one rear brake getting too hot

Motorama · Post by **Motorama** » Wed Sep 04, 13 12:11 pm

be careful continuing to use the car whilst you have this issue, a couple of years ago i had a rear tyre explode on a 61 Cadillac i had just purchased because the rear shoes were fitted wrong by the previous owner and dragging, melted the rubber caps on the wheel cylinder and removed all the material from the shoes,

MilesnMiles · Post by **MilesnMiles** » Wed Sep 04, 13 12:20 pm

Yep sounds bad.
That said, my car rolls withour resistance, the drums are not hard to pull off and there is no visible wear marks beyond the wear of the shoes themselves. Nor does the handbrake stick. All very odd.

Motorama · Post by **Motorama** » Wed Sep 04, 13 1:00 pm

I've had it on older 50's Mopars where the brakes grab if they aren't adjusted out enough as they don't hit the drum square, they are a nightmare to set up right.

Are you sure its not a rear wheel bearing getting hot if the brakes seem ok? Does it smell hot as dragging brakes do?

Steve · Post by **Steve** » Wed Sep 04, 13 1:01 pm

im really sympathising with you on this Miles....I thought mine were fixed until I went out last night. 5 up...30 miles or so and both rears smoking again!!!

Had a look this morning....backed both right off and started again. Adjusted up so not touching at all on jack and wheels spin freely. Went out....braking poor and warning light on. Wheels off again...adjusted out more till brakes work but dont bind. Another run..one hot....one cold. Light not on. Adjusted hot one back off....cwaited till cool...run...both hot again!!!! Like you....rolls fine...parking brake not binding.

They work and MOT tomorrow so will just have to cross fingers and have anither look at the weekend

Cheers Steve

Steve · Post by **Steve** » Wed Sep 04, 13 1:02 pm

im really sympathising with you on this Miles....I thought mine were fixed until I went out last night. 5 up...30 miles or so and both rears smoking again!!!

Had a look this morning....backed both right off and started again. Adjusted up so not touching at all on jack and wheels spin freely. Went out....braking poor and warning light on. Wheels off again...adjusted out more till brakes work but dont bind. Another run..one hot....one cold. Light not on. Adjusted hot one back off....cwaited till cool...run...both hot again!!!! Like you....rolls fine...parking brake not binding.

They work and MOT tomorrow so will just have to cross fingers and have anither look at the weekend

Cheers Steve

latil · Post by **latil** » Wed Sep 04, 13 1:33 pm

That sounds like pushrod adjustment or a collapsing flexi pipe acting as a one way valve.

MilesnMiles · Post by **MilesnMiles** » Wed Sep 04, 13 1:41 pm

Steve, best of luck with it all.

I'm wondering about the bearings, but i think brakes more likely.
Just about everything local to the brakes is new including wheel cylinders, hardware, the brake lines and union on top of the axle, new axle bearings and rebuilt diff etc.
It's all pretty spotless.

Just a thought, but how hot should brakes be after a thrash with plenty of braking not to mention the shuffle down my narrow drive?
Nothing smoking on the brakes. The front discs are cooler (wheel is warm to the touch), but they are exposed to the air more than the drums

Pete · Post by **Pete** » Wed Sep 04, 13 1:55 pm

Fronts will always get warmer than the rears if working correctly.

Just been through all this with the Dogrango........

Pete · Post by **Pete** » Wed Sep 04, 13 1:57 pm

...and I have had a similar problem in the past to the collapsing hose that Latil mentions....

MilesnMiles · Post by **MilesnMiles** » Wed Sep 04, 13 2:31 pm

Latil, refering to the 'pushrod adjustment', do you mean the one into the master cylinder because I did originally get that wrong. I then backed it off into the servo a touch and I do now have some free play at the foot brake. Can't see how this would act negatively though?

Pete · Post by **Pete** » Wed Sep 04, 13 2:40 pm

Nope.
I had a rear hose collapse internally - no outward signs.

In my case I could take the rear drums off, run the motor with a Servo, stand on the brakes and the rear pistons would not move.

