15 replies to this topic

[MikeF]

This lowers the final drive ratio of the F23 gearbox on the VX220 Turbo by 14.9% for faster acceleration.
Price £POA

does anyone have any experience with the above? and more to the point what it costs?

im interested (especially by 14.9% acceleration) but it all seems a little far fetched

any views would be great?

[Jim_Cross]

I think you've misread that. It lowers final drive by 14.9%, not increasing acceleration by 14.9%

[MikeF]

good point that helps a bit since i was confused how final drive could lower accelration by 14.9% ok basically it must be expensive as it £POA but some figures or more info would be helpful the reason i ask is that while my engine is stripped is worth the fitting

[x-isle]

It shouldn't be that expensive, it's only a final drive ratio? Should be around £100 at a guess? It will also decrease your top end by quite a bit, also the only thing I've found in the past with changing final drive on a road car is that you end up changing gears hell of a lot. Ok, it may accelerate quicker, but say for instance a 0-60 run, you can just about do it in 1st and 2nd, you probably have to grab 3rd, so you're not so quicker by the time you've changed gear.

Edited by x-isle, 16 November 2005 - 04:30 PM.

[MikeF]

sounds rubbish then

[x-isle]

No, probably very good, just may add more gear changes. With all the Chav's and modders out there that add stuff to their cars, doing the final drive is one of the cheapest "acceleration" mods you can do. I recon one thing on the VXT that it would be good for is overtaking. I sometimes find that keeping the car in 3rd and overtaking, is not quite right, and have to drop to 2nd. Changing the final drive would get around this.

[ad172]

If you are only concerned with 0-60 times Mike then it probably won't make too much difference because of the extra gear change needed, ie. 3rd. In terms of Mid range and Over taking It should make a massive amount of difference. Another way of putting it is how often do you drive at 150 mph!!!

Edited by ad172, 16 November 2005 - 04:56 PM.

[garyk220]

Fitted cost is pretty steep. Best speak to Jon at Courtenay. I've looked at close ratio kits for the F23 (of which there are no decent options, unless you have an engine revving to 7500-8000rpm) and this kit seems like a decent alternative to improve in-gear acceleration. The VXT does not need a close ratio box since the mid rev torque is massive, but lowering the final drive will improve acceleration in each gear. For track use, it should be equivalent to an extra 20-30bhp... so a Stage2 with the lower FD should accelerate as quickly as a Stage3 with standard FD. I'm planning to get mine done along with a lightened flywheel and uprated clutch next year, when the egine and gearbox are removed. If you are competing, or doing a lot of track work, it is worth considering, but for road use, I'd spend the money on a remap and chargecooling PS I'm investigating a slightly cheaper option, which involves fitting the Zafira Z22SE gearbox internals (this has the 4.17FD fitted as standard) inside the VXT housing. Not 100% sure this is possible, but would keep the costs down by sourcing the box from a breakers.

[PaulCP]

Another way of putting it is how often do you drive at 150 mph!!!

Or time yourself doing 0 - 60

[Black Knight]

shorter gears will make you accelerate a bit faster, especially 0-60 since you have to flip to 3rd gear anyway to reach 60.. so the number of shifts to 60 remains the same, acceleration simply must be better.. anyway, shorter gears make sense if you're sure that is what you want.. let's say you do regular track days on a track where you have some bend where 2nd is just too slow/weak and downshifting to 1st gear most of us don't really want to do, or should do so this way you get a stronger/shorter 2nd gear and don't need to downshift to 1st.. on most tracks you will probably not reach top end anyway so there's no loss there. and you will reach the usual top speed you get on a track faster and manage to top it.. it makes most sense for hillclimbs... all cars doing hillclimbs basicly HAVE to have short gear ratios.. basicly the hill makes you accelerate slower, it takes longer to reach the red line in any gear.. having shorter gears make you go through revs faster, accelerate faster.. basicly as if you were on a flat road and not a hill... and you shift just as much as if you were on a flat road... there's no chance you'll go near the top end on a hillclimb so nothing is really lost... personaly i'd install it... this car is most fun at speeds below 100mph IMO.. so having more gears to choose from in that range is definitely a plus IMO... i have this track where 50% of the time I can't decide to go for 2nd or 3rd... it's just so between... in 2nd I only have a few revs to go through before I need to upshift and I usually need to upshift just after I start making my corner exit, but still before I'm going straight on, so that's a pain shifting practicaly mid bend, and in 3rd I'm a couple of revs short from being "on cam" when I start exiting.. and it's a whole combination of bends one after another with just short acceleration runs in between...so it would be ideal if I could run them all in the same gear.. shifting up basicaly ruines the entire short acceleration run i was talking about all this is for the NA.. i probably wouldnt bother for the turbo as it simply doesn need it.. the bigger part of the rev range is more usable

Edited by Black Knight, 17 November 2005 - 12:57 AM.

[DrJ]

it's a similar story in a Caterham with the 6 vs 5 speed box. The 6 speed box is great for track work as it's frantic gear changing and great fun but the car is flat out at 125mph and a pain in the arse on the road as you're forever changing gear. The 5 speed is a much easier and less hard work drive. Depends what you want

[x-isle]

let's say you do regular track days on a track where you have some bend where 2nd is just too slow/weak and downshifting to 1st gear most of us don't really want to do, or should do
so this way you get a stronger/shorter 2nd gear and don't need to downshift to 1st..

How many tracks have ever required a shift down to 1st?????????

[Black Knight]

Well, we don't have a lot of tracks or track days around here so I attend any track day I know about, some of them are on tracks made for go-karts Thus some hairpins should actually be done in 1st.. But it just hurts the car too much IMO Also, there's this famous hillclimb just north of my town. A one way hill climb road, about 800-900 meters height difference. The road is also used in rallyes and hillclimb races. There's a lot of uphill hairpin turns that require 1st if you're in maximum attack mode..

[MikeF]

a couple of replies to that lot.....

Fitted cost is pretty steep. Best speak to Jon at Courtenay. I've looked at close ratio kits for the F23 (of which there are no decent options, unless you have an engine revving to 7500-8000rpm) and this kit seems like a decent alternative to improve in-gear acceleration.

engine should be doing exactly that. Im looking at redline of 8k

If you are competing, or doing a lot of track work, it is worth considering, but for road use, I'd spend the money on a remap and chargecooling 

both already done


So basically i change gears more but accelerate quicker, but the increased redline will help with those gear changes anyway. how much top end am i likely to lose, anything less that 140mph really isnt an option

thanks for the help with this - i understand it a lot better now

Edited by MikeF, 17 November 2005 - 04:56 PM.

[garyk220]

The Quaife site has software for calculating speeds in gears. Below is a comparison of cascade graphs for the standard 3.63 and revised 4.17 FD ratio.

Attached Files

•  F23_Standard_v_4.17_FD.jpg   64.28KB   1 downloads

[garyk220]

And I've done one for the 4.17 FD with an 8000rpm limit. As you can see, the increased limit more than makes up for the drop in speed in each gear. Up changes to 2nd and 3rd would mean quite a big drop in revs to around 4800 and 5600rpm. BUt on track, revs would probably be in the 6000-8000rpm range for the most part.

Attached Files

•  F23_Standard_v_4.17_FD_8000rpm.jpg   63.61KB   0 downloads