Rear brake is driving me nuts...

[Big_John]

Yeah, but it's a rear brake and the flex hose feeds both sides so that doesn't really fit the symptoms.

True, but the car I mentioned also was an issue with one rear brake. I didn't think it could be the cause either.

IIRC, everyone figured that one side had enough spring pressure to return, but the other side didn't.

I'm not saying that this is the cause here... just saying that it happened.

 

[66Newyorker]

Sure sounds like your rear brake has pressure still within the lines. One quick check, get the wheel to hang up, raise the rear end and support with jack stands. Crack the bleeder on the wheel hanging up.If the wheel turns freely you have pressure being trapped in that line. At this point you just have to find where it is trapping the pressure. Remove the line from the Y block and the wheel cylinder on the rear axle, you can use wire or compressed air to check for an obstruction.
May also be something in the Y block. If you find rubber replace your rear flex hose to the rear axle. Hopefully you haven't pushed anything into the wheel cylinder.

 

[Polara_500]

True, but the car I mentioned also was an issue with one rear brake. I didn't think it could be the cause either.

IIRC, everyone figured that one side had enough spring pressure to return, but the other side didn't.

I'm not saying that this is the cause here... just saying that it happened.

I personally have never run into that type issue with a hard line so didn't really consider it, since you have seen the problem then he should definitely take steps to verify. Thanks for the lesson, hope I never run into the issue but it may save me some time somewhere.

 

[luigi164]

Thanks for all the replies, tips, tricks and suggestions. Unfortunally didn't have the time to work on the brakes last weekend but hope to work on it the next day's (evenings...)
I'm gonna change the shoes from one side to the other and see what happens....
No result: disamble the steel brake line to the RR and check...

 

[luigi164]

Yesterday switched the braskeshoes from side to side and adjusted them the best I can. I'm becoming pretty handy in placing brakeshoes
Today I made a testdrive. Just a few firm stops, not thát hard and a 8 mile drive with normal cruisespeed . I bought myself a IR-temperatur meter and measured some points on the wheels.
Wheels turn free after the ride.
Results:
It seems the leftside is heating up a little more now then the rightside...
Right wheel: Left wheel:
rim 120 142
center 145 148
drum 150 157
backingplate 150 160

All in degrees F

Must say that these measurements were taken after about 15 min after I stopped and the wheels cooled down a bit. Outside temp was about 62 F
A quick measurement with the IR-meter right after I stopped showed higher values, up to 200 F !!

Now, are these normal values?
For example: I drive the whole day in a VW Polo with rear drums and they feel hardly warm at all.

 

[luigi164]

Update:
After a long(er) drive on the highway, with almost no braking right ánd left drums/wheels got very hot (200 degrees F)
Today a mechanic checked everything on the rear brakes. Wheels turn free. Brakelines etc are all clean inside. With rear on jackstands, engine running, rearwheels are braking good and release immidiatly after brake pedal is released. We tried building up pressure by pumping the brakepedal multiple times but no, brakes release completely....
It seems that the heating up appears more, and on both sides now ! after a longer testdrive..
His suggestion was that the proportioning/meteringvalve could be the cause of the issue ???
Any comments on this? Could this, maybe bad valve, cause all this problems?

 

[Big_John]

There is no proportioning valve in your car. There's a metering valve in the front brake line, but that won't affect your rear brakes.

You've said that you've checked the brake lines, but what about the rear brake hose? It's a $10 part that probably ought to be replaced anyway if you don't know the last time it was changed. At this point, $10 is pretty cheap just to make sure that isn't the problem.

 

[luigi164]

There is no proportioning valve in your car. There's a metering valve in the front brake line, but that won't affect your rear brakes.

You've said that you've checked the brake lines, but what about the rear brake hose? It's a $10 part that probably ought to be replaced anyway if you don't know the last time it was changed. At this point, $10 is pretty cheap just to make sure that isn't the problem.

Hose is already replaced....just like everything else, see my first posts...
About the valve, I allready thought so but wasn't sure. So that can't be the cause either..
I'm running out of options..

 

[65sporty]

Do they ever get any hotter than 200? How hot are the fronts? How well are the fronts working?

