Frank Wiesmann

I need new brakes and was thinking of upgrading to slotted and/or drilled rotors in stock size on my 1991 300TE. Has anyone ever done this? Are there significant improvements in braking power?

CaliE320

I have Brembo X-drilled on mine. They're ok I noticed a slight improvment. I plan on adding steel braided hoses soon. They're supposed to add more brake pressure..

~Cali

Ron in SC

Cross-drilling is said to improve braking by decreasing brake temperatures, reducing rotor mass, improving bite and increasing brake pad to rotor contact by effectively reducing brake pad out-gassing.

I have them on one of my cars, not on my 92 300E though. Actually in some cars the holes are cast, supposed to not crack as easily. They are effective on the track, especially at tracks that are hard on brakes. The down side is it you will replace them more often since the heat will cause cracks going from the little holes outward, spider cracks. When they get longer than 5 mm at least on a Porsche they should be replaced.

cap'n jasper

Cross drilling will reduce braking efficiency for any given rotor size.

Bigdot

i have slotted on the 420. i cant tell the diff. but they look cool!


mark

Ron in SC

What facts lead you to reach the above conclusion?

If you start out with identical disks and drill one set it can be said that you have reduced the material needed to absorb the heat. However, cross drilled brakes cool much quicker than their undrilled counterparts.

brianw430

I put crossed drilled rotors on my 92 400E along with stainless steel brake lines. The rotors made no noticeable difference, the ss brake lines made for a much firmer pedal feel, but still no improvement in braking. You really need to investigate larger diameter rotors and sticky tires for the best results.

I still really like the pedal feel with stainless steel brake lines.

Jim's500E

Go with slotted if you want performance...drilled rotors are no good...the rotor acts as a heat sink really, when you have holes in them, there is less mass/material to soak up the heat generated by the pads friction.

Drilled looks cool and could reduce weight a bit but genarally they will crack and warp faster if you heat them up as compared to good ole solid rotors. Of course, if you have a race team and big $$$s, you can easily go thru drilled rotors all day long and throw them out when they fail. Cross drilled do not cool any faster either; that's what the internal vents are for; cooling.

Cyro-genetically treated rotors last a bit longer and absorb more heat but still...solid or solid slotted rotors are best for real performance. NASCAR now uses solid rotors, again, I'm pretty sure ; just for an example, not that I'm a NASCAR fan.

Ron in SC

A lot of people who run their Porsche 993's at the track bemoan the fact that slotted rotors are not available for the 993. I think that is the high performance chose, although the rotors with the cast or drilled holes are supposed to be pretty good in the wet.

ashman

Go for slotted with good pads and stainless steel brake lines and get your brake fluid flushed and refilled and bled.

AshMan

AMG_Eric

i have slotted rotors in a the atomic symbol configuration. the car stops better. however i have noticed the anti lock is not functioning correctly. dont know it is a result of the aftermarket rotor not getting hot enought to cause lock up or what.

also vent/slots do just that. they allow the heat/gas to expand more efficiently. they do not make your pads wear quicker nor do they make you go thru rotors quicker.

most drilled rotors crack at the HOLES. i went with vented because my buddy that runs an offroad shop and builds race toys said that the ventilation helps quite a bit.

also consider getting BIGGER brakes. a 6 piston or a 4 piston set will do much more then the stock setup. check with rami he has brembo 6 pistons on his 500e.

cap'n jasper

Brakes work by friction so the only way to increase the friction is to increase the size of the disks and pads.
Since the disks are already vented, the gain in cooling by drilling or slotting will be more than offset by the loss of friction area.
Unless this 300TE will be regularly used on a race track the best way to improve the brakes would be to upgrade to 24v or 500 brakes (expensive).
ATE do make 'Powerdisks' for the 300TE. Might be worth a look but I'm still dubious about any real benefit.
ATE Powerdisks

Jim's500E

I had to have my 500E rotors custom slotted locally as no one I found makes them.

There are several vendors also that advertise in the Grassroots Motorsports rag that will slot rotors and cryo-treat them. Chances are one is near you.

With the W124, its sooo easy to upgrade to SL600 or 500E brakes that its a no brainer if you need more stopping power. Don't be fooled by pretty painted calipers and wildly drilled rotors at big $$$s. And one only needs to upgrade the fronts...80% of the braking is handled up there. But beware that bigger brakes/rotors means more weight and you may notice it. I had SL600 brakes on the front and ditched them as ,to me, it negatively affected the way my car felt on a track; and didn't really offer any better stopping power than my stock 500E brakes.

