GTI Edition 40 / Clubsport Thread

[AdamD]

You might want to try a drive in a Renault Sport Trophy R. They absolutely do power oversteer. And at respectably safe speeds on wet roads. Huge fun!

I assume you're referring to the Megane RS Trophy R. Although I've been in several Megane RSs I've not driven a Trophy R, but that doesn't mean that it can subvert the laws of physics I'm afraid. Power oversteer is caused when the rear driven wheels lose traction under power (wheelspin), causing oversteer. This is not physically possible when the rear wheels are not driven.

Oversteer is of course possible with a FWD, but in order for oversteer to occur (as opposed to a four-wheel drift), the rear wheels must be at a greater slip angle than the fronts. This can occur when the rear tyres are unweighted relative to the fronts (i.e. under braking, or even just when rolling if the rear tyres are over a low-friction surface like water or oil). You won't get oversteer under power because under acceleration the weight transfers rearwards, naturally endowing the rear end with more grip than it would otherwise have, so unless there's a major failure (tyre blowout, suspension damage etc), the rear won't step out under these conditions, because it would be practically undriveable at speed if so balanced.

I'm guessing what you're referring to is a four-wheel-drift, which is easy to achieve on a well-balanced and neutral car like the Megane RS, when you're cornering hard without excess weight over either front or rear axle, and the cornering forces exceed the grip available to all tyres. This condition has the car moving around in a more- or less-balanced fashion and can often be adjusted by carefully modulating throttle and brake inputs, and might even require correction to keep the car straight - but it's not power oversteer.

[urxtream]

Just placed an order on a 034Motorsport Dogbone mount. I'm considering doing the CTS Turbo Intake and Downpipe too. Thoughts or experiences?

[Dutch77]

Just placed an order on a 034Motorsport Dogbone mount. I'm considering doing the CTS Turbo Intake and Downpipe too. Thoughts or experiences?

Wouldn't that kind of defeat the purpose of taking the cheaper supposedly warranty proof JB1 route?

The flipside is a good ECU tune plus a downpipe does definitely generate very good results.

[urxtream]

Wouldn't that kind of defeat the purpose of taking the cheaper supposedly warranty proof JB1 route?

The flipside is a good ECU tune plus a downpipe does definitely generate very good results.

I understand where you're coming from but I just spoke to my mechanic (a VW/Audi and Porsche specialist) and he said VW is still able to identify the JB1 even though it's unplugged from the car. I'm gonna be seeing him soon to get the 034 done, so I'll ask him in detail when I see him.

[LibraR]

I assume you're referring to the Megane RS Trophy R. Although I've been in several Megane RSs I've not driven a Trophy R, but that doesn't mean that it can subvert the laws of physics I'm afraid. Power oversteer is caused when the rear driven wheels lose traction under power (wheelspin), causing oversteer. This is not physically possible when the rear wheels are not driven.

Oversteer is of course possible with a FWD, but in order for oversteer to occur (as opposed to a four-wheel drift), the rear wheels must be at a greater slip angle than the fronts. This can occur when the rear tyres are unweighted relative to the fronts (i.e. under braking, or even just when rolling if the rear tyres are over a low-friction surface like water or oil). You won't get oversteer under power because under acceleration the weight transfers rearwards, naturally endowing the rear end with more grip than it would otherwise have, so unless there's a major failure (tyre blowout, suspension damage etc), the rear won't step out under these conditions, because it would be practically undriveable at speed if so balanced.

I'm guessing what you're referring to is a four-wheel-drift, which is easy to achieve on a well-balanced and neutral car like the Megane RS, when you're cornering hard without excess weight over either front or rear axle, and the cornering forces exceed the grip available to all tyres. This condition has the car moving around in a more- or less-balanced fashion and can often be adjusted by carefully modulating throttle and brake inputs, and might even require correction to keep the car straight - but it's not power oversteer.

Hi Adam, yes I was referring to the Trophy R, and didn't mean to offend in any way, or suggest for that matter that that Renault has found a way to subvert the laws of physics.

To ensure we are talking about the same thing, I was certainly referring to the outward slipping of the rear wheels compared to the front during cornering including under power on a wet surface. I accept the premise that under outright acceleration, the weight transfer to the rear makes the loss of traction of driven rear wheels in corners the catalyst for the rear breaking away - power oversteer.

