wussy performance from new pads/rotors

[BabyM]

I figured I would ask the question here becuase it's the greatest concentration of brake discussions on the board.

Last month I did my first DE. The night beforehand we changed out my dealer-installed pads and rotors and replaced them with Ate powerdiscs in front, regular Ate rotors in the back and Hawk HPS pads. We also flushed the brake lines with Superblue.

We bled the brakes once on Sunday because I felt like I had to really stomp to get the car to slow and that the braking distance was greater.

Since then it seems my braking distance continues to be long on the street, even when I mash the pedal with a lot of force.

Is this a sign that the lines shoud be bled? Or is this behavior normal for my new set up?

TIA

[Spencer]

Could be the fluid.

What method did you use to bleed the brakes?

How does the pedal feel? Is it firm or mushy?

Also, did you bed in the brakes after you installed them? This is important to getting proper "mating" between your rotors/pads.

[Def]

I've never driven on Hawk HPS, but most "street performance" pads will tend to take a stop or two to bring them up to a good working temp. They'll feel a bit weak while cold, then one or two hard stops and they should grab about as well as the OEM BMW pads(which are really good street/cold response pads if you can live with the dust).

Improperly bled brakes will leave you with a really mushy pedal that has a LOT of travel due to compressing the air in the lines. If the pedal is pretty firm, then air in the lines is not a problem.


Keep in mind you need to bed new pads - about 5 moderately hard stops from 40-5mph, let cool while not using the brakes much for 10 mins. About 5-6 moderately hard stops from 60-5mph, let cool a bit while not using the brakes and then park the car. This varies for each type of pad, but it's a general guide to get the brakes up to temp slowly and then let them cool back down allowing them to "bed in" to the new discs.

[vodomagoo]

hp+ pads are my street pads and most def need a few stops to warm them up

[John V]

If you didn't bed in the pads, that's the problem. I have a fair bit of experience with the "street" Hawks and they need to be properly bedded, then rested until cool, before they will work at all.

When they do work, they will positively suck your eyeballs out when you stand on it.

John

[///Mracer]

I did not like the HPS pads on the track when I had them last year. Not enough stoppping power and they fad. I just put a set of HP+ pads on friday and embedded them in and was amazed . I was coming from axxiss ult. btw. I cannot wait to hit the track!

[Jed]

I did not like the HPS pads on the track when I had them last year. Not enough stoppping power and they fad. I just put a set of HP+ pads on friday and embedded them in and was amazed . I was coming from axxiss ult. btw. I cannot wait to hit the track!

Matt-

I want to toss the Axxis for the HP+ to use dual purpose-how do you think the cold bite will be for an autox? I loved the Axxis for autox and street, but they didn't stand up too well at Summit Point during my 2nd session...

[Jed]

Also-a general question. I've heard that getting both new rotors AND pads isn't a good idea. I remember reading that you should break in new pads with older rotors and new rotors with older pads. Any truth to that?

[///Mracer]

Jed, the purple BSP monster uses HP+ for auto-x only so I think they should be ok for auto-x use.

I will let you know after the SEDIV. I will see you down there, oh, that's right, you back out

[John V]

I haven't ever had a problem with new pads plus new rotors at the same time - but it does take a bit longer for the pads to bed properly than if you're doing new pads with old rotors.

John

[Jed]

I will let you know after the SEDIV. I will see you down there, oh, that's right, you back out

I know...

Damn, you guys are gonna have so much fun!!!

[DocWyte]

HP+ have plenty of bite for an auto-x. I had issues with them on my car tho, as they're so harsh on the rotors they were kicking bits of the rotor up on my wheels, which then would corrode into the wheels! Other than that and the copious dust they put out, they're incredible pads. Oh, and your car will sound like a garbage truck coming up to a light stop.

[///Mracer]

Oh, and your car will sound like a garbage truck coming up to a light stop.

true dat!

[mijgilbert]

Also-a general question. I've heard that getting both new rotors AND pads isn't a good idea. I remember reading that you should break in new pads with older rotors and new rotors with older pads. Any truth to that?

I don't think so. I believe it's actually best to have new rotors and pads at the same time so you don't get the gooves from the old rotors in the new pads and vice versa.

I always have the best brakes on a properly bedded in new pad/new rotor setup.

-Mike

[mijgilbert]

Since then it seems my braking distance continues to be long on the street, even when I mash the pedal with a lot of force.

Is this a sign that the lines shoud be bled? Or is this behavior normal for my new set up?

TIA

I would say it's almost definitely the fact that you are mixing compounds without properly bedding in the brakes and therefore the pads and rotors are not optimally going to stop the car.

Brakes work mostly because the rotors get pad material on them (bedding)and then the pads stop against that material. If you have a foreign material on the rotors (from stock pads) and then put new pads and then expect them to stop the same or better, it won't happen. When you put track pads on that have a different pad material than the stock, you need to use some sort of scouring material and brake cleaner to remove whatever old pad material you have on the rotor, and then you need to properly bed in the new pads to the rotors.

