Spring brake chamber again

[randygk]

After asking about replacement spring brake chambers or parts and not getting much response, I started to dig into them a little deeper. I read about someone here replacing the diaphragm, but stating it had to go in upside down didn't give me a warm and fuzzy feeling. I called Haldex and talked to a tech that told me parts are no longer available and will no longer be supported. Ryder claimed to have a replacement
which is a Haldex Model 1216012. Upon ordering some, none were in stock and none expected to arrive. I luckily found 4 new ones at a shop and bought them as I had two that were leaking.
I replaced one today and it works fine. The service and emergency ports are in reverse position and only two ports instead of three, but not an issue on our truck.
Haldex sent me this drawing, but it's a tad small.

 

[acme66]

I put mine in upside down/backwards so it was probably my post/video you were looking at. Have since learned that old diaphragms take a set and it wasn't so much in backwards as it wasn't 'shaped' yet. Another old mechanic told me it doesn't matter much as long as they go together its fine. I personally don't know, just relating. Anyway that truck went on to do about 8000 miles of mountain tour service before I lost the motor in it and everything worked normally. The trucks get a daily inspection of everything before I enter the days service and a yearly full DOT inspection by an outside company for my commercial insurance.

If you ever track down a good source for cans I would be interested as I would like to carry a spare set. It is a big no-no I am sure to operate the tour with a caged brake all day.

Ken

 

[Floridianson]

Yes they were up side down do not take a set. As said the pancakes we get are the wrong ones but they work upside down. I called lots of places that might have parts for our Stop- Master off road axles and no correct pancakes. If you take out the original one and place it next to the only ones we can now get the new ones are taller and go in as said upside down. Find my thread were I rebuilt the chambers and there is a pic side by side of the two pancakes. They are different and as said no such thing as them setting the wrong way and loosing two inches of height.

Making you tube vids is great but it helps to know or have done the work before.

 

[randygk]

I get the feeling there are two types of truck owners, those that rebuild the spring chambers and think nothing of it and those that won't touch the spring chambers. I was just trying to give a little info for those that just want to change the whole thing and be done with it, that the whole replacement spring chambers are hard to find. Several of the military truck suppliers have the whole brake stem and spring chamber assy for sale, but they are NOS and I suspect the age and condition of the rubber diaphragms may not be much better than what you're replacing. Napa said they could get me one (at $220 ea, I paid $ 160 ea for four), but I never ordered it.

 

[M35A2-AZ]

I have replaced 3 or 4 of the spring brake diaphragms and they have worked fine. But it does make you think about that big spring setting there
ready to get you. The two diaphragms needed are a t12 for service and t16 for the spring brake side.

 

[Floridianson]

Just set the key and chamber. If it holds long enough to drink a beer it will hold. Liquid courage can be a good thing and then just like a gun barrel don't point the chamber at anyone or something you like. Keep the Dust cap on the chambers so the keys will slip in with no problem. If the parking diaphragm is shot oil the key threads before you try and run the nut down. If the parking diaphragm is good then air up the truck and release the axle air parking brake in cab. Now you will not have to run the nut down under pressure just run it up with your fingers till it hits the can. Air down the system and you are ready to get to work or drink another bottle of courage first.
Just watch the key and it should and must turn 1/4 turn to lock. If you don't have keys the 939 series runs a standard 3/4 inch key.

 

[VPed]

To follow up with what Floridianson said, I suggest as I have learned from others here, thoroughly inspect your cage bolts before use. And maybe he's had a few too many cans of courage already today, as the setting the parking brake releases the air pressure, thereby extending the springs. What I think he meant to type was: air up, chock the truck, release the parking brake (thereby compressing the springs with air), install the cage bolts, then set the parking brake (releases air pressure) to proceed with the work. This is if the diaphragm is good or only slightly leaking. Forgot to add that I to used the T12 and T16 diaphragms.

 

[Floridianson]

I thought SOP was to chock the truck no matter what when we hit the ground. Who knocked over my beer?

 

[73m819]

Do not use the OM caging bolt, You do not know its history or use, BEFORE you do any caging of the spring brake go BUY some NEW ones from Napa or a truck parts store

 

[Floridianson]

To follow up with what Floridianson said, I suggest as I have learned from others here, thoroughly inspect your cage bolts before use. And maybe he's had a few too many cans of courage already today, as the setting the parking brake releases the air pressure, thereby extending the springs. What I think he meant to type was: air up, chock the truck, release the parking brake (thereby compressing the springs with air), install the cage bolts, then set the parking brake (releases air pressure) to proceed with the work. This is if the diaphragm is good or only slightly leaking. Forgot to add that I to used the T12 and T16 diaphragms.

Yea thought that is what I said but I did edit to make it a little clear. That air cage thing is done when we are replacing the service brake diaphragm and as said we have a good parking brake chamber diaphragm. Don't think any hole in the park brake diaphragm will allow this trick. All the ones I have seen are ripped from lots of pressure.

 

[VPed]

When I did mine it was due to a slow leak on one spring brake chamber.