Help With R32 GTR Drag Setup

[keith cowie]

Hi everyone i am new here.

I want to ask if anyone has come up against the problem that I am experiencing

with my R32 GTR drag car.

when I run the car on the 1/4 mile it wants to change lanes,no matter how hard I try to hold it straight

it wants to pull me either into the wall or into the other lane ????.

It feels like the front steering is toeing out but it is not,it is set at one degree toe in

the car has OS Giken diffs front and rear,the car has HKS drag dampers not sure what springs are fitted

the rear runs with 1 degree positive camber and one degree toe in.

Here is some info on the car and a few photos if anyone is interested

Car weighs 1210 KG.

Cusco front adjustable tie rods.

HKS drag dampers with HKS top mounts.

Midori top front adjustable camber mounts.

Border hicas removal kit.

Midori rear beam location kit.

Cusco rear top adjustable camber rods.

Midori rear tie rods.

Hope someone can give me some ideas to try

thanks Keith

[DICKY]

what a great looking car, I am about to have a giken rb 30 powered 32 finnished so am looking forward to seeing some reply's to this thread

[keith cowie]

Hi Dicky

So am i.

the car is ok in 1st and 2nd but i have to lift off at about 7000 revs in 3rd

because i cant hold onto the car :cuss:

Keith

[Beer Baron]

Keith, how much power is the car making? I'm guessing over 800ps? Also what tyres are you using, and is the ATTESSA system running as standard or are you using some kind of torque split controller?

BTW good effort on getting the car down to 1210kgs!

[keith cowie]

Keith, how much power is the car making? I'm guessing over 800ps? Also what tyres are you using, and is the ATTESSA system running as standard or are you using some kind of torque split controller?

BTW good effort on getting the car down to 1210kgs!

Hi mmmgtir

Not sure on what power it is making to be sure

It is a Trust 2.7 with 290 11.5mm Tomei cams,it runs at 2.5 bar boost with a pair of 3037S

turbos,rev limit is 9500 revs,all controlled with Autronic Ecu and CDI unit

i would think it is making something between 850 and 1000 ps

All the std 4wd system has been removed from the car it now has a

mechanical system in place for the 4wd.

the car runs on 16" M/T slicks

thanks Keith

[always_me]

what times have you run

[DICKY]

so never been on a dyno ? think how much more is there to be had ! I hope a/f ratio is safe

[Beer Baron]

Keith like all forms of motorsport at the pointy end, it's going to require some serious tuning (suspension, tyre pressure, engine, etc) to get this working the way you want.

I really don't know of any meaningful advice many people on this forum can give you as not many of us run 800ps+ GTRs on slick tyres.

Mario Tobrac (not sure on spelling), www.exvitermini.com is one that has trodden this path and it took a LOT of work on the car setup to get his car runing straight and getting good times. I don't think there will be a magical fix that will cure this problem, just got to keep tweaking the car till it improves. Maybe send Mario and email through his site. He may be able/willing to help you out.

Good luck.

[Marlin]

G'day Keith, from my perspective, it's a by-product of the Cusco front diff centre and the cross ply tyre your using.

Theo (a mate w-/ 9 sec GTR) experiences this now since installing a front 1 way locker. He installed this diff when the car started turning the front tyres alternately at high MPH under load.

He says it was even worse when he tried a "traditional" drag tyre as well. A stickier tyre will increase the effect of axle wind up due to unequel length front drive shafts. It was enough to touch the wall in fact! (He normally runs off the shelf Federal street tyres). Apparently he now has to release the power and straighten it up during a run.

Feel free to contact him, he'd be stoked to talk to you. [email protected]

Great looking car mate. All the best with it!

[keith cowie]

G'day Keith, from my perspective, it's a by-product of the Cusco front diff centre and the cross ply tyre your using.  

Theo (a mate w-/ 9 sec GTR) experiences this now since installing a front 1 way locker. He installed this diff when the car started turning the front tyres alternately at high MPH under load.

