Technical Odd brake issue.

[Marx]

Hello everyone, new member here. Rhd 1972 Fiat 500 L with abarth "bits".
We have an odd issue i wonder if we could get some more ideas on please
Our brakes have been pulling sharply to the left on hard braking. Normal braking the car stops fine in a straight line. This should mean the right hand side is not braking properly so we have changed the cylinders,drums, shoes and flexible hoses on both sides and bled and bled the system. The problem remains.....We have clamped off both rear brake hoses and had a quick drive to see if it is the front or rear that is actually causing the issue and the problem still remains. So the issue is definitely at the front? Either right front brake not working properly or the front right doing something odd.....does anyone have any ideas what we can check now to sort this out? Our tracking seems correct and after changing everything we can think of we still have the issue. Many thanks.

 

[the green vanper]

Hello,

Might be that obvious you have not thought to write about it:

are both front tires same, in good shape and with correct pressure?

 

[Marx]

Hello,

Might be that obvious you have not thought to write about it:

are both front tires same, in good shape and with correct pressure?

Thank you for the reply, yes they are and we have even tried swapping wheels over.

 

[timmycm850]

Can I ask please if you have changed the brake shoes as a set and they are not getting contaminated with fluid.

Tim

 

[the green vanper]

I'd say to compare the braking fluid flow through the pump and the hoses (left to right). Might be one side is clogged somewhere. The car is more than 50 years old, I know you've changed the rubber hoses, but there are still the steel ones.

 

[Marx]

Can I ask please if you have changed the brake shoes as a set and they are not getting contaminated with fluid.

Tim

Thsnk you for yhe reply, Yes we have, we had this issue and have now changed everything we can think of and we still have the issue. The right front wheel is locking under heavy braking. We have an imbalance but can't find why.

 

[Marx]

I'd say to compare the braking fluid flow through the pump and the hoses (left to right). Might be one side is clogged somewhere. The car is more than 50 years old, I know you've changed the rubber hoses, but there are still the steel ones.

Thank you, we seem to have good flow through both, next step may be to changed the solid pipes and then the master cylinder? We are locking up the front right wheel, I should have mentioned that.

 

[timmycm850]

Hi. Some of the modern brake shoes have different material on the self adjusters so the don't always holding optimum position. The left front ones may be sliding backwards and forwards when in use. Check that ideally

 

[Marx]

Hi. Some of the modern brake shoes have different material on the self adjusters so the don't always holding optimum position. The left front ones may be sliding backwards and forwards when in use. Check that ideally

Thank you, we bought all four fronts at the same time, from same supplier and these were bought ti replace the previous set when we already had the issue. Someone has mentioned the posts they attach to as a possible cause? Possibility?

 

[timmycm850]

Alternatively you have corner weights of the car being significantly different.

If your car is lhd then

Put two passengers on the side of the locking brake And see if it's different. Front suspension bushes could be clamped up understrain or a weak rear spring on one side could change things.

Tim

 

[Marx]

Alternatively you have corner weights of the car being significantly different.

If your car is lhd then

Put two passengers on the side of the locking brake And see if it's different. Front suspension bushes could be clamped up understrain or a weak rear spring on one side could change things.

Tim

Thank you, we have rhd car. By front suspension bushes do you mean where the bolt goes through the bottom of the hub into the spring?.

 

[timmycm850]

All the suspension bolts on the front can have an effect

 

[Marx]

All the suspension bolts on the front can have an effect

Thank you.

 

[timmycm850]

When you jack the car up at the front( using the jack ponit below the front panel, does one side front wheel lift off the ground first.

 

[Marx]

When you jack the car up at the front( using the jack ponit below the front panel, does one side front wheel lift off the ground first.

I dont trust that area but lifting the front via the centre of the spring does lift one side first slightly, can't remember which side....will check later.

 

[Marx]

When you jack the car up at the front( using the jack ponit below the front panel, does one side front wheel lift off the ground first.

Hi, just checked left hand side lifts off the ground about 15mm before right hand side. Brake locks up on left. Does this point to anything? Thanks.

 

[timmycm850]

Maybe less contact with the ground. You only got about 120kg on each front wheel at 125mm wide. Look through the back window and compare it to the front window and see if they line up( twisted body ). See if the rear springs support the rear of the car equally.

 

[Marx]

Maybe less contact with the ground. You only got about 120kg on each front wheel at 125mm wide. Look through the back window and compare it to the front window and see if they line up( twisted body ). See if the rear springs support the rear of the car equally.

Thank for the reply Tim, the front window lines up perfectly. Rear height....we have half an inch (about 10mm) difference left to right at the rear drivers side taller(rhd car). Have doubled checked the fronts too, both exactly the same height from bottom of wheel to arch, and floor to arch. But with one person only in car (right hand side) car still pulls and I assume rear suspension height would be closer to level as it is higher in drivers side with no one in it?

 

[Marx]

Thank for the reply Tim, the front window lines up perfectly. Rear height....we have half an inch (about 10mm) difference left to right at the rear drivers side taller(rhd car). Have doubled checked the fronts too, both exactly the same height from bottom of wheel to arch, and floor to arch. But with one person only in car (right hand side) car still pulls and I assume rear suspension height would be closer to level as it is higher in drivers side with no one in it?

I suppose we could swap rear springs over and see if it changes anything....we also have complete old front stub axles we could fit on one side temporarily to see if that makes any difference....? Quite a lot of work though.

 

[timmycm850]

So rhd rides higher, also lifts of the ground first so I suspect passenger rear spring is weaker. Removing rear sprigs and swapping is easier than the front upright.