Brakes Still Crap - What's Next?

[MrStabby]

Setup: R32 GTR, UAS 324mm rotor upgrade, DS2500s, Motul 600, rebuilt calipers

Here's what they look like after a track session;

And when they get that blue colour around the outside they shudder badly. I can sand it off with wet and dry and things go back to normal.

So what should i try next? Maybe

- DS3000s (are 2500s really good enough for track?)

- Cut off backing plate/guard

- UAS brake cooling air deflectors

- ???

[ferni]

What power? What tyres? What did the brakes feel like on the track? Was shuddering the only thing wrong?

[MrStabby]

What power? What tyres? What did the brakes feel like on the track? Was shuddering the only thing wrong?

The power's in my sig (242kw). Tyres are Federal 595SS's - adequate street tyres, not very grippy on the track tho. Brakes held up much better since i rebuilt the calipers, but after not that long they went off and got more and more shudder. Yeah shudder was the only problem, i think they were still pulling up ok but i do tend to back off when they start to shudder badly.

1:15.5 (using Racechrono - its pretty cool) around Wakie with a fair bit of understeer.

[Duncan]

tyres first (like ferni said)

then brake less

then upgrade brakes once you are under 1.10 or have over 300kw you need bigger brakes

or if you want to upgrade brakes anyway, buy the g4s from Just Jap

[MrStabby]

tyres first (like ferni said)

then brake less

So its normal?...I never had this problem in my Porka 928S with shitty single piston calipers and shitty EBC greenstuff pads. I could beat the crap out of them all day with no problems at all.

[260DET]

The first thing I would have done is remove the backing plates and then deflect air towards the rotors. Its all about getting rid of heat, make that a priority.

[Duncan]

well they are pretty crappy brakes and a heavy car, so ultimately you would need to upgrade them.

But if you think about tyres, if you can go through a corner 20km/h faster then now, you have saved a heap of braking....times every corner on the track...makes a big difference.

[ferni]

Actually Duncan i found I started having troubles when i went from Street tyres to R-Comps. I think it puts more strain on the brakes (but for shorter periods of time). Don't forget if you're cornering faster you're also hitting faster speeds on the straight hence having to pull off that extra speed before the next turn....

From the picture you posted, it looks like the pad is only using half the disc, how can it leave so much crap around the edge? It should be clean like the inside of the disc. Is the pad sitting flush with the disc all the way? Is the other side the same?

Shudder is usually caused by the discs.... Either they need machining, or pad deposits need removing... Did you bed in the discs properly? Are you warming up the brakes properly on your warm up lap or are you just jumping on them straight away?

You are going to struggle for brakes if you upgrade much more... but for 250rwkw and street tyres i think you should be able to get away with it.

I don't think the issue is heat related. Heat would cause Pad fade, or boil your fluid (soft pedal)... if you're not getting this then heat isn't the issue (yet).

I'd still remove the backing plates, fit braided lines and fit a master cyl stopper, because you'll need them anyway.

Here is a link i read the other day that may be vaugly replated:

http://www.zeckhausen.com/avoiding_brake_judder.htm

Ohh and keep in mind, I'm no where near an expert..... so i could be completely wrong

[r33cruiser]

hey mate, i read about removing the back plate too. but doesnt it leave the whole brake and rotor assembly vulnurable to damage=rocks and debris

[ferni]

Yes it does... But what about the front of the disc, it doesn't have stone shields

How often do you drive down a dirt road?

It's all a compromise. Like hard suspension will put more strain on the chassis and give you a harsher ride.... but if you want to go fast.............

[Roy]

Maybe another picture of the rotor? In that pic posted it doesnt look like you are using 50% of the pad, which is not good. Who installed the brake upgrade kit? Is everything all square and tight. Its unusual that so little of the pad is beign used....but that woydl explain why you are getting the heat spots.

Also, for my money, lots of people pull their d1cks over DS2500s. I have used two sets and sure they are ok...but in my eyes they are no better then RB74s etc. Im currently using Endless CCr and quite like them...far better then DS2500s.

But the shudder is something different then just pads...

