How come L/R brake rotors are the same?

[SheeperS]

Seems to me the left and right rotors are the same . So when they're put on different sides, the hole pattern and the ventilation slots between the rotors surfaces have different rotational orientation.

Why did lotus put rotors this way ? or is it a common practice ? The Power Slots rotors on my bmw had "L" and "R" markings on them, and they have mirror image slots.

[Stan]

It's a cost savings measure which does not affect performance. Lotus tested this setup and the temp differentials side to side were there but of no consequence. Compared to most cars, Elise brakes are huge for the vehicle weight and temps are much lower than many experience with "normal" cars. A stock Elise runs lower disc temps than many fast cars running Stoptechs or Brembo aftermarket kits for example.

You can read more about this if interested by doing a forum search.

[jtanner]

Reg Reimer experimented with the direction of the rotors on the MKIV Supra Turbo. After some fairly exhaustive tests (including multiple stops from 100+ mph), he determined that there was no measurable difference between mounting the rotors "correctly" and mounting them "backward".

Jim

[008]

Because they're cheap.
Stan, have you taken rotor temps side to side yet? Last time I was at the track there was a gentleman there in a Yellow Elise and he hit his rotors with the pyrometer. The fronts had a 20 degree difference side to side according to him. The backs weren't as much. I'm going to take temps next time. I wonder how this will effect rotor and pad life over a period of time.

[Stan]

>>>Stan, have you taken rotor temps side to side yet? Last time I was at the track there was a gentleman there in a Yellow Elise and he hit his rotors with the pyrometer. The fronts had a 20 degree difference side to side according to him. The backs weren't as much. I'm going to take temps next time. I wonder how this will effect rotor and pad life over a period of time.<<<

Having designed and built racing brake systems...I can tell ya that a 20 F differential is nothing. No effect of any significance. Your pads and discs will not wear any differently side to side due to this small differential. It's just not enough to do anything. I think this was a good cost/benefit/performance decision on the part of Lotus. We get the bling discs which are stronger due to the curved vanes, at an affordable cost compared to bog standard straight vaned discs which are weaker. CV discs were first used on 60s endurance racers (Shelby I believe) and they resist cracking better than conventional when they spend a lot of time at high temps with constant ups and downs. No real benefit for the street except for the bling. Same disc is used at all four corners of the Elise.

[008]

Those were not my numbers, just what I was told. At what temp difference do you think there will be a difference translated to rotors, pads, fluid, etc.? I'm going to take some temps myself to see what my differences are. It may be even less. I agree that this car has a great brake to weight ratio, one of the best of any car I'd wager.

[Stan]

>>>Those were not my numbers, just what I was told. At what temp difference do you think there will be a difference translated to rotors, pads, fluid, etc.? I'm going to take some temps myself to see what my differences are. It may be even less. I agree that this car has a great brake to weight ratio, one of the best of any car I'd wager.<<<

It depends on the temperature. At lower temps a greater differential can be withstood but this is rare anyway. I'd be worried if it was say 200-300 F different from side to side and say 900-1000 F on the cool side. In that case you can still use the same setup, just get more cooling air to the hotter side. And this would only happen on the track anyway.

Remember that there are different kinds of brake fade. And that when a pad is fading, it is also wearing rapidly. Some guys at the track say they never get fade...and then go through a set of pads in a half day! Well...they WERE experiencing fade.

Spoon rotors for the Honda S2000 have only one "side" and are curved vane discs. One owner reports about an 80 F difference up front. No noticeable drawback. An S2000 has to do more of it's braking up front due to the ~ 50/50 layout versus our pronounced rear weight bias. This bias allows the rear brakes to contribute more than usual to hard braking efforts...which offloads the work from the front of the car. The Elise should experience low fade and long parts lives compared to many other cars that show up at DEs.

[008]

Sounds good. I seriously doubt the differences are anywhere near what you say is unacceptable so there should be no noticeable difference. I have seen however certain aftermarket setups installed "backwards" resulting in much quicker pad wear. I also can't imagine it would cost much more to have a separate mold for each side. But hey now we can rotate rotors!

[Cisitalia]

The L/R thing does not matter to me. I understand that the performace difference is negliable. It is nice from a spare parts inventory that all four disc rotors are interchangable. What is not nice is the dealer price of $189 each per rotor.

My question is where can I get the stock rotors or OEM equivalents for much cheaper? I hope to get them cheaper because I will track the Elise and will use up rotors faster.

Thanks for any help some one may have.

