Calipers without dust boots

[toast]

I'm looking at getting the 'non-wilwood sanctioned' Wilwood kit for WRX's that fit our cars. My only concern is the lack of dust boots. I live in the NE, we see snow and salt every winter. Some people say that will kill them in a season, others say that boot does nothing for a stainless piston.

Anyone out there with a couple seasons of use in winter care to chime in?

[churchx]

"Fits", as in you can bolt on it without any modifications. I still wouldn't like it's brake bias shift (just like STI brembo-s swap), as it seems not wise to pay myself a lot for braking to become worse then stock with exception of increased heat capacity.

[bhmax]

I've toyed with the idea of that kit because of the weight loss. Also because I could transfer it over to a FF 818 kit car. It looks like the standard kit has aluminum pistons with dust boots, although almost identical calipers are available with SS pistons without dust boots. I'd probably go for the SS pistons and anodized caliper if I ever get a kit. I've been playing around with bias calculations here: http://www.tceperformanceproducts.com/bias-calculator/ It looks like they (TCE) can put together Wilwood kits to your liking.

[toast]

Originally Posted by churchx

"Fits", as in you can bolt on it without any modifications. I still wouldn't like it's brake bias shift (just like STI brembo-s swap), as it seems not wise to pay myself a lot for braking to become worse then stock with exception of increased heat capacity.

For $1000 you save 16 lbs of unsprung weight per corner. Based on some threads of people who bought the kit brake performance went up for street and light track use. I don't go to the track.

[churchx]

Unsprung and even more so, unsprung rotational weight, reduction is very good thing to do. Even though slightly, but increases everything, acceleration, braking, handling, grip, comfort. But imho playing with putting on brakes made for other cars with different brake bias still doesn't justify gains. Brakes are important enough car subsystem i'd never wish to have anything compromised at, even for daily driven only cars. Not loosing control or braking system working at max capacity with right brake bias and resulting shorter stopping distances in case of need for emergency braking may be the difference between accident avoided or not, with victims and/or high repair bills.
Wilwood also makes 'native' kit for FR-S/BRZ/GT86, i suggest rather getting that, if you insist on getting willwood's BBK. IIRC APR formula kits had dust boots (but it might be outside budget) and they also fit stock wheels. Haven't dug much info about other alternative BBKs like brembo/stoptech/RR and so on.
Generic advise would be to keep using stock brakes if you daily drive only. Rationale being - you won't be using main gain of BBKs (increased heat capacity), also secondary one (cheaper wearable costs. Not that important at pad/disk wear rates of daily driving). You'll get only gains of relatively little importance like reduced weight and bling factor, but still will have to pay full price of (expensive) aftermarket BBK. Better keep using stock brakes (very adequate for daily driving and even light track use for sessions up to 10-11min), and spend those $2-4K on something else of more importance/gains/returns.
P.S.
You can also think about getting lightweight forged wheels, if you are set on reducing rotational unsprung weight. They are expensive though, so maybe worth hunting for set of used ones among auctions/classifieds on misc. sites including this and eg. nasioc.

[toast]

Originally Posted by churchx

Unsprung and even more so, unsprung rotational weight, reduction is very good thing to do. Even though slightly, but increases everything, acceleration, braking, handling, grip, comfort. But imho playing with putting on brakes made for other cars with different brake bias still doesn't justify gains. Brakes are important enough car subsystem i'd never wish to have anything compromised at, even for daily driven only cars. Not loosing control or braking system working at max capacity with right brake bias and resulting shorter stopping distances in case of need for emergency braking may be the difference between accident avoided or not, with victims and/or high repair bills.
Wilwood also makes 'native' kit for FR-S/BRZ/GT86, i suggest rather getting that, if you insist on getting willwood's BBK. IIRC APR formula kits had dust boots (but it might be outside budget) and they also fit stock wheels. Haven't dug much info about other alternative BBKs like brembo/stoptech/RR and so on.
Generic advise would be to keep using stock brakes if you daily drive only. Rationale being - you won't be using main gain of BBKs (increased heat capacity), also secondary one (cheaper wearable costs. Not that important at pad/disk wear rates of daily driving). You'll get only gains of relatively little importance like reduced weight and bling factor, but still will have to pay full price of (expensive) aftermarket BBK. Better keep using stock brakes (very adequate for daily driving and even light track use for sessions up to 10-11min), and spend those $2-4K on something else of more importance/gains/returns.
P.S.
You can also think about getting lightweight forged wheels, if you are set on reducing rotational unsprung weight. They are expensive though, so maybe worth hunting for set of used ones among auctions/classifieds on misc. sites including this and eg. nasioc.

Not to be a d!ick, really, but none of this is what I asked.


All of your concerns were hashed out repeatedly here:

http://www.ft86club.com/forums/showt...hlight=wilwood

To assuage concerns (again, not the point of the thread)...

1) The kit in question can be purchased for under $1k
2) Our front brakes are the exact same ones used on a car 500 lbs heavier. If this kit stops that car without exploding in a panic stop it will stop ours as well.
3) The piston area on a stock WRX/BRZ is 4.46^2". This kit is 4.12^2", so bias moves rearward. Wilwood must consider that a good thing because the 'sanctioned' kit for the BRZ has a piston area of 4.04^"2, moving bias even further rearward. If you buy their rear kit as well it moves even further rearward.
4) The 'real' Wilwood BRZ kit is $1700 and only saves 6# per corner
5) 32 freaking pounds! I drove an STI with the brakeman setup that is for drag cars before and after installation. It had a similar weight savings and that was on a 3500# car. The difference in feel was tremendous.
6) swift996 used this kit on his car for quite a while, including track work. He said it was great up until he added heavier wheels/tires and went FI. My wheel/tire combo is lighter than stock and I don't use the car on the track, that is what my bike is for.


I'll have to look at the Wilwood site again, I could have sworn there weren't boots on this kit.

*Edit - #3 above is clearly wrong because I was ignoring rotor diameter, see dialogue below.

[toast]

I just looked @bhmax, you were right. The calipers that come with this kit are aluminum pistons with dust hats, solves my last concern.

[bhmax]

I'll have to check my math. The numbers I used are at home, but I calculated the Wilwood would move bias forward by 2%.

[toast]

Originally Posted by bhmax

I'll have to check my math. The numbers I used are at home, but I calculated the Wilwood would move bias forward by 2%.

Huh. Not sure how that is possible leaving all things fixed and going to a smaller piston area.

[bhmax]

Originally Posted by toast

Huh. Not sure how that is possible leaving all things fixed and going to a smaller piston area.

Slightly larger rotor. I'll have to check the piston sizes I used.

[toast]

Where did you get the pad Cf? If you used Wilwood's numbers maybe their pad that they include is more aggressive?

[toast]

Originally Posted by bhmax

Slightly larger rotor. I'll have to check the piston sizes I used.

Yeah, I didn't even think of that.

[bhmax]

Originally Posted by toast

Where did you get the pad Cf? If you used Wilwood's numbers maybe their pad that they include is more aggressive?

That would of course change things further. I just used the same number for the comparison between stock and Wilwood kit.

[toast]

So I used that sheet to calculate the bias of Stock BRZ, Wilwood WRX and Wilwood BRZ taking into accounts rotor diameter as well.

Stock BRZ is 57.5% front, Wilwood WRX is 58.4% front and Wilwood BRZ is 61.9% front

Just FYI for others considering this swap. The WRX kit rotors are taller and have aluminum hats so their thermal mass is probably better than stock but they are 1mm thinner so they won't cool back off as efficiently in constant prolonged use.