Maybe turn the wheel to full lock and get us a good pic of the inside of the rotor. I would want to be sure that the caliper is still parallel with the rotor and not at a slight angle that is causing only the bottom of the pad to come in contact with the rotor

[r33cruiser]

thats a good point. but i would be worried about driving on new roads with bituman residue and stuff. i totally get wat your saying. but perhaps it would be a safer investment to go a cross drilled and slotted rotor?

[MrStabby]

From the picture you posted, it looks like the pad is only using half the disc, how can it leave so much crap around the edge? It should be clean like the inside of the disc. Is the pad sitting flush with the disc all the way?

Yep its sitting flush. I think its using the whole surface, but perhaps its getting hotter near the outer edge, causing the problem.

Shudder is usually caused by the discs.... Either they need machining, or pad deposits need removing... Did you bed in the discs properly? Are you warming up the brakes properly on your warm up lap or are you just jumping on them straight away?

Going by past experience shudder can be stopped by sanding the blue deposit off the rotor. To bed in i just drive normally and let it happen. I gradually raise my braking intensity on my first lap, then go pretty hard from there.

Here is a link i read the other day that may be vaugly replated:

http://www.zeckhausen.com/avoiding_brake_judder.htm

Ohh and keep in mind, I'm no where near an expert..... so i could be completely wrong

Link is interesting - i could use DS3000s as the race pad option. Thanks for your non-expert feedback - its all good.

[ferni]

Read what Roy wrote, he knows more than me.

I use DS2500 on street, i don't think much of them, they are ok.

I use DS3000 on track, they are better for track, give a better bite.

r33cruiser: Using slotted/drilled disc isn't the same thing, The slots don't really cool down much, they just release gasses etc.. help keep the pad clean. Removing the stone shield is going to allow WAY more air to flow into/around your disc and run much cooler. The stone shied heats up and keeps all that hot air in near the disc on the inside.

[Roy]

Im running the same rotor with the GTSt caliper relocated and you can see that whilst my pad wear isnt great or 100%

So you can see somehow for whatever reason your pad wear appears to be off base. You shouldnt be having the pad deposit problems regularly, maybe occassionally but the should clean themselves up with a bit of normal driving

[blind_elk]

Shudder is usually caused by the discs....

What about ABS?

[MrStabby]

Maybe another picture of the rotor? In that pic posted it doesnt look like you are using 50% of the pad, which is not good. Who installed the brake upgrade kit? Is everything all square and tight. Its unusual that so little of the pad is beign used....but that woydl explain why you are getting the heat spots.

You're onto something here (and so was ferni, sorry man). Just checked the inside face of the rotor and its discoloured at a shorter radius, if you know what i mean, so opposite to the outside. This means that the caliper is not sitting in exactly the same plane as the rotor. I will pull it all apart and check the dimensions with verniers.

I installed it. Its all torqued up correctly. I didnt like how much material had to be removed to get it to fit (John warned me about that). Perhaps its not sitting 100% flush because i need to remove more material, or perhaps the brackets aren't quite right.

Maybe turn the wheel to full lock and get us a good pic of the inside of the rotor. I would want to be sure that the caliper is still parallel with the rotor and not at a slight angle that is causing only the bottom of the pad to come in contact with the rotor

To the naked eye it looks ok, but i'd imagine if it were a fraction of a mm off it would still cause problems.

thanks

[giant]

backing plates must go!

you can buy the original n1 brake air guides for the gtr r32 from nissan they are rubber and very effective, we have them on our 32 and it has extended disc life.

we couldnt get 6 laps out of qr on a set of rotors without cracking right through! (genuine nissan disc's brand new and bedded in)

cheers russ

[MrStabby]

backing plates must go!

you can buy the original n1 brake air guides for the gtr r32 from nissan they are rubber and very effective, we have them on our 32 and it has extended disc life.

Do you have a pic? Are they the ducts that run from the front lip back to the wheel arch?

[giant]

i dont have a pic, but they are similar to the unique auto ones but made of rubber and bolt to the castor arms, pretty effective.