mounting sti brakes on a lgt.

[Tuned200]

i found a set of stock sti brakes (front), calipers and rotors all for 800. It seems like a good deal. They have less than 2,000 miles on them. The problem is the rotors are drilled for 5x114.3.

 

What are my options?

 

Redrill rotors?

Buy new or aftermarket rotors $$$

 

Pass on the deal.

 

Is 800 for the complete front set a good deal? what aboutthe master cyl? How will the petal feel with these and stock rears?

[Xenonk]

pass on the deal, the STi setup isnt going to be the improvement you are looking for.. what you need are better tires and brake pads. The LGT rotors are actually big and it's not that much smaller than the STi Rotors.. I doubt you would want to mess with brake bias when changing to the other calipers.

[Tuned200]

what about rotor dia.? thicker =better

[rougeben83]

what about rotor dia.? thicker =better

 

You mean rotor thickness? The LGT rotors are a little over 1" thick IIRC. STi's are 1.2" thick. STi rotors are 12.7" in diameter. LGT's are 12.3" in diameter.

 

In either case, it's going to take a lot of braking to wrap or fade the brakes with either setup.

 

What you're paying for is the 4 pot calipers with the bling-bling brembo appeal.

[Tuned200]

You mean rotor thickness? The LGT rotors are a little over 1" thick IIRC. STi's are 1.2" thick. STi rotors are 12.7" in diameter. LGT's are 12.3" in diameter.

 

In either case, it's going to take a lot of braking to wrap or fade the brakes with either setup.

 

What you're paying for is the 4 pot calipers with the bling-bling brembo appeal.

 

 

to bad those calipers wont work on the stock rotors.

 

a friend had a honda that had aem big brake rotors on stock calipers. 5% ofthe pad didnt touch the rotors, which is not a good idea, but they looked good

[EJ255_alan]

sorry for being OT

 

so keefe, if the STI BBK didn' make much improvement over the stock 2pot setup, what would you suggest? i did use hossier slicks and falken ST115 with the endless SSS pad+stock rotors+DOT3 fluid @ track days, performance-wise they are fair, but they didn't last long(not referring to pad life), around 20mins of beating the steering wheel would shake like Elvis whenever you brake(but after you take a break for 10 mins or something it'd be good again)

 

perosnally i'm thinking of getting some DBA slotted rotors and DOT4 fluids, would that be good enough?

 

 

thanks

alan

[edmundu]

^^You are overworking your pads! You need higher temp pads. Better Rotor's may be able to dissipate the heat little quicker, but it is really all in the pads...

[rougeben83]

^^You are overworking your pads! You need higher temp pads. Better Rotor's may be able to dissipate the heat little quicker, but it is really all in the pads...

 

Agreed, aren't SSS pads aggressive street pads? On a lighter car, you could use an aggressive street/autox pad for track use, but on something like a LGT, Something like a Carbotech XP10 track pad would be more appropriate...

[EJ255_alan]

thanks for the reply edmund and ben

yes i do know that i'm overloading the pads, so i guess I'd just tough it out, take it a bit easier for the next tracking season(now I'm using the OE pad for winter), depends on how my wallet is like =)

 

and actually SSS aren't much more agogressive than the OE pad...I'd say around 5% improvement on braking power and prob. 25~30% better(in terms of durability, heat resistance) when you track it..it take roughly 20mins of hardcore laps to make the SSS become less effective, but on the othr hand the OE pad prob. good for 12to15mins

 

thanks

alan

[Xenonk]

sorry for being OT

 

so keefe, if the STI BBK didn' make much improvement over the stock 2pot setup, what would you suggest? i did use hossier slicks and falken ST115 with the endless SSS pad+stock rotors+DOT3 fluid @ track days, performance-wise they are fair, but they didn't last long(not referring to pad life), around 20mins of beating the steering wheel would shake like Elvis whenever you brake(but after you take a break for 10 mins or something it'd be good again)

 

perosnally i'm thinking of getting some DBA slotted rotors and DOT4 fluids, would that be good enough?

 

 

thanks

alan

 

wow, hoosier slicks and then using ST115s all in the same day? That must have been day and night. And you were using SSS pads?? oh man.. you need an upgrade to at least some Carbotech XP12s pads for track days and stick with the Hoosiers or something with good grip. What you are feeling is that the SSS pads are fading on you, you are literally overheating the brake pads, NOT the rotors.. the SS-S are not meant for track driving, they were designed for spirited daily driving (as they only can handle up to 750 degrees or so, which are equivalent to a set of Carbotech Bobcats).

