Brake Bias Controller, Lightened Pulleys + Tail Shaft

[justinfox]

Hi guys.

I'm looking into these goodies for my R32 GT-R at the moment. Would appreciate your opinions:

Brake bias controller for my 6-pot AP's:

http://www.skylinesaustralia.com/forums/in...howtopic=153693

Lightened pulleys + tailsshaft:

http://www.skylinesaustralia.com/forums/in...howtopic=153711

[djr81]

Hi guys.

I'm looking into these goodies for my R32 GT-R at the moment. Would appreciate your opinions:

Brake bias controller for my 6-pot AP's:

http://www.skylinesaustralia.com/forums/in...howtopic=153693

Lightened pulleys + tailsshaft:

http://www.skylinesaustralia.com/forums/in...howtopic=153711

Brakes: Two things come to mind.

1. Try them first. Depending on the caliper piston area & the rotor diameter you may not have changed the bias that much. Have a look at the different master cylinders for the R32's. The one for the Brembo equipped cars is different (larger bore) than the Sumitomo equipped cars & the balance is slightly differrent. Which one have you got?

2. Get a data logger & examine your braking. It is VERY easy to lose time under brakes. Mash them really hard when you first apply them on the circuit & concentrate hard on the heel & toe downchanges.

Lightened pulleys etc:

Your GT-R will weigh more than 1500kg with you aboard. Losing 1kg from the car will be completely undetectable. Lowering the rotational inertia is better than dumping straight out dead weight, but again 1kg is not detectable. The money for this stuff is better spent elsewhere.

However you may want to look at an undersize harmonic balancer as these will also slow the ancilliaries & the water pump. Much cheaper than a carbon driveshaft. Don't believe anyone who tells you the light weight will make or lose you any more rwhp.

[justinfox]

Cheers for that!

[Neil]

If I was running that brake set-up I would not even think of not running brake bias. Whats wrong with spending some more money and run tilton pedals and 2 master cylinders. At least that way you won't be half guessing. You gotta love another dial to play with.

I love my Bias and a big fat arse GTR needs one as well.

Neil.

[SteveL]

By all means go for the full balance bar, etc if you have the $$$ and this is to be a serious racecar. However a simple adjustable Wilwood proportioning valve costs maybe $150 and for a bit more you could have it plumbed into the cabin. I've run one in the Z for years and it's essential AFAIC.

[Lunatikk]

Mate the best thing you can do is bolt 'em up & see how they feel.

I spent a stupid amount of time worrying about & trying to work out what the balance would be between these:

http://www.skylinesaustralia.com/forums/in...c=93935&hl=

& the std non-Brembo 2-pot rear brakes & to my surprise once I got them on the car (finally) they were 100% fine. F-R balance is great (on the HT-10 pads, haven't tried the PFC-93's), modulation right at the point of ABS stepping in is also no probs & the fronts work hard enough to glow cherry-red with no fade or change to the above etc so stop stressing, bolt 'em up & if you do have a prob, try playing with diff pad compounds to dial 'em in.

Also take a look at these articles, worked a treat for me & some of the best advice I've read or heard on bedding in brakes. Good Luck & Enjoy!!

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

http://www.stoptech.com/tech_info/wp_bedintheory.shtml

http://www.stoptech.com/tech_info/wp_bedinperformance.shtml

[JAGR33]

If I was running that brake set-up I would not even think of not running brake bias. Whats wrong with spending some more money and run tilton pedals and 2 master cylinders. At least that way you won't be half guessing. You gotta love another dial to play with.

I love my Bias and a big fat arse GTR needs one as well.

Neil.

Funny you say that Neil, there are about 5 hardcore track GTR's down here in Melb, all of them have aftermarket brakes, none have a brake bias controller....

[Swiper the Fox]

Funny you say that Neil, there are about 5 hardcore track GTR's down here in Melb, all of them have aftermarket brakes, none have a brake bias controller....

ill certainly vouch for that!

[Neil]

Funny you say that Neil, there are about 5 hardcore track GTR's down here in Melb, all of them have aftermarket brakes, none have a brake bias controller....

