Downshifting will not harm the drivetrain if done right.Don't try and downshift into 2nd gear while going 75mph,besides our electronically controlled transmissions will not downshift until it is safe anyways.Your instructors weren't to knowledgeable,I downshift all the time and have with every vehicle I've owned with no issues and some of the vehicles ranged back to the early '70's.Heck my '75 Cutlass and '84 Blazer had manual valve bodies in the trans that I installed,would not shift automatically anymore(up or down) and both also had trans brakes installed also and again zero issues and both where behind very healthy V-8's.

Cool, I always wondered about that info.

Another piece along the same line was that you should never coast in neutral in an automatic transmission. Don't understand that one either.

He was a great instructor in terms of having fun working on cars, but I always wondered about some of the advice he gave.

_________________
2005 Liberty Renegade
Old Man Emu HD Coils, OME Struts, OME Shocks
Tow Package with Champion Receiver Shackle
RB1 Navigation
245/75R16 Goodyear Duratrac's (Installed November 24, 2010
Slightly Trimmed Front Bumper and Wheel Well Liner
Pinch Weld Pounded
Custom Rock Rails
Rock Crusher Diff Cover (Not installed)

Some professional insight on drilled vs slotted rotors.............

Darrick Dong; Director of Motorsports at Performance Friction:
"Anyone that tells you that drilling makes the disc run cooler is smoking crack."

Wilwood Brakes:
Rotors are drilled to reduce rotating weight, an issue near and dear to racers searching for ways to minimize unsprung weight. Drilling diminishes a rotor's durability and cooling capacity."

From Waren Gilliand:
(Warren Gilliland is a well-known brake engineer in the racing industry and has more than 32 years experience in custom designing brake systems ...he became the main source for improving the brake systems on a variety of different race vehicles from midgets to Nascar Winston Cup cars.) "If you cross drill one of these vented rotors, you are creating a stress riser that will encourage the rotor to crack right through the hole. Many of the rotors available in the aftermarket are nothing more than inexpensive offshore manufactured stock replacement rotors, cross drilled to appeal to the performance market. They are not performance rotors and will have a corresponding high failure rate"

Baer Brakes:
"What are the benefits to Crossdrilling, Slotting, and Zinc-Washing my rotors? In years past, crossdrilling and/or Slotting the rotor for racing purposes was beneficial by providing a way to expel the gasses created when the bonding agents employed to manufacture the pads...However, with today's race pad technology, 'outgassing' is no longer much of a concern...Slotted surfaces are what Baer recommends for track only use. Slotted only rotors are offered as an option for any of Baer's offerings."

Grassroots Motorsports:
"Crossdrilling your rotors might look neat, but what is it really doing for you? Well, unless your car is using brake pads from the '40s and 50s, not a whole lot. Rotors were first drilled because early brake pad materials gave off gasses when heated to racing temperatures, a process known as "gassing out." ...It was an effective solution, but today's friction materials do not exhibit the some gassing out phenomenon as the early pads. Contrary to popular belief, they don't lower temperatures. (In fact, by removing weight from the rotor, they can actually cause temperatures to increase a little). These holes create stress risers that allow the rotor to crack sooner, and make a mess of brake pads--sort of like a cheese grater rubbing against them at every stop. Want more evidence? Look at NASCAR or F1. You would think that if drilling holes in the rotor was the hot ticket, these teams would be doing it...Slotting rotors, on the other hand, might be a consideration if your sanctioning body allows for it. Cutting thin slots across the face of the rotor can actually help to clean the face of the brake pads over time, helping to reduce the glazing often found during high-speed use which can lower the coefficient of friction. While there may still be a small concern over creating stress risers in the face of the rotor, if the slots are shallow and cut properly, the trade-off appears to be worth the risk. (Have you looked at a NASCAR rotor lately?)

AP Racing:
"Grooves improve 'cleaning' of the pad surfaces and result in a more consistent brake performance. Grooved discs have a longer life than cross-drilled discs."

Some more tech, from Brembo:

http://www.brembo.com/US/Performance/SportRotors/

Brembo Sport rotors are drilled OR slotted, never drilled and slotted.

Who should use Brembo Sport drilled or slotted discs?
Anyone looking for better braking performance with a simple change from your current brake discs to genuine Brembo Sport with either a drilled or slotted braking surface to maximize the interaction of the brake pad to the disc. Anyone who needs a better solution for their vehicles that are submitted to heavy braking. Anyone who has open spoke wheels and is looking for a finished “racing inspired” look to their brakes.

Should I use drilled or slotted Brembo Sport discs?
Brembo recommends the use of either the drilled or slotted design for normal road use.

What is the difference between drilled and slotted discs?
Drilled Brembo Sport Discs will operate at a slightly cooler temperature than the slotted version disc because of the added air surface created by the drill pattern. Slotted Brembo Sport Discs are recommended when using racing brake pad materials or the vehicle is submitted to extreme braking duties such as towing or hauling heavy loads. Both designs were engineered by Brembo to improve pad “bite”, improve wet weather performance, continuously refresh the brake pad and prevent gas from building up between the brake pad and disc.

Why are there so many holes in a cross-drilled disc?
The number of holes in a cross-drilled disc is part of the engineered system. Brembo has done extensive testing with regards to the number of holes, their size, their location and their chamfering. This attention to detail is what truly sets Brembo apart in the world of braking. The same attention to detail that is delivered to the Ferrari Formula One effort is a component of the high performance program.

