john banks

Harvey, posted here rather than off line so hopefully we can all learn a bit from you if that is OK.

Re spec of your car: "Front and Rear LSD with up-rated centre viscuous coupling"

Where did you find or where do you think the weak points are in the Subaru diffs/driveshafts etc? What diffs and driveshafts have you got on your car and what do you recommend? Would you specify anything different again? What would you suggest on a UK car with an uprated gearset, clutch, lightened flywheel, but otherwise standard diffs/driveshafts with 400lbft target for daily use?

David_Wallis

I think this 'daily use' thing as you put it john can be confusing..

Your daily use might be revlimiter everyday.. someone elses might not be..

My daily driving normally represents a trackday.. but out in the country

Every set of traffic lights is a drag race..

Seriously though.. maybe you should ask for 'spirited driving' as I suspect your roads are good enough..

driveshafts should be ok, but they are cheap enough not to worry about for the moment.

edited as I clicked send before I'd finished

[Edited by David_Wallis - 10/17/2003 10:43:52 AM]

T-uk

john is a straightline god , unfortunately since decent suspension does not add bhp or torque , he won't buy any .he will race everything in a line though, cars, bikes , helicopters and his shadow if nothings about

[Edited by T-uk - 10/17/2003 1:03:42 PM]

David_Wallis

lmfao

john banks

I chase power for a reason... because I use it a lot. Braking more than T-uk would for a corner is just an excuse to use more power on the way out of it and because I am no oversteering god like him (I even made my 406 swap ends unintentionally ).

So the diffs will get a workout.

David, do you think I will damage the standard UK viscous diffs with this power level?

KW v3 will be ordered once/if the engine is sorted.

[Edited by john banks - 10/17/2003 2:41:17 PM]

David_Wallis

erm.. I reckon possibly.. mark thought I would kill my rear diff with my power.. so I bought a spare..

Much cheaper.. doesnt take much space up..

My front diff is suretrac.. think centre diff is just viscous, however I plan to change that to either cusco tarmac or dccd..

as I like oversteer.. (M3 argument again )

David

harvey

iTrader: (48)

Hi John : Been busy so just seen your post. The uprated viscuous centre LSD was fitted as a replacement for the knackered one when Scoobysport fitted different ratio diffs front and rear which screwed the centre viscuous.
I have also added over standard a front LSD and this has improved the car both for exiting corners and straight line take offs particularly in the wet or damp. All the drivetrain work, or at least the supply of parts was from John Pye Motors at Bishop Auckland, County Durham. John is a wizard in all transmission related matters and builds winning rally cars. It`s a bit like a production line this year.
I have not broken anything in the drivetrain so far and my gearbox and Bob Rawle`s are both STi ver 5/6. I think Bob is in the process of replacing his centre viscuous diff.
I am looking around for another gearbox so that when mine eventually breaks I have a replacement or at least know what I am going to do. I have already discounted the Lateral/PAR kit and believe also that Dog Boxes are not an option for everyday road cars, partially because of the horrendous noise.
My clutch is an uprated AP Organic and the original one failed when I rived the centre out of it despite the fact that the friction material was hardly worn after 20,000 miles or thereabouts. I would stay with an organic clutch as it softens the shock loading on the transmission and I recon if you want to screw a gearbox then fit a paddle clutch.
My flywheel is 5.2kg from Roger Clark Motorsport. There is absolutely no problem with this for an everyday driver but it requires a much more accurate technique for reliable drag starts. The previous flywheel was 9.2kg and if I was doing it again with the same clutch set up I would not want a flywheel less than 8.5kg.

Personally, I think the STi 6 transmission is pretty tough and it will last indefinately with an understanding driver while I am sure a boy racer will find the weak points that much earlier. I think everybody who has seen my car perform at Scooby Shootout will agree the transmission has not had an easy life.

After fitting a front diff I guess the next move would be an uprated centre viscuous.

Hope this proves helpful.

harvey

iTrader: (48)

BTW it is important to pay great attention to the ratios available and compare these with the gears being replaced. Give a lot of consideration to the implications of any change in ratios to avoid spoiling the car.

john banks

Thanks Harvey. What uprated centre diff options are there? Is the centre diff considered the weak spot then (presuming this is because it splits the full engine torque rather than just half of it or so to each axle)?

dowser

I'm wondering if my rear diff is knackered; leaving a multistorey carpark with an uphill circular exit ramp (540 degree total) sees a lot of rear end hop on my car, as if the diff is locked.

Equally a spirited t-junction exit sees it drift the rear immediately.

However, I've just refitted my Quaife front...with paddle clutch and PAR gearkit (whoops, Harvey ). Paddle is very aggressive, PAR gears are very noisey....but it's all worth it when caning it The Quaife front means the rear is much more likely to lose grip.

I'm investigating whether to get a DCCD or Cusco centre, and whether a Quaife or clutch LSD would be better for the rear. The Quaife works on power, not on coast - I guess an LSD that works on coast too would give very good response on track (allowing lift off oversteer at will on corner entry)....but may be a bit extreme for road use (picture trying to avoid something; lifting and turning at same time....immediately side swiping whatever you were trying to avoid ).

I would love to try a car with each before buying - but seems unlikely really

Richard

harvey

iTrader: (48)

Hi Richard: You could be O.K. with your set up but as you know I think the violence/shock that the paddle transmits to the drivetrain is what does the boxes in.
I have not experienced any snatching from front or rear diffs on the STi but on a XJS with an uprated diff it was a feature from the day it was fitted and after thousands of miles the diff is still OK. Was particularly evident on smooth concrete as you describe and full lock.
John: An uprated viscuous is not cheap but it will show greater benefits on cars with higher torque figures. Mine was whatever John Pye fits to their rally cars so I would imagine that Rally Colin could sort that out. If you are still stuck let me know.

fuz

Harvey

Jusy got a Fidanza Flywheel - 9.5 lbs

what do you meen by "requires a much more accurate technique for reliable drag starts"

thanks

edited to say its 4.32 kg

[Edited by fuz - 10/21/2003 6:06:03 PM]

harvey

iTrader: (48)

Hi Fuzz: With circa 9.5 kg I am sure you will be OK.
My experience was that with the heavier flywheel, drag starts were easy and the technique not too dificult to master. The exact revs for a good start not too dificult to find and quite a bit of tolerance. It will vary car to car but around 4.5k rpm from memory to avoid bogging or excessive wheel spin.
Now with the lighter f/wheel a lot more precision is required and to avoid bogging, maybe 5.5k rpm, which is starting to get a bit high and the difference between a good start ie no bogging and no excessive wheel spin is much finer.
Anyway, in the real world how many times will most people do drag starts? Very definately not good for the car or the wallet in the end so I am happy to have the benefits of a light flywheel for everyday use and suffer the consequences on the strip, not that I have been badly hindered yet.