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Has anyone had any problems with there front rotors warping on the svx? I just got mine ground today and new pads and the guy ( I personally know him) said that with them being ground and my driving style that it wont be long before i warp them. Anyone think this may happen? I dont do too much hard braking just repeated braking throught the mountains here while running them fast. And one more thing. I heard you can cross drill your own rotors with alot of time and good drill bits. Anyone personally dont this or know anything about it? THanks
Jared

[Beav]

You have to consider what causes them to warp. Many will tell you the same tried and true story of "Subaru never built a car this heavy before, that's why they warp so easy." While there may be some truth to this, it's not the complete story.

Rotors are cast iron and susceptible to density variation, in other words certain areas of the rotor may have more or less molecules of iron than other areas. As the different areas heat and cool at different rates the rotor expands and contracts differently, thus creating lateral run-out. The quality of the manufacturing process added to the driver's usage determines how often and how much warpage will occur.

When I lived in the mountains it used to kill me (laughingly) how easy it was to spot new residents by their driving skills. Newbies had to use their brakes at every single curve - going uphill. Nothing like taking your foot off of the gas a second or two earlier and letting gravity do the job...

Brake rotors will warp on a car. There's absolutely no avoiding it. As far as I know, it's virtually impossible to find brakes which will never warp. However, certian measures can be taken to prolong the life of the rotor.

As The Beaver pointed out before, rotor warpage is due primarily to inconsisteincies in the material. Uneven heating & cooling can over-stress the metal and cause it to warp. If you've got any friends who are glassblowers, they can attest to this. When you're done making a piece of blown glass, you need to put it in a special oven which cools it down over a period of anywhere between 14 hours and 15 days. If it cools down too fast it will shatter everywhere because some areas of the piece have cooled and contracted quicker than others.

With an aggressive driving style, brand-new SVX rotors could warp within a few months, and freshly turned rotors can probably be warped with one rapid stop. I'm not speaking from experience, but from spending seven months lurking around the message boards and from having my own rotors warp shortly after purchasing my own car.

As it's the front rotors which recieve the bulk of the braking pressure (is there such thing as a brake balance controller for the SVX??), they're most often the ones which warp. Replacing the front rotors can cost anywhere from roughly $140 to $375 depending on whether or not you feel comfortable remaining with stock equipment. It is possible to order rotors which have been slotted, cross-drilled, cryogenically treated, or any combination. If coure you'll need to pay, and the order I placed with ART (applied rotor technology) nearly one month ago has not yet shipped to me.

So choose wisely. I'll let you know what I think of ART's when I finally get them installed.


-Adam

[Trevor]

Beav,

In the mid sixties I raced an SP250 V8 Daimler sports car, one of the first to feature disc brakes, as I have previously mentioned. Since then I have raced many cars all with disc brakes and have never had any problems with discs (rotors) warping nor have there been reports among my racing friends of any real problems in this area.

The brakes on the SP250, being a first, did have some problems but nothing major. Suitable wheel bearings had not been developed and some lateral run out during hard cornering would cause the pads to space back off the rotor between applications and it was necessary to give two strokes on the pedal with the second bringing up a good pedal.

However they were excellent brakes and I well remember on one fairly short straight I would consistently go for the brakes alongside the 75 yd. marker at a genuine 115 MPH before setting the car up sideways for a very tight hairpin corner. One thing I had added was pressure shut off valve to limit rear wheel braking to stop the rears locking up as weight transfer unloaded the rear. No fancy pedal balance bars in those days!

On coming into the pits in dull weather the rotors could be seen glowing red and it was necessary to use the hand brake to stop as without the motion of cooling air the fluid would evaporate in the wheel cylinders. At first we used to bleed the brakes after each race as a precaution but gave this up as everything returned to normal when cooled down and cooling only took a few minutes. Later model cars I raced did not exhibit these problems but none had in fact any better brake performance

Now the point of all this not to point out my racing experience but record that very severe braking and often in long races did not cause brake rotor warping. I think you are onto something when you report bad driving in automatic cars when there are lengthy descents involved.

The work the brakes must do to hold back a heavy and laden car must be considerable and if no cooling periods are provided and the application constant there would be very prolonged heating and may be this the cause. What is more they probably experience brake fade and apply still more pressure with the aid off hefty brake boosting and hefty right foot.

What is your further opinion?

Regards, Trevor,

Thanks alot guys...i learned alot of new things....so does anyone know about crossdrilling your own rotors???/

[Trevor]

Why would you want to cross drill your rotors? If this were any worthwhile cost effective advantage it would be an OEM feature. However there will be a lot of advertising bumph from gimmic manufacturers looking for your money. If you want to look cool you will also have to paint your callipers a very bright snazzy colour to show you have are real fast car.

