Brake upgrade needed when going to 18s?

[OkieSnuffBox]

Originally Posted by CSG Mike

Selling lightly used pads is really, really easy.

I took this when I was trying a bunch of pads for myself....

Ha! There is $1800ish+ in pads right there.

[CSG Mike]

Originally Posted by ZZT86

The OP's question to brake feel now that he has 18's resonates with me also as I recently did the same & almost immediately felt the difference in that initial "bite" especially when cold, pedal feels slightly softer too. With me I went str8 from a worn stock Primacy 215/45/17 tyre on a stock 17x7+48 rim to a reasonably sticky 225/40/18 tyre & 18x8.5+42 rims square. Is it purely increased grip levels that makes the initial brake feel seem less effective than it used to be or is something else like the change in wheel offset and/or width, tyre is only 15mm wider than stock, the weight of new wheel/tyre package is slightly less than stock so it's not that, or is it the -1.5deg neg camber up front & a little more at the rear (the rear will soon be dialed back to -1deg ie stock).

The other day I flushed the brake fluid for something more able - Super Dot4 full synthetic 525F but I can't see any diff there atm. Car is babied mostly & is a DD. Very interesting topic.

Cheers

Feel in the pedal via fluid change will be based on the compressibility of the fluid. 525F DOT4 tells me that's a fairly typical off-the-shelf DOT4. Try something a bit higher up, like RBF600, RBF660, or Project Mu G-Four. Torque RT700 is even better (less compressible), but has been backordered forever (going on 8 months now....).

Having more grip means you can have more bite, without breaking traction from a sudden increase in braking force. I find the ST43 on a BBK impossible to modulate on a low grip tire, but with a racing slick, they're awesome. Likewise, street pads modulate well on a low grip tire, but you'll struggle to threshold brake on a racing slick, because the street pad lacks the raw stopping power (friction coefficient).

Different pads all have different characteristic, and there's no one pad that fits everyone. Just have different basketball players have different strengths, different pads have different characteristics. The only way to figure out what you like best, is to try it out. Unfortunately, few people ever go through more than a few sets of pads over their length of ownership of any given car.

[ZZT86]

@CSG Mike - OK ! Guys locally have recommended the DS2500's which supposedly give what I'm after with a bit of extra dust & noise thrown in over stock, noise could be negated if pads bedded in properly as you have recommended elsewhere on this forum. Carbotech XP10/XP8 are also another option as you have suggested/tested.

And yeah as I do a lot of fwy travel pad wear is very low for me & typically my braking system still looks like new even after 3 years & 58K kms

Appreciate your opinion Mike

edit: out of curiosity would the above 2 pad types increase disc/rotor wear & to what degree ?

[wparsons]

Originally Posted by FR-Slide

One of my favorite aspects of this car when stock was the OEM brakes were very good. Probably better than 90% of the competition in both performance and feel.

I just swapped on staggered 18s (8.5 front, 9.5 rear) running 235 and 255 rubber, and while the extra grip is great, I definitely feel like I lost some braking performance and increased my stopping distance. This car is my DD, with light canyon use and rare track/autox days, so I want to keep something still street friendly, but not overkill. I just want a good pedal feel back, as well as to reign in the stopping distance to stock or better. Honestly (and I must be getting older now that I'm saying this...) I really want to upgrade for safety first, as I know I don't truly NEED performance/fade-proof brakes for the track.

Is a simple pad change sufficient (and if so, what do most people recommend for street+ driving)? Do I need to start looking at lines + fluid? Or is something like new rotors and/or calipers (STI swap or similar) really needed?

Can you still engage ABS with the new wheels/tires? If so, the increased stopping distance (real or imagined) isn't from the brakes. The new tires might not have as much grip, which could greatly affect stopping distances.

[FR-Slide]

Originally Posted by wparsons

Can you still engage ABS with the new wheels/tires? If so, the increased stopping distance (real or imagined) isn't from the brakes. The new tires might not have as much grip, which could greatly affect stopping distances.

I've not tried to lock them up yet, but I can test later. My OP was just from normal street driving, and I've not had any full-stop situations that warranted engaging ABS yet. All I can tell is that it takes increased pedal pressure to decelerate, and that it FEELS like it takes longer time, as well.

However, to clarify, I don't think the increased distance/perception of distance is from the brakes at all, but rather from the increased rotational and unsprung weight per corner. I have very little doubt that the new tires have MORE grip than stock (235 and 255 series Ventus V12 over OEM 215 Primacy's), so if anything, I now have too much tire for the brakes rather than too much brake for the tires as before. My desire to upgrade pads and supporting items is mainly to get back that super-confident brake feel of OEM with my larger rolling stock.

[infinity21]

I got a BBK primarily for additional thermal capacity plus reduced long-term running cost for track days like other guys have mentioned. If you're not going to be doing HPDE days, get more aggressive street/hybrid pads and call it a day imo.

[CSG Mike]

Originally Posted by ZZT86

@CSG Mike - OK ! Guys locally have recommended the DS2500's which supposedly give what I'm after with a bit of extra dust & noise thrown in over stock, noise could be negated if pads bedded in properly as you have recommended elsewhere on this forum. Carbotech XP10/XP8 are also another option as you have suggested/tested.

And yeah as I do a lot of fwy travel pad wear is very low for me & typically my braking system still looks like new even after 3 years & 58K kms

Appreciate your opinion Mike

edit: out of curiosity would the above 2 pad types increase disc/rotor wear & to what degree ?

DS2500 is much closer to the AX6/XP8, than the XP10.

Both will increase rotor wear, but the degree to which, I cannot say without knowing your driving. If your pads look new after 58km, then I would say most likely the additional wear will be minimal, and possibly not even noticeable.

[ZZT86]

^^ From past experience in a similar car both front & rear are likely to last me more than 200K kms, it sees at least 60% fwy & mostly relaxed every where else, I rarely give the brakes a hard time, the discs never need attention. Which of these would you recommend & are quieter/less dusty: DS2500/AX6/XP8 ?

Many thanks for your time

[CSG Mike]

Originally Posted by ZZT86

^^ From past experience in a similar car both front & rear are likely to last me more than 200K kms, it sees at least 60% fwy & mostly relaxed every where else, I rarely give the brakes a hard time, the discs never need attention. Which of these would you recommend & are quieter/less dusty: DS2500/AX6/XP8 ?

Many thanks for your time

DS2500 or AX6. Both will make a little bit of noise...

[wparsons]

Originally Posted by CSG Mike

DS2500 or AX6. Both will make a little bit of noise...

I ran my old DS2500's all winter because I couldn't get the stock pads back into the carriers, barely louder than stock except on really cold days (-15C).