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[feeutfo]

so of all the options, 4.22 will lower the gearing by the least amount/make the least differance? any other dif will be too low, to put it another way?

i'm just looking for a bit more go, dont want to compromise economy and engine noise too much.

as 2woody said, try a 4.22 and see, can always re fit the 3.9.

ex plod 3.2 i drove, newer than mine, was noticably quicker, so presume a 4.2 will be the same, hopefully.

[Kevin Wood]

so of all the options, 4.22 will lower the gearing by the least amount/make the least differance? any other dif will be too low, to put it another way?

Hang on... You have a 3.9 currently. The only option that will lower the gearing is the 4.22. All other commonly available ratios will raise the gearing and achieve the opposite.

i'm just looking for a bit more go, dont want to compromise economy and engine noise too much.

as 2woody said, try a 4.22 and see, can always re fit the 3.9.

ex plod 3.2 i drove, newer than mine, was noticably quicker, so presume a 4.2 will be the same, hopefully.

It must have had a 4.22 then. Did you notice the difference in speed versus RPM?

FWIW, I don't think the difference in gearing will make a huge impact on economy or noise. I probably wouldn't go to the trouble of changing the diff myself but nothing ventured nothing gained.

Kevin

[serek]

so of all the options, 4.22 will lower the gearing by the least amount/make the least differance? any other dif will be too low, to put it another way?

i'm just looking for a bit more go, dont want to compromise economy and engine noise too much.

as 2woody said, try a 4.22 and see, can always re fit the 3.9.

ex plod 3.2 i drove, newer than mine, was noticably quicker, so presume a 4.2 will be the same, hopefully.

was auto or manual?

[CaptainZok]

Sorry to Hijack, but have a question, been trying to work out whether my Ex Met 2000 Project FL is 3.9 or 4.2 (Auto), any pointers on what the revs would be per MPH ?, assuming box locked up, standard 15" wheels.

Chris.

Bung the reg/chassis no into the EPC and it should tell you what diff it left the factory with.

[feeutfo]

so of all the options, 4.22 will lower the gearing by the least amount/make the least differance? any other dif will be too low, to put it another way?

Hang on... You have a 3.9 currently. The only option that will lower the gearing is the 4.22. All other commonly available ratios will raise the gearing and achieve the opposite.

i'm just looking for a bit more go, dont want to compromise economy and engine noise too much.

as 2woody said, try a 4.22 and see, can always re fit the 3.9.

ex plod 3.2 i drove, newer than mine, was noticably quicker, so presume a 4.2 will be the same, hopefully.

It must have had a 4.22 then. Did you notice the difference in speed versus RPM?

FWIW, I don't think the difference in gearing will make a huge impact on economy or noise. I probably wouldn't go to the trouble of changing the diff myself but nothing ventured nothing gained.

Kevin

Well that answers that then, 4.2 it is.


And yes 3.2 plod did rev higher, and owner was complaining of fuel costs, but didn't do the mpg maths verses mine, and it was a Auto.

[TheBoy]

To clarify, speedo will be unaffected, as the ABS sensors are on the rear driveshafts, so the only thing that could affect speedo is circumference of the tyres.

[2woody]

posted this somewhere else, too.....

it's easy to work out what diff you have.

mph per 1000 revs = 60000 divided by ( wheel revs per mile x gear ratio x diff ratio )

alternatively, send me the speed your satnav says at 3000 revs and in which gear, together with the size of tyres you're on and I'll tell you what the diff ratio is.

p.s. 3.9 to 4.22 is a big difference.

[Mr Skrunts]

Fitting the LSD 4.2 diff would reduce the top speed, this is acceptable as you are trying to increase the acceleration and in one form or annother will affect grip.

Motorbikes - you can change sprokets to suit whether it be MPG or performance.



Some of the best accelerating and handling things arround only have small wheels and tyres and as we know are called go karts.

What about the best of both, but would it work and would it be effective.

I was thinking a while back of fitting wider tyres to one of may cars which means a lower profile for the same rolling circumference.  But the added (hopefull gain) would have been stiffer tyre walls and less roll on the car in a corner.

So, if the width of the tyres remained the samem but lower profile fitted, would this not improve acceleration, and possiblry tighten the handling.

This then with a spare set of wheels and tyres gives a non permanent performance mod.

As per normal, i may be talking out of mu arris, but thought I would mention it anyway.

[feeutfo]

posted this somewhere else, too.....

it's easy to work out what diff you have.

mph per 1000 revs = 60000 divided by ( wheel revs per mile x gear ratio x diff ratio )

alternatively, send me the speed your satnav says at 3000 revs and in which gear, together with the size of tyres you're on and I'll tell you what the diff ratio is.

p.s. 3.9 to 4.22 is a big difference.

