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Operation of E450 parking brake
Larry W or someone else.  About the operation of the older Ford E450 transmission mounted parking brake.  Does the ATF operated brake need fluid to keep the brake off? Or does the foot pedal provide fluid to operate the brake on?   If fluid were to slowly leak out would the brake shoes inside the drum start rubbing? Could the friction surfaces wear away slowly enough that it would not stop the vehicle after awhile, even when applied?
    Curious about a friend's non operational parking brake.
    (My '99 E350 has 'top hat' type brakes in the hubs of the rotor, like many cars have.  They need new lining's now and aren't adjustable.)  RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Operation of E450 parking brake
Reply #1 –
As I understand it, being the victim of an exploding parking brake, the fluid is necessary for the bearings that are in the assembly.

The brake shoes appear to be cable operated. I did not see the damaged parts.

Your friend may have a cable out of adjustment or worn brake shoes.

I do not use the parking brake.
Harry 2006RB
Re: Operation of E450 parking brake
Reply #2 –
Hey Ron,

I am not quite sure what specific information you are looking for. IF your friends transmission mounted parking brake is not working, my belief is that the problem is not likely from the lack of the transmission fluid. The transmission fluid, to the best of my understanding is to keep the components in that drum cooled down. If I am incorrect, I hope someone more knowledgeable will clarify that.

But, if the transmission fluid leaks out of the transmission mounted parking brake, it could damage the parking brake and possibly the transmission. You do *NOT* want to drive with that reservoir dry!

I may have been one of the first Lazy Daze Owner's to have had my transmission mounted parking brake rebuilt. Our 2003 rig was 6 years old and had 76,000 miles at that time. As I recall, Larry W was interested in the parts that were used and I think he was curious about examining a failed unit. I very much appreciated Larry's attention to this matter. The leak was evidenced by a small drop (around the size of a 50 cent piece, remember those?)  of an oily substance on the driveway below the parking brake drum. There was also some fluid on the bottom of the drum. I have no idea why my unit leaked; there was some speculation that driving the rig with the parking brake activated could heat up the brake and cause the leak. Consequently,  some folks were installing parking brake alarms to remind them to release the brake before driving. That was definitely NOT the cause of my parking brake leak since I NEVER use the parking brake.
 
I am not sure I answered your original question. If your friends parking brake is leaking, my understanding is that as long as you can top off the fluid (not an easy task) it would be safe to drive until the system could be repaired.

Steve K
Steve K

2003 Mid-bath
Re: Operation of E450 parking brake
Reply #3 –
The parking brake unit is a short housing attached to the rear of th transmission. It has a shaft that is supported by two roller bearings,. At the front end of the housing the shaft is attached to the transmission’s output shaft, and the other end has the parking brake and has a plate that the drive shaft attaches to, leading off to the rear axle.. The housing is filled with a few ounces of ATF, the same as the transmission. If it runs out of oil. it can be badly damaged and possibly tear the end of the transmission off if the brake’s bearings seize.
The parking brake is an old-school mechanical brake, similar to a drum brake parking brake. It is activated by a cable attached to the parking brake pedal. It uses no fluid to activate the brake, it’s purely mechanical.
The brake linings do need occasional adjustment as they wear. Driving with the brake on can overheat and destroy the braking lining and overheat the brake’s oil, this can damage the oil seal and cause the small oil supply to leak. and damage the rest of the brake if not discovered early enough. Checking for oil leaks should be regularly done, no less often than at oil changes. The brake can be rebuilt or exchanged for a factory rebuild. it is beyond the scope of most home mechanics.
These photos may help[ explain things.
E450 parking brake rebuild | Flickr

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Operation of E450 parking brake
Reply #4 –
Hi Larry, Good pictures, I must have missed them. So the brake drum and linings are dry.  How does this 'few ounces of ATF' get into the roller bearings?  I also can see the splined slip joint. Is there an eccentric cam to expand the brake shoes?
     My friend says that his mechanic takes care of everything. I'm hoping that includes this few ounces of ATF. But he has no operation of parking (emergency) braking. At 180K miles, maybe the cable has stretched enough and lining thickness has decreased, and that he just needs adjustment; to engage the friction surfaces when the brake is applied.  No 'star wheel' to adjust?
   He lives in flat land, so really doesn't need, and may not use the parking brake often. Here in San Diego, almost nothing is level, so Parking brake use is always needed. The expense of replacing a parking pawl is very high compared to having the parking brake applied. (my Lexi automatically apply and release the parking brakes).
     A little story: where I worked 19 years the parking lot was very  unlevel and a fellow worker would slam his Volvo into park while still moving a bit!  He didn't customarily use the parking brake.  (Software guy, and apparently not much  mechanical knowledge).  I warned him that all somebody else had to do was nudge his bumper and the car could go rolling away!  But he did it to himself. One stop many days (weeks) later and the pawl broke, pieces got into the transmission, several thousands of dollars and a week or so of repair (a rebuilt tranny?, hard to find in the early '80's). I don't know if he started using his parking brake then. He wouldn't talk about it to me.     RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Operation of E450 parking brake
Reply #5 –
The parking brake linings wear and need periodic adjustment, there is a nut used to shorten the brake cable.
Worn linings can be replaced.
Here is how fluid is added to brake, it is mostly done by touch.
Parking brake oil fill | Flickr