This is a good thread as there are many differing views and schools of thinking. Lotsa food for thought.

vraa

If you check with www.tirerack.com , you can see that on a 1992 300E, there are plenty of different types of rotors that are slotted. I'm sure even drilled exist as well. They are however, expensive on that site. If you are looking for something specific, you can PM me with what you want, and I'll try to find you the best price.

AMG_Eric

um those are my rotors. so whatever statements i made apply to these rotors.

C43AMG

I have cross-drilled / slotted rotors on my Maxima ( haven't upgraded my C43 yet ) my experience is that the slotted rotors act like a deli slicer on your brakes pads and tend to need replacement at more frequent intervals.

cap'n jasper

From Tirerack's own website...
So slotted and/or drilled disks will reduce the braking efficiency and you'll never get them hot enough on a road car to get the benefit of reduced fade.
So, other than looks, there is no point whatsoever in using these type of disks!

AMG_Eric

that is a myth. you can call a few of my buddies that own race shops. slotted rotors DO NOT effect pad wear at all. if anything they would prolong it based on the fact that they can allow the gases to expand and disapate more quickly.

additionally think about it this way. if the slot are made with a bevel and not a sharp cut how could they shave away at your brake pads? ie this pattern \/ the pads dont flex into the slotted cut. they surely cant expand into the cut fast enough to shave them.

cap'n jasper

deleted.....bored with brakes now...

AMG_Eric

there is a point. using slotted rotors will decrease the wear on the rotor itself because it doesnt get as hot as a stock rotor to warp or wear at the same rate. actually that is why i bought them is the simple fact they are 20 bux more a rotor to go vented yet i will replace them less often then stock.

i believe you get like 1 maybe 2 brake changes out of a stock rotor before you either replace it or if you are lucky have it turned. i am betting and counting on 3-5 on the vented ones simply because they dont get as hot.

you might ask well how often do you do your pads? well in L.A. stop and go traffic quite often. i think like every 15-25k miles. which is like every 6-12 months.

AMG_Eric

to quibble about words would be pointless; however its 1st point is brake power. i would have to equate brake power or strength of brakes to stopping power. you may disagree but i dont want to be in a pissing match over 1 word and its meaning.

additionally one must ask the simple ? that is in everyones mind. if they are just for show why does every race vehicle use slotted and vented disc brakes? answer is because they keep heat to a minimum over conventional NON-slotted or drilled rotors.

Ron in SC

With enough heat they all crack.

YNVDIZW124

i can get set of ATE O.E for only $45 a set so to change them every 6 months is ok with me. Anyways if you like your rotors don't let no one stop you! LOL I think x-drilled (zimmerman) and sloted (ATE) look cool if you have a cool set of rims to show them off. As far as braking power is the same thing if you install a ram air system and you only drive 65mph? Looks cool huh!

The difference between racing x-drilled/slotted is that they are made of different material that have a higher heat range (carbon/kevlar) and the major thing is that all race cars have cooling ducts going straight to their brakes to reduce brake fade. I don't know of any member who was this on this forum? so those are my .02 c.

TO ALL YOU PEOPLE WHO COMPLAIN ABOUT WHICH IS BETTER X-DRILLED OR SLOTTED THEN JUST BUY THESE! LOL WORST ROTORS IN THE WORLD READ COMMENTS AT TIRE RACK!

94 E420

Hey at least there gold.

AMG_Eric

lol those are not mbz rotors for a w124. i can take mine off and show you rotors with 2000 miles and have been used in 100mph braking situations and still look BRAND NEW. showing old nasty rotors only distorts the point you are trying to make. its like saying a knock off AMG wheel can withstand the same forces a true AMG wheel can. just because it looks and smells like the real deal doesnt mean it is the real deal.

btw i have the continous slot/groove NOT drilled. drilled WILL CRACK if they are cast and the metal has not been treated.

additionally everyone is missing the fact that the pads themselves off gas which is why when u have slotted rotors they dont heat up as fast.

you can post all you like its a fact ALL RACE CARS, almost ALL motorcycles, and RACE TRUCKS come with either slotted or drilled rotors. now either there is a conspiracy or they actually work better at disapating heat.