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My (new to me) Verde's front rotors are warped. According to the maintenance logs they are only 12,000 mi. old. What are the main causes of this and which type of rotor should I install? Do the benefits of Cross-drilled/slotted outweigh the price difference? Will they prevent this from happening again?
 

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My (new to me) Verde's front rotors are warped. According to the maintenance logs they are only 12,000 mi. old. What are the main causes of this and which type of rotor should I install? Do the benefits of Cross-drilled/slotted outweigh the price difference? Will they prevent this from happening again?
I went through a ton of the stock Brembo rotors over the years. I think as rotors (set per year) go they are butter-soft and not great for longevity. I have also tried a bunch of different pads from aggressive to mild. The last set of rotors (current ones on the car) I got the drilled slotted ones from IAP and couldn't be happier. They seem to wear much better and they stop better too. And this is with a simple metallic pad that is cheap and nothing fancy. FTR, they weren't _that_ much more expensive.

All that said, next up I want to tackle the whole race caliper and rotor project if I can get somebody to hook me up with the CAD or drawings for some Wilwood brackets or something close :)
 

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But Mad North-Northwest
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Well, if you want a different opinion, I bought the IAP slotted rotors and they were junk. They warped soon after I got them, I had them turned which fixed the problem, and they warped again. If you do a search on here you'll find the same has happened to others IIRC.

My mechanic's advice when I told him about it was that yep, they're junk, and to stick with Brembo. I put the stock Brembos back on and no further problems.
 

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My (new to me) Verde's front rotors are warped. According to the maintenance logs they are only 12,000 mi. old. What are the main causes of this and which type of rotor should I install? Do the benefits of Cross-drilled/slotted outweigh the price difference? Will they prevent this from happening again?
I would suggest OE or non-slotted/non-drilled Brembo. They are fine.

Cross drilled/slotted not necessary unless you have already exhausted options of adding ducts to brake discs and have good pads and fluid. If you have a street car it is absolutely unnecessary.

Call up performatek and ask him about Brembo vs. other rotors (and which companies actually start w/ Brembo rotors before they machine them and call them their own, and which do not). He has the good stuff.
 

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Well, generally speaking, warped rotors is caused by heat.

Cross drilled or slotted rotors are made for race. Anything race is developed to improve performance, no so much longevity. In the street world, pads are consumable (we expect a couple/three years out of tires and rotors). In the race world, pads, rotors and tires are consumables expected to last only a couple of races. They tend to crack.

I've had Shankle cross-drilled rotors all around (NLA) and had no problems, right now, I've got R1 cross-drilled and slotted only on the rear. Stock Brembo in front (IMO GTV6/Milano front rotors are small enough already, don't want to remove any materiel) however, my cars are street.

The R1's look cool but they are not cadmium plated. They use some cheap black e-coat looks more like paint, than an e-coat. Flakes-off overnight.
 

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Exercise caution with drilled rotors: I have seen several catastrophic failures at high-performance driver education track events leading to crashes. True, these were not on Alfas but it could happen to anyone. If you get drilled rotors you must frequently and carefully inspect for cracks or be ready to replace the rotors often just to be safe.
 

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I built a custom aluminum hat, heat treated cast iron rotor assembly knowing I would be using the Carbotech pads recommended by Performatek. The race shop (Coleman Racing) states that some pads do not work well with drilled rotors or gas slots and advises a call to the pad company. I did call Carbotech and they recommended against drilling and slotting.
 

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Before I went the custom hats, rotors, and calipers route, I used stock vented rotors (non-crossdrilled, nor gas-slotted) but switched to Porterfield Brake Pads (from the stock ATE pads) on all four corners.

Braking performance was greatly improved, and the amount of brake dust went down considerably. Keep in mind I track my Alfa Milano with some regularity and I never warped the rotors (this was, of course, after many driving schools which taught me how to use my brakes without abusing them).

Eventually, I got fast enough to want to brake deeper and crossed the envelope of operation of the stock rotors and went to a custom setup. However, it took me several years to outgrow the stock brake setup augmented with the Porterfield pads.
 

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On a Street Car, Warping is not Normally the Problem

You can do many searches on-line. Many will tell you that on street cars, the pedal pulsing is not due to warping the rotors, and instead is due to the buildup of pad material on the rotor. Turning the rotor removes this buildup and restores normal pedal operation (for a while).

Also be aware that many shops will not turn drilled or slotted rotors, which requires that you replace them. This is because the "interrupted cut" caused by the drilled holes or slots will damage their cutting tools, although they will tell you that the rotors are "too hard."

I have standard Brembos on my 164Q with performance pads, and although they will not lock up the Michelin PS2's (225-17) on dry pavement, are a very good brake package.