This is why a lot of people use performance friction PF97s on the track, then change to PF Z-pads on the street. They use the same basic compound so they don't interfere with eachother when exchanged. Call Jeff or Joe at HMS Motorsport (www.hmsmotorsport.com)to discuss this - they'll help you figure out what is right for your specific application.

-Mike

[BabyM]

Thanks guys!
Lots of good info here.

When we put the new pads and rotors on I bedded them in according to the manufacturer's suggestion: 5-6 stops from 30-40 mph. I did that on the way to the track, braking harder with each successive stop. I like Def's version better though, it seems more thorough.

We used a combination vacuum and pedal stomp to bleed the lines.

At this point the pedal does seem soft compared to when I was on the stock setup and there is definitely more travel. Although it's good to know that these pads do require warming up (that I can live with)

I would say it's almost definitely the fact that you are mixing compounds without properly bedding in the brakes and therefore the pads and rotors are not optimally going to stop the car.

eek! What improper mixing am I doing so I can correct it? Or are you thinking that I'm switching pads? I simply went to the new pads and rotors because it was time --I didnt switch back to the old pads. I hope I didn't mess anything up...


So, should I try the bedding in process again? --even though the pads/rotors are a month old?

It definitely sounds like I should bleed the lines again so I'll go ahead and do that when I put my new suspension in

Thanks for all the help!

[Jed]

There might be air in the system. My friend had his brake fluid changed to Super Blue on his 323is and the pedal was softer than stock-another mechanic found that the last guy didn't do it right and re-bled them and now they are great.

[Spencer]

This is why a lot of people use performance friction PF97s on the track, then change to PF Z-pads on the street. They use the same basic compound so they don't interfere with eachother when exchanged. Call Jeff or Joe at HMS Motorsport (www.hmsmotorsport.com)to discuss this - they'll help you figure out what is right for your specific application.

-Mike

Thats what I use. Has worked great so far. No problems switching pads.

Not to mention, I've got a lifetime warrenty on the PF Z-Rated pads from Autozone. I've gone thru 3 sets, all for $120.

[Jim O.]

There's a big difference between the Hawk HPS and the Hawk HP+ pads - I don't know why half the posters in this thread are talking about the HP+'s...

Anyway, when I tried the HPS pads, I felt that the initial bite wasn't very good, so the braking felt like it wasn't as good as with other pads. That might be part of the problem that you're seeing. Another thing is that they're definitely street pads - their heat range isn't as great as the more track-oriented pads, so you have a much better chance of cooking them on the track. Pull them out and check them for glazing, and cracking. You might want to try hitting them with some coarse sandpaper, to break through any glaze that might be on the pad surface.

There are three main things that cause brake fade:
1. Pad outgassing (green fade)
2. Boiling the brake fluid
3. Overheating the pad compound

Green fade is pretty much a thing of the past - pads really don't outgas very much any more. If you did the break in correctly, that should just about eliminate this problem. You might have boiled the fluid - that usually shows up with a spongy pedal, though. Change it anyway, just because it's easy and cheap. Third is that you may have exceeded the heat range for the pad. If you still have a hard pedal, but the car doesn't stop (and your vacuum booster is OK), then there's a good chance it's a pad issue...

Jim

[///Mracer]

There's a big difference between the Hawk HPS and the Hawk HP+ pads - I don't know why half the posters in this thread are talking about the HP+'s...

Jim

I was informing him of my experience with both pads and that I like hp+'s better.

[Jed]

I was just curious about the HP+'s after reading about the HPS. Just thought it would be a decent discussion.

Doesn't hurt to learn a little more...

[cajunroadster]

I bled my brakes the same way, with a vacuum bleeder, and am having the same problem. I was told that pressure bleeding is the way to go. How did your friends problem get fixed?

There might be air in the system. My friend had his brake fluid changed to Super Blue on his 323is and the pedal was softer than stock-another mechanic found that the last guy didn't do it right and re-bled them and now they are great.

[SteveB]

I may have missed it but I think I read all the posts. I''l agree with the idea of bleeding the brakes again first with a power bleeder then flowing up with the old pump...pump...hold method. I did that last time on my car and the pedal felt better than it had in a long time.
Something that I didn't see mentioned or asked was about stainless steel brake lines. I don't remember how old you car is Baby M but it may be time to look at SS brake lines. They make my pedal much firmer, along with a good bleeding, and under heavy braking the pedal stayed as firm as it started out. My car had a lot of miles on it when I switched to SS lines so I might notice a change more than someone with a newer, lower mileage car. Something to think about?

[John V]

My car is a 60k mile '95 with stock rubber hoses, and I have a rock-hard pedal. I don't think she should need to install braided lines to get a firm pedal.

I have had good success with doing a couple full ABS stops and then going back and bleeding the brakes again. I use a one-way valve fitted to the brake bleed screw. I crack the screw just enough to let the fluid flow freely, pump until I see clean fluid and no bubbles and close the valve.

Hope this helps.

John V

[dorikin_86]

I use cool willys from turner motorsport..they work wonderfully even in 110F summer weather