ERA / Wilwood brake noise

ERA Chas · #1 (**permalink**) 10-10-2003, 02:20 PM

Bob'
The PROBLEM[S]; 1. Loud squealing noise on heavy and repeated brake application from front Wilwoods. 2. Light rotor contact of rear pads.
The SET-UP; ERA 12.18" Wilwood kit with Sierra 31YF-"soft pads" [what the box said], purchased 9/2001. Installed on chassis #112. Tilton masters already in place. Jag. rear modified ventilated rotor kit with bridged calipers from Mike Bontoft.
The STORY; Front Wilwood noise occurs during 120-30 mph applications [end of drag strip], or heavy, repeated stops to 0 mph from highway speeds. No noise during regular street or highway use. Also, it stops quite well, but seldom locks a front and NEVER locks the rear. I've inspected and found no rotor grooves, scuffs or other marks. The pads also show no blemishes. I swapped pads outboard to inboard [inverting them] on each side and applied disc brake lube to pad backs and piston edges. [thin coat] Also chamfered pad edges. Noise continues. Rotors are centered in pads as assembled by Doug, and make full contact with pad surfaces. The separate problem in the rear is that they don't appear to be doing much work. The rotors are barely scuffed and still show cross-hatch marks from machining, quite clearly. I've adjusted as much rear bias at pedal linkage, following your "washer stack" procedure, as possible.
Could each problem, though different, be caused by wrong pad compounds at each end of car? I don't know which pads Mike sent with the rear, but he told me they are "street type" pads.
HELP and THANKS.

Bob Putnam · #2 (**permalink**) 10-11-2003, 06:25 AM

I don't know what pads Concours West supplies, but we've found that Girling makes the only rear pads that don't squeal. They may also have a different coefficient of friction. The Girling pads are hard to find - we must get them directly from England for our rears.

I hope that you've moved the spacers from the inside to the outside of the pedal pivot...

ERA Chas · #3 (**permalink**) 10-11-2003, 07:46 AM

Bob
Yes that's correct, spacers to the outside of pivot. That's why I'm stumped about the lack of bite back there. Sorry if I confused you but the squealing noise is from the FRONT, Wilwoods. Any ideas about that problem? I just have two different things going on at the same time. Noise in front and lack of bite in rear.

Bob Putnam · #4 (**permalink**) 10-14-2003, 04:51 AM

Chas,

I don't think that there's much you can do about the front brake noise. These are essentially racing brakes. You can try another pad material, but we've found that the ones we supply are the best compromise for the street. I think Carbon Metallic and Wilwood make pads that will fit too.

In the rear, you can try the Girling pads. They may have a different coefficient of friction than yours.

rdorman · #5 (**permalink**) 10-14-2003, 06:45 AM

Make sure that the caliper is perfectly square to the rotor. Make sure that the pads do not have taper. Make sure that the rotor run out is within spec. If these are all correct, they generally will not squel. Mine sure don't, ever. We are talking about less than .003". .000" is best but unlikely. I have used Wilwood T, D and J(BIG dust) compounds all with out a hint of squel. I also sounds as though you may be getting out of the temperature range that your front pads where designed for. Do you notice any signs of fade? Think about when they are squeling and you will know why I ask!

If you can not get the front and rear to lock by adjusting the balance bar, then most likely your inherent balance is off or the balance bar is binding or you have a failure some where. A pressure gauge is a big help here. Balance is affected by pads cf, rotor size, pistons sizes (caliper and master cylinders) and even tires and compounds.

I use EBC pads on my girling calipers in the rear. Really like them.

Last but not least, Bob is the expert here!

Rick

ERA Chas · #6 (**permalink**) 10-15-2003, 12:16 PM

Thanks to Bob and Rick.
Bob, I think the Wilwood/Sierra front pads that you supply are probably fine. Possibly they're a liittle too cool on the street as they bite really well when hot. Yes Rick, I checked run out and pad taper and found 001-003 at most, as you suggest. Also ,no bind in linkage and I adjusted as ERA procedure recommends. Don't suspect a failure in the system as it stops like hell , repeatably, when up to temps. Sorry to be a sour sister but I'm starting to think I'll have to live with noise as Bob suggests. The problem is just not responding to all this investigation. No obvious faults. EBC's are a good tip as I have used them on my Audi and Passat and also like them. I didn't know about the Girling application so I may look into that for the rears. Thanks again.

rdorman · #7 (**permalink**) 10-15-2003, 01:08 PM

Siera had no useful information on their site about their pads so I sent them an email.

Did you check that the pistons them selves are square to the rotor face?

If all this doesn't work, you just have noisy pads!

I am assuming you have Wilwood calipers correct?

Here is some info from EBC on the subject:
http://www.ebcbrakesuk.com/catalogue...4_jan_2001.pdf

The rear calipers, those are the standard two piston girlings that have been split and bridged for the thicker rotors? If so I think the EBC part #s will be DP2101/3101/4101 (green, red, yellow) 80x66x15mm pad.

Rick

ERA Chas · #8 (**permalink**) 10-15-2003, 04:42 PM

Rick,
Very, very kind of you to delve into my problem with so much effort and experience. Yes, pistons are true in bores and yes,they are Wilwood Superlite II's. Affirmative on the split rear Girlings and ventilated rotors. Thanks too for the website work and especially the part nos. Very valuable to me and I'll definitely investigate. Hope I'm NOT stuck with noisy pads after all this, but I'm becoming afraid you and Bob are right! Again, many thanks.

rdorman · #9 (**permalink**) 10-23-2003, 06:31 AM

Well after eight days and a couple of email I finally received a response from Sierra. I asked them for the coeficient of friction and temperature range of their pad compounds. Preferably a graph compairing the two on X,Y axis.

The response was all but useless. They stated that they do not have that information but they have documented caliper temps of up to 600 and rotor temps of up to 1050.

Sooooooooo, any pad change you make will be a bit of a shot in the dark because we have no idea what the properties of what you are running are!

That is one thing I like about Wilwood. Unlike most pad manufacturers they have all the information right there, readily available. That is SUCH a big help when it comes to brake design, tuning and problem determination. It is also a primary factor in why I am going all Wilwood.

You would think that pad manufacturers would have this information available wouldn't you? Are they saying that they have never run their pads on a brake dyno as part of their R&D? Are they hiding something? Lazy? Blows my mind. Would we buy a camshaft, tires, safety equipement based solely on '...we make good stuff......'

I think NOT!

By the way, the pads could just be glazed, that causes sqeal.

I have a set of 'J' compound Wilwoods pads if you need them. CF averages .58, stop cold or hot (actually a lot better cold than the 'cold' stopper pads), good for over 1300 degrees. These are racing pads. Dusty as he!! and unless you are running them hot, 'rapid' wear. Part 15J-7222K.

Rick

ERA Chas · #10 (**permalink**) 10-23-2003, 03:52 PM

Rick,
I christen thee the R&D chief of Columbus Ohio! You have the patience of a saint. Hate to keep nixing you , but I've de-glazed the pads twice [and they weren't glazed!] , to no good effect. They stilled yelled. I've tried everything my feeble brain eeked-out to no avail. I'm most likely going to Wilwood stuff in the near future, however I'm first going to try some "secret stuff" I just found and bought. If it works, it will be salvation to squealers EVERYWHERE. I promise I'll let you know as soon as I have the result. Sorry for the mystery for now but we can have some fun for a little while. As always, THANKS.