Of course, the slotted/drilled rotors do look cool, and I seriously considered them prior to purchasing the standard Brembos.
 

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Richard Jemison
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What??!

Pegletom, your post is chock full of misinformation. :(
READ instead of typing!:rolleyes:
 

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But Mad North-Northwest
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Tom, I did not change pads when I went back to the Brembos. So I doubt brake material build up as the root cause.

The shop didn't raise any issues with turning them.
 

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I have standard Brembos on my 164Q with performance pads, and although they will not lock up the Michelin PS2's (225-17) on dry pavement, are a very good brake package.
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Most likely they will not lock due to ABS, if your brakes can't lock up the tire, barring ABS interuption, you have serious brake problem
 

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2015 Chevy (Holden) SS, 1989 Milano (Shankle Sport), 1991 164S
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Actually, as designed, rotors do develop a film of pad material on them to make the pads work correctly. This was discussed extensively in the 164 Section of the forum several years ago. The "breaking in" period of new brakes is the forming of the film.

I suspect that "big name" rotors (Ate, Brembo, etc) which are slotted or drilled do work properly and safely, but some aftermarket versions may not due to lack of proper design/workmanship/tolerancing.

I remember reading in a major car mag a few years ago a Ferrari rep saying, when asked about drilled/slotted rotors on some Ferraris, that basically drilled/slotted rotors were for show, others were for go. Having mentioned that, I do also remember reading in a tech journal that the oval slotted Ate aftermarket rotors were supposed to be a little superior in performance testing than plain or drilled rotors. Inconsequential for street driving of course. I think they look maybe a little "cool" but doubt I would buy them. The stock rotors have never let me down.
 

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On a stock Verde with stock BWA phonedial wheels, GTV6 with stock Campagnolo's, you won't even see them. If you have open spoke wheels like the Team Dynamics, than you might appreciate the look of cross drilled, slotted, or both. You'll pay twice as much but it's still not a whole lot.
R1 GTV6 rear rotor on car.jpg
Found this pic in my files. These ran about $150 delivered. Ferodo pads, another $50.00. Installation, and adjust parking brake properly? Somewhere around $400.00 (all you need are one or two of them bolts on the half shafts to get stripped or otherwise cause problems and you add a couple hours just like that). Later models and Milano use the Allen style bolts. this is an '84.

Front rotors are like any other. Just need a press to separate the hub. Install new seals.
 

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i always read how drilled rotors do not improve performance but i sort of don't believe this because porsche & ferrari (as well as nearly all of the performance marques) equip nearly all of their cars with them. porsche almost never just uses something for looks. i guess it's possible that they don't improve performance but i'm sure that they don't hurt performance either. and just using logic you can obviously see that with drilled rotors there is more surface area to improve cooling. so better cooling equals better performance generally, provided you're using the brakes harder than average.

of course with that said, i have switched to slotted rotors on one of my cars and never noticed a difference. for the money, you are so, so much better off putting that extra money into a better brake pad. you will feel the difference there. or add some SS brake lines and some high performance fluid. these will definitely improve braking from where your car is now.

also, nizam, which porterfield pad are you referring to? R4 or R4S? i've used the R4S's on my porsche for years and liked them. and the fact that they are much cheaper than the competition is what brought me to them. just for info though, my car is street although i do run thru the canyons fairly often, to the point that i can smell the brakes. the R4S's have pretty nice initial bite and can handle street levels of heat but just barely. personally i wish they were a little better with the fade. i tracked the car once with them and they didn't do so well but i also had old fluid so can't say for sure what caused the problems. i will say that i have seen smoke coming out of the fronts on quick downhill runs in the canyons although fade was not present yet.

ahhh, gotta love brakes since it is the highest G you can pull in any car.
 

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Originator may want to check some other things that could possibly be culprits of excessive heat (esp. on stock Brembo's on a street car). Sticking or frozen calipers (will be obvious due to pulling), or maybe wheel bearings set too tight. Otherwise, most likely due to abuse.

When I say "improves performance", I don't mean slap on a set and see better stopping distances (you won't). These are methods used to control brake fade - in this context is where the "improved performance" is applicable. Beyond where the brakes are at operating temperature and when they are going through repeated heat cycling (uh, racing). So, brakes that continue to work perform better than those that don't due to fade.

In front I'm using stock iron Brembo's with Hawk HPS and they work great, even with spirited driving.

It's common knowledge that the rear brakes fade-out before the fronts on 116/119 cars.
 

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The originator of this thread is Michael who works with me at HMA. He isn't online much so I thought I would comment.
We are going to put his Verde up and do a "Drag test" of the front calipers, then we may be able to determine if that was the cause of warping of relatively new rotors or not. Heat can be a powerful force,, for good OR bad,,,
 
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