Brad

[Stan]

>>>My question is where can I get the stock rotors or OEM equivalents for much cheaper? I hope to get them cheaper because I will track the Elise and will use up rotors faster.<<<

Maybe you won't!

I know some folks who get 1 track day out of their Z06 brakes. But replacements are dirt cheap.

The Elise rotors will last far longer than that!. For more life, get some cooling air in there if temp studies locate a potential issue.

On BMWs I have open tracked, a decent ducting setup can roughly triple disc and pad life. 'Course the Bimmers hit high front brake temps which the Elise won't approach. If you Brembo most BMWs you still have less brake for the weight than the Lotus. Plus the Bimmers hit the front brakes hard due to the 50/50 distribution and the forward weight transfer. The Elise can spread out the work much more and has larger vented brakes than many much heavier cars - and they are put to use!

[Enigma]

Originally posted by Cisitalia
The L/R thing does not matter to me. I understand that the performace difference is negliable. It is nice from a spare parts inventory that all four disc rotors are interchangable. What is not nice is the dealer price of $189 each per rotor.

Thats still less than what an M3 rotor cost... I bet these will last me more than 2 days at Laguna Seca.

FYI: by comparison the Z06 rotors are ~$30, lots of track guys just replace them when they do the pads.

[Ground Loop]

When I took the car out to 'bed' the pads, I had a particularly difficult time getting some heat into them. It got to be pretty amusing.. "Are they HOT yet?"

The G35 had smoke pouring into the windows standing still after six rapid stops.

In the Elise I had to lean out the door and sniff to see if I was doing anything at all.

I'm still coming to grips with the whole "lightness" thing.

[sleepless]

Originally posted by Cisitalia
I will track the Elise and will use up rotors faster.

I'm expecting the rotors to last a LOT longer than they do on a Z06 which for some reason eats rotors as fast as it eats brake pads. At best I got 4 track days out of a set of front rotors on the Z06. I'm betting the rotors on the Elise last at least 10 track days.

[Cisitalia]

I know the Elise rotors will last much longer than most cars. But that does not detract the point they will have to be replaced more often when used on the track for let's say 25 track days/year.

Doe anyone know where to get rotors for less money than $189 each from the dealer?

My Z06 depending on the track went through 4-6 tracks days before replacement. I had extended brake cooling ducts and spindle ducts which helped slow the wear rate on the rotors/pads. Yes rotors are dirt cheap at $25 each delivered to your door and very easy to replace.

My previous E36 M3 went throught rotors not as bad as the Z06 and the Euro floating rotors cost about $100 each plus S/H.

Ok, since the Elise will encounter less temperature for the rotors/pads, then a lower temperature race brake pad is in order. Therefore less agressive and the wear rate will be slower. So what is a good track brake pad for the Elise. I am an experienced instructor so I want some thing that will perform. I will be doing the following tracks: VIR, Road Atlanta, Barber, Carolina Motorsports Park, Roebling Road, Rockingham, Atlanta Motor Speedway, Lowes, Watkins Glen and Shenendoah.

Thanks, Brad

[Arno]

Originally posted by Cisitalia
So what is a good track brake pad for the Elise.

Ah.. A topic of much religious debate

But the general idea (because the car is relatively light with large brakes) that you can usually uses more 'endurance' type pads with a medium friction coefficient (around 0.45 or so).

This usually matches up as the endurance pads sold by different brands already don't get the very high friction numbers (over 0.55) that the shorter lived 'race' pads do.

Too high friction pads on the Elise is a problem because the car gets over-braked and the pads become too 'grippy' to be able to have good and smooth control of your braking effort, which is a pain on the racetrack.

A much overlooked part is also the release-characterisic of the pads. Some types (esp. the high-friction ones) tend to 'hang on' to the disc and won't release very gradually.

In europe the 'defacto' choice for track work are the PAGID RS14 pads and the RS4-2 for combined road/track use. Both offer a high level of control over the brake process, good release properties and a very stable response across the whole temperature range.

When people used the 'improved' RS15 pads on the Elise they found them to be too 'grabby', so it would lock up (no ABS of course) very quickly and it was hard to modulate the brake pressure. The same problem happened on more lightweight cars, so PAGID now makes both the RS14 and RS15.

Some people do run RS15's on the back of the Elise to play around with the brake bias a little.

I'm currently running SBS ProTrack pads and they seem to be working very well too, but as I said.. The choice for a specific brand/type is usually a topic of much religious debate.

In the USA I'd take a long hard look at performance friction (esp. the 97 compound).. I talked to them and they did know their stuff..

Bye, Arno.