Which direction should the discs rotate?
It is a popular misconception that drillings in a disc determine the direction of rotation. In truth, for an internally vented drilled disc, the geometry of the vanes dictates the direction of rotation. There are three vane types in use:
- Pillar vane (comprised of many small posts)
- Straight
- Curved vane
The first two vane types are non-directional, and can be used on either side of the vehicle. The curved vane disc, however, is directional. A curved vane disc must be installed with the vanes running back from the inside to the outside diameters in the direction of rotation. Orienting the disc in the manner creates a centrifugal pump. The rotation of the disc causes air to be pumped from the center of the disc, through the vanes, and out through the outside diameter of the disc. This greatly enhances the disc’s ability to dissipate heat. Additionally, all of Brembo’s slotted discs are directional, regardless of the vane geometry. The discs should be installed such that the end of the slot nearest the outer edge of the disc contacts the pad first.

_________________
2006 Magnum SRT8
1969 Cutlass


SOLD

Never did like brembo,they've gotten real cheap the last few years,shotty made rotors.You should never use drilled rotors for a DD,everyone I've seen come into the shop has been cracked and hot spotted.

From Wilwood's website.................

Q: What's the difference between slotted and drilled/slotted rotors? Which rotor will be best for my application?
A:

Slots or grooves in rotor faces are partly a carryover from the days of asbestos pads. Asbestos and other organic pads were prone to "glazing" and the slots tended to help "scrape or de-glaze" them. . Also, cross-drilling and/or slotting the rotor for racing purposes was beneficial by providing a way to expel the gasses created when the bonding agents employed to manufacture the pads began to break down at extreme temperatures. This condition is often referred to as "outgassing.” When it does occur, the driver still has a good firm brake pedal, but a significant reduction in friction. Normally this only happens at temperatures witnessed in racing. However, with today’s race pad technology, “outgassing” is no longer a concern with pads designed for racing.
So in the final analysis, drilling and slotting rotors has become popular in street applications for their pure aesthetic value. Wilwood provides rotors slotted, drilled or plain. For most performance applications, slotted is the preferred choice. With certain pad material, slotting can help wipe away debris from between the pad and rotor as well as increasing the coefficient of friction between the rotor and the pad. A drilled rotor provides the same type of benefit, but is more susceptible to cracking under severe usage; however, for street and occasional light duty track use, they will work fine. For more severe applications, we recommend slotted rotors.

I can only speak of my personal experience. When I was shopping brakes for my 2000 Land Cruiser, my friends dad recommended calling raceshopper.com and talking to them. They really knew their business and had been helping him with his brakes on his track cars. Most of the weekend warrior guys he was rally racing with were using them too. So I talked to them and they recommended trying the SP slotted rotors and some Hawk LTS pads (truck and suv). After 60k miles the pads were not yet done and the rotors were still fine. Did lots of wheeling with those brakes and never a problem. They worked better than stock and never had a problem cleaning out.

What they say about slotted rotors:

"We recommend slotted only rotors in any extreme service application. These would include racing, autocross, larger trucks and SUV's, and vehicles that exhibit chronic brake problems.

The nature of the slotted only rotor gives the greatest amount of braking surface, helps keep the pads clean, and increases initial brake 'bite'."

SP rotors are made in the USA. Delivery from raceshopper is fast and accurate both times I've ordered. That combination worked awesome, so I decided to try it on the Liberty as well. I'm going to install them in the next couple days and I'll post up some impressions when I get back from a week of wheeling. I hope they work as well for me as they did last time.

_________________
2002 KJ Limited
Select Trac
3.7L V6
45RFE automatic
OME heavy springs
Bilstein HD strut and 5125 extended rear shock (not quite bolt in - just some spacers needed)
Yokohama Geolander AT-S 245 75r16

I avoid a lot of the brake talk these days but I do agree that drilled rotors have no real business being used on the KJ. The brakes already have enough problem dissapating the heat generated from stopping and here some people are taking away metal from the heat sink [rotor.]

_________________
02 Liberty Limited
Silver Outside & Taupe Inside
Heated Seats, Sunroof & Infinity speakers
USA Spec I-Pod adaptor, Mopar Sub, Garmin GPS
Tow Package, Select-Trac
Rock Rails, Tow Hooks

I'm a wholesaler, and we actually just stopped carrying Brembo. And I work on the operations side of things, so I don't deal directly with the customers like a salesperson would... so my experience with Brembo is limited.

Just find it interesting that their opinion of drilled rotors seems to be different then everybody else. I will say, their rotors are much heaver then a stock replacement, maybe the density of the metal outweighs any weight loss from the holes... so cooling is not negatively affected by drilling.

_________________
2006 Magnum SRT8
1969 Cutlass


SOLD

Putting your trans in neutral while coasting at speed, then placing it back into gear while still at speed is simply hard on the transmission. It goes from spinning at 0rpm to spinning at engine speed too quickly. You can pop your xmission into neutral, but it's usually recommended you coast to a stop before placing it back into gear.

None of these things 'break' your xmission, they merely shorten its life.

_________________
-=Stock, but goin' places=-

04 3.7 Sport.
Auto Trans
Yokohama Geolandar AT/S 235/70/R16
Garmin GPS on RAM Mount

Mileage Trend:

Just put in my Powerslots and Adaptive one Ceramics:

_________________
-=Stock, but goin' places=-

04 3.7 Sport.
Auto Trans
Yokohama Geolandar AT/S 235/70/R16
Garmin GPS on RAM Mount

Mileage Trend:

I doubt they are any more dense than other rotors. If they are heavier they are probably larger in some dimension. All steels and stainless steels are equal in density, within 1%. Maybe if the stock rotors have cavities in them...

_________________
2005 KJ Renegade
Fabrications for sale: Aluminum Roof Rack (See Page 9)
Aluminum Gas Tank Skid -- Radiator Skid -- Front Strut Shims
Coming Soon: Rear Bumpers with lots of options