Brakes, Brakes and more Brakes

Bertone · #1 (**permalink**) 07-02-2005, 01:10 PM

Well guys. It has been over a year and am still working on my 72 GTV. It all started with papa sending me a copy of the wiring diagram. One thing led to another and pretty soon everything was new. The brakes. I changed my disks, bearings, pads, rebuilt and painted the calipers. When all was done my master cylinder leaked. After realising that the PO had replaced the Ate with another brand I got a new original Ate. No matter how much I bled the system my brake pedal still goes all the way down to the floor. I test drove the car and I noticed that I have grip in the rear brakes but nothing up front. Any Ideas. PS how critical is the setting of the angle of the front brake pistons cutout. I do not have the tool for it I am guestimating. Could that be the problem?
Regards to all

Bill77 · #2 (**permalink**) 07-02-2005, 02:43 PM

Quote:

Originally Posted by Bertone

Well guys. It has been over a year and am still working on my 72 GTV.

series1gtv · #3 (**permalink**) 07-02-2005, 02:45 PM

How did you bleed the brakes? You should start at the caliper furthest away and work your way in. The order should be passenger side rear, then drivers side rear, passenger side front, and drivers side front. I have just replaced my MC and used a power bleeder. Even with the power bleeder it took three or four bleeding sessions to get all the air out of the lines. I would try this first if you don't have a power bleeder you can probably borrow one from yr local club or order one from IAP they're around $40 if I remember right. I have had mine for about a year and it has paid for itself many times over. Another thing you might want to try if you get most of the air out after multiple bleeding sessions but can't get that last little bit. Stick something between the brake pedal and the base of the front seat (I used a piece of two by four). Basically you are trying to push the pedal all the way down. Then leave the car overnight and the next morning that little bit of spongyness should be gone.
Good luck
Jeff

**rogerspeed** · #4 (**permalink**) 07-02-2005, 04:13 PM

Two ideas: are the front calipers installed correctly? are the bleed screws up! if you have interchanged the calipers the bleed screws will be pointed down, you'll have trapped air. If that is correct check the flex lines, they can expand if old, diminishing brake performance. Braided steel flex lines are superior, but first diagnose the lack of brakes. Hope this helps, rk

**tubut** · #5 (**permalink**) 07-02-2005, 05:41 PM

Bertone, a couple of questions:

#1: Does the brake pedal feel hard? Spongy?

#2: If you quickly and repeatedly pump the pedal, does the pedal come up?

#3: Could it be that the previous owner not only changed the brake master cylinder but also the front calipers? Should this be the case, you may have a mismatch between the volume of brake fluid the calipers require to activate the brakes and the amount the master cylinder can provide.

60sRacer · #6 (**permalink**) 07-03-2005, 03:19 PM

Did you replace the brake fluid with new DOT 4 stuff? This is made for silicone seals, and causes older rubber seals to turn rock hard. And stop sealing. I had this happen to my Dueto when I rebuilt the master cyl and brakes - all new parts. In two days the seals failed and I had no brakes. Since you have some rear brakes (car after 69?) you probably have dual circuits with the front circuit failed. Use DOT 3 brake fluid only if your seal kit is OEM with rubber seals.

BTW - it also affects the seals in the discs. They may also need replacing. (rebuild kit).

Robert

Bertone · #7 (**permalink**) 07-03-2005, 03:20 PM

Thanks to all, I'll try to answer to most of the questions.
1- The brake pedal feels extremely spongy. After pumping a few times it only gets little harder.
2- I have St. Steel braided lines installed so that eliminates the old brake lines.
3- I am not sure but I don't think the calipers have been changed when the previous PO changed the master Cylinder. Though I cannot confirm this 100%
4- Most importantly my bleeder screws are at the bottom. Did I mess up Royally?

What about the piston angles as mentionned in manuals does that have a major affect ?

Thanks again

Bertone · #8 (**permalink**) 07-03-2005, 03:26 PM

I think I did mess up ROYALLY with the bleeder screws. Will reverse them next week

Alex · #9 (**permalink**) 07-03-2005, 07:18 PM

I use Dot 5 silicone brake fluid for its anti-hygroscopic properties. I've never had any problems with my seals. How is Dot 4 different?

**tubut** · #10 (**permalink**) 07-03-2005, 07:43 PM

Quote:

Originally Posted by Alex

Most importantly my bleeder screws are at the bottom. Did I mess up Royally?

**papajam** · #11 (**permalink**) 07-03-2005, 08:09 PM

Quote:

Originally Posted by Bertone

What about the piston angles as mentionned in manuals does that have a major affect ?

enormous sage · #12 (**permalink**) 07-04-2005, 05:41 AM

Quote:

Originally Posted by Bertone

I think I did mess up ROYALLY with the bleeder screws. Will reverse them next week

60sRacer · #13 (**permalink**) 07-04-2005, 08:17 AM

Pat Braden's book has an exact pattern for the piston alignment guage. Just xerox and cut out of aluminium.

Robert

**papajam** · #14 (**permalink**) 07-04-2005, 07:48 PM

Pic of the brakepad spreading tool. To turn the pistons, put the ears of the tool into the piston, tighten the screw to lock the tool into the piston and rotate.

Bertone · #15 (**permalink**) 07-06-2005, 11:39 AM

Hi Guys,
How important is the angle at which the cutout is set. Rotating the piston might be simple enough but I suppose the angle at which it is set is the important part. As for Pat Braden's book he mentions 2 tools on page 256. The A20160 for the front and A20149 for the rear. The template on the page is for the rear. How is it different than the one for the front?