Rear brake on driver side engage TOO MUCH - 1989 Ranger

[45-70]

Hi!
Got a problem with my ol Ranger -89 4x4 2,9l V6
Rear brake on driver side locks the wheel really early. Got a fault on car inspection on this too (live in Sweden...) som I can't ride it, and I can't see anything wrong! Nothing loose, nothing that should not be there.
On a gravel road or on whet asfalt the wheel locks just when normal braking before turn or traffic light. It's a bitch! Tires screaming in town people jumping

Never had a brake that worked too well before, lol, so I don't even know what to look for. Wheel spins freely, nu gunk in assembly, everything fastened and looking all right. Adjusted the brake for more play but no difference.
Parking brake semes to engage quite even though, so I assume it's something to do with the hydraulics.
If my right brake cylinder got stuck, would all the force go in to the left instead and cause this to happen?
Any other ideas?

 

[Uncle Gump]

You sure there is no contamination on the drums/shoes? Drums look good... no hot spots?

These trucks are prone to locking the rear wheel(s). In part due to the rear of the vehicle being so light. There was a TSB that addressed water intrusion. Had you seal up any open points in the backing plate.

Very important that the park brake is not hung up too. With the park brake struts in place... the tops of the primary and secondary brake shoes must be fully seated on the backing plate anchor pin. If not... address the park brake adjustment so they do seat on the anchor pin fully.

I have a theory that having the rear brakes adjusted to loose will cause a rear brake to lock up...

Under normal drum brake operation... when you apply the brakes fluid is sent the the wheel cylinders and pushes each piston equally and pushes the primary and secondary shoes out to contact the drum. Rotation of the drum causes the drum brakes to self energize. Meaning the primary shoe will react to drum rotation and force the secondary shoe back to the anchor pin. The fluid that was holding out the secondary shoe is now displaced back onto the primary shoe wheel cylinder piston. So the theory is that the further amount of distance the shoes have to travel... the greater amount of fluid that gets displaced onto the primary shoe during self energization. Thus locking up the brakes.

I always favor the tighter side of the rear brake adjustment for this reason... and it has worked well for me for many years without locking up my rear brake(s). Once you get them adjusted... pumping the rear brake pedal several times while rolling backwards will keep them adjusted properly.

 

[superj]

it could be a stuck opposite cylinder. for sure. or a clogged line to the opposite side. does the opposite side work?

 

[Dirt Squirt]

You may also have a warped drum.

 

[45-70]

You sure there is no contamination on the drums/shoes? Drums look good... no hot spots?

These trucks are prone to locking the rear wheel(s). In part due to the rear of the vehicle being so light. There was a TSB that addressed water intrusion. Had you seal up any open points in the backing plate.

Very important that the park brake is not hung up too. With the park brake struts in place... the tops of the primary and secondary brake shoes must be fully seated on the backing plate anchor pin. If not... address the park brake adjustment so they do seat on the anchor pin fully.

I have a theory that having the rear brakes adjusted to loose will cause a rear brake to lock up...

Under normal drum brake operation... when you apply the brakes fluid is sent the the wheel cylinders and pushes each piston equally and pushes the primary and secondary shoes out to contact the drum. Rotation of the drum causes the drum brakes to self energize. Meaning the primary shoe will react to drum rotation and force the secondary shoe back to the anchor pin. The fluid that was holding out the secondary shoe is now displaced back onto the primary shoe wheel cylinder piston. So the theory is that the further amount of distance the shoes have to travel... the greater amount of fluid that gets displaced onto the primary shoe during self energization. Thus locking up the brakes.

I always favor the tighter side of the rear brake adjustment for this reason... and it has worked well for me for many years without locking up my rear brake(s). Once you get them adjusted... pumping the rear brake pedal several times while rolling backwards will keep them adjusted properly.

Can't find anything wrong with the parking brake. No hang ups. No water intrusion problem. Don't se anything out of alignment at all...
I'll try adjusting brake pads tighter.

it could be a stuck opposite cylinder. for sure. or a clogged line to the opposite side. does the opposite side work?

It does, yes, but not very good.
Test result was 1,4 rear left and 0,4 rear right. The numbers might not tell you anything, lol, but the ratio is pretty clear. Thought that if one cylinder don't take all the fluid, the other ought to get it instead

I'd like to have 1,0 and 1,0 on the test...

 

[45-70]

You may also have a warped drum.

Don't think so. No pulsing. But I'll change sides on the drums and see if it makes a difference

 

[superj]

when i had rear brakes working to well in previous vehicles, it was the distribution block working incorrectly by the master cylinder.

 

[Uncle Gump]

I'm no hydraulics expert. But the fluid is sent in all directions equally... if one cylinder is frozen... it won't divert that pressure onto the opposing cylinder. At least that's what my non expert self believes.

 

[Uncle Gump]

when i had rear brakes working to well in previous vehicles, it was the distribution block working incorrectly by the master cylinder.

That will cause both drums to lock up. at least it should.

 

[pjtoledo]

pull the rubber end caps back on the wheel cylinders and inspect for movement & rust.

while the drums are off, depress the brakes slightly to lift the tops of the shoes away from the anchor pin about 4-6mm, then bang on the shoes one at a time
to shift them left then right. does everything move freely in both directions?

 

[superj]

I'm no hydraulics expert. But the fluid is sent in all directions equally... if one cylinder is frozen... it won't divert that pressure onto the opposing cylinder. At least that's what my non expert self believes.

you are correct. it will indeed equally go to all points.

 

[pjtoledo]

another trick I do is to mark the shoes with a magic marker then spin the drums, remove and look where the contact areas are.

 

[45-70]

+1 for Uncle Gump's theory on slack calibration causing locking brake!
I tightende it up really well (can't get the f-n drum of again LOL) and the brakes are looking very good!
Back still locks before front, but evenly now and way later!
I'll get back to you after next inspections when I get the new results

Thank's allot everyone! This forum i f-n great! Thank you god for internet...

 

[pjtoledo]

+1 for Uncle Gump's theory on slack calibration causing locking brake!
I tightende it up really well (can't get the f-n drum of again LOL) and the brakes are looking very good!
Back still locks before front, but evenly now and way later!
I'll get back to you after next inspections when I get the new results

Thank's allot everyone! This forum i f-n great! Thank you god for internet...

well, sometimes the internet is good

 

[45-70]

I'm no hydraulics expert. But the fluid is sent in all directions equally... if one cylinder is frozen... it won't divert that pressure onto the opposing cylinder. At least that's what my non expert self believes.

About that... Isn't the pressure directed like 60/40 front/back? Shouldn't that mean over preassure from the front can't leak to the back at least?
I'd like to adjust them to more like 70/30 i fact. Just cus it is so light in the back. Gets really sketchy on the as it is (which we got a lot of half the year up here...)