Chloe...Jack...download a schematic of a 6sp 'box to my PDA! ZT CDTi Q&A?

[ajgoodfellow]

The acoustic dampening in a Rover 75 is better than in an MG ZT

The Rover 75 is the better cruiser

 

[burns]

That would assume a linear relationship between engine speed and the speed of the car, which isn't the case since the resistive forces do not increase linearly with speed.

Roffle. Thats just plain wrong unless the clutch was slipping or he was wheel spinning along the motor way. Or had a CVT. Either way on a manual box there is a linear relationship between road speed and engine RPM.

 

[Simon]

That would assume a linear relationship between engine speed and the speed of the car, which isn't the case since the resistive forces do not increase linearly with speed.

Oh my....

Go back to school

 

[[TW]Fox]

I love it when people try and argue technical stuff with Si

 

[Kappa]

That would assume a linear relationship between engine speed and the speed of the car, which isn't the case since the resistive forces do not increase linearly with speed.

how do you figure that out without a 3rd piece of data?

Is there ever an advantage to 6 speed or even 7 speed gearbox? surely it would get annoying changing all the time.

edit - is it something to do with lots of power which might bust the gearbox if theres not enough gears or something?

 

[robbiemc]

So you want to save some money on fuel, and to do this you're prepared to spend a considerable amount of money in replacing the gearbox? It'll take years to claw back the money spent on that.

Don't forget that the cars value will drop also, I'm sure not many people will be happy to buy a car thats had a replacement gearbox, especially when its a buyers market for this level of car.

 

[OllyM]

Mercedes now fit a 7 speed auto gearbox to certain models, for some reason. It's on the C320 CDI, and the E280 and E320 CDI, as well as most of the bigger petrol engines (apart from the AMG versions).

Apparently it's quite good!

 

[Oracle]

Snip

Where the hell did I ever mention economy!? I just love the way diesels drive, and being a Diesel does make my some 66k a year mileage a bit more cost effective.

The reason for a 6th gear is to keep the car quieter on the motorway, yet retain it at peak torque should the need for a foot down overtake and blatt arise!!

Si, i'm only commenting on what the dials showed, bearing in mind the speedos read slightly out, and in all honestyi didnt fully notice the actual revs at 80, I just know that at 300rpm the speedo (in 5th) shows 91mph (ish).

 

[Fett]

...can you remember where 6th gear put you in the rev range at similar speeds!?

80mph @ just under 2000rpm in 6th for a 330d, if that helps.

 

[Alibaba99]

I find it amusing that diesels, an engine of which one of the major selling points is the large wodge of mid range torque, have power bands that in many cases are so narrow they require 6 speeds boxes to make them driveable.

The only car with a 6 speed box that I have driven that makes any sense is the original 1400 Caterham 7 supersport where 6th in the new box was lower than 5th in the old 5 speed unit.

 

[dilated]

The problem is that most of the 6 speed boxes I can think of have simlar top ratios to a 5 speed box with closer spaced ratios.

Are there any boxes with an overdrive 6th? What about the 6 speed 1.9 golf gti?

 

[RiPz]

KAD do a 5 speed straight cut gearbox for the A series engine (found in minis), they cannot simply *add* a gear, because it requires major changes to the changer mechnism (and thus layout of the gear shifting), it doesnt help top speed (i.e. top speed in the 4 speed gbox is the same as the 5 speed gbox), all they are able to do is give you more, closer ratio gears, i.e. more accurate powerband changes for track racing... it has no economic or speed gains whatsoever..

i'd assume the limitations for adding gears in any other box would be very similar...

not to mention it's taken KAD (very well-educated auto mechanical engineers) a long time to develop such a gearbox.. i cant see it being a one-man-army job to do