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Discussion Starter · #1 ·
I know this is a long shot but I will ask it anyway..
In my quest for ever increasing power I have now hit a brick wall (not literally)..to balance the power I need TRACTION..
So wider tyres I thought 265 or 275 section would be appropriate
I am at the limit widthwise of what my present rims will accomodate so..
it will have to be 9" rims..
the question is (with the appropriate offset of course) fit in the wings
Eyeballing it does looks tight..
I vaugely remember an american bloke running 9" rims with slicks but I cannot remember where..

Anybody tried/know of anybody with these wide wheels ?
 

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I know someone with a CC style 9000 (therfore the smaller arches) running 255/35 or 255/40 by 18's and all he had to do was grind off the protruding bolts on the wheel arch trims.

They did look big though!

Andrew
 

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Discussion Starter · #4 ·
What about LSD and a racelogic traction controld?[/b]
got that already....
tcs not racelogic
and a nice quaife lsd

still not enough traction...

tcs works to a point but the wheels spin for a several revolutions before the tcs kicks in..
 

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Probably worthwhile getting the 'arches flared out, I've seen this done on a CC which was at Goodwood two years ago. It can be done relatively simply by putting spacers at the bottom of the wing IIRC. However, if you want to fit larger tyres at the rear as well (I guess you would) the rear arches would need to be flared, I'd imagine that this would be more problematic (and expensive) as it would require more extensive bodywork mods.
 

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It should be a fairly simple operation to roll and delip the arches, a common trick the boyo's use to fit 17's on shopping trolleys. You should get another 10mm or so clearence which might just be enough.

Matt
 

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Discussion Starter · #7 ·
unfortunately there is the arch trim piece which is bolted into position..the threads of which do project into the arch cavity a few mm's

I think I will try and get a single wheel of the right width and offset and fit a part worn and see what the probs might be...
 

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Would the wider rim with the right offset be any different than fitting a worn tyre of the right size to one of your existing rims? OK the sidewall will be stressed, but that doesn't matter for testing purposes. Or do you want to have more offset so that the tyre centreline is further out and the inner sidewall in the same position?

What about doing away with the wheel arch liner and doing something canny with the arch trim, like replacing it with something slimmer or losing it altogether?

Might be worth considering wider tyres at the front than the back. I've seen hot rod minis set up like this and they worked well. My 96 rally car liked 185s on the front and 165s on the back, but made it a bit loose on the limit though.
 

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Discussion Starter · #9 ·
offset goes down the wider it gets to maintain the centre line...
so I need both the rim and the tyre...

bigger at the front ..yes maybe (it is already pretty loose at the back !!)
 

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Originally posted by ylee coyote:
[qb]offset goes down the wider it gets to maintain the centre line...
[/qb][/b]
Offset is measured from the centre line. So if you want to maintain the centreline position you should keep the same offset.

Changing the offset is usually done to keep the outside edge of the wheel inside the wheel arch.
 

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What's the suspension like? I found super-stiff suspension at the rear worked wonders for traction. Even with 330lbft (no boost limit) in 2nd gear and 4.05:1 final drive, I could put all the torque through standard Aero wheels and Bridgestone S-03s with no problem. That should be pretty close to whatever torque you can get through the wheels in 3rd gear upwards.

Of course, running 17" wheels won't be helping your case at all when it comes to straight-line traction.
 

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A friend of mine with a turbo eclipse after upgrading turbo experienced more traction because of more lag. Also he purhased some drag radials for his two front stock wheels and tires, and uses them when he takes the car to the drag strip. The drag radials make a huge difference with little tire spin in first and no spin when shifting into second. Reasonably priced too
 

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Discussion Starter · #13 ·
What's the suspension like? I found super-stiff suspension at the rear worked wonders for traction. Even with 330lbft (no boost limit) in 2nd gear and 4.05:1 final drive, I could put all the torque through standard Aero wheels and Bridgestone S-03s with no problem. That should be pretty close to whatever torque you can get through the wheels in 3rd gear upwards.[/b]
its at 2 clicks on the rear koni's...
but I have been looking at auxilliary air springs for these occasions...
It rides pretty low and altho you can get loads in the back you have to watch the weight
Air springs would help on this but would stiffen the rear for the track or strip...

not expensive either
the us ones run less than $100...
do not make them for saabs tho but I just have to find another (us) car with the same dimension rear spings...

ps the torque is 400 lbs/ft....
 

