Axle ratio

[sgroves]

I am just about to confirm my order for a Superlite. The standard ratio is 3.6/1 but I have been advised to change it to a 3.9/1, this is based on competitiveness for sprinting. However I will probably only do 3 or 4 sprints a year, maybe a few track days and some autotests. My question is "has anyone changed ratios, either way, recently, and what were the overall effects to road use?" I will use it on the road far more than in competition.

 

Steve G

[Dave H]

Steve,

 

just an idea you could consider. You could fit the lower ratio for to give you that competitive edge you'll want, and adjust the ratio by havng two sets of wheels, 13 inch for the track and 14 or 15 for the road.

 

Dave H

[F355GTS]

Dave

 

had a 3.9.1 in my Supersport (virtually Superlight spec) and it went very well on trackdays accelerating hard but ran out of puff around 115 MPH (with a windscreen which didn't help) personally I prefered it, no bogging down and for sprint/hillclimb I would have thought it was ideal. Do bear in mind though that it isnt a major job ( so I am led to believe!)to change between the two and 3.91 Crown and Pinions seem to be available for circa £50

 

Rob Grigsby drove my car back from Imola via Monte Carlo, by the end of it his ears were ringing and he was completely knackered, it wasn't what you would call relaxing to cruise on long distances, 100mph = 6,500 revs but for a blat round the lanes though it's perfect

 

Mark

[KevSull Too]

First question should be 'what gearbox have you gone for?' is it the proper SL spec (with 6 speed and LSD?)

I run a SL with the 6 speed box, and 3.6 diff, and this works well (although it is a little low geared if you take it on the m/way. Personally I wouldn't want to go to the 3.9.

 

If you know your car (and you will in a very short time!) you can easily avoid bogging down on the starts.

 

If you have the 5 speed, I'm not qualified to comment (never stopped me before), but the 4th gear ratio is the same as 6th on the 6 speed. This may be a little easier on the revs in top gear.

[sgroves]

It will be the full spec ie 6 speed and LSD. Interesting comments so far thank you

[Richard J Darnell]

I'd second Dave's comments.

 

I upgraded to a 6 speed box which means I have the 3.9 diff.

But I also have big diameter wheels - they are 13" wheels but wider than normal (7J rather than 6J) which allows 205/60 tyres - this gives a diameter very similar to my old 16" wheels with 205/45 tyres (I measured it)

 

when I played around with a gearing program I found this combo gave me almost identical gearing to a standard superlight with the 3.6 diff

[Paul Bowden]

I have a standard SL with the 3.62 CWP. I toyed with the idea of 3.9 but I am glad I did not go for that. I have not got vast experience of performance cars and I am no Michael Shmacker, but the acceleration of the SL is fantastic, personally I don't need any more. However on the occasion I find myself on a A road I would not like to run out of Puff at 115 mph. In standard form you can cruise at 80 mph = 4000 rev . The wind noise is far greater than the gearbow/engine noise in my car, but then again I have no windscreen