I think I am referring to a slightly different situation, but definitely it occurs under power (lets call it constant or moderately increasing power), and is not related in any way to lift-off oversteer. I am not referring to four wheel drifting as the front is planted and tracking on line.

In the case of the Trophy R, the weighting of the vehicle front to rear (approximately two thirds to the front), and the combination of the PSC2 tyres and the Perfohub/LSD combination and font end geometry is such that it will indeed step the tail out on wet roads, even under power, on corners. This includes in some uphill situations, subject to road geometry etc.. I'm guessing the weight transfer to the rear under power is still small compared to the huge grip afforded by the front end, resulting in the rear moving out on wet roads.

When driving one of these cars, the technique is "never back off", or the lift oft oversteer is dramatic to say the least!! You would need to be very confident to try that on a wet road in one.

The suspension in a Trophy R is adjustable (unique to that model) and can be dialled to achieve either oversteer or understeer - or more correctly I guess, adjust back to neutral any tendancies towards either case.

From the factory they come set up with a slight bias towards the rear stepping out under the circumstances outlined above, but on dry roads, they are very neutral, and but for a little "notice" through the steering that the power is being transferred to the outside wheel by the diff, pulling the nose in towards the apex, it is well masked that they are even FWD. A very balanced thing indeed as you suggest, and significantly different to drive even than the other RS Megane models.

It is worth looking at some of the overseas YouTube vids of various journos driving them on wet race tracks, and you will get the idea of what I am talking about. They are the FWD car that behaves more like a RWD vehicle.

Anyway, hopefully that explains what I was referring to, and places my comments into perspective.

[Dutch77]

Interesting - some would say your mechanic doesn't exist with that kind of view.

But as you'd know from the Mk6 (or maybe not if you were only at stage 1 there based on the sig) these cars do respond well to the downpipe mod, so given your choice of car and driving style I'd say do it.

I also note your sig now identifies that 'other car with OZs'.. nice one.

[urxtream]

Interesting - some would say your mechanic doesn't exist with that kind of view.

He is very experienced and fairly well known in the VW/Audi/Porsche arena in Sydney. I'm not saying I'm gonna trust everything that he tells me. I'll suss it out when I see him to get the 034 done.

But as you'd know from the Mk6 (or maybe not if you were only at stage 1 there based on the sig) these cars do respond well to the downpipe mod, so given your choice of car and driving style I'd say do it.

I've only owned the MK6 R for 2 months before I lost my licence

I also note your sig now identifies that 'other car with OZs'.. nice one.

You have a very good eye...yeah the OZ wheels are very rigid and light. Since my car is N/A, there's not much I can do to gain power. So weight saving it was...exhaust is lighter by about 2-3kgs, wheels are lighter by about 4kg each corner. The BMC air filter + the Captristo exhaust is music to my ears

[LibraR]

Just placed an order on a 034Motorsport Dogbone mount. I'm considering doing the CTS Turbo Intake and Downpipe too. Thoughts or experiences?

It will be interesting to hear your thoughts on the 034 dogbone mount after it is installed. I looked at these and ended up going for the BFI instead (road version). Mainly I guess as I could relate to the idea of a PU infill material as opposed to a cast alloy device. The BFI one was softer than I expected, being more like a stiff rubber compound than poly urethane if that makes sense. I was expecting a stiff plastic type of device, but it isn't. Installing it was simple enough, but you could feel the material deforming slightly installing it (you need to wiggle the original mount a little to get the two "ends" of the mount in place correctly. A quick snip of the torque wrench and it's done.

I can feel the difference in the shifts even in the R, but as grip is not an issue with them, it didn't suffer from any wheel hop or the like beforehand, so nothing to report there.

At idle, it is absolutely same as standard, so seems to do what it advertises.

I am tempted to try (for comparison) the performance version of the BFI mount, as it is stiffer PU material. I am interested to see if it makes even more noticeable difference to the changes (maybe not, even during spirited road driving - perhaps on tracks only), and if it vibrates at idle (as suggested it may do).

Thee must be a fine line in material stiffness between vibrations at idle transmitted into the cabin, versus it not happening.

Look forward to hearing how the 034 mount goes for you!

[urxtream]

I've just been told there's two versions of the 034 - street / track density. I wonder what the difference is!

[urxtream]

http://www.carsales.com.au/private/d...4293714/?Cr=10


If anyone is after a manual 40 years, there's a grey one on carsales with delivery km only.