He says it was even worse when he tried a "traditional" drag tyre as well. A stickier tyre will increase the effect of axle wind up due to unequel length front drive shafts. It was enough to touch the wall in fact! (He normally runs off the shelf Federal street tyres). Apparently he now has to release the power and straighten it up during a run.  

Feel free to contact him, he'd be stoked to talk to you. [email protected]

Great looking car mate. All the best with it!

Hi Marlin

Thanks for the help,i was on the phone to Theo a few hours

ago he told me the same thing about the diff.

Keith

[DICKY]

oh fark, I have a 'yet to be run' 1.5 cusco rs front diff !so what front diff is best ?

[Marlin]

oh fark, I have a 'yet to be run' 1.5 cusco rs front diff !so what front diff is best ?

Maybe a stonger set of billet drive shafts for the front will minimise the wind-up? If you have got huge power, your gonna need something in the diff aren't you!

I've heard good things about the handling transformation on a circuit with these diffs. Are you a straights or a corners man?

[keith cowie]

oh fark, I have a 'yet to be run' 1.5 cusco rs front diff !so what front diff is best ?

Hi Dicky

My car runs OS Giken transmission parts

6 speed sequential box,front and rear diffs and a 4 plate clutch

Keith

[igor]

Don't mean to whore the thread, but Keith, you car is absolute dead set hardcore.

Is there any way of making the drive shafts the same weight/length? If that is the cause of the problem.

[NXTIME]

Keith, you still haven't told us what times and MPH your car runs

Beautiful car you've got there. Do you have any interior shots?

[keith cowie]

Keith, you still haven't told us what times and MPH your car runs

Beautiful car you've got there. Do you have any interior shots?

I have not done a full 1/4 mile run in the car yet

that is the big problem I have.

When we were mapping the car we were going from 30 mph / 50km to

over 200 mph / 300km in a distance of only 800m

Keith

[blk180]

http://www.croydonautosports.com.au/ they have the third fastest GTR in the world and have used a 6 speed sequential box before changing to an air change box. also willall racing have australias fasts street tyred car if your still using those nitto's dont know there number maybe some else will post up for u.

[keith cowie]

Does anyone that posts on here have contact details for willall racing.

Thanks Keith

[Munro]

With a 1.5 way front diff, you might just need to back off the front bias once you get past 2nd gear ( I know things are a bit busy about then) but the torque steer is the problem & no way around it with that much power. i am a bit out of touch 'cause I haven't run my race GTR for nearly 2 years, but I remember crossing the traps at 153 mph with a 1/4 turn of steering lock to keep it straight so I understand the problem.

i am looking at going to slicks with my new setup, so will probably face the same problem.

All I can suggest is put more power to the rear & steer the thing at the traps the best you can. Welcome to fast GTRs. Never seen a really fast run that wasn't all over the track!!!

The HKS team told me to stiffen up the rear suspension & keep the car as flat as you can.

They have much less weight to deal with then us (mine around 1270 kg), so direction changes not as hard to deal with. Smoother gear changes will also help keep it straighter.

Easier said then done I know!!!

Keep up the good work, ultimately it's the testing that will give you the best results.

We are only just starting out.

[keith cowie]

With a 1.5 way front diff, you might just need to back off the front bias once you get past 2nd gear ( I know things are a bit busy about then) but the torque steer is the problem & no way around it with that much power. i am a bit out of touch 'cause I haven't run my race GTR for nearly 2 years, but I remember crossing the traps at 153 mph with a 1/4 turn of steering lock to keep it straight so I understand the problem.

i am looking at going to slicks with my new setup, so will probably face the same problem.

All I can suggest is put more power to the rear & steer the thing at the traps the best you can. Welcome to fast GTRs.  Never seen a really fast run that wasn't all over the track!!!

The HKS team told me to stiffen up the rear suspension & keep the car as flat as you can.

They have much less weight to deal with then us (mine around 1270 kg), so direction changes not as hard to deal with. Smoother gear changes will also help keep it straighter.

Easier said then done I know!!!

Keep up the good work, ultimately it's the testing that will give you the best results.

We are only just starting out.

Hi Munro

Thanks for the info on the diff.

When are you going to be running your car next

Keith