Easy for you maybe woody, you had an education clearly, I was over the fields on me bike.   

As our phone conversation, whack a 4.2 in and see???  For now at least. Seem to remember plod 3.2 adding about 400rpm at 70 in top, it was an auto. That example the revs where a fraction higher than I would like, but the extra go was noticeable too, if it was a 4.2 dif that will be fine I think, without seeing the fuel receipts of course.

[2woody]

Fitting the LSD 4.2 diff would reduce the top speed, this is acceptable as you are trying to increase the acceleration and in one form or annother will affect grip.

I was thinking a while back of fitting wider tyres to one of may cars which means a lower profile for the same rolling circumference.  But the added (hopefull gain) would have been stiffer tyre walls and less roll on the car in a corner.

So, if the width of the tyres remained the samem but lower profile fitted, would this not improve acceleration, and possiblry tighten the handling.

you're kinda down the right lines there. What is key is that the hub height and the wheel revs per mile are the key things - no alteration is advisable.

regarding the reduced sidewalls, yes this will tighten the handling, but won't improve it. I always think as handling as the opposite of grip - handling is the art and science of managing the tyres slip angle either through design or whilst driving. So, with lots of tyre slip going on (tall sidewallls), then there's lots of handling. Conversely, with short, stiff sidewalls, there's plenty of grip, but no handling to exploit.

it's quite difficult for a car designer - on one hand, you've got to provide a car which handles nicely and predictably, is comfortable, doesn't tramline and doesn't use tyres - all of which point to narrow, high-profile tyres. On the other hand, you've got to fit large brakes behind the wheels and provide decent levels of grip, plus the stylists are always on at you to fit big wheels with low-profile tyres - these all make the first set of aims much harder to achieve.

out of all the V-cars I've had, the best handling one was my 12V Carlton GSi, and that was on 195's. Mind you, it did have quick steering and LSD, too. Conversely, the worst-handling is the facelift MV6 on 235's.

just to show how this is all complicated, I'd love to have the Evo on 195's, but I've go to have 18" wheels to clear the brake setup. Then again, the Holden is on 265's in order to counter wheelspin, not surprising with 400 horsepower.

[Mr Skrunts]

Fitting the LSD 4.2 diff would reduce the top speed, this is acceptable as you are trying to increase the acceleration and in one form or annother will affect grip.

I was thinking a while back of fitting wider tyres to one of may cars which means a lower profile for the same rolling circumference.  But the added (hopefull gain) would have been stiffer tyre walls and less roll on the car in a corner.

So, if the width of the tyres remained the samem but lower profile fitted, would this not improve acceleration, and possiblry tighten the handling.

you're kinda down the right lines there. What is key is that the hub height and the wheel revs per mile are the key things - no alteration is advisable.

regarding the reduced sidewalls, yes this will tighten the handling, but won't improve it. I always think as handling as the opposite of grip - handling is the art and science of managing the tyres slip angle either through design or whilst driving. So, with lots of tyre slip going on (tall sidewallls), then there's lots of handling. Conversely, with short, stiff sidewalls, there's plenty of grip, but no handling to exploit.

it's quite difficult for a car designer - on one hand, you've got to provide a car which handles nicely and predictably, is comfortable, doesn't tramline and doesn't use tyres - all of which point to narrow, high-profile tyres. On the other hand, you've got to fit large brakes behind the wheels and provide decent levels of grip, plus the stylists are always on at you to fit big wheels with low-profile tyres - these all make the first set of aims much harder to achieve.

out of all the V-cars I've had, the best handling one was my 12V Carlton GSi, and that was on 195's. Mind you, it did have quick steering and LSD, too. Conversely, the worst-handling is the facelift MV6 on 235's.

just to show how this is all complicated, I'd love to have the Evo on 195's, but I've go to have 18" wheels to clear the brake setup. Then again, the Holden is on 265's in order to counter wheelspin, not surprising with 400 horsepower.

Making sence to me so far, which probably why I like the GLS on 205/15's rather than the Elite on 225/15's, I drive the Elite like a chauffer and on the road to my mates , all open twisty county I drive that route as if I stole it.

I was going to put leather in and upgrade the back springs and keep the car. but I miss the Elite spec now.

The GLS looks from previous invoices like its had one rear coil spring fitted to sell it on, to when pushed it hanfles better on a left bend than a right bend, so if I do keep it then I may just fir stiffer springs on the back end to counter the body roll. (Which I feel would improve it)  but not sure about lowering the back - because then if I did I feel the whole car would have to be lowered, amd only being a GLS spending money like this sadly is a waste.

[2woody]

just one spring - they're havin' a larf

[Mr Skrunts]

just one spring - they're havin' a larf

Pathetic, under normal drivng and speeds you cant tell the difference, it doesnt get driven that often but gets a "good run out" when it does.