Brake Backing Plates what do they do?

bspurloc

Original poster
Member
Dec 27, 2012
295
The backing plates have been rotted off my daughters car for the last 3+ years.
what exactly is their purpose? keep dirt off the rotors? stop a rock ding?

I see replacing them requires pulling the axles, so they are not going to be replaced in my lifetime.
The front ones are still good to go though.


maybe I am calling it the wrong thing??? the steel barrier that hovers the inside part of the rotors. you know that go ting ting ting when going bad... or scrape when bent into the rotor!
 

DocBrown

Member
Dec 8, 2011
501
Mine rusted away on my old TB. It took me a long time to realize that the scraping noises that I was hearing were the deteriating shields. I broke them off and never worried about them again!
 
May 5, 2013
434
Cut that trash off and throw it in the garbage
 
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RayVoy

Member
Nov 20, 2011
939
Like you suggest, the backing plates are there to keep dirt out of the brakes. They're actually a throw-back to the days when cars/trucks all had drums. The backing plates where part of the brake mounting system, the wheel cylinders were mounted to them, the shoes were fastened to them, the pivot point for the bottom of the shoes was attached to the backing plate and the park brake (rear wheels) was attached to the backing plate. Just keeps the dirt out now.
 
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Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
There is a hold down spring/clip, that holds the parking brake shoe, on the lower part of the backing plate. IIRC, it keeps the shoe from rattling.
 

IllogicTC

Member
Dec 30, 2013
3,452
I find the rear brakes interesting as they're sort of a disc/drum hybrid. Drum parking and disc normal brake. The part covering the "disc" part I certainly wouldn't find too important, the part covering the "drum" I personally would keep but it's all up to individual preference.
 

bspurloc

Original poster
Member
Dec 27, 2012
295
Ok... I am pretty sure everything is ok directly at the emergency brake shoe area. it is just the metal protecting the back of the rotors is rotted and gone.

I did notice on the right side the ebrake drums there is no shoe on one side. not sure if that is intentional or not...
 

bspurloc

Original poster
Member
Dec 27, 2012
295
ok checking rock auto... yeah there is a shoe missing... interesting. I wonder who did that! I know it wasnt me... I have to assume that has been missing for 4 years...

oh wait... I see on youtube the 1 shoe parking brakes are normal...
or maybe not!
 
May 5, 2013
434
I read somewhere that a lot of shops just gut the rear drums if there's a problem in there. Perhaps one ebrake ceased and some one gutted it. I could be wrong though.
 

Sparky

Member
Dec 4, 2011
12,927
These trucks should have shoes on both sides for the parking brake. If there isn't then the other side probably won't work as it requires tension on both sides to operate.

I no longer have the parking brake hardware on my truck because the passenger side cable rusted and seized up, which locked up the parking brake on that side. I didn't want to spend the money and time replacing all the cables (the rest aren't in too great of shape either). Cost vs benefit... parking brake on my first car never worked, never fully worked right on my second, originally didn't work on the TB until I put hardware back into it and now it doesn't work again, so whatever...
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
First of all, those are not e-brakes. They are parking brakes. As an e-brake, they are pathetic and would take forever to stop the truck if you were to use them alone at speed.

Next, a lot of jurisdictions require regular safety checks and just removing or disabling the parking brake is not an option. I had to fix mine by replacing the shoes, when I first bought my truck, to register it.

Even though I don't have to use the parking brake on a regular basis, I do use it occasionally to keep it functional. It does happen when I park on a hill or other situation where it would put too much tension on the parking pawl in the transmission I use the parking brake. The pawl could also skip.

Now why did GM go with this stupid design is beyond me. My Montana SV6 has a screw/ratchet system built into the caliper that actuates the same pads (it can even lock the wheels at speed). This type of system has been in existence since the '70's on Cadillac Devilles and Trans Ams. Might have to do with lever vs pedal type but then my son's Honda Prelude has a lever and has the built-in parking/e-brake.

Even crazier, I've seen electric parking brakes on a recent Ford car :crazy: . Tried it at speed, all it did was do a rumble strip type vibration.
 

