Brake Rotor Question

[andrewjscott]

I've been looking into a big brake upgrade and i had a couple questions. What is the brake rotor offset for our cars? If i know that I can look around for rotors from different models/manufacturers that might work. I had a friend that did it with 12" vette brakes onto a Fiero, just wondering if there are any options like that for us.

 

[andrewjscott]

I just realized it doesn't really matter, if i plan on using the stock caliper I'll need to make up brackets to suit, and if the offset is a little bigger, i can just draw up the bracket to accomidate.

 

[AiR]

Just to let you know it would be pointless to use the stock caliper and put big brakes on it, the pads would still be touching the same amount of rotor.

 

[wret]

Not totally pointless. A bigger rotor would theoretically have more mass to absorb and diffuse heat.

 

[bjones18]

Just to let you know it would be pointless to use the stock caliper and put big brakes on it, the pads would still be touching the same amount of rotor.

Hold on sugar.....Daddy's got some heat to dissapate

Your brakes have 3 x the horsepower of your engine. Physics! (from E = 1/2 mv^2 )
Power = Energy/time (the 3 x because your stop time is 1/3 your accel time 60-0 vs 0-60)

Sooo.... your brakes have about 600 HP! This is a MASSIVE DOSE of Energy dumped into your brake rotors/pads is a really-really short time. (have you seen race car brakes glowing red hot?). The temp your rotors get up to is based on your speed, vehicle weight, rotor mass and rotor specific heat.

If your rotors cannot get rid of the heat... it will conduct into your pads, brake fluid, bearings wheel/tire and so on

So how do you get rid of the heat energy you injected into your rotors? conduction, convection, & radiation. Conduction is generally bad cause the components the heat conducts to can't take heat. (mentioned above). Radiation....it is only significant if you can see the heat (red or orange)....and boy-o-boy does it transfer....If you are reading this and learning DO NOT COUNT ON RADIATION AS A MEANS OF HEAT TRANSFER...THIS IS FOR RACING EXPERTS who flush more money than you make in 10 years...YOU WILL MELT YOUR CAR. This leaves convection as your primary means of expelling the heat energy in your brake rotors. Heat transfer by convection requires rotor-surface-area and air-velocity.

Big brake rotors have more heat-transfer surface area. Some rotors are a very effective centrifugal air pump (slanted or curved vane). cooling ducts and open style wheels are also very effective at increasing the air circulation to the rotor.

One stop isn't the problem. Engineers design the brake system hydraulics so that you can stop with tiny rotors....the problem comes in when you want to go really fast...stomp on the brakes.....tromp on the accelerator to 130 mph...stand on the brakes.....accel WOT up to 140mph.....then stand on the brakes going into a 40 mph turn Sound fun? it's RACING! if you do this with small brakes you will quickly learn what every trucker knows... brakes will FADE (i.e. stop working) when they reach a certain temperature....because the pad material coefficient of friction drops

So.... If you want to race competitively or drive real fast....big brakes are more important than your life insurance policy.

 

[Todd TCE]

Just to let you know it would be pointless to use the stock caliper and put big brakes on it, the pads would still be touching the same amount of rotor.

No, actually as the caliper is out further on the new rotor is has a new effective radius.
Thus rotor torque is up. And perhaps quite a bit if the rotor is larger enough. Swept area would also be up and that means more total capacity.

Pad size has nerly nothing to do with brake torque beyond that which determines its ER.

 

[bjones18]

Big brake rotors have more heat-transfer surface area. Some rotors are a very effective centrifugal air pump (slanted or curved vane).


320x32mm
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[andrewjscott]

My friend with the vette brakes loves them, he has Axxis Metalmaster pads and during our driver training he experienced no fade, nothing. Some of the civic's out there had glowing rotors but not him. anyways, back to the options available, i found a few on Brembo's website; they have a great "search by dimension" tool. anyways, this is what I found:

Stock 91 Talon TSI AWD

Fronts:
Diameter 256mm
Thickness 24mm
Total Height (what I called offset earlier) 45.1mm

Rears
Diameter 256mm
Thickness 10mm
Total Height 49mm

As for Big Brake options:

Rears:

Alpha Romeo 166 (Brembo part#08.6768.10)
Diameter 276mm
Thickness 10mm
Total Height 51.7mm (a slight difference but can be made to work)

