1978 Eldorado Parking Brake does not work at all

[www.eldorado-seville.com]

Hi,
I bought this fantastic low mileage 78 Eldorado recently and until yesterday I thought that everything on this car works perfectly as it should.
I applied the parking brake for the first time and NOTHING happened. It did not brake the car at all...
I checked the cables and everything is fine. They are properly adjusted and I can see the lever move at the rear disc brakes.
I lifted the rear of the car but if I fully apply the parking brake there is not the slightest braking going on on the rear wheels. The regular brakes work perfectly.

I'm completely new to rear disc brakes as this is the most modern Cadillac I own and that's why I have no idea on how to diagnose the problem.
Unfortunately the shop manual is not exactly helpful regarding my problem, and to be honest I do not have the slightest idea how this parking brake works...

Can you please tell me how this can be repaired or where I should start trouble shooting?
As mentioned above - the cable is moving and the levers are moving as well.

I really hope its an easy fix...

Thanks in advance!
Gerald

[joeceretti]

I don't know your car but typically with rear disc brakes of this vintage are there not shoes inside the rotor drum solely for the parking brake? Kind of, or actually a, type of hybrid disc for the power and drum for the parking.

Again, I am not at all familiar with your car so this may not apply at all.

[Commodore]

Well, the first thing is how is the brake pad lining? If it is worn down to nothing the e-brake will not work.

[www.eldorado-seville.com]

I don't know your car but typically with rear disc brakes of this vintage are there not shoes inside the rotor drum solely for the parking brake? Kind of, or actually a, type of hybrid disc for the power and drum for the parking.

Again, I am not at all familiar with your car so this may not apply at all.

Thanks Joe,
There are no extra shoes for the e-brake like on more modern cars. The parking brake works through the regular pads on the 78.

[www.eldorado-seville.com]

Well, the first thing is how is the brake pad lining? If it is worn down to nothing the e-brake will not work.

The pads are not really worn at all. It looks like that some sort of mechanism is not engaging ?

[TJ Hopland]

This is not an Eldorado but its pretty much a typical rear drum brake setup.    If you see the lever moving but its not doing anything to the shoes what is most likely missing is that horizontal bar I circled in the photo.   Its often one of those 'extra' parts you have when you finish a brake job your first few times.

[TJ Hopland]

Whoops, as soon as I hit post it dawned on me a 78 Eldo has rear disc.  Those are a little more complicated.  If you see the shaft going into the caliper moving the adjuster is likely stuck internally.   Its a lot of moving parts that live in brake fluid that usually does not get changed very often.   The extra holes and seals for the parking brake just give more chances for moisture work its way in.   

I believe those calipers are now made new because they are popular for use in converting trucks to rear disc brakes.  The hard part to to find used to be the brackets and levers for the parking brake, those did not come with new or rebuilt calipers till recently. 

[www.eldorado-seville.com]

Thanks TJ!
Do you think I could repair my original calipers and if I have to get new ones I could still use my original brackets and levers?

[Glen]

I am also not familiar with your model car, but on some rear disc the E brake is applied by pumping the lever vice a single press of the brake.  It rotates a drum that presses on the disc pad. 

Is it possible yours works that way?   

[Commodore]

OK here is photo of the rear brake caliper. When you apply the e-brake, you move the lever black spring is attached to.



Here is a photo of some of the internal e-brake mechanism. When the level is moved the screw threads push the brake piston and pad against the rotor. If the threaded shaft is frozen or the threads worn, the e-brake will not work. You need to check when apply the e-brake does the threaded shaft move or just the lever. If just the lever moves you need to remove lever to see what is damaged.  In any case you need to repair or replace the calipers. New calipers with the e-brake parts are available but pricey about $320 per pair. Rebuild calipers w/o e-brake parts are about $50 - $100. Rebuild kits are also available.

 

[76eldo]

These self adjust when you back up and apply the brake.
True, something can be stuck if the car did a lot of sitting but just try backing up and applying the brakes and the E brake about 20 or 30 times and what is stuck might get unstuck. Nothing to lose, that's a free repair.

I'd try that before taking them all apart.

Brian

[TJ Hopland]

I didn't think backing up had anything to do with the disc, that was a drum thing.  The disc does not know backward and forward but the drums do.  On drums going backwards 'jogs' the whole assembly which puts pressure on the adjuster.  If it moves far enough it will advance the adjuster one notch.   

To adjust the disc you just need to be holding the regular brakes when you release the parking brake which is natural for many people, especially in the cad since the auto release works when you shift gears and if you were not in the habit of using the brake when shifting before you are now if you drive anything that was built in the last 20 years since everything has an electronic do dad that forces you to do it.

Inside the caliper is a clutch like mechanism that allows the adjustment to work.   Think of it like a bolt going into piston and the parking brake lever being a regular ratchet wrench.    IF you move the wrench with no regular brake pressure on its like the nut is just loose so you don't get any ratchet action.  If you engage the parking brake then the regular brake its like holding the nut.  When you release the parking brake your 'wrench' will ratchet back to its rest position so next time you apply it you will actually be 'screwing' it out further which eventually will hopefully mean you are applying enough pressure in that 1/4 of a turn to apply some brakes.

[www.eldorado-seville.com]

Thanks a lot for your explanations gentlemen. The car is low mileage and so I assume the parking brake was not used very often...

[76eldo]

I realize that the caliper does not adjust with backing up like a drum setup but I know that somehow the parking brake adjusts.

Brian

[Commodore]

This web site gives the procedure for adjusting the e-brake.

http://www.justanswer.com/cadillac/2bvsp-hi-i-calipers-1979-cadillac-eldorado.html

[TJ Hopland]

That link is describing adjusting the cable on a typical rear drum system.   Rear disc was standard on 79-85 Eldo.  76-78 too but it was a slightly different caliper.   The asker even is describing disc brakes.  Guess the 'expert' does not know that era Cadillac and also cant read.  I also just noticed the asker said he has calipers from a 79 Eldorado so its some sort of swap thing going on which makes it even a more difficult question to answer.

Maybe later I will have time to go look for one of my 76-79 manuals. 

[Commodore]

In the web site I referenced the author talks about  rear disc e-brake adjustment in the section below the drum brake adjustment.

[TJ Hopland]

I saw that but its for a 86-89.   I guess I should cut the guy some slack since I too posted about drums before my brain remembered it was disc.  I have never worked on a 86-89 so I don't know if they are the same as 79-85 or even 76-78 that we are asking about here.  Seems like my 95 had the mini drums but I could be remembering wrong.    I do like the mini drum idea, it eliminates that whole screwy parking brake mechanism.  I'm pretty sure the Corvettes had the mini drums pretty early on in the drum era I suppose cost was the reason other cars didn't get em till much later.   

[76eldo]

Two things come to mind, one, what does the shop manual say? Two, try calling a Cadillac dealer and ask if you can speak to someone in service with a question. You might be surprised at how helpful a Cadillac dealer may be.

Brian

[TJ Hopland]

Try calling a Cadillac dealer and ask if you can speak to someone in service with a question. You might be surprised at how helpful a Cadillac dealer may be.

You must have much more helpful dealers in your area than there are in my area.   When I went in for parts and service for my 95 in 2003-2004 they barely would talk to me.   When I asked about my 73 I thought they were going to throw me and the 95 out.   Pretty much the same experience I have had with most dealers.   I did find a really nice Dodge dealer in Wisconsin when I had issues on a road trip but its not worth a 400 mile round trip for regular service.   Even the dealer I bought a new car from 6 months ago is only so so.