Rear Drum Brakes Backing Plate

[ernesto]

Trying to get the Drum Brakes Backing Plate off of the strut assembly on my 1975 280z. The strut is off of the car and the stub axle is removed and well as the companion flange. The four bolts on the backing plate have been removed as well as the brake line. The backing plate and the axle tube appear to be one piece due to rust. I'm pretty sure they are two separate pieces but I don't want to damage anything using an air chisel to separate them. Can anyone confirm this? Really appreciate it!

E

[Yarb]

You can try a oil a rust penetrant like Kano Kroil or PB blaster and soak it. The other option is heat. Sounds like it’s seized on there. 

[Jeff G 78]

You should be able to drive a narrow putty knife between the hub and backing plate to create a gap.  Like Yarb said, soak the hole where the hub meets the backing plate and all around the perimeter of the joint.  A good penetrant is a 50/50 mix of ATF and Acetone.  Heat on the backing plate outside the hub flange might also shock the bond.

[Captain Obvious]

They are not one piece. They just need a little persuasion.

Take the bolts out:

Turn it over and give it a judicious whack. Don't go postal on it, but some BFH persuasion might be necessary.

And here's a shot with the plate removed:

[Jeff G 78]

How does everybody manage to take photos and/or videos while working on a project?  I am always too busy and my hands are always dirty, so getting my phone out take pics mid-job never happens.  I do try to stop and document a few times once I finish a task and clean my hands and always do at the end of the day or when the project is completed.  I guess many of you have kids that you can lean on to be the photographers.

[siteunseen]

They are teachers! Keep up the good work. 

[Captain Obvious]

Haha! I got two parts to the answer to that... First is that the pics of that backing plate work was a special situation where I had other people over for a "rear bearing party". I was doing mostly directing and telling other people what to do (clearly, as it should be). On that day, I got to hold the camera and take pics of other people doing real work. That's not me swinging the hammer, it's one of the other attendees.

The second part to the answer is "I've found it worth the effort to try to make it happen." By that, I mean... I do so many car projects (that I have to refer to again sometime in the future) that I really now try to take pics along the way.

Still, there are plenty of projects that, just like Jeff, I'm in hurry-up mode and can't deal with the camera at the time. And as Murphy dictates, those hurry-up jobs are invariably some of the ones I WISH I had pics of at some point later.  

[ernesto]

Thanks for the pics! That is exactly what I was looking for.

I also take photos every step of the way for my own reference. It really helps to be able to look back at something  you worked on weeks ago, especially when you are putting it back together for the first  time. As far as how I take the pics......I use Nitrile gloves to work on almost everything so the hands stay clean. I'm always pulling them off to take pics.

E

[Captain Obvious]

Glad to help. So yeah, it's just age and rust that's holding it together (like me). Clean some rust and old paint off the spindle snout where the plate rides, douse it with penetrating lube of choice, and give it a whack on the back side.

Out of curiosity... Why are you taking it apart in the first place? Disk brake conversion? Cleaning everything up for paint?

The reason I ask is that if you already have the bearings out and those plates off, I would take the opportunity to upgrade to the 77-78 style backing plates so you can use the better wheel cylinders. I would try very hard to not go back to the 70-76 style floating cylinders. They're not nearly as reliable as the newer system.

But that's just me... I've got a 77.   

[ernesto]

Removed the backing plates! Used some Deep Creep and then hit it a couple of times with a rubber mallet. Came right off. I have the whole rear suspension apart. I plan on replacing all of the bushings, new struts, spring and new brakes. I have not decided whether to go with the disc brake upgrade or not. If I don't,  I will put new backing plates on and will definitely look into the 77-78 style. Everything needs replaced so the

better wheel cylinders sound like a good idea.

 

.

[Captain Obvious]

Well I don't know the availability of the 77-78 rear plates, but if you decide you're not going for a disk brake mod, I'd look into it.

Lets see... what would you need? You would need 77-78 style:

rear plates
wheel cylinders
parking brake arm / adjuster mechanism
rubber grommets for adjuster arms where they feed through the plates
brake shoes and hardware kit

The wheel cylinders, shoes and hardware kits are cheap, plentiful, and easy to find. The grommets are a dealer only thing, but they're not expensive. The only parts you would have to hunt for are the backing plates and parking brake adjuster arms. You'd need to find someone who pulled those parts off a 77-78.

[Captain Obvious]

Oh, and glad you got the plates off! It's often just a matter of being sure you're doing the right thing.