BMW 518i, 520i ect.. (Brembo part #08.5174.30)
Diameter 300mm
Thickness 10mm
Total Height 61.1 (bigger difference from stock, but its only further back, there is no obstructions)

For the fronts:

i can only find DSM 276mm brakes from 93+ AWD


So from this I can put a full set of the 276mm all around, but I'd really like to find a 300+ front rotor so i can use the BMW 300mm rotors in the rear. (i don't want to have larger brakes in the back than in the front)

The thing I noticed is that they do not have a lot of sports cars listed (Chevy Corvette and Ford Mustang just to name two) does anybody know the thickness of Mustang brakes; or any other make model with rotor thickness of 24mm?

 

[Todd TCE]

Just kinda passing through on this one....but....

You DO realize that simply buying some larger or alternate rotor is only part of the problem with fitting them to your car right?

Larger dia and a change in offset moves the caliper to a new location. This means a relocation bracket. And to keep it simple; you can seldom move it only a little bit. Meaning a dia change of say 1" moves the radius only 1/2" and that's not too easy to do. I won't go into it real deep but bracket changes like this are nearly impossible.

You also would chnage the center line of the rotor so that bracket has to be able to center up the caliper as well.

Lastly change in width means either you have spacers behind the pads for a skinny rotor (not what you had in mind I bet) or used pad in the caliper for a fatter rotor (your plan more likely) as you'll never get proper pads in the caliper with a wider rotor.

I guess if you're onto complete new calipers from some other app as well you might pull off something. On the other hand as you spend countless hours engineering something that may or may not work others might be driving around on a pre done kit from various suppliers. What's your time worth?

 

[FORMONTOYA]

if you have about $900 to spare (cheap for a good set of street/track brakes f/r)...power slot plus (rotors 11.7f/11.5r and relocation brakets), fresh calipers, ebc greenstuff pads (or your choice), and ss lines. a really nice setup for the eclipse...and not some exotic, expensive setup you will never really get the full potental (sp?) from. how many of you guys really need 13" 4 piston caliper setups...a handful at most. 99% of you will be more than satisfied with above setup.

jim

 

[ACM]

Overheating stock DSM brakes is really quite easy, even on the street running normal street tyres. The advantage of larger rotors is that they allow more frequent stops from higher speeds than the stock brakes can tolerate.

An afternoon in the Vt/NH mountains can reduce a set of Porterfield R4Ss to a sad example of the white crumblies with stock rotors, whereas switching to the AEM big rotors will allow an entire weekend with very little wear at all on the same pads.

DSM brakes are way too small - even for autocross speeds, never mind anything else. We end up spending a fortune on pads because we don't have the heat sink mass in our brakes, so we need fancy pads to put up with the thermal stresses.

All depends on how/where you drive. Anybody who can get by on EBC Greens or Metal Masters etc clearly has no need of improved brakes, but there are plenty of people who fry that setup immediately.

Any kind of competitive use requires significant brake upgrades on a DSM, be it $200/set R4-1 pads, $600/set AEM big rotors, $900/axle big brake kits or combinations thereof. Even lowly autocross speeds require jumping through (expensive) hoops to get DSM brakes to survive.

Charles

 

[FORMONTOYA]

All depends on how/where you drive. Anybody who can get by on EBC Greens or Metal Masters etc clearly has no need of improved brakes, but there are plenty of people who fry that setup immediately.

agree totally...the reason i bumped to the power slot plus is because i first went to just ebc greens and ss lines (w/noticable improvement), and in no time i cooked the front rotors...the pads held up to the abuse, but the tiny rotors were so stress cracked it was unbeleivable. probably cooked the rubbers in the calipers also (fresh ones just in case). as stated...if you want to go fast, you need to be able to stop fast...and shutting down a 3000 lb car more than once requires more than a set of 10" brakes.

jim

 

[ACM]

The problem with Powerslots et al is that you're carving even more mass out of a part that's mass-deficient to start with. The last thing in the world a DSM needs is lower mass rotors. That allows them to heat up faster and to a higher temperature, so that a higher temp pad is needed, which in turn almost always reduces cold bite to unacceptable levels ($200/set R4-1s excepted). This reduces the consistency and predictability of the brakes to problematic levels.