Sooner or later someones gunna get smarter than the rest and they'll all follow like sheep. I have noticed the GTR's at wakefield getting loose in the rear end,,,a little adjustment to the rear would fix a lot of it.

I often adjust mine on the run and use different settings for different tracks.

Neil.

[JAGR33]

Sooner or later someones gunna get smarter than the rest and they'll all follow like sheep. I have noticed the GTR's at wakefield getting loose in the rear end,,,a little adjustment to the rear would fix a lot of it.

I often adjust mine on the run and use different settings for different tracks.

Neil.

Does that mean all GTR's are like that?? The cars I mentioned earlier have no such problems...

We even run ABS aswell..

The cars you mention at Wakefield, did they have aftermarket brakes??? If they were a bit taily then an easy fix would be to use a more aggressive pad in the rear to even it out..

Don't see the point in spending all that money in brake bias controllers and aftermarket pedals....

Don't take this the wrong way, this is not a shit fight. Just voicing my opinion on experience...

[GTRgeoff]

You mean less aggressive rears Jack, but anyway. Skylines are too easy to make taily and we've seen a couple of rear loss of controls down here in the last 12 months and one of those had big front calipers and stock rears. ABS is an absolute no go on the track else you can roll straight over the traps.

I've done the hardcore track and rally thing and yes adjustable bias is necessary when you are racing for real, but I recall Justins car is a primarily road car, and a bias valve will automatically make it unroadworthy.

Easy solution. A dedicated track car and a road car that gives some giggles.

[JAGR33]

Which car are you talking about Geoff?? I s it Snowy??

Besides, Justin is going for a front AND rear package, well balanced...

[Neil]

Great debate boys,,,love it.

As most people that know me know that I don't post unless I have something constructive to add. That said,,, my thinking is that he's spent a shit load of money on really high quality brakes and you would have to think also discs,,,why not go the full monty and run bias.

The cars I mentioned at wakefield were NSW and VIC GTR's. If you watch them after the kink the back end of the cars are squirming around under brakes which tells me theres to much brake at the front. Adjusting more to the rear would have to help settle the car down. Duncan's combined touring car does the same thing with standard brakes and so does the car that sydneykid looked after.

I have spent a lot of time standing on pit-lane watching every GTR 32,33 & 34's I can. One of my jobs is to take as much info back to Mr Handley as I can. I've even been to car/race meetings he wasn't even running in. I must admit I don't go looking at what brakes they are all running,,,but to me they all do it.

Remember the primary goal of the rears is nothing more than to settle the back of the car down, which makes your turn in smoother which makes for quicker corner/exit speed.

Neil.

[JAGR33]

Very well said Neil, I was one of the GTR's from Vic, but unfortunately couldn't make Wakefield, went to EC instead. Since I've never been to Wakefield I'm assuming the kink you're referring to is the one on the front straight leading into turn 1. After looking at some incar vids and speaking to a few other Vic guys that attended, it seems like that kink is pretty close to turn 1, so its hard to maintain speed through there without unsettling the car at the same time wash off speed for turn 1. In other words your braking while turning. Is this correct?? Sounds like the perfect section of track to determine how well balanced the cars brakes are, as turning and braking don't go hand in hand, this where trail braking comes into play...

Have you noticed any GTR's doing the same thing at any of the other tracks?? From memory there was one corner at EC where it goes slightly right before a left hander (turn 6?) before corporate hill, and also the second last corner has a slight right before left, under brakes..

Here's some footage of myself, you can see which corners I'm talking about

So I guess the problem of the car getting 'taily' gets worse when braking and turning at the same time...

P.S Sorry for long post...

[Roy]

Its impossible to keep a car perfectly planted in all conditions. What is good for one corner wont be ideal for the other. Sure, try to get the car as sorted as possible...but there will always be corner entries/exits where you have to nurse a car.

As for brake balance. I tend to think you will be ok. If you are serious then give Melbourne Perfrmance Centre a call. They do custom brake setups for somne quick GTRs including pedal boxes.

