Mixing brake rotors?

SVXMAN2001 · #1 10-19-2005, 11:01 AM

I was once told by a mechanic that mixing rotors (fronts slotted and rears stock) would cause severe shaking when stopping...is this true?

sperry · #2 10-19-2005, 11:32 AM

Quote:

Originally Posted by SVXMAN2001

I was once told by a mechanic that mixing rotors (fronts slotted and rears stock) would cause severe shaking when stopping...is this true?

It hasn't caused a problem on my car.

SilverSpear · #3 10-19-2005, 11:38 AM

Quote:

Originally Posted by SVXMAN2001

I was once told by a mechanic that mixing rotors (fronts slotted and rears stock) would cause severe shaking when stopping...is this true?

if you displace them diagonally, they might cause severe shaking, i mean Front Left slotted and rear right slotted and front right stock and rear left stock.

Also shaking is caused by wavy rotors. (when the rotors are very hot and you throw water at them, they get wavy)

SVXMAN2001 · #4 10-19-2005, 11:45 AM

interesting cause i bought the race concept rotors a while back and kept the stock rear brakes...the slotted brakes worked great for about 5-8k miles and then got progressively worse. They seem to feel as if they are severely warped (lots of shaking when stopping) i asked a mechanic about that and he said it was because of the setup i had with stock rotors in the back. So either that's true or i messed up something with the install of the front brakes...

SilverSpear · #5 10-19-2005, 11:59 AM

Quote:

Originally Posted by SVXMAN2001

...or i messed up something with the install of the front brakes...

This is your problem, most probably.

or you are stessing a lot on your new rotors causing them to get wavy.
Also check if they got cracked, if not apparent from the exterior have a look at them fron the interior, the side of the chassis.
When slotted rotors get cracked they cause this shaking...

sperry · #6 10-19-2005, 12:58 PM

I don't know the details of those specific rotors, but if you installed them swapped left to right (i.e. the left rotor on the right, and vice-versa) there's a chance you have a cooling issue.

If the rotors are directionally ventilated, and they're on backwards, they won't cool down easily. And if you come to a complete stop on hot rotors, the pads will tend to leave deposites on the rotors, which build up over time, and will cause vibration such as you described.

Usually, slotted rotors have their slots cut angleing in the opposite direction of the ventilation vanes (it makes 'em stronger that way), which means the slots should be leading with the outside edge of the slot (i.e. the same way the stock SVX wheels spin).

For example, this is a right front rotor:

If I'm not making 100% sense, let me know and I'll bust out photoshop and draw a picture that describes what I'm talking about.

Tim · #7 10-19-2005, 02:18 PM

That's actually something I never considered but I'm glad you guys brought them up. Glad i saw ths before I installed my rotors

Red SVX 92 · #8 10-19-2005, 02:30 PM

And all this time, I thought they had different P/N#s for the left and right sides just for the looks...

I'm putting slotteds on the back of my Civic. I'll let you know if I have problems.

BTW, buybrakes.com currently has a free shipping on orders over $100, as well as a $10 off coupon. I think it lasts til the end of the month, but I'm not sure. Either way, it's not a bad deal.

Earthworm · #9 10-19-2005, 02:35 PM

Not matching rotors front to back will cause one set to do more work than usual. If your front brakes are upgraded they will grab better than the rears and therefore do more work than they were intended to resulting in higher temperatures and potential warping.

I'm not sure the actual extremes of this though.

sperry · #10 10-19-2005, 02:50 PM

Quote:

Originally Posted by Earthworm

Not matching rotors front to back will cause one set to do more work than usual. If your front brakes are upgraded they will grab better than the rears and therefore do more work than they were intended to resulting in higher temperatures and potential warping.

I'm not sure the actual extremes of this though.

While that is true, the rotor itself won't dramatically change the brake balance. Using different pad materials will have a much greater effect on balance than rotor slots.

Also, with regards to "warping", it's extremely difficult to actually warp a rotor. In 99.9% of the cases, the vibration is from hot-spots and pad deposits. Check out the StopTech whitepaper on the topic for the specifics:

http://www.stoptech.com/tech_info/wp...rakedisk.shtml

It's actually a minor point, since the brakes still vibrate to all hell whether or not it's actually a warped rotor vs. pad deposits, but the details as to why the're vibrating can lead to some insight into how to prevent it from happening... for example, after coming down a long hill, don't come to a complete stop until you've let the car coast for a bit to cool the brakes.

Red SVX 92 · #11 10-19-2005, 02:55 PM

Quote:

Originally Posted by Earthworm

Not matching rotors front to back will cause one set to do more work than usual. If your front brakes are upgraded they will grab better than the rears and therefore do more work than they were intended to resulting in higher temperatures and potential warping.

I'm not sure the actual extremes of this though.

My back rotors are currently shot. It's fun working with half your normal braking capacity!

Beav · #12 10-19-2005, 04:03 PM

I thought the rear rotors on the old Lincoln Versailles were the only directionally ventilated rotors on a mass produced automobile. Putting them on backwards certainly would result in baked brakes, in a hurry. I was always suspicious that nobody else did that because they were easily assembled incorrectly by the uninformed.

thundering02 · #13 10-19-2005, 04:30 PM

Quote:

Originally Posted by sperry

That would be the driver side for the race concept....and I had the fronts slotted with stock rears for about 3 months even racing never noticed any problems other than I could stop better.

Earthworm · #14 10-19-2005, 04:49 PM

Quote:

Originally Posted by Beav

I thought the rear rotors on the old Lincoln Versailles were the only directionally ventilated rotors on a mass produced automobile. Putting them on backwards certainly would result in baked brakes, in a hurry. I was always suspicious that nobody else did that because they were easily assembled incorrectly by the uninformed.

They were talking about these kind of rotors on "The Adam Carolla Project". He was upgrading the brakes on his Aston Martin.

sperry · #15 10-19-2005, 05:32 PM

Quote:

Originally Posted by thundering02

That would be the driver side for the race concept....and I had the fronts slotted with stock rears for about 3 months even racing never noticed any problems other than I could stop better.

If the slots on the Race Concept brand rotors are opposite from those in the picture I posted, chances are the vanes underneath aren't directional (i.e. swirled, just straight). Rotors that have vanes and slots parallel tend to crack easily. If the vanes aren't directional, then it really won't make much difference if they were swapped left to right.

Also, check this out:

http://www.stoptech.com/tech_info/faqs.shtml#16

It has nice pictures describing why there's a difference between left and right directionally vented rotors.

Quote:

Originally Posted by Earthworm

They were talking about these kind of rotors on "The Adam Carolla Project". He was upgrading the brakes on his Aston Martin.

That explains why Adam Corolla was at Laguna Seca w/ the Aston Martin team last weekend for the ALMS race. I was wondering wth he was doing there, and why he got to start the field's engines.