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Operation of E450 parking brake
Reply #6 –
Hi Larry,
Question on the images you posted at the end for refilling the fluid. I’m not a mechanic and asked my friend who is if he would please check it for me. I think he has no clue what was going on and basically told me ask was well and nothing needed to be done. I know that’s not right because the previous owner left me ask of his notes. He especially left notes about this and laminated it so that I would pay attention. Ok, so more I am going to have to get under there and do this myself which won’t be fun (I have RA) but it’s my home. So when you remove the plug, how am I supposed to put fluid in it? And Transmission Fluid right? Not motor oil? I saw in some notes that it said when I had the oil changed, check that at the same time. So I’m just making sure of the correct fluid.
Wendi C. 1998 30' TB
Re: Operation of E450 parking brake
Reply #7 –
Not Larry but a squeeze bottle will work to add the ATF fluid. A smaller mustard container also works. When I had mine rebuilt they said ATF type H ATF fluid which I had to special order at NAPA.
Harry 2006RB
Re: Operation of E450 parking brake
Reply #8 –

The parking brake reservoir uses the same fluid as used in the transmission. In your case, Mercon V.
I use a large irrigation syringe to top off the oil. The brake only has DEPEPE 2pcs 100ml Large Plastic Syringe with 2pcs 47in Handy Plastic Tubing... a few ounces of fluid, so it is important to keep it filled

The parking brake used in the 1998-2007 transmissions in the wide body chassis is very unusual; most mechanics have no clue how it works or how to check the oil level. That's why I included photos on how to find the oil plug. The plug is difficult or impossible to see; it is found primarily by touch.
Failure to maintain the oil level can result in expensive repairs, up to and including the destruction of the transmission.

Larry

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Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Operation of E450 parking brake
Reply #9 –
Thank you both for your answers. That’s what the previous owner had written. I showed my friend. It just boggles my mind when people can’t admit they don’t know and instead smile and say, “No, you are good!” Besides who is going to pay for those repairs when they happen?
Can I ask if any of you have ever had an issue with gear fluid leaking out of the rear tire area down a tire? I noticed this recently and my friend has come to fix that. He thought he had gotten it, but is still leaking (which you only see after it’s Been driven for a bit) so I’m waiting for him to put a new seal on it that I had bought. I’d do it myself but don’t know how. I need to move my RV this week and I’m worried about driving it without this being fixed.
Wendi C. 1998 30' TB
Re: Operation of E450 parking brake
Reply #10 –
Is the axle seal leaking differential fluid?  

If so, you can probably top off the differential fluid and move it a short distance unless the leak is catastrophic.  

If it's something like brake fluid (also in the rear tire area), I would get it fixed before moving. 

If I had 1 axle seal go out of a 1998 that I owned, I would consider replacing both axle seals and the pinion seal.   You don't want to pay to replace a differential.

Rich
2003 MB
Re: Operation of E450 parking brake
Reply #11 –
A rear wheel bearing seal isn’t something you or your friend is going to change. It requires removing the wheels and then the hub to access the seal.. A special socket is required to tighten and set the bearing pre-load, along with an inch- pound torque wrench.
Amazon.com: Powerbuilt Spindle Nut Socket, 4 Lug, 2-3/4-inch Outer, Ford,...

The pinion seal is another seal that when needing changing requires professional attention, it’s not a shade tree mechanics project. It only needs replacing if it is leaking.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
 
Re: Operation of E450 parking brake
Reply #12 –
I had such a leak. It was the outside axle seal which is a minor repair. Yours may be different. I took it to a shop that was able to repair any failure in the rear axle. That was their diagnosis and repair. $135 if I remember correctly.

They had to add oil, lift the coach off level to fill the axle end with oil, do it for the other side, check oil level again and add as required. Hope you find a good mechanic.
Harry 2006RB