I recently put on a set of new Coleman rotors which warped in no time, less than one hour. The rotors were stress releived prior to use and used pads were used for initial break in. Took them off and measured offset. Came up with 0.009 - 0.010" on one and 0.005 - 0.006" on the other. These things will shake your teeth.

What is interesting is the presence of one spot on the rotor which has what looks to be thermal fatigue cracking. That doesn't make any sense to me to have one localized spot. The rest of the rotor looks fine.

Here are a couple of photos. You can see the good and the one bad area. Any thoughts?

Rotor


Bad Side



Good Side



Defect Closeup

 

I have the same rotors, except that mine are slotted. Mine needed turned when they were brand new, then the shake went away (This is according to the person I bought the rotors from. I bought them with a couple of hours on them, they were almost new). I've never seen any cracking, though. I just went and looked at mine and they are fine. Maybe you got one with a bad batch of metal? Weird.......

Tifo

 

The reason for your problem is quite simple:

Coleman rotors are junk.

Chris Cervelli
Technodyne Inc.

 

I have to agree with Chris on this one, for our puposes we really need high quality rotors like Alcon, BTW I need some new Alcons for my car, anyone know where I can get a pair? The shop I bought them from is notoriously high priced and I'd rather just buy the rotors and new bolts and do the job myself.

 

Dave,
The reason I bought these was to save a few bucks on the last set of rotors for the season. I calculate $375.00 as pretty expensive on an hourly basis <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

The Alcons which came off were worn almost to the bottom of the slots. Dead flat and not an iota of vibration.

So much for Coleman's.

Alan C. ( no relation to the Coleman rotors )

 

Hey Alan, were those the grey iron rotors or the steel ones?

 

I was tempted by the price on those too, didn't mean any offense, my alcons have that heat cracking consistently all over at this point and braking hard above 120 when hot really causes alot of shaking. What type of ducting are you using to cool your brakes?, it sounds like you got a more consistent life out of your alcons than I did. Any ideas for sources on new Alcons, and have you heard anything about the track use of Stoptech rotors?

 

While I think the Alcon discs are great, I know that Porsche rotors provide the best compromise between cost and quality.

With Porsche rotors you know they are going to be flawless right out of the box and that they are going to last a long time.

I think the Alcon discs, which are typically quite a bit lighter than an equivalent Porsche disc, is more suited to a professional racing car.
The Alcon certainly provides better performance due to its lower weight, but doesn't last as long for the same reason.

Also remember that generally Zimmerman Porsche rotors are not as good as the ones you get in Porsche boxes.

Coleman discs, on the other hand, are more expensive than Porsche and as I said before, are junk. Couple that with the fact that the Coleman company itself is difficult to work with, and you can rule them out right away.

Chris Cervelli
Technodyne Inc.

 

Try <a href="http://www.prospeedmotorsport.com/index.htm" target="_blank">Prospeed Motorsport</a> as they carry Alcon. I don't know the prices though.

 

Wow, nice to find out that my rotors are "Junk". Sould I be concerned? I assume the Alcons will bolt up the the Powerhaus hats that I have? My colemans are the steel ones.

Any suggestions?

Tifo

 

[quote]Originally posted by Alan C.:
<strong>
Here are a couple of photos. You can see the good and the one bad area. Any thoughts?
</strong><hr></blockquote>

Just one totally off-the-wall thought... Could the heat-checking be the result of a banzai stop from high speed, after which the car then sat totally still? For street cars, my tech/buddy recommends allowing the car to slowly roll just a tiny bit after a hard stop, situation permitting, to avoid concentrating / trapping the heat in one spot under the pads. Apparently, this is suspected as a possible cause of warpage on some thin OEM rotors.

Jim, "The early bird gets the worm, but the second mouse gets the cheese..."