New Brakes, Old Problem...

mikeatfhc · 01-23-2007, 09:16 AM

Ok, so I decide to repair the nearly 30 yo brake system on my 78 SC. (Street for now).

The car had a pull to the right under heavy braking. As I intend to restore the car I decided that I would rebuild the entire braking system.

In the process I decided to make it pretty as well.

So, here's what I did front and back...

1. New drilled rotors
2. new pads
3. new SS brake lines
4. rebuilt all calipers - painted red
5. new Master Cylinder - old was fine, but I wanted a NEW braking system.

I put it all together, bled the system and took it for a test yesterday.

Still pulls to the right! During the removal I found the following hard brake line (coincidentally on the right side) was bent - do you think this is the problem?

TIA.

mikeatfhc · 01-23-2007, 09:20 AM

Here's a photo of the driver's side that is undamaged. Do you suppose that the straight section of hard line before the fitting change to rubber line allows the brake fluid to 'flow' better than the damaged passengers?

Looking up the line on our host - the part is NLA. Maybe someone local to N. CA has a used available?

Rikao4 · 01-23-2007, 11:18 AM

someone who knows will correct me, given your info
I would think it should pull to the L, as that side would take before the obstructed side.
Rika

mikeatfhc · 01-23-2007, 12:09 PM

Thanks for the input...

Here is what I was thinking - that the pressure that is applied to the fluid from the brake pedal/booster that that force would be greater than the force of the caliper piston seal trying to pull back on the caliper piston, therefore the piston goes out faster than returns causing the car to pull. I can't say definitively if I noticed that the pull occurred more 'after' applying the brakes - but I think that is what I remember from my tests.

I should also point out that I repacked the front wheel bearings with Mobile 1 synthetic and replaced the front wheel seals - I noticed nothing wrong with the wheel bearings.

Mmmmm.

john d 81SC · 01-23-2007, 12:23 PM

Since it sounds like everything you've done is correct, I don't want this to sound like an off-the-wall Q, but are you certain the roadway where you tested your brakes was absolutely level? I've had my brakes seemingly pulling to the right when on roads that have a pronounced crown.

juanbenae · juanbenae's Garage

i would start with fixing the hard line. you can get hard brake line at any auto parts store, you will need to get a tube bender too and mimic the good side in reverse.

cbeers · 01-23-2007, 12:50 PM

If you want a used stock one, contact Parts Heaven, Silver Star etc.

Otherwise, the grocery cart guy has it right.

-Chris

rick-l · 01-23-2007, 01:59 PM

How about this for a guess?

If the bent tube kept the piston from retracting.... Would a hot brake pad work better than a cold one?

I'd fix the line just on GP

mikeatfhc · 01-23-2007, 08:42 PM

Road was pretty level, so I don't think road crown was it, but 5 points for originality.

Well I got ahold of Parts Haven and a used line on order... I figured I had to fix the old one anyway.

Lets see if that fixes the problem.

Thanks for all of the replys, this board is great.

mikeatfhc · 01-30-2007, 08:16 AM

Problem - 98% solved.

I replaced the hard brake line with a used one from Parts Haven. I also bought myself a gift for all of my hard work - a Motive Products Pressure Bleeder (what a marriage saver).

Under hard braking the car tracks true center - but on every now and then I get a little bit of a right hand pull, slight but there. Wierd thing is that it is random. It still seems that it occurs at the end of the braking - as the car slows to nearly a stop, that's when it pulls - tires, rims perhaps? I'll try switching the fronts and see what I get.

I haven't noticed any suspension damage so I don't think anything is bent. The car does not pull going down the road - only when braking. And again, it's either random, or so slight that I don't notice it as much after all of the brake repairs.