Brakes...Still...I give up!!

midnight sun · June 08, 2006, 07:37:42 PM

Yeah I know weve discussed this about 10 times and I still aint got it figured out.

Bottom Line, Soft Pedal. Have to push mightily to stop the Model A. It wiill stop but I definitely would be in troubel if I had to do it quickly. It has been this way since day one and Ive driven it about 3,000 miles but I would like to figure out what is wrong. Booster is below the floorboard. Its a 7" with a 1" dual M/C. 2lb front and 10 lb rear residual valves and an adjustable proportional valve in the rear line.

I have read and reread and reread all of the previous posts on braking. I plugged off both outlets on the M/C and got a good hard pedal. I then reattached the front line to the M/C and left the rear portion plugged off. Soft pedal. I then reattached the rear line land plugged off the front outlet and got a good hard pedal. Okay so I surmise that the problem is somewhere in the front system (disc). I unhooked the line just before it goes into the thru frame fitting where it proceeds to both calipers. Hard pedal. Plugged off the right side. Soft pedal. Plugged off the left side. Soft pedal. So its in the calipers, right? I removed the calipers, and caliper mounts and tried different combinations to see if I could get the bleeder valve any more upright. No good. I cant figure out anything else to do. Im sure its in the calipers somewhere but they are not leaking anywhere so Im out of ideas.

Re-bled everything about 10 times and of course I have the same soft pedal I had before. I am at a loss and like everyone else that has to go through this crap, sick of messing with it.

Yeah I know WAAH.

enjenjo · June 08, 2006, 08:13:58 PM

Wilwood residual valves?

C9 · June 08, 2006, 09:57:34 PM

I'll go along with Enjenjo on the Wilwod residual valves.

How would it work for you if you unbolted the calipers and rolled them around the rotor so the bleeder screws are at the very top?

One at a time for sure, but I think this would allow you to bleed the calipers like they should be.

Another way out would be to put a spacer block in between the pads while the calipers are hanging off to the side.
The spacer block the same thickness as the rotors so the pads will have something to bottom out on.

It sure looks like air in the calipers from here.

Dumb question and I'm sure you've thought about it, do you have the calipers switched from side to side and that's what's keeping the bleeder screws from being at the top?

Ar you using Silicon brake fluid?
It can be difficult to get a hard pedal with it.

SKR8PN · June 08, 2006, 10:17:23 PM

Is this a soft pedal while you are DRIVING, or when you just fire it up and hit the pedal?

??
I gotta think "air in the lines" as well............

midnight sun · June 08, 2006, 10:53:35 PM

Quote from: "enjenjo"Wilwood residual valves?

Yeah they are Frank and I would have suspected that but where I took the line off up front and then plugged it off was on the other side of the valve and I would assume that if it were defective I would not have been able to get a hard pedal. Is that a bad assumption?

No silicone Jay. Ill take another look regarding switching the calipers. I looked at that today but it was toward the end and I was getting a little frustrated and sometimes you start missing things when that happens. I actually thought about your suggestion regarding a spacer too. Im gonna make one up tomorrow and try that. Also Ill post a picture of the calipers. In my humble opinion, there is only one way the bleeder can be at the top which is the way they currently are.

I definitely agree that there is air somewhere and everything points to the calipers but from there Im stumped.

The soft pedal is present all the time. I could tell a huge difference when I blocked off the front line. Pedal only went down about 3/4 to 1". Usually it goes down about 2 to 2 1/2".

Bruce Dorsi · June 08, 2006, 11:23:06 PM

Quote from: "midnight sun"
In my humble opinion, there is only one way the bleeder can be at the top which is the way they currently are.

I definitely agree that there is air somewhere and everything points to the calipers but from there Im stumped.

Jack:

(1) Does a second pump give you a hard pedal, or does it remain soft?

....From my experience with the crappy 2# Wilwood rpv's, a second pump of the pedal will build a firm pedal.

(2) Although everyone advises that the bleeder screw should be at the top of the caliper, there are some calipers that will trap air, if they are installed that way.

I know this may sound irrational, but there was a picture on the web showing that the bleed screw could be below the top of the caliper, as long as the PORT leading from the caliper bore to the bleed screw is at the top (highest point) of the caliper bore.

