SUB TOPIC - ROTOR WARPING

88coupe, you said rotor warping was likely due to peoples driving habits... I beleive that entirely... But my dad has always maintained that rotor warping's #1 cause was not torquing your wheel nuts evenly. All the guys at my work make fun of me for beleiving it, but I can see that also!

What do you think, has his belief got any ground to stand on?

Yeah, i heard that too. In particular, my wife used to drive an '89 Crown Vic that had a bad disc. The guy across the street owns 3 crown vics, always buys them. He said the Ford dealer verified what you said about torque procedures on them. Another friend of mine that teaches Votech auto class also knows about this. 88 coupe, about driving habits and brake wear. I agree, my daily driver is the '76 Omega, not a performance car by any means, more of a "pony car" wannabe. Anyway, it has discs in the front and drums in the back, and my '69 Delta has four corner drums, i always leave lots of room between my front bumper and the car in front of me. Brake longevity is very high in both of those vehicles.

Hi 88delta88, all


Since my wheels are always done correctly, and I've never seen a warped rotor, I can only speculate.

I think it's possible, but the design and construction of any rotor I've seen would (in my opinion) make it unlikely.
I do know that specs must be followed religiously with many aftermarket wheels.

I anyone has a chance, check out one of your rotors and see if you can see how excess torque might cause warpage. I'm curious what those with the newer cars might find.

In the meantime I'm expecting Stroker to check in with some real facts.

Regards, Norm

The weight of the rotor effects HP at the wheels correct? Well thats what some car show on speedtv noticed, after doing a brake upgrade to bigger rotors, they loss HP and slowed there 0-60 times, but the bigger brakes lowered there track time. A thinner material rotor would be more prone to wrapage id imagine. Do you guys usually get ur rotors machined once or twice before you get new ones? Also would it be okay to sand the surfaces of the rotor with a very fine grit sand paper just to make the already smooth rotor a bit smoother? Metal is never 100% smooth at the micro level.
I know Nissan coats there pistons with a special coat that makes the surface smooth, sorta explains how there able to get higher HP outta small engines. I think GM is doing it on some of there new engines.

Royal purple oil claims to fill in those unsmooth surfaces at the micro level, cause it claims its oil increases hp and torque. Wouldnt think it would last long though, royal purple would have to be used every oil change id imagine.

that is because the engine has to overcome more rotational inertia to accelerate/decelerate the vehicle/driveline. the more weight a rotating part has the more power it takes to rotate it (parasitic losses) hence a two spd racing powerglide trans takes less power than a TH400 (exagerated comparison) with it's heavier/stronger parts and in racing every little bit helps...on the same point this is the reason you dont see drag slicks for 20inch+ wheels and 15's the most common. the bigger brakes would have also increased the cars unsprung weight which will affect handling and the same with bigger/heavier rims.



I have seen many times where i will install out of the box rotors (china or USA/Canada made/machined) and gotten a pulsating pedal to fix it you need to tru the rotor. many times i have noticed that the rotor litteraly has folded in the middle (actually on one side of the hub so not the middle)because of the way it was stored/shipped our local napa stores them flat on their shelves and we never seem to have a problem (though they are more $$ and not often ordered) but the ones from any other supplier we now throw on the lathe right out of the box to keep from pulling the brakes apart a second time.



yes-but mainly to get a unidirectional pattern on the rotor (kinda like the pattern a dual action (random orbital) sander makes) to prevent the brakes from squealing(most lathes have a grit wheel on a handle to provide this pattern) also nowadays manufacturers require a certain RA finish texture on their rotors and use ceramic pads (most cars manufactured after 97-99 use ceramics from the factory) they require this because of NVH requirements (new car owners are terribly fussy about hearing morning sickness (that groan with cold brakes) or squeaks/clicks (one of the reasons they come with disimilar metal shims behind the pads-usually regular steel and stainless-both metals have different resonace frequencys and help cancel out the squeak (a high frequency vibration).
the antithesis to this is you dont want your rotor polished mirror smooth as it will not let the pads "bed in" properly and make a proper surface for friction to occure at max efficiency.



allot of manufacturers nowadays use thermal/antifriction/dryfilm lubricants in modern engines (the new 5.7 Hemi, the LS2/7, ford Modular engines etc) the one engine i saw used most of this technology was in a drag racing engine being built at my local machine shop (Milo said that all the coatings added over 1 G to the price!), a BBF with oil shedding coatings on the rods/crank surfaces, dry lubficant film, coated bearings/timing chain/piston skirts and thermal barrier coatings on the piston tops/combustion chambers/ports/valves. this technology is fairly expensive and has to be aplied properly and the thickness taken into account for machining specs/clearances.
for racers looking to eek out that 1 or more Hp from their engine (by reducing friction) or to reduce the chance of detonation (thermal coatings), or bearing failure (from loosing the oil wedge, or wear occuring at startup-dry film lubricant will keep major damage from happening for a little bit till the oil gets back in there) these new technologys help them do it and make it more durable--for them price is no object when winning/losing is determined by thousandths of a second.

speed/power = $$$$

James

ok from what I have researched ceramic is much better but only if used with high end rotors. Not sure what the quality of those are but ceramic is the way to go if you can afford the rotors.

