The chamber will come off by just undoing 2 bolts or studs. However putting it back on will require the drum to be off to get the wedge between the rollers on the shoes.
Title: Re: 1985 35 oshkosh
Post by: 1985 on January 16, 2018, 10:39:38 pm
Thanks I have the MH up and ready but the weather here in Texas just went crazy cold. A friend with the same unit said take the bolt off of the first band not the big one but I am not sure
Title: Re: 1985 35 oshkosh
Post by: Protech Racing on January 17, 2018, 09:24:03 am
 Do not loosen the band strap  bolts.  The retainer bolts are two  bolts surrounding the  plunger rod.  If you would like tocall me later today with a smartphone I can send a pic of the assembly from my books.
 352.428...8.983  Mike
Title: Re: 1985 35 oshkosh
Post by: nyd on January 30, 2018, 01:49:28 pm
OK sorry it took so long but weather finally helped and work so last night I finally went at it and I jacked the unit up and removed the two wheels on drivers side the lug nuts are left handed threads and the stud is normal. had to heat the 5 Phillip head screws that hold the drum on to axle. this is when I realized that wheels do not have to come off. I could off changed all six brake chambers out faster than removing wheels. ( lots less effort also). The brake chambers on this unit have the caging tool right on the chamber. i am going to change all six chambers not the diaphragms cause the two in this chamber were very dry rotted. the job is not to bad now that I understand how it works.  any questions feel free to contact me. I also have extra air switch for the parking brake light at switch.

P.S. if you cage the chamber you can take anyone of the bands off
Title: Re: 1985 35 oshkosh
Post by: craneman on January 30, 2018, 03:35:36 pm
i am going to change all six chambers not the diaphragms.

P.S. if you cage the chamber you can take anyone of the bands off
So you mean to say you are changing the 6 diaphragms not the cans?
Title: Re: 1985 35 oshkosh
Post by: its toby on January 31, 2018, 09:07:27 am
Having seen the cage bolts slip and/or pull through the bracket taking the wrong band off is still a horrible idea. Newer chambers come with a no serviceable band because of this.
Title: Re: 1985 35 oshkosh
Post by: craneman on January 31, 2018, 10:39:02 am
The last ones I bought still had a removable service brake band as there is no spring pressure there.
Title: Re: 1985 35 oshkosh
Post by: 1985 on January 31, 2018, 02:29:22 pm
Yes I am changing both piggy back chambers but only changing the diaphragm on the other six. I do not think the drums have ever been taken off of this unit every nut , bolt and screw still have paint and no chips at all unt now has 83,000 miles and brake shoes look brand new
Title: Re: 1985 35 oshkosh
Post by: stump on January 31, 2018, 04:24:43 pm
Your replacement piggy back chambers will probably have longer threaded rods extending from them. Measure your old ones lengths and cut the new one to the proper length.thread the clevis locknut down the shaft so after you cut it removing the nut will clean the threads. Thread new clevis on rod and locknut at same length as old one and install chamber on coach. This can be done on the bench and it makes it easier than trying to do it under the vehicle.
Title: Re: 1985 35 oshkosh
Post by: nyd on February 01, 2018, 10:44:16 am
This unit has wedge brakes I am only changing from the diaphragm back. Which the only thing involved is caging the chamber removing the first clamp closest to backing plate removing three air lines and installing new diaphragm and chamber no need to remove wheels etc.
Title: Re: 1985 35 oshkosh
Post by: 1985 on February 01, 2018, 03:52:13 pm
I just noticed that I am on here with two profiles I don't know how but I narrowed it down to office computer and classroom computer can I combine or how do you delete one?
Title: Re: 1985 35 oshkosh
Post by: Old phart phred on February 01, 2018, 11:33:39 pm
Hey, you can get twice the amount of coach stuff done! Or maybe just 1/2 IDK.
Title: Re: 1985 35 oshkosh
Post by: stump on February 02, 2018, 06:58:18 am
This unit has wedge brakes I am only changing from the diaphragm back. Which the only thing involved is caging the chamber removing the first clamp closest to backing plate removing three air lines and installing new diaphragm and chamber no need to remove wheels etc.
I see now. I Iooked up how they were set up. I see the Chamber is way different in how it mounts than the s cam setups that I am familiar with.
Title: Re: 1985 35 oshkosh
Post by: Protech Racing on February 02, 2018, 10:56:30 am
 Now you can talk to yourself . And have it make sense.

 His brakes are also different than  my 88. 
Title: Re: 1985 35 oshkosh
Post by: 1985 on February 06, 2018, 03:23:13 pm
quick update,,, My piggyback chambers came in with no diaphragms so I ordered 6 from Finditparts .com for 60.00 and found them at Orielly auto parts today while shopping for another item for less than 2.00 a piece.
Title: Re: 1985 35 oshkosh
Post by: craneman on February 06, 2018, 03:28:56 pm
quick update,,, My piggyback chambers came in with no diaphragms so I ordered 6 from Finditparts .com for 60.00 and found them at Orielly auto parts today while shopping for another item for less than 2.00 a piece.
Very unusual, find it is very good on pricing. Are you sure they were the exact same diaphragm?
Title: Re: 1985 35 oshkosh
Post by: 1985 on February 07, 2018, 10:27:17 am
#16  Brakebest brand installed two last night 4 more to go.
Title: Re: 1985 35 oshkosh
Post by: craneman on February 07, 2018, 02:15:00 pm
quick update,,, My piggyback chambers came in with no diaphragms so I ordered 6 from Finditparts .com for 60.00 and found them at Orielly auto parts today while shopping for another item for less than 2.00 a piece.
What did you get that was $10.00 per unit?

F224731 by FORT PRO USA - F224731 | 16 DIAPHRAGMS | Replace 236665 | MDP-4160 (https://www.finditparts.com/products/8699743/fort-pro-usa-f224731)
Title: Re: 1985 35 oshkosh
Post by: 1985 on February 07, 2018, 02:42:01 pm
thats pretty interesting cause that is not the price I got from them.
Title: Re: 1985 35 oshkosh
Post by: 1985 on February 07, 2018, 02:45:47 pm
234189 Bendix @5.93 each plus shipping i ordered 8 so I could have two extra in unit just in case
Title: Re: 1985 35 oshkosh
Post by: Protech Racing on February 08, 2018, 10:14:39 am
 Hey when you get to the front air bags, please let me know. It sure looks like the axle has to drop to access the bottom nuts. Maybe you could cut them and not put the nuts back on? Not sure that you would need the bottom nuts as the bag just set there. 
Title: Re: 1985 35 oshkosh
Post by: 1985 on February 08, 2018, 10:27:33 am
I did look at it last week and it does look like that but I will look at my Oshkosh manual I have the original that came with MH and let you know.
Title: Re: 1985 35 oshkosh
Post by: Protech Racing on February 08, 2018, 08:35:57 pm
Got  a plan , Loosen  both wheels,  Jack the nose , air it up tight,  Remove one tire, stuff the tubes between the trailing link and frame. Loosen the axle bolts  about 6 turns both sides.  Drop the axle from the same side as tire is off.  Good chance that the weight of the tire/wheel  will give a little counter balance  to the axle for bolting back up.  As long as one side is bolted, it should go back together well.
Title: Re: 1985 35 oshkosh
Post by: 1985 on February 14, 2018, 02:41:53 pm
FYI changed piggy back chambers for parking brake and other diaphragms and my air stays up for hours with no leak down.

Thanks everyone for the help