I've cooked 2 or 3 sets of EBC Greens used under different conditions in my street 98 - they are simply unsuitable for this car. They have great cold bite, but overheat far too quickly, after which they never work well again. They are probably fine for a non-turbo, as they are comparatively light weight and simply can't get back up to speed fast enough to stress the pads - everything's cooled down by then. On an AWD they are simply not up to the task. Greens with something like AEM large rotors would probably be a decent street setup, they probably won't overheat under normal use.


Charles

 

[c5chris]

Im interested in hearing more of that Corvette brakes on the eclipse. I have a few sets of rotors and calipers that Im not using and would be good if I can retrofit them on the DSM.

Todd (TCE), I know youre an expert on this, any way I can do it?

 

[L2RTSiAWD]

I know (on a 1G at least) someone fitted mustang cobra 2-piston rotors and calipers.

 

[wret]

I was just eyeing a set on ebay this morning.
http://cgi.ebay.com/ebaymotors/ws/e...ry=33564&item=7962058846&rd=1&ssPageName=WDVW

 

[FORMONTOYA]

The problem with Powerslots et al is that you're carving even more mass out of a part that's mass-deficient to start with. The last thing in the world a DSM needs is lower mass rotors. That allows them to heat up faster and to a higher temperature, so that a higher temp pad is needed, which in turn almost always reduces cold bite to unacceptable levels ($200/set R4-1s excepted). This reduces the consistency and predictability of the brakes to problematic levels.

I've cooked 2 or 3 sets of EBC Greens used under different conditions in my street 98 - they are simply unsuitable for this car. They have great cold bite, but overheat far too quickly, after which they never work well again. They are probably fine for a non-turbo, as they are comparatively light weight and simply can't get back up to speed fast enough to stress the pads - everything's cooled down by then. On an AWD they are simply not up to the task. Greens with something like AEM large rotors would probably be a decent street setup, they probably won't overheat under normal use.


Charles

maybe a misread...i bumped to the power slot plus, not just the oem sized slotted rotors...they bought out aem big break division last year or before...same exact thing aem had before the sell. however, i agree that just a set of oem sized rotors that have been machined is not doing any good. if you do not use greens, have you tried the reds? i thought the reds would not give a good enough cold bite for the street which is why i use greens. the bigger rotors seemed to help on the hot side...but my turbo took a dump before i could give them a good repeat test.

jim

 

[ACM]

maybe a misread...i bumped to the power slot plus, not just the oem sized slotted rotors...they bought out aem big break division last year or before...same exact thing aem had before the sell. however, i agree that just a set of oem sized rotors that have been machined is not doing any good. if you do not use greens, have you tried the reds? i thought the reds would not give a good enough cold bite for the street which is why i use greens. the bigger rotors seemed to help on the hot side...but my turbo took a dump before i could give them a good repeat test.

jim

Sorry Yes I mis-read, and forgot that Powerslot had bought the AEM range - apologies. That setup is, I think, a great bang-for-the-buck upgrade.

EBC...As soon as I heard they were moving into car pads I called them up; I helped EBC UK identify which Evo pads matched the 2-piston DSM calipers . I sent the first set of Greens back to the UK and they confirmed they'd simply fried. I was sent a set of Reds to try which, once warmed up, were pretty good - but cold bite was miserable, so those went on the shelf as well, and I switched to Porterfield R4S.

Skip a couple of years...Once the undrilled AEM big rotors came out I switched to them, and decided to try the latest iteration of Greens at the same time. Things seemed OK, but the pedal was quite soft. Ultimately we turned the rotors which turned out to be warped, faced the pads off and tried again; Better but still soft. I faced off a set of used R4Ss from the racecar and tried those in the front. Night and day - hard pedal, great bite. New R4S pads all round and it's been great ever since.

I really wanted the EBCs to work out - I've used them on all my bikes (albeit HHs) and love them, no complaints. But I can't get them to work on the car. I still use EBC in all my bikes, but I keep coming back to Porterfield for the cars every time I try something else.


As an aside on the Mustang setup - check the rotor weight before going that route. Plus, if the 'buy it now' price is indicative, I think TCE's kits are no more expensive - and he uses 2-piece rotors, barely heavier than the stock ones. That's an awfully lot of unsprung weight.