IT IS VERY COMMON on the bigger gm cars now days like bonnie, pa, lesabre,lss,niney eight, etc to have brake warping problems since they are still too small to be hard on the brakes.

Plus as was mentioned no dust and no squeeks usually.

If you use your brakes a lot it is better for ceramic, wont make you stop any better just will be nicer feeling smoother braking.

Got the new pads and new rotors installed today. All went pretty well!
Probably would have went quicker if I had a lift though.....

Took it for a test drive and it works good. Old rotors were definately warped...don't have that sound any more. And the ceramic pads are pretty quiet, I had the window open. No squeaks except for the first couple of stops in the driveway, to get the pads seated. It's probably just my mind playing games, but it does seem to stop a tad bit quicker than before, but that's probably just because my old pads were pretty worn down...close to have the little warning strip rubbing the rotor.

They look good too Just the caliper is out of place...probably paint them over the summer....little cold right now.

All lug nuts were torqued to 100 ft lbs.

TOC Admin
Brando

no bleeding of brakes?

No disconnected line = no bleeding brakes

TOC Admin
Brando

NEW SUBTOPIC - BLEEDING OF BRAKES

Ok, got a question, maybe you guys can answer. What ways can air bubbles formulate in your brake lines besides letting it in by removing a line? Once an air bubble is in the line, will it sit still at the end of the line, or can it travel back up to the master cylinder?

If it were to travel back to the master cylinder, would the bubble not surface in the reservoir, effectively eliminating the need to bleed?

The need to bleed - Brake technician's theme song

I dont think i have seen air (acumulate/just appear) in a properly maintained brake system if you have old moisture contaminated brake fluid and you heat up the fluid enough (brake fad will occur) the water will evaporate and make a spongy pedal then when the fluid cools down it will reabsorb the moisture. air in a brake system usually travels to the highest point in that hydraulic system whether its a raised section of line or the master cylinder (the ABS unit on modern cars have pockets that air likes to hide in) with (some) ABS modules you usually have to "home" the unit and bleed it out seperatly to remove all air. the brake system in a few cars i have worked on have basicly self bled but each car has different spots fer the air to collect (like the RF brake line that sometimes drops down under the engine/k member then up to the master-the air stays trapped because not enough fluid flows through the line and back into the Master for it to "bleed" out the master.) it really depends on the vehicle.
The MAIN reason to bleed your brakes is that brake fluid is hygroscopic (sp?) and absorbs moisture from the master cylinder cap (when opened etc) and even through the rubber brake hoses the moisture lowers the (wet) boiling point of the fluid and accelerates internal corrosion, you get brake fad earlier and parts rust up inside. if you flush (bleed) your brakes regularly you prevent both these problems from occuring (at the worst possible time...) and resulting in a crunched car or replacement of components. if you change your oil regularly why not any of your other fluids...hmm? PS/brake/coolant, people just usually overlook the brakes until they have a problem/failure.
I have bled brakes on many euro-pee-on cars as part of reg (factory rec) maint and have seen BMW's etc with over 180K on them with all the original brake parts, because of reg maint (pays off real quick if ya knew how much a caliper for a 99 BMW 755i costs (175$!!!)) I flush my vehicles brakes approx every year or two (bleeder screws removed and greased to prev rusting tight!) and havent had to replace more than pads/shoes and two wheel cylinders (they didnt look too hot so i went ahead and replaced them) besides i love the feel of brake fluid on my hands...lol
you aint dun it right till you've bleed, while bleeding brakes lol
james

i'll be replacing the brakes ina my alero in about 10-15K miles. It has 4 wheel disc brakes. I was thinking about slotted rotors but I agree they are mainly for show. I'll probably just get some real good delco pads. i might even let the local Olds dealer change them but they might want 5 arms and 2 legs for it, we will see.

Slotted rotors are different. The slots actually slice the pad, giving the pad a new layer on every stop. This is great for racing to prevent glazed over pads. Strictly for racing, drilled rotors on the other hand are much more friendly towards pads.

TOC Admin
Brando

5 arms and two legs is just too much to change brakes. Tell them you've only got 3 arms to offer.

I just ordered one of these. So I'll be changing the brake fluid on my cars.

TOC Admin
Brando