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Discussion Starter #1 (Edited)
This thread is in response to specification questions on the standard brakes. It will include standard specifications and as time permits upgrades and newer versions (and anyone who wants to add their specs please feel free to do so).


Brakes:
The standard brakes on the Elise/Exige are a cross drilled and ventilated iron disc.
Brake disc thickness
New = 26.0mm
Minimum service thickness = 24.0mm.

Runout
New maximum- 0.03mm
Service maximum - 0.10mm

Note: this is the correct figure (direct from Lotus UK) - there is a typo in the early versions of the service manual where it incorrectly states the service minimum as 24.9mm (the figure for the early S1 alloy discs).
 

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Just what I was looking for. My Elise has around 21500 on odometer and has gone thru the stock front pads and a set of Pagid Blues. My primitive caliper measures ~25mm on front rotors so they should be fine for at least one more set of pads right? Maybe even 2 sets. Any advantage to replacing the stock rotors early? They are smooth and true.
Rears are ~60% thru second set of pads which are DTC-30's and have a similar thickness left
 

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Thinner rotors can't hold as much heat. It shouldn't be a problem unless you do track days.
This depend of the brake pad since the disc can run hotter with racing pads.

For brgelise: if you don't have cracks on disc it is ok and point out that you do not generate so much heat on discs. No crack = no disc replacement. The cross drilled disc have tendency to crack around the holes.

It is 2 reasons replacing discs when they start to be too thin: for heating capacity, heavier disc authorise running less racing oriented brake pads; with wear out pads, if the discs are too thin, the piston start to be at the end of his stroke, at the extreme with very thin discs, the piston seal can start to leak...
 

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Discussion Starter #5
Just what I was looking for. My Elise has around 21500 on odometer and has gone thru the stock front pads and a set of Pagid Blues. My primitive caliper measures ~25mm on front rotors so they should be fine for at least one more set of pads right? Maybe even 2 sets. Any advantage to replacing the stock rotors early? They are smooth and true.
Rears are ~60% thru second set of pads which are DTC-30's and have a similar thickness left
They should be fine - and they are easy enough to measure in service anyway :)
Thinner rotors can't hold as much heat. It shouldn't be a problem unless you do track days.
I would think that while thinner rotors can't hold as much heat the rate of dissipation should be the same (no effective change in surface area).
 

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Thanks everyone, was going to use some Xmas money for some rotors but I'm sure it will get put to good use somewhere else! I'll buy some next year when i find a good deal. Seen as I run DTC30's instead of HT10's at present, my heat issues aren't quite as severe.
 

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My rotors have many many circular grooves going around the disc, but the car still brakes fine i think.

Should i have to replace them soon?, what about resurfacing them?
 

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don't do anything except spend more time to bed new brake pads after installation.
 

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My rotors have many many circular grooves going around the disc, but the car still brakes fine i think.

Should i have to replace them soon?, what about resurfacing them?
It depends upon how deep the grooves are. You can pull them and take them into a shop. They will measure to determine if recut will leave rotors too thin. An honest shop will give you the right answer, but if they are not too deep they will resurface them for great results!
 

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some cracking is allowable, here's what AP has to say about cracks

Care & Safety of Discs
Discs must be regularly and frequently inspected for excessive heat crazing and cracking.
Discs with cracks emanating from mounting holes / slots, inside diameter, scallops, or outside diameter should be changed immediately.
After heavy and prolonged use some surface crazing will often be evident. If this turns into distinct surface cracks which are radiating towards the inside or outside diameter the disc should be changed.
IF IN DOUBT REPLACE
Cracks like these AP Rotors are not bad,
 

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308mm Ap racing s240 260 rotor wear specs

This may be a double post but I had trouble finding this info quickly, so I'll post it here just in case. The standards for the 308mm AP Racing 2 piece rotors are not the same as the smaller 288mm rotors that came on all the cars prior to 2008. This is from the Lotus Manual. Take note to the 26mm new, 25mm service limit -eek--eek- not much room for wear.

Front Discs:
The front discs are increased in diameter from 288mm to 308mm, and are cooled by internal curved
vanes which trail the normal direction of rotation, to result in distinct RH and LH components. Each disc is
mounted to its hub via an adaptor 'bell' from which it should not be separated under normal circumstances.
Torque of disc to bell mounting bolts; 14 Nm. Note that these discs are fitted only on the front, with standard
discs on the rear.

New thickness of the front discs is 26.00mm; minimum service thickness 25.00mm
 

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I'm glad I found this thread. I need brake pads but the rotors looked good so I wasn't going to replace them. When I had the car in for the oil cooler recall, the dealer said the rotors needed to be replaced because they were at 25.04-25.12mm. If the minimum spec is really 24mm, then I can run another set of pads through them! Whew, what a blessing that is since I just had to buy a radiator!

p.s. Why do rotor prices range from $60 on rock auto for a Centric slotted rotor, to $300+ from Sector111, dealers, etc? There must be a best "bang for your buck" for a normal, stock, street driven Elise right?
 

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Money is talking on brake parts. The dealer have interest to replace rotor quite often. In practice, too thin rotor can be hazardous if the caliper piston can move out and leak with wear out pads. In this case, if the spec call for 24 mm minimum, this is probably the safe minimum to avoid this trouble.

Also, thickness of the disc is important for the rotor mass itself. The mass is important to accumulate heat during braking. More the mass is, and less the rotor temperature will rise. Now, the Lotus have quite big disc for the car weight, and in street, good luck to create overheat of the pads. The car is able to track with standard components. If you don't experiment brake pads fading during your usage, this mean that the discs are heavy enought for your application.

Brake disc price difference? Not an easy one to answer. Typically, more expensive disc are welcome to be more stable and stay straight at high temperature. Also, depending of the brake pads you are using, the disc must not wear out too quickly. And also more expensive disc may have better air vans to extract heat after braking to cool down quickly. If you use very agressive brake pads, harder disc are welcome. If you use standard pads on street and run smouth and not create high temperature, you can use cheaper disc. If you use agressive compound brake pads like Raybestos ST-43, hard disc are more than welcome (I am using Alcon disc $500 each for 3 years now street and track with the ST-43 and more than 300 hp). For the sector disc, you can have 2 pieces discs, it save weight and since the hub is an aluminum and not part of the disc itself, the disc have less tendency to curve at high temperature. One piece rotor is good for low temperature, and 2 pieces are welcome for high temperature, and save few pounds of not usable mass.

The car have typically too much braking bias on the front, big brake in front just increase this already wrong brake bias.

A lot of options down here, and all make sense for different application.
 

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Here is a question for correct bedding. "Burnished" rotor is a part of that process. So when we use aggressive pads its more important to bed in brake pads(transfer of pad material onto the disc surface etc).It can be more helpful than just to buy another rotor.Even "that" most expensive rotor can not give ideal brake performance without correct bedding with exact pad,but good bedding can make any brake system better.
 
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