My 2c its money you dont have to spend. Just because a car may be a bit sketchy in the rear under brakes i wouldnt be looking to brake bias to fix the problem. I would make sure my toe setting and general alignment is right. Then i would make sure my ride heights are correct...then i would play with pads to give the car a nice feel.

If there is an obvious brake balance issue then sure...go the whole hog. But is supect your setup will be fine based on the AP sets i have seeen for GTRs. Unless you have spec'd a strange selection of calipers with wierd piston sizes and rotor diameters.

[GTRgeoff]

Jack, one in particular was the white 34 that turned around at the last flip flop at Calder. Big APs on the front and stock rear and I was already concerned when he went out. I drove Matts with the Brembo front and stock rear GTt and found that to be pinchy in the rears even on ABS. You can get used to it and drive around it but it is always reducing your confidence int the car when trail braking.

I just think it's too much of a risk to have this in a road car Neil. It is a major defect so the car cannot be driven and I have seen the results of a novice getting in a car with bias. Not knowing what it did he just cranked it fully one way which was full rear. Without testing the result he then went out at Sandown for his first track lap and braking for turn 1 just locked the rears and slammed into the right hand barrier. Nothing to stop anyone getting in a road car doing the same and the reason that such a change (a new brake setup) must be engineered as they will conduct braking tests to determine the balance and suitable operation. Sure we can argue that it simply must be better due to the type of setup etc, but that depends on the installer.

Nothing wrong with a long discussion post either Jack, else we all end up with Ash's 1 Line zero value added efforts, hence demonstrating our lack of understanding.

[JAGR33]

You mean the silver 34, clayton's one?? Yep I was there that day, got away with murder, the damage was minimal considering what happened. That was due to oversteer and lack of control, but I do see your point.

A firm example of this would be Snowman's car, huge AP's with 375mm rotors up front, standard calipers rear. I'm not sure if he runs a brake bias controller but you'd think it would be seriously unbalanced. Every time I've asked him he seems to think it works well.

Hopefuly he can shed some light and see what he's experiences with such setup is like...

And Geoff, you've hit the nail on the head in regards to the use of a brake bias controller in this situation...

[Roy]

Chris says Snowies brakes feel great. But i think both of them have commented that Chris's R33 GTR with std Brembo calipers front and rear may actually stop better.

The big APs seem to be more consistant...but the car doesnt automatically stop any quicker, the possibility is there that they dont stop as quick. I dont think Chris has said it feels unstable under brakes or has a balabnce issue.

I love my brakes, but being honest i feel it is more a driver confidence thing. Which to me is 99% of the battle if you want to go quick

[GTRgeoff]

Thanks Jack, yep Claytons car.

I know a lot of folks get all excited about brakes, the bigger the better (Troy??? ) but for the limited laps we run they just make minimal difference to good pad and fluid combo and a great suspension setup and alignment. Better setup means less braking and higher corner speeds. Those claiming to have great brakes, have they ever raced in a properly setup race car to actually have something to compare with? Other than Benno who is actually lapping fast enough to compare favourably against the old GT production cars (Comparos in Troys thread on lap times)?

Of course it's great to say how fast our road car laps, but there is something special about taking out a dedicated race car so I'll be enjoying the 25t a little while after this engine build while I put together something cheap and fast. The $10K project.

[Roy]

I think Jack has done a 1:18.9 or 1:19 or something at Sandown...a track thats pretty hard on brakes. So at the speeds and numbers these guys are doign i dont doubt brakes help you get the lap times.

Especially since they are AWD, they would tend to look after the tyres so they would need the 3rd or 4th lap to have enough temp in the tyres to do your best time. Most of the cars with the brakes also have the radiators and coolers to boot so that they are all set with good tyre temps to GO!

You would hate to have to nurse the car because the brakes are a lap or two past their best.

To put it into perspective most of the Vic GTR guys have V8 Supercar power, with 300-350kgs more weight to carry, with less aero and cornering grip. So i dont doubt for a second they need some better brakes when the rest of the cars as so developed.