Traction Issues R33 Gts25T .

[discopotato03]

Story is this , have mild RB25 just GTRS and R34 SMIC SK Bilstein suspension Rays 17 x 8.5s with 235 45 Michelin PS2s and I can't get this car to hold its feet in the dry when it comes on boost with the boot in - in at least 1st and 2nd .

Not sure how much of this could be from that VLSD or just Skylines less than even weight distribution front to back .

To save me finding out the expensive way do mechanical LSDs and bit more rubber make a worthwhile difference or not really ? I suspect 245 45 or even 255 40s would go on 8.5 inch wheels but does it make much difference ?

It kind of defeats the purpose of having more than 2.5L if the std capacity donk makes more power than these cars can use .

So , is this a my car thing or just the nature of RWD Skylines ?

Cheers DP03 .

[R31Nismoid]

Decent diff and wider tyres will certainly make a difference. You shouldn't be losing traction in 2nd at all.

I could put around with 270rwkw without much trouble in RWD and using 255s and 2nd would put full power down.

[Dajae]

As stated above.. Good diff with some nice tyres. I was able to road test a friends set of ku36 a while back before my car went in for the build, and could put down 260rwkw without too much traction loss.

Not-so-stiff suspension also goes a long way..

Even on 225 shitters, it would only break step if i launched like a knob. Driving style maybe?

[GTSBoy]

Old tired VLSD is not worth a piece of shit.

[discopotato03]

Seriously this not dial up 5000 revs and "drop" the clutch kiddy style , this is take off at part throttle and increase to almost WOT and somewhere about 3800-4000 just spins and gets a little trampy at least in first . Second is sort of similar but watching the road so guessing similar sort of revs .

Also I'm talking about that smoothish hotmix road surface not that gravelly secodary road type stuff .

It did it to me out of a two lane roundabout recently in second and the road wasn't quite straight , that 96K old VLSD is doing somethink because it never single spins like open diffs do . It got a bit out of shape and needed hauling back into my lane .

I would have thought that Michelin Pilot Preceda 2s were reasonable things and they don't have much more than 8-9000 on them and plenty of tread depth .

As I said 235 45s on 8 1/2" wheels and the rims look wider than the tyres . Theres a chance that 255s would sit outside the bodywork and thats not acceptable . Wheel offset escapes me ATM but I think its the same 34 as my Evos RPFIs have , exact same dimension all round actually .

I think I remember looking at 245 45s when I bought those tyres and they were considerably more expensive in the same type of tyre . I gather 245 45s are a bit of an odd size and lower volumes make them more expensive .

I researched the GTR diff bits into RWDs and if I could find the bits for reasonable money I'd give 1hat a go . I'd just swap centers and fit the rest outwards from there . I reckon one of these CLSDs set up to std specs would be livable in a street car , not really interested in hops skips etc round slow bends driving in citizen mode .

Cheers A .

[GTSBoy]

I thought my VLSD was still behaving as an LSD too. Then I swapped an S15 helical into it, and it is night and day. The old diff felt like it was driving the inside wheel (which is the one that would spin up and axle tramp on a typical left turn onto main road sort of thing, and the helical feels like it is driving the outside wheel (by comparison).

I use KU36, and at the same age as your Michelins, they are nearly stuffed. 235/45-17, same as yours. I can get them to break traction with <<200rwkW in 1st if the car is not lined up straight. Not being a knob, either.

[Dose Pipe Sutututu]

how's your camber setup?

what condition are your shocks & springs in?

I held ~250 rwkWs using cheap Kumho KU31 tyres on the rear, it would barely light up 2nds on a hard flat shift, I suspect either of this issues:

- too much camber

- ultra stiff suspension, not enough squat

- tyres are too old

- tyres inflated wrong

[simpletool]

Actually it sounds about right for street tyres. 230rwkw, 240rwkw, 260rwkw, the peak power reading is largely irrelevant since they probably have the same mid-range torque at the wheels as you with a GTRS. Actually the GTRS probably hits HARDER at the mid-range than those making a fraction more power from a larger turbo.

It's not unusual to light up 235mm street tyres in 2nd on smooth hotmix. I have 230rwkw and light up 2nd gear on most surfaces (no clutch jump, nothing). 235/40/18 Sumitomo Z3, properly inflated (33psi), flat mounted diff with pineapples, SK suspension, stock ride height, 1.5° camber, stock diff.

If you put better tyres on such as KU36, 595RSR it will grip. Also a helical LSD will help.

[nos man]

as above mentioned but get your alignment checked, get a proper wheel alignment place to check the toe

[discopotato03]

I bought this car must be 5 years ago (I think) off a member here and he'd just had the full SK Garys Whiteline Bilsten kit fitted new and its done ~ 11000 Km .

Tyres wearing evenly and it drives straight too . I have no reason to believe any settings have changed back or front . It was set up to Garys spec and while I speak to him occassionally I can't remember his numbers off hand . My guess is that its partly that dryer and its ability to make good mid range torque .

