Need more brake help for Wilwoods

[jhaynie]

Ok, I'll try to not get too wordy while still describing the situation:

Problem: Unsatisfactory braking performance in Unique with Wilwoods.

1. I bled all four calipers, no air detectable, fluid is clean.

2. When bleeding front calipers, pedal goes full stroke from return nearly to floor, lots of fluid flushed through. Rear rod disconnected.

3. When bleeding rear, pedal has very short stroke (no more than an inch or two) but good fluid flow. Front rod disconnected.

Tried several adjustments on balance bar with similar brake performance. I don't think thats a problem.

Adjusted length of push rod on either master cylinder with no effect (except now the brake pedal is sitting at an angle). I am going to undo that tomorrow.

Running out of options. I was wondering if pedal on front going to floor with little effort is indicative of some problem with the master cylinder and/or calipers. If there was a mechanic in my area I felt comfortable taking my car to I would do it in a minute. Braking performance after above attempts is still basically the same.

[mrmustang]

Perhaps you need an inline presssure "plug".....Wilwood makes them, they come in 5lb, and 10lb units and get plumbed inline with your brake line......Also, as with most Wilwood brake setups, your going to get a soft almost spongy feeling until the brakes actually warm up........This will be dependant on which composition pad your using.....


Bill S.

[Bob Putnam]

Jhaynie,

Brevity is nice, but just what is "unsatisfactory"? Bad balance? Soft pedal? Hard pedal but poor braking?

[Shell Valley]

Which calipers are you using and are you also using Wilwood rotors?, Wilwood master cylinders?

Dana

[Dirt Cowboy]

If you have the front rod going to the floor, with the bleeders closed, you have a bad master cylinder, the seals are shot. Rebuild it or change it out.

Bill, why would Wilwoods have a soft spongy feel until they warm up? If your brakes are soft and spongy, you have air or water in the system, period. If you are using metallic or ceramic pads, you won't have much braking until they reach temperature, but they still don't feel soft or spongy. Regardless of the manufacturer of your particular braking system, soft and spongy denotes air or water in the line. Replace the fluid with a high quality fluid, not the Pep Boyz discount brand. I've used Wilwoods for years and for the money, they are hard to beat.

[jhaynie]

Bob,

Very poor braking. It gets scary when people pull out in front of you. The pedal is very hard also. You get about an inch or two of travel and have to really lean on it to get the car to stop. No nose dive when braking and you cannot lock them up.

Dirt,

I was thinking a bad master cylinder on the front also. If I spin the wheels although, and apply the brakes, the wheels to stick. Does that mean that the master cylinder is working, or would you still get some brake pressure even with a bad MC?
What about the rear cylinder? It doesn't move hardly at all (no pedal).

John

[jhaynie]

Oh,

And this is the standard Unique setup with no modifications. If that answers any questions about rotors/calipers/pads etc.

John

[coyled]

I wonder if your pads are not seated in yet or if you have way too hard of a compound pad. The pads won't work properly until they have been seated and a race type pad will not work until it is hot. What pads are you running? What size masters are you running for the front and rear? scott

[rdorman]

Perhaps one of the most misunderstood parts of our braking system. Problems like you are describing can be many, many things. But I think you should check this one first.

You spoke about the rear travel only being a inch or two. Be sure that the piston can FULLY retract in the master cylinder with the peddle released. It sounds as though yours may not be doing this. I don't know what peddle assembly you have but if you have the type where the balance bar is inside a tube then you must be sure that the bar does not bind in the tube when pressure is applied to the brakes.

Either way, the bar must never bind, it needs to always be free to move. Plus the push rod angle should never exceed 5 degrees. Does you peddle go past 'center' when you push it? It shouldn't.

As a note, most manual disc system are designed to have maximum braking with 75 to 100 pounds of force applied to the peddle. For those of us used to power brakes, 100 pounds is a LOT. Put a bath scale up against a wall and press on it until you hit 100 pounds. You will see!

Measure the pressure at each caliper and make sure there is no problem there. You can do the math to see if it about right. Keep up with the bleeding, it can be very trying.

You are not running taller tires than recommended are you?

If all else fails and the brakes are functioning correctly but you are still not happy, you can go to a higher CF pad. Just be aware that many don't get to maximum CF until warm. However, there cold torque could still be above that of the 'cold stopper' type pad.

As in the case of Polymatrix T vs A pads. The T pads are know as the 'cold stopper' where the A pad is considered a race compound that does not work until hot.

BUT, this is a big but The T compound has a CF of .40 at 100 degrees (cold) and the A compound is .55 at 100 degrees F.!!!! What is often said about race compounds not working at cold tempeture is sort of true. The fact is that they don't work as well. The A compound CF will raise to .7 when hot (one hard stop is enough). The difference between .55 and .7 is huge. If the brake system was designed for .55 and you heat them up to .7 then you end up with a system that will lock up easier and you will have to carefully modulate your braking pressure. If you design the system for .7 and you have a .55 pad cold, you are not going to stop at the full potention of the car until the pads come up to temperature. Hence the saying about race pads not working until hot even though technically they often work better than softer compounds when cold!

Phew!

Happy trial braking!

Rick

[Mr.Fixit]

Maybe the master cylinder's bores are too big, so they need way more pedal effort than you can apply.

[rdorman]

I was going on the assumption that the system is as engineered by Unique and Wilwood. But depending on use of the car, and personal factors, they may not be right for you.

As Mr. Fixit mentioned, smaller cylinders would reduce peddle effort at the expense of increased travel. Higher CF pads will reduce peddle effort but at no cost in travel. Although there could be other costs!

Check the balance bar. Have a pro bleed them and check the pressures at the calipers and go from there. Just my 2 bucks worth

Rick

[jhaynie]

I called Alan Weaver and until talking to him didn't realize that the Wilwood caliper had a bleeder on the inboard side of the caliper . I guess I better try that first. Alan said he has no problems with the standard setup. The pedal drops like there is air in the system, it still returns, there is just no pressure built up. As I put it to him, when you apply the brakes it feels more like an anchor was dropped off the back of the car and it just drags to a stop. No nose dive whatever.
Back on the jacks it is! Boy I feel like a dumba$$.

John

[rdorman]

All of us 'experts' forgot to mention the two (actually four) bleeders per caliper!

Rick