I think the picture was in the technical info of Master Power Brake's website, but I could not find it tonight.

I don't know if the calipers you are using fall into this category.

enjenjo · June 08, 2006, 11:25:17 PM

Bad assumption. The front valve is defective. There are two ways to tell, first, when the front brake calipers are out of the picture, the pedal is hard. Number two, ALL Wilwood 2 psi valves are defective. If anyone had a 2 psi Wilwood valve, and there is no problem, then they didn't need it in the first place.

EMSjunkie · June 09, 2006, 12:26:56 AM

Quote from: "enjenjo"ALL Wilwood 2 psi valves are defective. If anyone had a 2 psi Wilwood valve, and there is no problem, then they didn't need it in the first place.

That suprises me, I thought WilWood was one of the big players in brake componets.

I have 2# WillWood residual valves front and back on my Coupe. the pedal isn't as hard as I'd like, but it stops pretty well. but my master cyl is mounted on the firewall. I guess I really didn't need the RPV's, but I figgered better safe than sorry. :?

Vance

BFS57 · June 09, 2006, 10:58:11 AM

Hello;
You know, this issue hits home with me too! My '32 has a "mushier" than I would like pedal. Now, when I start the car, I "pump" The pedal a couple times and I get a "better" pedal (still not great). I have the residual valves as this set up is in the frame. However, On my '57 Chevy, I have a firewall mounted booster and master with only an adjustable valve to the rear drum brakes and that set up is Strong enough to throw you through the windshield, if needed!
OK, If I go on the assumption that the 2 lb residual is "bad" what would be the alternative for this solution? As I believe it is stated that all residual valves from Wildwood are bad! Who else makes these? Or do we really need these like it has been stressed for proper breaking?
I do know that if you adjust the rear brake shoes, it can play a large part in break pedal being firmer!
Another thing is that there is adjustment between the master and booster that can take up slack! I know it doesn't take much adjusting but it can be adjusted. Just take off the master and the rod from the booster should be able to be "screwed" out to make the contact between the master and booster more sensitive but be careful as a very little adjustment goes a vary long way!

Bruce

kb426 · June 09, 2006, 12:51:38 PM

I'm in agreement that Wilwood isn't the best. I've had problems with their calipers and master cylinder on dragsters.

sirstude · June 09, 2006, 01:33:49 PM

It is some work, but the best solution, imo, is to mount a remote filler to the master cylinder higher than the brake calipers and then forget the residual valve to the calipers. I have done this on several cars over the years, now there are kits out there to do this, and never had soft brakes. We corrected my friends 41 Chevy with the same problem that way. I know we don't like anything on our firewalls, the the design of calipers was not to use residual valves. I don't know of any disk brake car that comes from the factory with low mount master cylinders. I am going so far on the Olds that I have gone to firewall mount brake pedal.

Just my 2cents worth.

Doug

model a vette · June 09, 2006, 03:24:46 PM

ECI makes valves that work.

Mikej · June 09, 2006, 03:46:26 PM

It could be the front flexible lines. If the residual valve was bad you should be able to pump the pedal a couple of times and get better brakes. It would just be letting the piston retract to far. I have vet rear brakes and I had a hard time bleeding them until I figured out they have to ports per side.... :oops: Do you get a little air every time you bleed the brakes?

midnight sun · June 09, 2006, 04:55:58 PM

Quote from: "enjenjo"Bad assumption. The front valve is defective. There are two ways to tell, first, when the front brake calipers are out of the picture, the pedal is hard. Number two, ALL Wilwood 2 psi valves are defective. If anyone had a 2 psi Wilwood valve, and there is no problem, then they didn't need it in the first place.

Okay. Ill change it out tomorrow. I have some residual valves from Stainless Steel Corp that I bought for the 47. Also here are a couple of pictures of how the calipers are mounted.

Leon · June 10, 2006, 12:21:54 AM

I would imagine the bleed hole goes in a straight line as the bleeder till it intersects the piston bore. That would put it below the highest point the way you have them mounted on your car. You might be trapping air, I'd look into where the bleed hole passage goes. It can be seen if you take the bleed screw out, or worse case pop the piston out and see where it is for sure.