Slotted Rotors...

[5-90]

I know this isn't a strictly OEM part, but I'm not modifying anything else (yet) so I thought I'd put it here. Does anyone know where I can find a set of slotted rotors for an 89XJ/4.0/AW4? My wife has had something like 4 sets of pads shatter in the last 3 years, and I know it's not her driving that's doing it. I think the brakes are overheating, and going with a set of slotted rotors should help with "gassing" of the pads and keep them a bit cooler.

Since I don't have a Bridgeport lying about (yet) - I can't do them myself. No ball mills, either. So, while I know how to setup and mill rotors, I just don't have the mechanical means to do it.

I don't think this is an overly odd request, as I seem to recall having seen them somewhere before - I just didn't write down where. Must keep my notebooks updated...

5-90

[LiquidOps]

I would like to know as well... if not... what is recommended.... i need to replace mine... beyond turning

[5-90]

If you are simply having pads wear down, getting slotted or drilled rotors is an extra expense you probably don't need (the milling results in an additional $20 or so per disc, usually.) I don't like drilled rotors because there is too much opportunity for stress risers if it isn't done the right way - and it's easier to setup and execute slot milling than cross-drilling anyhow.

Before you get something beyond OEMR, check your brake wear. If you have had several sets of pads start to shatter on you, slotted rotors may help. If you are having uneven wear between inboard/outboard pads, that is an installation issue. If you are simply having them wear down, you don't need an exotic replacement.

Note that anytime you mill or drill rotors, you slightly decrease the service life of your brake friciton - it's a tradeoff...

5-90

[Sarge]

I've seen them at Car Quest.

Sarge

[sticksnstonesrus]

www.quadratec.com

-Sticks

[imma honky]

I saw some in my summit racing mag. It was an issue from about 4 months ago (last one i got).

[KarmirXJ]

cross drilled rotors are a big waist of money. some quality rotors and pads. and a mechanic that knows what his doin im sure can solve your problems, not cross drilled rotors. if you do get them. expect them to shatter earlier than your convensional rotors.


those cross drilled rotors are a joke (Ive installed a pair on my brothers comaro, dont feel any difference, until you get into Extreme conditions, which I think your XJ will not meet) so save your money and invest and wiser solution.


just my .02

[XJ-ARMOR]

Crossdrilled or slotted rotors can actually help a LOT with keeping the rotor and pad surface much cooler, especially in harder driving conditions such as a track. The only similar environment an XJ would see is a long downhill needing lots of braking. Gasses can expand and leave the rotors surface with crossdrilling, and even lead to less warping. Some of these crossdrilled rotors are a joke, and are poorly made, in which case stick with solid rotors. Performance is worthless if it doesn't last and you need to replace it again and again.

[2offroad]

i have slotted rotors on my 98, i like them, more petal feel under hard stopping.

or i may be nuts.

[5-90]

A badly done crossdrilled rotor is useless, but a properly done job can extend the life of your brakes *in the correct setting.* Slotted rotors enjoy greater longevity (fewer stress risers) and tend to cause less accelerated pad wear than drilled.

If you are not having brake trouble, there is no need for additional venting. However, brakes can get VERY hot in traffic, and as brake pads are heated, gasses are released form the friction composition and if they are allowed to build up you can get shattered pads. Shattering of brake pads is almost NEVER caused by installation, and I've been swinging wrenches for 23 years (so I know it's not me - I do my brakes the same way but spend more time on the freeway and therefore have less trouble.)

You are not likely to notice a difference in pedal feel (I think that's a "Butt Dyno" thing,) but you WILL notice a difference in service life if all is done correctly. If you are not having trouble, you won't notice much of a difference with the extra venting over OEMR. I don't remember the numbers prezaktly, but I think it's something like 10% lower heat and 20-25% faster cooling with the additional venting (and at brake temperatures that can be signitficant!) which contributed to longer fluid life, seal life, bearing life, lube life, caliper life, pad life, and rotor life under high heat conditions.

The average 'crawler just don't go fast enough to benefit - but someone who spends a lot of time in city stop-and-stop traffic will! That's the guiding principle here.

Sorry for the lecture, I just wanted to clarify my thinking process for those who don't understand what I'm after...

5-90

[tom from boston]

cross drilling does not help with rotor / pad cooling, air flow over the components and the width of the rotor and the surface area to cool do. if you think a cross drilled rotor (wich actually yeilds LESS surface area for pad friction to contact is going to improve your braking, you're nuts. no offense to anyone who's bought them. we aren't talking about 1960's pads here that would have all sorts of gassing issues, we're talking about modern pads that unless they are TOTALLY abused, will give you enough stopping power to lock the brakes easily. now, if she's having problems with fade, that could indicate that a higher quality pad is necessary, but seriously, what's she doing that would put that much strain on the pads/rotors?
-tom

[5-90]

It's not fade (I checked) and it's not her driving style. It's mainly Bay Area traffic that's the problem (the stop-and-stop syndrome.) I'm also looking into improving airflow over the parts, and I'll have to rebuild the calipers anyhow, but I want to take a shotgun approach to solving this one because I'm tired of dinking around with it... As far as lost surface area - that depends on how much material you remove, and you really don't need to take out much. Besides, that's why I prefer the milled over the drilled - better structural integrity, less material removed, and they actually vent better if done properly anyhow!

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