Sparky

Member
Dec 4, 2011
12,927
I used to use my parking brake every time I parked. Never stopped it from seizing up. Just made it so I couldn't drive anywhere for a minute while I fought with it to get it released.

The only time I really miss it is when parked on a hill.

Most of Ohio doesn't have any sort of checks at all. Just e-check near the lake. Interesting thing is they used to have random safety checks by the side of some roads near the various highway patrol offices, but I haven't seen one now for years. Fine by me when I couldn't even afford to fix the parking brake on my first car - that would have cost more than the car was worth :crazy:

This design is simpler than the screw-type caliper and the screw type typically requires a special tool or method to compress the caliper during a brake overhaul.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
I make sure mine always work as well as they can, even if they're wimpy, because if I tear off my hydraulic brake lines on some Sierra Nevada shelf road at 9000 feet, and all I have to stop me is the ebrake, and steering into the uphill terrain/trees/boulders and shifting into reverse and killing the tranny - I'm going to use all three of those ideas to stop. YMMV - for me, keeping that system in good repair isn't an option. It's a trail leader thing.
 

Sparky

Member
Dec 4, 2011
12,927
If I was anywhere like that then yeah I'd fix mine. And my next GMT will have a working parking brake.
 

IllogicTC

Member
Dec 30, 2013
3,452
Mooseman said:
First of all, those are not e-brakes. They are parking brakes. As an e-brake, they are pathetic and would take forever to stop the truck if you were to use them alone at speed.
Can confirm, it wasn't too impressive when I was limping down the 8% grade with shoddy front pads waiting on the parts needed to fix. And a cursory test at very low speed in reverse, it makes some noise and I immediately had let off it, as I'm not willing to push it. Works good at keeping the vehicle stay still though :rotfl:
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Sparky said:
This design is simpler than the screw-type caliper and the screw type typically requires a special tool or method to compress the caliper during a brake overhaul.
I have to disagree on that. You're adding a whole separate braking system with it's own shoes and having to add a drum inside the hat of the disc which is also not self adjusting. I've worked with lots of the screw type calipers and all it takes is a $10 cube attached to a ratchet to turn the piston back in. Not difficult at all. All self contained, uses existing hardware and self adjusting. At 150K km, my SV6's parking brake works just as good as the day I bought it new, never needing adjustment although I did replace the discs and pads, which is normal. There's probably less cost with adding the screw and ratchet in the piston than the drum hardware and special disc.

I guess we can agree to disagree :cool:

They must use A LOT of salt in OH because I thought we use a lot with the winters we have here and I'm nowhere near as bad on the rust as your truck.
 

Sparky

Member
Dec 4, 2011
12,927
To be fair my truck was New York first several years, then Cleveland Ohio for the next several, so it got some of the worst of the rust belt right from the get go.

Not that they are that much lighter on the salt down in central Ohio though, the roads are white all winter, even long after the roads are plowed and dry :no:

I've never really dealt with the screw calipers. I've just been told they're more involved than a regular one (and more expensive to replace if something goes wrong).
 

NJTB

Member
Aug 27, 2012
612
Flemington, NJ
The screw calipers work fine UNLESS you don't use the parking brake. Then they freeze up. The lever will move but the brake won't apply.
FWIW, the quick fix is to beat hell out of the caliper with a brass hammer while a helper works the parking brake. Otherwise, do a caliper rebuild.
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
The backing plates are rock catchers and go in the trash.

I use my parking brake far too often to go without it. I think it is an intergral piece to keep functioning both on the road and off.
 
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bspurloc

Original poster
Member
Dec 27, 2012
295
I'll have to look into it more. forget about the heat shields or whatever!
I did notice the parking brake no pad side had recent wear too it as if my daughter had used ti recently.
I didnt check the driver side cuz I was in a hurry.
The parking brake shoes dont look hard to replace but it looked like the screw mechanism that tightens them up was rotted solid.

I could have swore a year ago or 2 my daughter may have tried to drive with the parking brake on which didnt work out well
 

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