I have a feeling that you may be looking for sound advice in which case you will accept my sarcasm. If not you will simply write me off as a silly old bastard and no harm done.

Trevor.

[Beav]

You may be on to something Trevor. But there may also be many other considerations to enter into the equation. The race car's brakes do see higher temperatures, but they only see maybe 500 - 1000 miles per year. A hard street driver may approach the same level of heat but he's also holding his foot on the brake at stop signs and taffic lights as the brake cools, another cause of inconsistent cooling. Race cars tend to have the best parts suppliers involved, usually using special designs and materials.

I agree some drivers are harder on their equipment than others, and they can be a pain in the neck for me at times. They can also mean more money to me too... The way I handle a customer that consistently has warped rotors is to find a better supplier. The rotors I buy that are from the U.S., Canada and Europe tend to create fewer problems for me than the iron that emanates from South America, Mexico and the Orient.

In that light I see that the cross-drilled and/or slotted rotors referred to here could be much less prone to warpage as they are probably better pieces to begin with, the holes and slots probably being of better value to the marketing department. Let's face it, the more metal missing reduces the size of the swept area. But the holes aren't strictly for cooling, they also allow for friction material out-gassing. Interesting concept, my problem with that is just how much gas can be created by the pad? Certainly not enough to warrant that much ventilation.

Regarding drilling your own rotors: If you percieve that this is something that you really want, consider this - some things are worth paying for. True, I can pour my own rum into my coke without too much difficulty. Plotting out a pattern of holes on a rotor that won't hit any vanes, reduce the integrity of the piece, throw the piece too far out of balance, and require more time and equipment than it's worth for a production run of two rotors just isn't worth it to me. It's not something that you're going to create with a Skil drill in the A-Team fashion. I'd rather pay someone else to do it while I make another rum and coke.

[Trevor]

Beav I would realy like to shake your hand and hope and wish that some time we may meet in person.

You say so much with your-- " The cross drilled holes & slots being better value to the marketing department " !!!!!!!

You are truly a man of common sense and wisdom and are no bull**** artist as so many are who post anonymously. I admire your frank, caring and honest attitude to all things. You are a rare animal and I hope the network appreciates the free advice you hand out.

Trevor.

[nubs]

Originally posted by Trevor
Beav I would realy like to shake your hand and hope and wish that some time we may meet in person.

You are truly a man of common sense and wisdom and are no bull**** artist as so many are who post anonymously. I admire your frank, caring and honest attitude to all things. You are a rare animal and I hope the network appreciates the free advice you hand out.

Trevor.

You could not have said it better Trevor,while I myself being an ex-mechanic, can usually figure thing's out by myself, it is great to have someone like Beav around. I am sure that I will need help with something some day and I am glad there is someone here that I trust will do his best to help any and all of us here. I to am looking forward to meeting him some day.

[svx_commuter]

Wrap rotor cure..... Go find a back road some where and get the car going fast and then stomp on the brakes as hard as you can until the car almost stops. Then do it a few more times.

This works for ME

I think the rotors warp from those panic jabs at the brakes and only half the rotor heats up........... So it warps.

However this did not work when I first got the car. I had to have rotors turned.

I also think new rotors need some breaking in. Uniform brake peddle pressure and uniform heating of the rotor.
On the car stress releaving.

There is also a new motorcycle brake disk that looks to address these problems. It has spiral slots cut between the hub and the disk pad at the OD. Maybe about 16 spiral slots about a 1/4" wide. It lets the disk section get hot and expand without pulling the hub to larger size and that helps prevent warpping.

[Beav]

Thanx for the kudos, this is a great group and I'm too happy to throw in my two cents worth.

I suppose that every car built has had someone, somewhere try to do something to it to make it better or do something beyond its original design. It can be fun when it works and doggone frustrating when it doesn't. Only the individual trying can gauge it's worth of effort. It's his time, his money, his smile or his frown ('Her' can be substituted at any time here, I am an equal opportunity kind of guy. ) In that respect I can't judge the value of what others do. However if they slip up and ask my advice.....

I was looking to do it for the sole pupose of added cooling even if it is not much at all. I have a really bad problem with the heat in the mountains i haul ass through. Brake fade is a bad issue...

[Beav]

The holes are really a ridiculous thing - they don't do much for the cooling and your greatest accomplishment by drilling them will be to reduce the amount of 'swept area', the total surface area that the friction material works against. So by drilling them you're actually screwing yourself out of braking power.

Try this: when I lived in the mountains I drove hard also but I did it by quick jabs on the brakes only when needed. Setting up the curve and finding your line is much more important - smoothness and consistency is what wins. When you do that right you'll get much more pleasure from it than toasting your tires and brakes.