R34 Gtt Brake Upgrade - Brake Bias

[chook]

Recently changed my pads after upgrading my C34 Series 2 Stagea F and R brakes to R34 Gtt last year.

Found that I had about 5% front pad and 90% rear pad remaining. I realise that the front does the majority of the work, but I think this is a little too much.

I did not change my master cylinder, so should i change it to a R34 Gtt one, is the proportiooning valve inside the BMC ?

cheers

[Duncan]

no you should be fine. I would be surprised if the bias was more than about 5% different from standard.

I've had the same wear on most of my skylines - front to rear pads has always 4 or 5 to 1...ie I've never replaced rears more than once on a skyline/stagea etc that I've had.

especially if your driving is a bit spirited.....they run a lot of front brake.

[chook]

thanks, checked FAST as well, same part number for master cylinder assembly for S2 Stagea RSfour and R34 Gtt, so bias must be same from the master cylinders.

[Sydneykid]

Recently changed my pads after upgrading my C34 Series 2 Stagea F and R brakes to R34 Gtt last year.

Found that I had about 5% front pad and 90% rear pad remaining. I realise that the front does the majority of the work, but I think this is a little too much.

I did not change my master cylinder, so should i change it to a R34 Gtt one, is the proportiooning valve inside the BMC ?

cheers

Not unusual, over 60% of the weight is on the front wheels and the weight transfer to the front under braking is a further 25% to 30% depending on spring and shock rates.

Cheers

Gary

[Birth]

Given that there is so much weight on the front of the car and generally such little bias; would it be beneficial to install a bias adjuster to provide greater rear bias to provide less pressure on the fronts and improve overall breaking?

[_Ryan_]

Given that there is so much weight on the front of the car and generally such little bias; would it be beneficial to install a bias adjuster to provide greater rear bias to provide less pressure on the fronts and improve overall breaking?

But doesn't a front bias brake setup help get rid of understeer? I know that my car goes through front pads twice as fast as rears, and that when i understeer, i just left foot brake and it pulls it all back into line

[Kinkstaah]

Offensive bump.

I just noticed today that my rear brakes and pads are effectively death. Braking at the track results in a very squirmy rear end to which I always figured everyone had to deal with.

Front pads (356mm D2/Ksport/Attakd kit) are the same pads as the rear. Changed at the same time. They have 50% meat left on them (approximately) while the rears are toast.

Considering people typically don't change the prop valve or even really report problems with this - Is something likely to have failed, or should I go out and actually get a prop vale to sort this out?

The fact that Duncan up there reckons he changes his front pads 5 times for every set of the rears makes me think something is clearly incorrect here!

[admS15]

I too seem to kill rear pads before fronts. Last set still had 20-30% remaining on front and rears where on the indicators. Previous set was about the same. 3 track days is about as far as a set of rears will go. I am running stock gtst brake setup with 324mm front disks.

[GTSBoy]

My car is also prone to locking the rear*.  Having said that, my car also exhibits the usual behaviour of needing front pads changed several times before needing rears.

My overall suspicion is that the OEM pads from Nissan had a somewhat less aggressive compound for the rear.  If you do what many/most of us do when replacing pads, which is to put the same pads in front and rear, then I suspect you are removing Nissan's built in front bias.  Ergo, with something like Intima SRs in the front, it would probably be wiser to put Intima SSs in the rear (rather than SRs).  Ie, go at least one step down in pad aggressiveness.

*This was the case many years ago with R32 brakes all around and Ultimates as pads all around.  Then when I put R33 brakes on the front, I put some OEM pads (that I stumbled upon) in and the bias got better.  Then I put upgraded pads in all around and I went back to rear locky tendencies.

[admS15]

I had tried that previously, I had qfm a1rm on the front and qfm hpx on the back. Rears still died b4 front. Next set was intima sr front n back. Same result. Currently have intima type d all round. I'll see what happens with these. I don't seem to get any rear lock. My car is non abs, occasionally locks up a front wheel.

 

 

[Kinkstaah]

For me, I'm not entirely sure whether it IS the rear locking or whether it's just a feeling of abs kicking in, or hard braking in general.

Looking closer, my wear looks closer to maybe less than half left on the front. Way more than the rear though!

Did your rear twitchiness change when you went from a matched pad to having a softer pad at the back?

I did initially have a softer rear pad... But then matched them all up later. Unfortunately my own mixed set initially was so bad it can't be used to draw a comparison.

[KiwiRS4T]

I put 330mm 8 pot D2s on the front and the non Brembo GTR rears (with Znoelli SP500 550deg pads) on the Stagea. Maybe it was the weight of the RB30 but the stock front pads chewed out in no time. When I changed to Pagid on the front they lasted 3x as long but the rears still pretty much kept in sync. The M/C is BM57 and the car always seemed to pull up straight at the track.

[Kinkstaah]

Sync... As in.. 1:1 replace rate front and rear? Or sync as in front wearing less than rear?

[Duncan]

lol very old thread.

I suspect your rear brakes aren't locking, and you are feeling something else.  rears locking first lead to a very distinctive feeling of leaving the track backwards, or having to work very fast to correct it before it loops.

On the other hand feeling light or squirmy at the rear under the brakes is pretty common on these cars.  They are way heavier at the front and under brakes if you run softer springs (and I prefer that) then a lot of weight shifts and the rear can get light. Some people like it, some don't. I find it helps point the car into the apex in slower corners, I someone else's evo who runs even softer than I do I found it really disconcerting in long fast corners.

Anyway, that was a bit rambling, but the point is it was unlikely to be locked brakes and rather just a light rear end. Go harder on the rear springs and shocks and see if it feels more stable.

Also, it can be exacerbated by suspension bush or balljoint problems in the rear, in particular hicas ball joints if they are still in place.

[GTSBoy]

I've left lines and done very rapid circles in the past to prove that I had rear locking tendencies.  Locking rears without the clutch pedal down also leads to a lot of banging and crashing from all the bits with gears and stuff.

[KiwiRS4T]

13 hours ago, Kinkstaah said:

Sync... As in.. 1:1 replace rate front and rear? Or sync as in front wearing less than rear?

As in wearing at about the same rate F&R

[Kinkstaah]

Given the posts in this thread, it seems my wear isn't that unusual, an in line with what adms15 reports really. So this is refreshing to know!

It probably IS just weight transfer, as I am very new to track driving really, and losing weight over the rear end when braking is a little unnerving, but I can see how getting used it is part of the game and beneficial. Won't know until I pull the front pads off to see how much there is left there, probably nothing major to worry about.

Given nearly no one (or anyone) bothers running a brake bias adjuster I am suspecting it's probably fine, but I was worried I wasn't getting the max out of the upgraded front brakes.

I guess the solution long term is upgrade the rear to 356mm to match the front (or maybe 330mm as the R34 doesn't run 296/296...)

[KiwiRS4T]

2 hours ago, Kinkstaah said:

Given nearly no one (or anyone) bothers running a brake bias adjuster I am suspecting it's probably fine, but I was worried I wasn't getting the max out of the upgraded front brakes.

I guess the solution long term is upgrade the rear to 356mm to match the front (or maybe 330mm as the R34 doesn't run 296/296...)

Builders of dedicated track cars will sometimes incorporate bias adjusters.

As you have observed the transfer of weight to the front under braking means that there is no point whatsoever in having the same size brakes at the rear as at the front.

[Hasitha]

Just wondering if anyone has tried changing R34 Gtt brakes with Brembo off a Z33 track edition