"Grinding" rear brake drums ...

[12Ounce]

I'VE FOUND IT!!, I'VE FOUND IT!! ....OK, I "think" I've found it. And I need someone who has "grinding rear brake drums" to do the same procedure and see if they have similar results.

This subject has been discussed in other strings, such as: http://www.automotiveforums.com/vbul...1073161&page=2
..... but I don't think I've ever seen exactly the same conclusions.

My '99 SEL has had grinding rear brakes, on and off, ...forever. I have looked many times for the reason ... never to find it. But I had a preconception, that proved to be invalid, ... I always thought it had to do with the brake shoes. NADA! Wrong!

My brakes were really ginding loudly this week. And so I thought I would take a look ... one more time! The van was jacked up and both rear wheels removed. I looked at the RH side, the worst for grinding, ... nothing! Disappointed, I reassembled it. On the LH side, I put on my reading glasses, used extra lighting, used a mirror ... looked everywhere ... and finally: I noticed shiny steel finings in the groove aroung the outside of the brake drum. Bingo!!

The grinding occurs between the turned-up edge of the steel backing plate ... and rust that grows inside the brake drum groove!

Using the handle-end of a 10" flat file, the rust build-up was removed from the groove. Using some sanding paper, or friction cloth, removes even more ... down to clean iron. One could also smear a greasy cloth into and around the goove. Careful ... don't leave enough grease that would run when hot! The grease is not a lubricant in this case... it is a rust retardant. Paint might work also. (Actually, I've yet to try grease or paint!)

So with just groove cleaning ... and checking the edge of the turn-up on the backing plate ... I now have quiet brakes!!!

ABSTRACT: The iron of the drum is "easy to rust", especially after a drive in the rain. The steel backing plate edge also rusts ... the two parts rust, growing closer together over time, eventually almost locking to each other. They separate once the vehicle moves ... but with brake-heat and expansion, they come in contact again.

[northern piper]

well this really fits with the same grinding problem that I couldn't explain a while ago. Here's what happened to me.

I went to pull the drums off and like normal they were tight. I backed off the self adjuster but still had a struggle. I ended up putting a small pry bar screwdriver between the drum and the backing plate, and gently pried the drum off. Now thinking about that motion, and putting force on the screwdriver handle, in prying the drum off using the backing plate as a leverage point would in fact bend the backing plate a tiny bit away from the drum. Funnily enough, in doing that and just cleaning the drum up a bit once off the grinding stopped. I couldn't find it so I was happy to have the noise gone but did wonder.

I really do think you've hit is 12ounce! Good job!

[Windstartled]

Kudos 12oz! Lord knows those grinding noises are nerve-wracking when you can't find the cause. In my case groove rust was my initial suspect but it turned out to be something else, as I mentioned in the other thread. An acquaintance of mine has a '99 Winnie he purchased new and still drives daily. He told me the grinding occurred twice while the vehicle was still under warranty and both times a Ford dealership simply replaced the drums. Guess it's cheaper for them to do that due to labor costs involved in cleaning out the rust, but not for us. A decent pair of drums adds up to $100+ and yet a lot of guys just keep buying new ones every 2 years, as evidenced by the 8 practically new drums I picked off retired Winnies at a bone yard last Fall. I swear every third van they had there had shiny rust-free drums. Paid $5 each lol.

[LTDzak]

12ounce, I can verify that I used a similar procudure to eliminate the grinding on the rear drums of my 99 - was certain the pads were down to the rivits but not so.

It was so bad that even with the autoadjusters all the way in I could not take the drum off, without using a screwdriver to "machine" the rust ridge off of the drum. Once the drum was off further filing and scraping needed to be done on the "rust ridge"

Has not returned since then (about 6 months). LTDzak

[wiswind]

I have mentioned.......one other thing that can factor in is the rear wheel bearings needing re-packed.
When they need re-packed....you get a little play in there, which can make that rust ridge rub the shoe lining.
I had that take place ONLY when cornering.....and the mechanic told me that it was because the rear wheel bearings needed to be re-packed.
Not just trying to upsell me because it was allready on the "to-do" list that I told them when I took it in.

Front wheel bearings, you cannot repack.......
Rear wheel bearings, need to be repacked from time to time....

[12Ounce]

I agree, a rear bearing that needs service or replacement will yield the same results ... the drum will "wobble" and touch the backing plate making the grinding noise. I've had the possibility of servicing the rear bearings "on the list" for some time, but could not detect any looseness in the bearing...so continued to look elsewhere.

[Windstartled]

Originally Posted by wiswind

I have mentioned.......one other thing that can factor in is the rear wheel bearings needing re-packed.
When they need re-packed....you get a little play in there, which can make that rust ridge rub the shoe lining.
I had that take place ONLY when cornering.....and the mechanic told me that it was because the rear wheel bearings needed to be re-packed.
Not just trying to upsell me because it was allready on the "to-do" list that I told them when I took it in.

Front wheel bearings, you cannot repack.......
Rear wheel bearings, need to be repacked from time to time....

Unfortunately rear wheel bearings on second-generation Winnies cannot be repacked, as per the service manuals at least. Apparently they are not the same as first-generation vans which use Taurus parts. Personally I am not convinced it can't be done because removing the bearings from the hub is not that difficult even on second-generation vans. That said, the one time I've done it the bearings only lasted a couple months before the airplane noise came back with a vengeance so in the end I replaced the whole hub.