SVX Network Forums Live Chat! SVX or Subaru Links Old Lockers Photo Post How-To Documents Message Archive SVX Shop Search |
IRC users: |
#1
|
||||
|
||||
Our rotors dont warp.
I have read this before and have been wanting to post this because it has worked for me on a couple of cars for me when the disc start to "warp" i put on some hard semi metalics and the "warp" goes away. I just know recived the link again from another subaru person after i lost it.
http://www.stoptech.com/whitepapers/...otors_myth.htm |
#2
|
||||
|
||||
Our rotors do warp.
Quote:
The problem you have described can occur with some cheap after-market pads but I have not heard of it happening with our OEM or decent pads. There does seem to be an overheating problem with our brakes, probably caused by the weight of the car. This can manifest itself when stopping from high speeds. Many of us have fitted replacement discs and pads which have cured all of the problems and improved braking performance.
__________________
Andy ------------------------------------------------------------------------------------ If I would be a young man again and had to decide how to make my living, I would not try to become a scientist or scholar or teacher. I would rather choose to be a plumber or a peddler in the hope to find that modest degree of independence still available under present circumstances. -- Albert Einstein, The Reporter, November 18 1954 |
#3
|
||||
|
||||
I have mentioned a number of times in posts that the semi-metalic (like Axxis from Australia) will go a long way toward keeping our rotors from warping. The metalic pads, in fact, wear on the rotor, effectively keeping them "trued up". The fact that the lug nuts have to be evenly and appropriately tightened is also a critical factor - I run about 80 ft lbs. High temp brake fluid is also a must.
Personally, I like the stock SVX brakes (with upgraded semi-metalic pads). I would like to go to the steel braided brake lines for a more firm feel to the petal, but that would move me out of the SCCA G-Stock class to modified. There is no way I could be close to competitive in a modified class. As for performance, I have run at both Summit Point and Virginia International Raceway and had no problem with brake fade (high temp brake fluide is very much a key to this as well as the hardware of the braking system). At my advancing age, I doubt I push the car more than 7 or 8/10's of its capability, but still, the brakes work really well. I have even had an instructor at Summit Point comment (while driving my car) going into Turn 1 at 115 - 120 MPH, "Wow! This car has brakes! Harry
__________________
newsvx 1992 SVX LSL, #1215 1997 SVX LSi, #370 "I live with fear every day. Sometimes she lets me go racing." "Getting Older and Slower" Locker: http://www.subaru-svx.net/photos/user.php?newsvx |
#4
|
|||
|
|||
Re: Our rotors do warp.
Quote:
Thanks |
#5
|
||||
|
||||
Re: Re: Our rotors do warp.
Quote:
__________________
Andy ------------------------------------------------------------------------------------ If I would be a young man again and had to decide how to make my living, I would not try to become a scientist or scholar or teacher. I would rather choose to be a plumber or a peddler in the hope to find that modest degree of independence still available under present circumstances. -- Albert Einstein, The Reporter, November 18 1954 |
#6
|
||||
|
||||
newsvx so the axxis pads dont have problems on the track with over heating because i want to track my SVX and dont want to run into that.
|
#7
|
||||
|
||||
Quote:
Harry
__________________
newsvx 1992 SVX LSL, #1215 1997 SVX LSi, #370 "I live with fear every day. Sometimes she lets me go racing." "Getting Older and Slower" Locker: http://www.subaru-svx.net/photos/user.php?newsvx |
#8
|
||||
|
||||
Re: Re: Our rotors do warp.
Quote:
How are things in Qld??? :-)
__________________
1992 charcoal grey SVX: 27 August 2002 to 27 January 2004 - she will be missed Was back in Sydney for a while but not hot enough so now in Dubai! Has it been that long since I owned SVX-33H! |
#9
|
||||
|
||||
I keep hearing that over-torquing lug nuts can cause brake rotors to warp. As a matter of fact, I've heard it since before I bought my SVX over four years ago. But I have yet to see an explanation for why this might be true.
Don't get me wrong - I'm not arguing that it will or will not happen, so I don't want testimonies. I want an explanation, please.
__________________
2005 RX-8 Grand Touring 2005 Outback 2002 Mercedes-Benz E320 wagon END OF LINE |
#10
|
||||
|
||||
The simple explanation is 'Thermal Expansion'
Do you really want the long explanation?
__________________
Andy ------------------------------------------------------------------------------------ If I would be a young man again and had to decide how to make my living, I would not try to become a scientist or scholar or teacher. I would rather choose to be a plumber or a peddler in the hope to find that modest degree of independence still available under present circumstances. -- Albert Einstein, The Reporter, November 18 1954 |
#11
|
||||
|
||||
Quote:
Thanks.
__________________
2005 RX-8 Grand Touring 2005 Outback 2002 Mercedes-Benz E320 wagon END OF LINE |
#12
|
||||
|
||||
Thermal Expansion is the "action" (normal in any braking system / rotor), and over tightening the loug nuts prevents this expansion in some areas, and allows it in others. The key is that there MUST be some expansion allowed. Further, when lugs are over tightened, the amount of torque on each one will differ, thereby causing different "amounts" of expansion. That causes the "warp of the rotor". And as mentioned earlier in this thread, if the uneven braking resulting from the warp in the rotor is noticed soon enough and corrective action is taken on the torquing of the lug nuts, all is good (usually). However, if it goes uncorrected for long enough, a bad wear pattern sets in making the warp permanent, and the only way to correct it is to turn the rotors, assuming they are not that bad. Of course, by turning the rotors, that makes the rotor thinner and more likely to warp from excessive heat. One of the probelms with modern cars today is that rotors are made as thin as possible - to save on overall car weight (for gas mileage) and to save on unsprung suspension weight (for better handling dynamics). And I won't address "and it is cheaper too".
Hope this helps. Harry
__________________
newsvx 1992 SVX LSL, #1215 1997 SVX LSi, #370 "I live with fear every day. Sometimes she lets me go racing." "Getting Older and Slower" Locker: http://www.subaru-svx.net/photos/user.php?newsvx |
#13
|
||||
|
||||
Thank you for the long explanation. Again, it's pretty much what I expected.
Now I wonder how much a rotor actually expands at operating temperature...
__________________
2005 RX-8 Grand Touring 2005 Outback 2002 Mercedes-Benz E320 wagon END OF LINE |
#14
|
|||
|
|||
Warping Disks.
The expansion rate of cast iron is very low,compared to other metals. The over torqueing of the lug nuts causes the top hat section to distort in a wave shape, this is magnified by the time you get out to the friction surface.
The other cause of warping that happens when long hard breaking heats the disk, is because the disk is a sand casting, that is chucked up in a machine, to machine the surfaces. If the casting is slightly off line when it is held in the machines chuck, the finished disk will have a difference in the amount of metal between the vents and the breaking surface around the circumference of the disk. This causes an uneven expansion and the disk surface will warp when hot. This warping will disappear when they cool down. Thats why some of the SVX s warp disks bad and some don't do it at all. The later after market disks have a more controlled casting and machining process to keep the disk section even, to prevent warping. Harvey.
__________________
One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#15
|
|||
|
|||
Great article, Brakes 101
This is a good article...please read....
|
|
|