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99 UK S-turbo
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Discussion Starter · #1 ·
OK, ignoring the recent icey weather we have had, I'm fed up with the front wheelspin in the foz, and am truying to decide what to do to fix it, my old Ford 4x4 didn't suffer from it (33/67 torque split and much stiffer centre diff) and I want that feeling back!
99MY 5MT s-turbo (circa 220bhp and 230lbft) running 04 Impreza STi suspension

Thoughts
1/ STi 20NM centre diff
+ More traction
- More understeer without extra mods that may or may not get it back to where it is now

2/ ALK replication using spacers to lower the wishbone mounting
+ reduced understeer
- only slightly improved front end traction

3/ DCCD from a classic STi
+ Rear biased torque split
- Expensive (and how) and extra compexity in fitting, also ABS doesn't like it!

Thoughts/ideas?

Simon
 

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99 UK S-turbo
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Discussion Starter · #6 ·
I was aiming for the DCCD from a 98-00 Impreza STi, not aware of any DCCD 5speed after that? (all 6 speed). but they sell for at least £350 ($500) so not cheap, installing it physically is easy, adding the electronics is harder (and can be pricey) or I could get it rebuilt as a conventional mechanical plate diff.

I have tried to find an Audi 'Torsen' (Helical) centre diff as its a similar layout (concentric front input/outputs) to ours and may be a cost effective way of doing it (although it may be an impossible job - who knows)

I'm running 19mm front/20mm rear bars, not sure why you ask though as the wheelspin is in a straight line!

Also as both front wheels are spinning, I'm not sure a front LSD will help, also its a much more expensive and time consuming mod than any other!

I have a Cusco rear plate diff, to fit but while its the fronts spinning, there seems little point!

Simon
 

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Discussion Starter · #8 ·
Thanks peter, may be good off road but will cause more understeer than the 20Nm centre which is an easier option!

Simon
 

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Discussion Starter · #18 ·
Jstorm, yes the Cusco centre is open and so not what I want really, nor do I probably want an 'open' DCCD although the post 97 ones are 60:40 so not too bad.

As far as I'm aware the 12Kgm (yes not Nm as I was using doh) centre is only availbale for pre 97, after that its 20 or 4.....

Looks like I'm down to a 20Kgm or a DCCD either electronicly controlled or with rebuilt clutch pack (more preload and a play with ramp angles) to act like a regular plate diff.

Simon
 

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99 UK S-turbo
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Discussion Starter · #30 ·
+20% springs front and rear at -1" on STI struts (not topping out at the front - checked), 20mm rear, 19mm front bars.

Marks on road suggests both front spinning, 225 tyres (Fairly worn but still around 2mm tread, new ones going on when I get home next week), obviously the inside spins out of tighter corners but at one open local curve I can understeer the front out wide with wheelspin (revs climbing) in 2nd gear.

Certainly not going to add even more weight over the front, I want it to corner as well.....

What i think I really miss is the rear biased torque split my old Ford (and 4or2wheels STi) has.

I didn't know a 12Kgm would fit with an older rear housing (which I already have somewhere I think LOL) - handy to know!

Simon
 

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Discussion Starter · #34 ·
Front LSD would be nice, but I think I'll try and get a DCCD centre first then (for the rear biased torque split)....adapted as plated or electronic control that is the Q!

Simon
 
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