Thermoquiet pads heat sensitivity (Page 1/4)
Formula Owner FEB 09, 12:41 PM
Just got my Formula out for the first time in a couple of months. It needed a new battery, so I ran out and got it replaced. On that errand, I wasn't particularly impressed with my brakes, which have Thermoquiet pads. When I got home, I took a little detour, and did some hard braking from 70ish down to 20ish. Made a u-turn, and repeated. After about the 5th hard stop, the brakes really woke up. The first 4 stops... it was all I could do to get the tires to chirp, and I couldn't lock them. Somewhere around stop #5... I had more than enough to lock the wheels easily. Did I finally burn off a glazing? Or do these pads need some heat to work properly?
Gall757 FEB 09, 01:44 PM
Spider webs on the rotors? Moisture in the pads? Depending on weather, brake rotors can have rust on them in 3 days.
theogre FEB 09, 01:52 PM
Could be normal for TQ, oil/grease contamination cause glazing, or could be problems w/ calipers etc. Like rear gets too much clearance.

Any pads change performance as temp goes up.
Normal pads fade at high temp.

Did you turn old rotors? If not then new pads take longer to "bed" on old rotors.

Did you use new rotors? If yes, Did you Clean the new rotors?
New Rotors have a coat of "oil" to prevent rust and need to clean that off. I clean them w/ Dawn dish soap in the kitchen. Oil is Veg base...

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

theogre FEB 09, 02:07 PM

quote
Originally posted by Gall757:
Spider webs on the rotors? Moisture in the pads? Depending on weather, brake rotors can have rust on them in 3 days.


TQ and most others doesn't care about moisture.
Normal Rusting should not cause problems. He drove enough before testing to scrub rust off.

Spider webs on the rotors? If you mean stress cracks, the rotors are in big trouble. Get new rotors, likely pads too, and fix dragging pads.
Slotted/drilled rotors are famous for stress problems even w/o dragging pads.
Formula Owner FEB 09, 03:23 PM
I'm pretty sure that hydraulically, my system is in good working order. When I installed the pads, I did a lot of other stuff, too.
- New rotors (that were cleaned)
- New roll pins (some of the old ones were bent)
- Cleaned & re-greased the sliders
- Repaired the e-brake*

* There is a thrust washer on the back of each of the rear calipers that must be there for the e-brake system to work and adjust properly. One of mine was missing. After replacing it (and properly adjusting my cable), I had a working e-brake for the first time ever. It will even hold on a hill, now. So I'm confident that there's no excess clearance on the rear pads.

That was back in Apr, 2010, about 8000 miles ago, so I'm pretty sure that they're about as bedded as they're going to get.

Re: rotor cleaning.... I ALWAYS clean the rotors before a brake job, whether they're new, or they've been turned. I've been bitten by not doing that in the past. New rotors, as mentioned, will have something on them to prevent rust. And turned rotors will typically have greasy fingerprints. I'm almost anal about cleaning. That's one reason I don't let shops do brake jobs for me. That, and the fact that I'm the only person who will use a torque wrench on my caliper bolts and lug nuts.

When I do a brake job, I always either turn the rotors, or I replace them.

Rust on rotors.... I'm SURE that they had rust, but that goes away pretty quickly. The first 2 or 3 applications of the brake are usually quite noisy. Then they quiet down.

The moisture in the pads sounds plausible. The car sits outside in the driveway, and this was the first time it had been driven in a couple of months. The errand didn't do too much to tax the brakes until I did the hard stops. So it seems possible for the moisture to still be there after a short drive.

About 6 months after doing the above brake job, I had to do a panic stop (idiot pulled a u-turn in front of me from the lane to my right). The fronts locked, the rears didn't, and that was with all the force I could muster on the pedal. In this most recent "brake test", the brakes started out worse than they were for the panic stop, but they improved to better than they were for the panic stop.

My question was more of the "Do Thermoquiet pads behave like this normally, or is this something else?" variety. I was kinda surprised that the braking improved that much, hence my curiosity.

Thanks for the replies.
Patrick FEB 09, 03:59 PM

quote
Originally posted by Formula Owner:

After about the 5th hard stop, the brakes really woke up. The first 4 stops... it was all I could do to get the tires to chirp, and I couldn't lock them. Somewhere around stop #5... I had more than enough to lock the wheels easily. Did I finally burn off a glazing? Or do these pads need some heat to work properly?



My question to you would be... What were the brakes like the next day?
Formula Owner FEB 09, 04:07 PM

quote
Originally posted by Patrick:
My question to you would be... What were the brakes like the next day?


I haven't driven it since. It has a problem with the cooling fan, so I'm not comfortable driving it to work (in stop and go traffic). I may try it tonight.
Raydar FEB 09, 05:53 PM

quote
Originally posted by Formula Owner:
...
About 6 months after doing the above brake job, I had to do a panic stop ... The fronts locked, the rears didn't, and that was with all the force I could muster on the pedal.
...



Mine is like that. It appears to be fairly common.
http://www.fiero.nl/forum/Forum2/HTML/134638.html

I don't have thermoquiets on mine. I have stock pads on the front, and Raybestos (standard replecements) on the rear.

Edit - Having said all that... I DO have thermoquiets on my G6.
They always work well, but seem to grab better after they're warm.

------------------
Raydar
88 Formula IMSA Fastback. 4.9, NVG T550

Praise the Lowered!

[This message has been edited by Raydar (edited 02-09-2015).]

theogre FEB 10, 12:18 AM

quote
Originally posted by Formula Owner:
I had to do a panic stop (idiot pulled a u-turn in front of me from the lane to my right). The fronts locked, the rears didn't, and that was with all the force I could muster on the pedal.


This is Normal operation for most cars w/o ABS. Locking rear cause car to spin very easy and often.

Prop valve's job is to regulate max pressure to rear brakes. Most OE prop valve are set so prevent rear lockup on many dry surfaces and damp to wet pavement.
See my Cave, Combination Valve
2.5 FEB 10, 10:46 AM
Where these pads new? I always thought you had to gently break in pads, such as multiple 30mph near stops, avoid getting them hot for a while to "bed them in".