If you are CERTAIN that there are no installation issues and the brake fluid is new, then you have to work through on a process of elimination.

Changing the rear hose may be the next logical step...

Mind you, if ONLY One rear brake is getting hot, it points to incorrect instalaltion / Drum out of round / some other issue yet to be identified.

MilesnMiles · Post by **MilesnMiles** » Wed Sep 04, 13 2:50 pm

PK, Pete thanks for your time. I clearly have more to do yet

Only a week to go to the Drags as well.

Dave999 · Post by **Dave999** » Wed Sep 04, 13 5:13 pm

MilesnMiles wrote:OK mate, but in principle we mean the same thing in that it acts on the adjuster that pushes on the brake shoes.

Here's a thing for your science head related to the above.
Went for 20 mile thrash on new carb last night. Lots of braking etc..
came back turned car off and decided to check the heat of the offending brake/wheel. Suprised to feel that it seemed less hot than before.
Went indoors for five minutes to open celebratory beer or so, came back and touched the same wheel and now its really hot! What have i not learned yet???

takes a while for your mighty hot drum to transfer its inner warmth to the wheel??

just back em off a bit when hot and binding and go for a drive with out doing much brakeing to cool them off

if no better

maybe you do have a collapsing pipe or one side of you wheel cylinder is sticking but they are new so they shouldn't do that

tend to get that when you put new shoes into a car thats stood and move the seals in the cylinder into an area previoulsy un swept since 1976 hence its a bit corrdoded

Dave

Dave999 · Post by **Dave999** » Wed Sep 04, 13 5:41 pm

heres a little ploy that might help and will keep you occupied on a summers evening

you need

1 vandals marker permenant and fat RED or Green would be good black you won't see
1 pot of nail varnish or paint (rampant fucsia or hemi ornage)
1 pot of tippex (tippex or liquid paper, don't sniff)

on each shoe

draw 3 lines one of each kind of stuff at the top end, 3 lines in the middle and 3 lines at the bottom

close together across the face of the shoe (i.e on the friction surface

the marker sinks in
the paint or varnish sinks in and sits proud
the tippex mainly sits proud

so one of them will wear away quicker than the next which will go quicker than the pen

do front and back shoe

drive for 1/2 an hour

and pull off hub

appriase the lines you drew

if you are lucky and something is left to see

this will indicate which bit of each shoe you are using

ends worn and the middle still there the shoes are of different curvature to the drums and will eventually bed in....run them out of adjustmnet or take off a bit of the depth of the friction surface at each end so the midddle actually hits the drum (wear a mask)

1 shoe nothing left the other shoe untouched indciates sticking wheel cylinder

OR

the shoe pad (flat areas where side of shoe backing rubs) on the backing plate have such a groove worn in them that the shoe isn't moving or is moving and getting stuck on the ridge and not returning

pull off shoe and file smooth the flat pads (if really bad they need welding to build up) on the backing plate. Then cover with a tiny smidge of copper slip the turned over edge of the shoe backing and the area it sits on on the backing plate that you just filed flat.

if the backing plates have been stove enammelled plastic coated or painted with thick gloopy hammerite the coating could be causing the issue. file/sand it off on the pads the copper slip will stop corrosion

do the thing with the lines of paint and pen again to see you have it working

bit of a faff but it might just work

Of course i haven't tried it...... too much like hard work

easeir to say than do.

dave

MilesnMiles · Post by **MilesnMiles** » Wed Sep 04, 13 7:59 pm

Dave, stretch and challenge

love yer work. But this evening I spent some while checking E brake release (it does) and getting my son to depress brake pedal whilst I watched various parts move. They did. At one point I thought the cross strut below the wheel cylinder wasnt returning correctly, but it was.
Got bored and wanted to drive. Did a quick 5 mile route involving just light braking to get fuel and some miles later pull into a lay by. Brakes were cool.
Did some honing, used lots of brakes around town and then they got hot. Not mental, just a bit hot to touch.
Maybe it's all new and just needs to bed in!