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Fitting wider tyres will not necessarily improve traction unless you drop the pressure, because the area of rubber in contact with the tarmac is a function the car weight divided by the pressure in the tyres. Wider tyres tend to assist cornering and turn-in feel (to a point)because they change the contact patch shape and that puts the shear force of cornering across a wider section, but may reduce traction as the contact area becomes wide and short, and easier to shear.
Kev.
 

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Originally posted by ylee coyote:
[qb]ps the torque is 400 lbs/ft....    :eek:   [/qb][/b]
Only in 3rd gear up, surely? I know from bitter and repeated experience that the 9000 final drive gears can't take 330lbft multiplied up through 2nd gear for very long, let alone 400lbft.

What I'm getting at is that my driveshafts were seeing 330 x 7.83 x 4.05 = 10,464 lbft in 2nd gear and I still had enough traction to transfer that to the road in a straight line in the dry with no wheelspin.

Your 2nd gear probably has a boost limit (standard Maptun practice - I asked them to remove it) so you'll be getting less torque than I was in 2nd gear. In 3rd gear, assuming a 3.8:1 final drive because I think you said you had it lowered from the standard 3.61:1), your driveshafts will be seeing 400 x 4.97 x 3.8 = 7,554 lbft. Even with a 4.05:1 final drive, it will be no more than 8,050 lbft.

Edit: for reference, 2nd gear is 7.83:1 and 3rd gear is 4.97:1
 

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Although I've repeatedly chewed the 4th gear clirclip (fix currently being engineered, will report soon
) I've not had any other problems specifically associated with repeatedly deploying 360lbft in 2nd gear (LSD, no boost limit)- and the early gearbox is not meant to be as strong as the later ones
 

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Discussion Starter · #17 ·
hanging the offset is usually done to keep the outside edge of the wheel inside the wheel arch.[/b]
I need to move the inside edge away from the suspension arm at the back..there is only a few mm of clearance
therefore less offset..(I think !)

Gearboxes ?
I have had a few, but too few to mention (sings badly !!)

(groan...)
I put it down to the tcs saviour ..thats why I am loathe to take it out ....
 

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Adding more traction will allow you to transfer more torque through the transmission, so that will increase the strain on the gearbox. It was only when I had the LSD fitted that I started getting transmission problems, even with all that torque in 2nd gear. Prior to that, wheelspin limited torque through the transmission.

As long as you accept that increasing traction will increase strain on the transmission, more traction is what you want.

I can't really see how traction control can be making any difference to your transmission's longecity. It limits output torque to that which will cause wheelspin. In the absence of TCS, wheelspin will do the same job. The only thing I can think of is if the 9000's particular implementation of TCS slows the rate of rise of torque, limiting the "shock" applied to the transmission. I'd have thought turbo lag would swamp any effect the throttle response might have.

If anything, I would think that with TCS being able to hold the maximum possible torque transmissable through the wheels, the use of TCS would ensure you can keep your transmission under maximum stress.

Mark, you get almost 2.0 bar in 2nd gear and don't suffer transmission problems? Have you measured peak boost in 2nd gear?
 

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Although my cars not in the same league as most of the tuned 9000's represented here, it does have quite a bit of mid range torque.

I realise that having the nannyish TCS, no LSD and only 205 width tyres is the reason why my cars boost spikes haven't killed my 'box already. I have no plans to upgrade either the wheel width, diff or remove the TCS (unless it breaks) whilst my budget is as limited as it is! So for now, I personally can live with a traction deficit.
 
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