Long story but necessary. I have a feeling there one guy that will know exactly what happened. Thanks in advance.

97 E-450 (E-Superduty) 7.3L PSD, E40D, 4 wheel disk brake, Cutaway 240k miles, was a paramedic ambulance now a work truck. Stock except Mag-Hytech deep Transmission pan.

While driving on the highway I heard a loud grinding noise start up and get louder. As I slowed and moved right the noise got chunkier and then i felt a binding and and the truck slowed down- it was as if I had wrapped a length of wire around a wheel. The binding slowed the truck down and the I felt a big snap and heard a pop as if whaterver it was had wrapped up, bound up and then let go.

The truck seemed fine except for the grinding noise and the incident that had just happened. The noise seemed to be coming from the transmission. I pulled over and looked it over. Nothing out of sorts.

Started it up - all vitals were good, oil, water, electrical, serpentine belt was good, no noises from front of engine, no noises while idling.

Pulled back on the freeway and got up to speed. engine pulled fine, tranny was strong and shifted. OD was on. No sway or squirm out of the rear end.

Shortly after hitting 65mph, grinding started again. It was on and off for the next 10 miles.

Nursed it home. Tran fluid had just been drained and refilled 2 weeks ago. Tranny was rebuilt at 132k. Not a lick of trouble and fluid changed every 15-20k. New filter annually.

Transmission: Drained transmission and fluid seemed just fine -no burn smell, color good, no metal. Dropped pan and it was pristine. Changed filter and put it back together.

Torgue Convertor: Pulled bell housing cover plate and it looked factory new. Did not do more than a visual inspection without turning the flywheel.

Differential: Pulled plug on Diff cover and the plug had normal amount of metal and fluid flowed out looking and smelling like new. Diff get checked quarterly and drained & refilled annually.

Rear Axel Bearing: Looked for grease and felt for excessive heat when I parked after this last trip. Nothing visible, no excessive heat.

Turned it around in the driveway and felt a binding slipping type sensation but it seemed to be from the rear end. Today I am going to pull the Diff cover.

The sound cames right out of the doghouse when I was in the cab and driving. While driving down the freeway i put it in nuetral and turned off the engine. The noise remained the same.

I am guessing it has to be the torgue convertor, transmission, overdrive, emergency brake, or rear end. The emergency brake unit is behind the OD and before the driveshaft. Not long ago the E Brake indicator light switch started failing and I may have been driving around with e-brake on a few times. It was not on when this incident happened on the freeway. I checked as soon as I heard the grinding and felt the binding.

Ever since I started using this site I have found a lot of useful information. When i get this solved I'll post the result so we all will know more. Thanks
Joseph

 

I have similar problem with 1995 fsuperduty I just purchased and have driven about 70 miles.
I believe my problem to be in the emergency brake assembly but have not yet removed
it for disassembly.
I am thinking something internal is broken and binding.
I also suspected it to be the differential when it happened
I am interested in whether this is a common problem?
how common is this type of parking brake? what years used it?

 

I have no idea. A few calls around twon (San Diego) yielded a couple of "Huhs" and one -"Don't touch 'em". If I can get a lead on what the product is I can work toward getting a diagram and getting it opened up.

 

I disconnected the driveshaft from parking brake, brake turns freely no binding.
when I lift rear tires off ground and turn tire there is a binding it appears to be front
bearing of differential is locking up due to lack of oil.
I am thinking I need repairs to differential. I was really hoping it was the park brake.

 

I took it apart today step by step - and isolated it to the parking brake. What is thing really called and where or who sells it?

 

It is called a Transmission Mounted parking Brake, Part Number 2598, only available as a complete assembly.

If I could post an image I'd put the parts diagram up.

Just drove it around. Seems back together correctly and strong. Did you know these things require 4.1 ounces of transmission fluid in a chamber that has a fill plug just like a differential?

I ended up fixing this myself because the first diagnosis I got, over the phone, was that it was the transmission. That didn’t make sense because the transmission seemed as strong as usual. I know what it feels like when the transmission fails.

Called 2 shops and got two diagnosis- transmission from 1, differential from other. None of this made complete sense. You read the full story on the ford-trucks.com post, right. This is even more telling of the “experts” out there: once I started asking about the parking brake aft of the transmission, they went numb. I took the removed unit and took it to one shop and 3 guys beat one it, disassembled anything they could get a wrench on, and tried everything but a cutting torch. I had the diagram right there and they still acted like democrats discussing how to get it apart.


So I learned a few things – 1) the transmission mounted parking brake requires lubrication just like the differential- 4.1 ounces of transmission fluid, 2) The last guy working under there may not have been as thorough as a mechanic should be – one of the U-joint star fastener was stripped, 3) Before you take a truck in to a shop, check the obvious. When I drained the transmission fluid and it was pristine and as pure as new and the rear end fluid was the same, that left two items – the parking brake and the carrier bearing (mid-ship drive shaft bearing).

If it had been the transmission I would have regretted not pulling over and calling a tow truck. Since it was not the transmission, I’m glad I nursed it home and solved the mystery myself. Last tow cost me $300. This time I was 2x miles away.