weird pedal feeling

[TheDeputy]

I've upgraded my valiant to front disc brakes from a volare, see http://www.forabodiesonly.com/mopar/showthread.php?t=169746&page=2

I drove it yesterday for the first time, and felt the pedal was a little spongy. I could get the brakes to lock up pretty easily, only I had to push the pedal pretty far.
I know that because my calipers are upside down it's difficult to bleed them but I'm pretty confident all the air is out.
The brake warning light for the brake pressure valve is off as well.

Could it just be the amount of fluid going into the calipers and the rear wheel cilinders that is causing this strange feeling, or just simply, air?
Oh and the MC has a 1 1/32" bore, and the rear wheel cilinders are 13/16". They are also adjusted correctly

Thanks,

Antoon

 

[TheDeputy]

Ok, today I took my valiant to the alignmentshop. Now it's easier to handle.
I also took it to work and put it on the brake tester, and guess what,

The brake deceleration is 7.6 m/s2, and it was dead straight, so I guess there is no air in the line, otherwise it would show either in left to right difference, or not enough deceleration.

Any thoughts on this?

Antoon

 

[BillGrissom]

From your other post, I notice you have manual brakes. Are you sure the rod is into the master cylinder all the way? Manuals have a rubber ring at the end, and an old piece might be jammed in acting like a spring. Also, did you use the rod that came with the master cylinder? I think some vary in length (power vs manual), so there might be some lost motion before the M.C. starts building pressure. Also, is the stand-off distance of the M.C. from the firewall the same as factory? I wonder about this since I put a 96 Breeze power M.C. on my Dart (w/ stand-off brackets) and had some lost motion until I adjusted things.

To verify no air bubbles in the calipers, you might unbolt them, place wood between the pads to hold the cylinders in and orient the bleed valve up while you bleed. Might wait until the next time you bleed since they work fine now. You probably know that you must refresh regular brake fluid every few years since it absorbs moisture. I would mention that I use DOT 5, but that sets off some FABO guys who have never tried it.

 

[rob_robinson87]

I'm not sure if my calipers are different than yours, but I was able to mount my hose (upside down) on the caliper so I could use it with the bleeder facing up. These are the F-body hoses that use the hollow bolt. I just removed the metal bracket that comes on it.

 

[TheDeputy]

I tried that as well, but somehow they just seemed too long, and they hit the frame when steering.
When I put it on the brake tester I pushed in the pedal gradually, and could see the brake forces rise gradually, with no difference in braking left to right, The hard I pushed the pedal, the more force the brakes were creating, so I don't think it's air, but just the way the brake pedal now feels.
The brake forces were exactely the same left to right, and I also don't feel it pull to one side when braking on the road.
The pushrod is the old one from the 9" drums, and the small rubber bushing holding the pushrod in place is installed properly.
I will drive my friends 65 coronet who says he has about the same pedal feeling, and see if it's just a matter of getting used to.

Antoon