Bad rear brakes

[rr70]

Hi i'm Starting to run out of ideas soon concerning My rear drums,
Before anything else is there someone who can tell me if a longer "front to rear brake line" will effect the pressure at the wheel cylinders?
The new line i got from Y1 is about 40cm (sorry i'm swedish) maybe 1,5 feet longer than the original one, probobly cause i have the prop valve on the framerail,
Anyway does this cause the bad action on My rear break shoes or do i need to look elsewhere?
Would be great help!

Linus

 

[Fran Blacker]

Should not make any difference. Are wheel cylinders frozen on inside?

 

[rr70]

Should not make any difference. Are wheel cylinders frozen on inside?

Hi no them move but maybe not enought, ive tested braking with car on stands and hardly no effekt on the wheels while braking, even thought wheel cylinder moves, really confuses me.
I'm having the drums refurbished and putting on new lining just to be sure..

 

[rr70]

Anyone else who knows if longer lines effect the pressure at the wheel?

 

[Fran Blacker]

Don't know if you can remove the rubber covers on wheel cylinders, some you can't. If you can look for rust, most brake fluid has alcohol which attracts moisture. If you a longer wheel base car the line would be longer so....

 

[Bill Monk]

The length of the line will have no effect on the brakes. Could be anything from the wheel cylinders, proportioning valve or even the master cylinder but not the line length

 

[rr70]

Don't know if you can remove the rubber covers on wheel cylinders, some you can't. If you can look for rust, most brake fluid has alcohol which attracts moisture. If you a longer wheel base car the line would be longer so....

That's true longer car longer line and same mc..
No rust the cylinder in new, and it moves

 

[Don Frelier]

It's possible that the adjuster on the bottom just needs to be spun out to make the shoes wider.
Try turning the starwheel on the adjuster to make the lower part of the shoes further apart.
Keep going until you can just barely put the drum back on. See how it works after you've done this.

 

[69a100]

How old are the rubber hose's? They have been known to collapse when pressure's applied causing problems. As said, the length of your lines doesn't matter at all. They could be a mile long and still do what they are supposed to do! Good Luck

 

[Fran Blacker]

If you have a brake spoon you can do it wheels on. Adjust until you can just hear them rub.
Link is to show you what I call a brake spoon.
https://www.lowes.com/pd/KD-Tools-A...MI2KqclpeB3AIVksJkCh3FBghLEAQYBSABEgL2xvD_BwE

 

[rr70]

The length of the line will have no effect on the brakes. Could be anything from the wheel cylinders, proportioning valve or even the master cylinder but not the line length

Ok thanks than i can move on
Bleed the mc, then the whole system again, put on the new shoes..
Cross My fingers..

 

[rr70]

It's possible that the adjuster on the bottom just needs to be spun out to make the shoes wider.
Try turning the starwheel on the adjuster to make the lower part of the shoes further apart.
Keep going until you can just barely put the drum back on. See how it works after you've done this.

Yes ive adjusted so i have slight drag, still wouldnt work

 

[Fran Blacker]

Recently had a member whose mc pushrod was to long. Would let mc come back far enough. Maybe check if all else fails. Hope another comment
s on this.

 

[Don Frelier]

Yes but I think his symptom one that one was that the brakes would drag after the engine compartment got warm.
Sounds like he has little or no pressure at the wheel cylinders.
Q. The brake pedal stays fairly high and does not slowly sink when you apply constant pressure?

 

[AR67GTX]

Make sure the drums are not turned way past their service limit diameter. It could be that you need to rebuild or replace the wheel cylinders. They aren't that much expense but may be hard to get parts over there. Also take a few minutes and test fit the linings to the drum and make sure the linings follow the same contour as the drum surface - they need to have contact over the full length. If not, the linings will need to be arced to fit or the lining material surfaced to fit the drum arc.

 

[Dragon Slayer]

Rubber brake lines do not collapse when pressurized when applying brakes. They collapse when piston returns and fluid tries to return to the MC.

Is the Proportion valve new? After Market? If it is stuck you won't get any real pressure built up.

Really need to know full set up. I assume Disc/Drum set up. Is it factory OEM type?

I know this may be hard to do, but put a pressure gauge on rear line in front of Prop. Do you get pressure? If not work way towards master cylinder. If you do, measure pressure after prop valve.

You need to find out where your loosing rear pressure. I assume your Brake warning light stays off? Does it work?

You also need to look hard at how you bleed system, including MC.

 

[Cranky]

Make sure the drums are not turned way past their service limit diameter. It could be that you need to rebuild or replace the wheel cylinders. They aren't that much expense but may be hard to get parts over there. Also take a few minutes and test fit the linings to the drum and make sure the linings follow the same contour as the drum surface - they need to have contact over the full length. If not, the linings will need to be arced to fit or the lining material surfaced to fit the drum arc.

How much would be way past their service limit? Before I swapped rear ends in my Belvedere, it had a 7 1/4 with 10x1.5 drums and would not accept a 2" drum and the 1.5" were grooved really bad. A .100" cut wouldn't clean them up but had to use the car so I cut em and then did a test. They worked fine and didn't explode plus I got em good and hot and hit em hard. Even a 1/4" cut (if they would take that) probably wouldn't be enough to expand the cylinders enough to make them not work and the MC has more then enough capacity to handle that too.

 

[khryslerkid]

How much would be way past their service limit? Before I swapped rear ends in my Belvedere, it had a 7 1/4 with 10x1.5 drums and would not accept a 2" drum and the 1.5" were grooved really bad. A .100" cut wouldn't clean them up but had to use the car so I cut em and then did a test. They worked fine and didn't explode plus I got em good and hot and hit em hard. Even a 1/4" cut (if they would take that) probably wouldn't be enough to expand the cylinders enough to make them not work and the MC has more then enough capacity to handle that too.

What happens when the drums are cut at their limit and the shoes are worn to their limit, you can have a wheel cylinder piston pop out. I've only seen it happen twice.

I think the OP should internally check the wheel cylinders for condition. They can be corroded inside and still not leak. All new components is worth the money when it comes to safe braking. They're hard enough to get stopped sometimes.

 

[Cranky]

What happens when the drums are cut at their limit and the shoes are worn to their limit, you can have a wheel cylinder piston pop out. I've only seen it happen twice.

I think the OP should internally check the wheel cylinders for condition. They can be corroded inside and still not leak. All new components is worth the money when it comes to safe braking. They're hard enough to get stopped sometimes.

I would hope that there was something else going on to cause the pistons to pop out besides the shoes and drums being worn to the their limits. I've never experienced that on a Mopar and do not have that much experience on other brands expect for Ford and can't say all that much on their engineering. On my Belvedere where my drums were .100 over, it did have new shoes and didn't notice the pistons being excessively close to their limits and I did pay attention to them.

 

[khryslerkid]

I would hope that there was something else going on to cause the pistons to pop out besides the shoes and drums being worn to the their limits. I've never experienced that on a Mopar and do not have that much experience on other brands expect for Ford and can't say all that much on their engineering. On my Belvedere where my drums were .100 over, it did have new shoes and didn't notice the pistons being excessively close to their limits and I did pay attention to them.

IIRC I've even seen backing plates that were designed to keep the pistons from coming out of the cylinder. You would have a hard time getting the rubber back enough to check for leakage.

That's the brakes!