Charles

 

[420a16g]

I dunno if this has already been said or not (got tired of reading) but AEM makes a big brake kit for the Eclipse that works with the stock components. I think it has 13" rotors and comes with new calipers i believe, cant remember. if i remember correctly a set it only about $400 too. so you could buy a kit for front and back for about $800 which isnt bad imo.

 

[FORMONTOYA]

I dunno if this has already been said or not (got tired of reading) but AEM makes a big brake kit for the Eclipse that works with the stock components. I think it has 13" rotors and comes with new calipers i believe, cant remember. if i remember correctly a set it only about $400 too. so you could buy a kit for front and back for about $800 which isnt bad imo.

yes it has...however power slot bought out aem big brake line...same thing as before w/aem. and no...11.7f/11.5r. and yes, f/r with relocation brackets cost less than $800.

jim

 

[housegsx]

The Corvette and Cobra brake setups use a PBR caliper and 13 inch rotor. Those calipers are the same as those with the Baer track kit. I got them for around $650 and the big brake power slot rears for $270. This setup works great for me. A four wheel big brake upgrade for under $1000. And you get those new front caliper to replace those garbage stock ones.

http://www.hopupracing.com/bafrtrclbrsy2.html

 

[420a16g]

yes it has...however power slot bought out aem big brake line...same thing as before w/aem. and no...11.7f/11.5r. and yes, f/r with relocation brackets cost less than $800.

jim

so if power slot bought out the AEM big brake line, where can you get this kit from? do you have to go to power slot or does AEM still sale them???

 

[FORMONTOYA]

so if power slot bought out the AEM big brake line, where can you get this kit from? do you have to go to power slot or does AEM still sale them???

you buy them from power slot...aem no longer sells big brake kits. i got mine here:

http://www.buybrakes.com/powerslot/power-slot-plus.html

$685 shipped when i bought mine...a little more now, but still for $800, you can not beat it.

jim

 

[andrewjscott]

All these replys are great, very informative. Unfortunatly 800USD turns into 1000 CAD for me, plus added shipping and GST AND PST (an extra 14%), plus brokerage fees if shipped by UPS/Fedex I'm probably looking at approx 1300 CAD. I'm only 19, I'm going to Univeristy full time and don't work enough to afford that. My front rotors are warped (have been since i bought it) and my rear rotors need replacing aswell and I'm definatly going to go with a high performance pad.

What i need is something cheap, I can replace with all stock parts (except for performace pads) for about 400 CAD alltogether. Now I have a little more than that, I can spend up to about 600-700 CAD. For me, ordering off the internet for brake packages is not practical due to extra shipping costs, brokerage fees, and tax.

I am going to buy all parts seperately I know a guy at a local parts store that can get me some pretty good discounts. I think i'll end up going with the stock one pistion caliper that came on my car, make my own mounting brackets, and go with the 276mm Mitsu 93+ AWD on the front and the Alpha Romeo 166 276mm rotors on the rear and performance pads. I would go with the 93-94 calipers but in BC theres only 2 autowreckers that have them and i can't seem to find any in the classifieds/ebay. The cheaper one wants 150/caliper (no guarenteee)....so that ain't happenin. In store i can get them for 120/caliper....plus a 60 core which is no good.

I've priced out the rotors and pads with my stock caliper, and it'll come to about 475 dollars but; seems to the jump from 276mm to 300+mm will be a huge cost increase. Unless somebody can come up with a 300+mm rotor that will work I thnk i'm gonna go with the above.

 

[Poloturbo]

Just installed the Cobra 2001 PBR kit last week. Few details:

225$US for calipers with stock pads from the Cobra
34.50$US for the rotors (the pair)
160$Can. brackets and rings and shipping

I bough Porterfield R4-E for track use also.

On the 2G you need a bit of grinding in the back of the steering knuckle to make it flat and fit the brackets, a few shims= 0.4" between the brackets and calipers.

YOU NEED ABSOLUTELY the bango bolts, but SS lines will fits with the banjo bolts.

Awesome braking power and for my purpose a lot more thermal capacity in 13"x1.10" rotors. Will fit any 17" wheels even stock ones.