 

[livininharrow]

looks like the one shoe is a lot thinner than the other. that one must be dragging possibly your cause of heat build up. I would look in that area. just a thought.

 

[livininharrow]

also like cantflip mentioned why the missing hardware. as in the cable that runs down to the adjuster?

 

[luigi164]

Do they ever get any hotter than 200? How hot are the fronts? How well are the fronts working?

Hotter then 200 ? Don't know because I stop driving as smoke is comming from the wheels, don't want to risk vapour lock...
Fronts (disks) are not hot and car is braking very good, no problem.

 

[luigi164]

looks like the one shoe is a lot thinner than the other. that one must be dragging possibly your cause of heat build up. I would look in that area. just a thought.

Shoes are brand new on both sides..

also like cantflip mentioned why the missing hardware. as in the cable that runs down to the adjuster?

Left them out to eliminate a probably cause heating up..

 

[cantflip]

I just looked at your pictures again...

In my mind that self adjuster seems wound out a pretty long distance for a bunch of new parts. I would call this a guess at best, but the circle the brake shoes make may be too far out of round and be related to your issues.

I would first, make sure the drums are the correct size and in wear tolerance. We have all had a wrong part or a poorly made substitution bite us before.

Second, I would look very closely at wear the shoes are showing contact marks... if you've had them smoking they should be a bit glazed where they touch. The primary would normally contact top and a bit towards center... if it shows anything at the bottom, I may be on to something. The secondary should show at the bottom either way, so don't look too hard there.

My thought are that MAYBE the bottom of the primary is dragging enough to generate enough heat/expansion to start to "self activate" as you drive. Another diagnostic test would be to drive until hot, jack the rear wheels in neutral and see how much drag there is when hot... something I would have expected the shop you took it to would have done.

If I'm correct... I'm a genius... If not... it's just a guess

 

[luigi164]

looks like the one shoe is a lot thinner than the other. that one must be dragging possibly your cause of heat build up. I would look in that area. just a thought.

That's right, primary shoe is thinner...Isn't that supposed to be ? That's how they came right out the box.

 

[1970cat]

are the slots in the spreader bar binding? from your picture it looks like it might be dragging on the left side. your adjuster looks pretty crusty. it wouldn't hurt to take it apart , wire wheel the threads and put it back together with some never seize. it shouldn't be out that far with new shoes as was said above. the right shoe looks like it's half worn. any i have changed have the same thickness primary and secondary. you should install the adjuster cable too. it all works together as a team.

 

[luigi164]

are the slots in the spreader bar binding? from your picture it looks like it might be dragging on the left side. your adjuster looks pretty crusty. it wouldn't hurt to take it apart , wire wheel the threads and put it back together with some never seize. it shouldn't be out that far with new shoes as was said above. the right shoe looks like it's half worn. any i have changed have the same thickness primary and secondary. you should install the adjuster cable too. it all works together as a team.

Everything and I say éverything is taken apart, cleaned, fresh grease on it etc etc...There was absolutely no rust or other dirt on all the parts..
And for the thickness of the shoes: on all the pics I've found from different suppliers, the primary shoe is thinner...So I suppose is has to be that way.
I'm planning to place the adjusters back, after the issue is solved.

 

[65sporty]

Another diagnostic test would be to drive until hot, jack the rear wheels in neutral and see how much drag there is when hot... something I would have expected the shop you took it to would have done.

If I'm correct... I'm a genius... If not... it's just a guess

This needs to be done so we know if there is pressure holding the shoes on, I know you changed the hose but because it's new doesn't mean it can't be bad.

 

[luigi164]

Car was at the shop yesterday for further investigation.
They took a long testdrive, wheels heated up as usual ( left ánd right)
Jacked the car up: wheels turn free, no drag at all...
Center of the hub was the hottest point on both wheels according IR-temp meter..

I was advised to check the wheelbearings and replace them because they could find nothing wrong with the brakes,
Could bad bearings be the cause of heating up thát much?

 

[65sporty]

Any noise from the axle bearings? When they test drove it were the brakes smoking? If the bearings were causing the heat they should be making all kind of noise.