 

Get some track pads, call up http://www.brakeswap.com and get yourself a set of at least some XP12s in the front and either XP8 or XP10 brake pads in the rear. The stock rotors have held up for me for a good 36,000 miles of driving (which included a good year's worth of track days [14 to 20 days worth]). I did a lot of testing of rotors, very seldom it's any kind of rotor issue, it's more so about the brake pads and your tires and suspension setup that makes the world of the difference when it comes to having proper all out braking. IF ANYTHING, for the people that are around stage 2+ and up, it's a good idea to get something like brake duct kits first over a set of bigger brake/rotor kits.. I honestly opt to get better suspension balance than to mess around with brake bias by changing caliper sizes.. it's not going to help anyone if your rear end keeps on lifting around the corners (as the tires will lock up anyways under braking)... so even if you do shift the brake bias to the rear and you keep the same softy-type of suspension, the rear is still going to lift and not touch the ground, so you are basically shifting more braking power to the rear where the tires aren't touching the ground? That simply doesnt sound too effective for braking.

 

Definitely call up Eric at Brakeswap.com.. We already came up with a good solution for those that track their GTs or want that kind of level of performance. A set of Carbotech XP12s/XP10s with some Motul RBF600 fluid or Prospeed GS610 [preferred] will do you wonders. If you really need rotors, get a set of the DBA blank rotors all around for track use.. they will be able to handle all 2 hours of straight track driving at 10/10ths driving for stock powered car on r-compounds.. fix the suspension balance of the car first before you mess with brake bias.. remember, any tire that is not on the ground isnt going to make you stop any shorter.. so keep that car from nose-diving and keep that back-end of the car from lifting under braking and you will see how much better your car will stop. That is when you can mess with brake bias and allow the tires in the rear to lock up quicker and allow better rotation under trail braking (which isnt bad since this can heat up the tires in the rear anyways and make the rear tires actually do some work for you).

 

Hope that helps.

[Xenonk]

what about rotor dia.? thicker =better

 

that is kind of a relative term.. you can have an overall thicker rotor (from plate to plate), but the real deal is the plates themselves and how well/efficient the vanes are designed.. you want a thick plate which will help with heat capacity, not thin plates.

 

Reason why Im not too worried about heat capacity is that I did a lot of tests in the past year with temperatures on the track and also been logging in some of my track conditions.. even at the worst case for brakes that I have experienced this year was being on the track on a 100F+ day with 50% humidity and the rotors (stock, dba, racing brake rotors, etc.) still didnt get above 1200F. Melting point for iron is well above that.. (think 2700F and boiling point I think is 5000F for typical iron grades). With that said, it's very hard for you to even drive that hard to get the rotor to start really feeling mushy (1800F to 2200F).. by then your brake pads would melt anyways (as even NASCAR HAWK brake pads are listed around 1500F to 1800F for their use).

 

Even if you are going to retain all that heat, the surface area along with the thinkness of the plates will be the deciding factor.. but here's the main issue: without air flow to cool down the rotor surface, you are just holding all that heat in that will be working against the brake pad's temperature operating range.. a bigger rotor will eventually deal with the similar fading issue, just a few laps later or so.. you need to balance out how the fast the rotor can get rid of that heat.. brake duct kits are very helpful for this very reason.. it doesnt allow for the rotor to build up heat as quickly.. buying a bigger rotor is only increasing the heat capacity, it doesnt truely solve the problem of having a cooler rotor. You are still comparing the same amount of cooling time between braking zones, and the heat dissapation rate isnt that dramatic of a difference between running a 312mm x 30mm rotor vs 322x 32mm rotor.. it's not enough to time for the rotor to cool down until the next braking zone..

 

A brake duct kit allows the temperatures to stay cooler and lower.. this will make it more effective for the brake pads to work in a better comfortable range (remember, the longer you are on the brakes the hotter it will get).. so starting off with fairly hot rotors isnt the ideal choice.. you want to have cooler temperatures and as you apply the brakes, the brakes will progressively heat up to the right amount of operating temperatures for the best stopping power.. it's hitting the TO the heat limit of the pads, not overshooting the heat limit of the pads during a braking zone, that's how you will get fade.. keep the rotors cool, and you'll be fine.. BBKs nowadays are a better ideal use for endurance racing.