Its not impossible that these tyres have gotten a bit harder over time and for much of the time with me this car did very few miles .

I must ask Gary if they used the GTR diff stuff in their R33 which saw a bit of track use . I think I'd prefer a CLSD to the S15s torsen and I like the idea of the larger stubs axles and hubs .

I run my tyres at slightly higher pressures than most ie ~ 36 hot because I find they wear more evenly and give less rolling resistance .

Could try them back at 32 33 and see what happens , cheers A .

[Dajae]

Interesting.. I think you're onto something regarding the tyres breaking down/drying/going brittle over time. But in saying that, have you had the same torque level the entire time? How does the car compare to itself 1, 2, 4 years ago?

I find the handling shocking at anything less than 36 psi. I usually run 40 psi.. Let us know how you go with the lower pressures

[Dose Pipe Sutututu]

I bought this car must be 5 years ago (I think) off a member here and he'd just had the full SK Garys Whiteline Bilsten kit fitted new and its done ~ 11000 Km .

Tyres wearing evenly and it drives straight too . I have no reason to believe any settings have changed back or front . It was set up to Garys spec and while I speak to him occassionally I can't remember his numbers off hand . My guess is that its partly that dryer and its ability to make good mid range torque .

Its not impossible that these tyres have gotten a bit harder over time and for much of the time with me this car did very few miles .

I must ask Gary if they used the GTR diff stuff in their R33 which saw a bit of track use . I think I'd prefer a CLSD to the S15s torsen and I like the idea of the larger stubs axles and hubs .

I run my tyres at slightly higher pressures than most ie ~ 36 hot because I find they wear more evenly and give less rolling resistance .

Could try them back at 32 33 and see what happens , cheers A .

You've mentioned 5 years since. Go spend like $60 and get a wheel alignment + your stock rear camber adjusted. Slight toe in on the rear will help too.

[discopotato03]

No it grew a GTRS 256 Tomeis and larger exhaust valves . Handling aside from traction is is unchanged .

Does anyone here run 255 40s on 8 1/2 inch wheels ? I found they are Rays Nismo 5 spoke LMGT4s and that makes them +30 offset .

A .

Edited July 12, 2012 by discopotato03

[nos man]

alignment goes out over time as bushes wear, this being a rear traction issue i would look into a proper wheel alignment place to adjust the rear. most normal wheel alignment places align the car like a normal road car so they'll run toe in when there's camber to compensate so tyres wear more evenly. a proper alignment shop will look at your rear suspension on full compression because wheels tend to toe in when under full compression so maybe a little toe out is needed or even go down the path of changing all the rear arms and get it set up properly. you have to go someone who knows what they're doing though

[simpletool]

Correct size would be 255/35/18. Fattest you can squeeze on 8.5" is 265/35/18 RSR with a slight bulge. The stock wheel Evo and Sti do it in the states and track them. No problems.

FWIW. 265/35 are cheaper than 255/35

[discopotato03]

These are 17" wheels not 18 - 17 x 8.5 x 30 .

[Dose Pipe Sutututu]

255/40/17 would be a good size & common-ish. I used to run 255/40/17 on a 17x9 rim (a tad under sized).

I suggest you get a wheel alignment, I don't understand how you guys have traction issues at 220 ~ 250 kW without stiff suspension.

Reduce the camber to around -0.5 ~ 1 degree & toe either side in by 1mm

[discopotato03]

For the record will 255 40 17s be flush or outside the bodywork on 17 x 8.5 30P wheels ? . The Sydneykid set up has a little bit of negative and toe in but I'll ask him the numbers when I talk to him .

DP03 .

[discopotato03]

I managed to speak to Gary yesterday afternoon to pick his brains on rear Skyline stuff .

Firstly their old 33 (GO33GO) Used to spin the rears and in ultimate form it had 266 at the wheels with similar specs to mine but with a GTR IC and OP6 GCG Hi Flow . He said their Viscous LSD was good for what they wanted and had very little to no single spin issues . Driveline wise it was pretty std apart from a gearbox rebuild and aftermarket clutch and lightened flywheel .

Suspension was all Garys kit and the wheels were Enkei 17 x 8.5 RPF1s that ended up on an Evo funnily enough . I think they used 245 45 tyres but he said 255 40s would work and stay inside the bodywork .

The GTR LSD would be better but that ultimately means hemisphere outwards and to stay weight neutral means changing the uprights and rear dampers to GTR style . I understand weight reduction is a bonus here because with the uprights its unsprung mass .

A .

Edited July 14, 2012 by discopotato03

[AngryRB]

My brothers car has a good setup, uses Rays 17inch with Kumho 265''s, Monroe sport shocks , pulls very hard with no slip in second

It does take a few squirts to really start gripping though, maybe those michelins just arnt up to the job...