 

Heck, even a lot of time trial race cars are on stock rotors with better track pads simply the fact of not needing to carry additional unsprung weight.. they do the job.. and have a 5 lbs worth of brake duct is way better than having a set of heavier brakes which could be more than 10 to 20 lbs difference (compare that to the bigger rotors, brake caliper brackets, and aluminum 4,6 or even 8 piston calipers). Oh, and by the way, Aluminum's melting point is around 1200F and has a boiling point of 4500F.. so if Im near 1150F to 1200F on the hottest day and if Im using aluminum bodied calipers, I might consider checking the shape of the caliper that it is in after driving that hard on the track. I doubt that there are many racing calipers that are full aluminum.. Im sure they still have steel/iron bases in them (which will add more unsprung weight to what you already have compared to a stock caliper).. Aluminum can dissapate heat faster (see aluminum rotor hats as an example), but remember, dont overload the heat, it can only dissapate so much heat between brake zones.

[EJ255_alan]

hey Keefe, thanks for the very infomative reply =)

well I didn't switch between the 115s and the slicks within the same session(I switch to slicks right before I go into the track, but i did have the 115s into track session at another day tho) I did felt a day n night difference in terms on cornering speed and stability, but for braking, i can't really tell X)

 

RE: i was using tein basic coilover, cusco tower bar + frt and rear sway bar for last summer, brake fluid were DOT3s that came with the car..

 

the SSS claim to be good for 500degree celcius

 

just curious, say, with the carbotech frt-XP12+rear-XP8/10 setup, is it still liveable at normal daily driving? or it's a strictly track use combo? brakeswap mentioned they strongly recom. this on R compound rubbers

 

just flipped around brakeswap.com as well...very helpful as well...

 

thanks a lot Keefe

 

alan

[Xenonk]

where did you read that claim of the pads handling to 500C? (that's 500 C to F: Tf = 9/5 * 500 + 32 = 932 deg F) which is really the SS-M pads, not the SS-S. Btw, you can tell the difference from the tires under braking power based on how well the brakes lock up (a stickier tire wont lock up as fast.. the ABS will know if the tires are locking up but the car is still moving forward.. using stickier tires should give you some feed back that you can get on the brakes with further threshold braking without activating that ABS. That is the difference you should be looking for).

 

SS-S and SS-Y are in the 750 degree range and they have a higher coefficient of friction than the SS-M.. the SS-M's trade off is that you dont get as great of a bite like the SS-S and SS-Y, but the temperature range is higher.. so you can modulate the brakes better and have a smoother braking transition.

 

Carbotech XP12 and XP10 are track pads.. even though they are rotor-friendly, they just dont stop well when they are cold.. you need to get them to about 300F before they start to bite well.. they are driveable to and from the track, but dont drive them daily.

[EJ255_alan]

mm...i got that figure form endless japan+europe's website, as endless usa's site is out of service

 

http://www.endless-brake.info/e_layer_compounds.htm

 

http://www.endless-sport.co.jp/brake_pad/s_sport/index.html

 

yes, originally why I picked SSS over SSY and SSM is because of the inital bite, but sadly i didn't consider about the effect of vehicle weight/heat carefully at first...so..o well...we'll see

 

but I'm seriously considering getting XP12/10 as my track pads

 

thanks

alan

[Xenonk]

mm...i got that figure form endless japan+europe's website, as endless usa's site is out of service

 

http://www.endless-brake.info/e_layer_compounds.htm

 

http://www.endless-sport.co.jp/brake_pad/s_sport/index.html

 

yes, originally why I picked SSS over SSY and SSM is because of the inital bite, but sadly i didn't consider about the effect of vehicle weight/heat carefully at first...so..o well...we'll see

 

but I'm seriously considering getting XP12/10 as my track pads

 

thanks

alan

 

Unfortunately that Endless doesnt have a friction/temp chart that shows how the brakes fade (the Mu's drop off as the pads overheat)..

SS-S were designed to have a meatier better grip around the lower range of temperatures.. during track conditions, it's very easy for the GT to get the stock rotors to well over 1000F (which the SS-Ms are rated to 530C or closer to 990F).. Either case, the Endless Street Pads were designed for street use, not dedicated track use. The SS-M can do a few good laps in, but dont expect them to perform all the way through a HARD 10/10th driving for the full 30 minutes in 80+F weather. The GT weighs in (at least in my Limited with a full tank of gas and me in the car) at 3500 lbs (3475 lbs to be more exact).

 

http://www.endless-sport.co.jp/english/eindex.html

 

I believe Eric at Brakeswap.com was introducing to me a set of XP14s to try out soon but I think they may be borderline to eating up rotors, but we'll see. There's a set of Hawk HP+ or Hawk track pads that Eric may be able to get for you for track days (your choice).. I havent found any other track pad worth buying for now and that is available to this date.

[Xenonk]

SS-S and SS-M are good enough for autox events since it's a very short amount of braking that you need to do under very short distances.. that's the good bonus why I recommend them for spirited daily driving and autox use (that and that the SS-M are dust-free basically)