Lower Final Drive

[lerroy]

hey

Adrian has a lower final driver listed as a bang for your buck mod for DC2R

now if im right the Gearing is lower on a Type R meaning better acceleration, get through the gears quicker, but less topend speed ( but hey i never go 180Kmh much)

So for a VTIR would i have to put in a Type R Gear Box and the lower final Drive, or just the lower final Drive

has anyone done this ?? improvments ?? Prices etc...


thanks Guys

[wynode]

Firstly, having been members for so long you guys shoudln't be spamming :thumbdwn:

The ITR comes with a 4.7 FD so if you got an ITR box you would have the benefit of an LSD and a 4.7FD (I'm not too sure on the gear ratios between the vti-r and type R so there maybe a benefit there also).

However if you just change the FD only on your gearbox (around $900 or so for the ATS kit + install) you'll only get that benefit. You can go for either a 4.7 or 4.9 FD (heck might as well get 4.9 to make it worthwhile).

[lerroy]

sorry wyn my fault

So in changing to a R gearbox i get a LSD and a lower final driver but a huge chunk outta my wallet...

Thanks so are you saying its not gonna make a huge difference probably money spent elsewhere ???

[bennjamin]

ITR gear box = "around" $1-1.5 k ive seen....installed add another $300ish - still , rather get the ITR stand-along box rather than muck aroudn with custom FD's or diffs or drvieshafts etc.

Q = I will assume ITR splines are the exact same as dc2 - hence being a direct bolt in ?

[lerroy]

Dam thats is alot that could go to cams etc..

well i will have a talk to adrian see what he says about it..
thanks

[r`Geno]

http://img139.imageshack.us/img139/3628/itrfds7on.jpg

[bennjamin]

so , in Lerroy's situation aiming for a AUDM spec ITR box - what FD figure is it ? USDM ? JDM ?

[lerroy]

Hmm nice pic

thanks

what does ATS stand for though ?
anyone done this ??

[r`Geno]

AUDM = JDM = 4.785 (Type R only).

[kOncept]

ATS stands for "Active Traction Service"

also consider the fact that your car will be sitting at rather high rpms on the highway (compared to normal), it's a great mod for acceleration gains :)

[lerroy]

ah yeah good point k0ncept
i dont really track the car and do a bit of highway driving so yeah thats a bit of a drawback

[aaronng]

Basically the gearbox ratios determine how much the revs drop when you engage the next gear at the same speed. ANd the Final drive in combination with the gear ratio determines your speed at a particular RPM.

So if you want quicker acceleration, change to a lower final drive. Your speed in each gear will be lower as well as your top speed.

But if you want to stay high in the rev range with only a small drop in RPM each time you upshift, then you'll have to change the gearbox ratios.

[string]

Changing from 4.7FD to 4.9, or even 5.1 will not yield worthy acceleration gains.

Download a program called Cartest and plug it in.

It will be a difference of .1sec or less over the quater mile.

It doesn't matter than the torque at the wheels is more; In the end you are still applying the same ammount of power to the wheels. The only acceleration gains you will recieve is in first gear when you are < 5000rpm as you are in that range for less time, which will probably be negated by the fact you will be changing gears more often.

[kOncept]

i don't think he has 4.7FD, 4.7 is the Type R box which he's also considering

lerroy i reckon just go the Type R box man...

[sydteg21]

just go for the type r box with LSD you can surely get great benifits out of it, you are in sydney, i believe that there are not that many box around australia, you have to go to some performance workshop to ask them import secondhand one from japan,it costs around 1900 fitted, you might be lucky to find one here, who knows

[Chi]

If you get JDM ITR gear box.

FD of 96 spec is 4.4 , and 98+ is 4.7

[edw-R]

If compare with 4.4 and 4.929. There are a huge different and improve. I don't think jdm 4.785 and Ats 4.929 have a huge different.

[string]

Improvement in what?

Improvement in the rate of rpm rising per time? Who gives a shit? People want their car to move faster. The answer is more power, not a higher final drive

[edw-R]

My friend is using ATS 4.929 lower final drive in his EK Vtir. When his EK vtir ( with toda A cam, power fc, 5zigen full exhaust ), he can't beat stock type R. After he intalled the ATS 4.929. He can beat the stock type R (one car length). It is a fact. Lower final drive can improve the acceralation.

[string]

My friend is using ATS 4.929 lower final drive in his EK Vtir. When his EK vtir ( with toda A cam, power fc, 5zigen full exhaust ), he can't beat stock type R. After he intalled the ATS 4.929. He can beat the stock type R (one car length). It is a fact. Lower final drive can improve the acceralation.
Yes, It *can*.

Tell him to take it from a rolling start, where he is allready in his powerband.

Final drive can't add more power, it can just get you to your power quicker; Don't be ignorant to this fact.

Oh, and 1 car means nothing. Thats a split second in the quater when your finishing at 170+kph

[ginganggooly]

to be honest, i don't think that the final drive is the problem, it's the spacing from 1st to 2nd gear...
you can really feel the motor falling out of it's sweet spot when you shift from 1st to 2nd. i'd say that a y21 (i think thats the code for the b16a hydro box) would be a nice little upgrade. a type-r box would be better though ;)

[wynode]

Final drive can't add more power, it can just get you to your power quicker; Don't be ignorant to this fact.

Who said it gives you more power? I'm sure there is a good reason why it is listed as a 'bang for buck' mod by someone who has the know how ;)

[string]

Who said it gives you more power? I'm sure there is a good reason why it is listed as a 'bang for buck' mod by someone who has the know how ;)
No one said it did. I said that to go faster, get more power, not change the final drive.

You believe everything everyone says? People say a lot of stuff to sell products... Something like this will just make it *feel* like you are going faster because you rev faster, but you don't actually move any faster (except in first gear below your high rpm powerband)

Like I said before, download cartest and see for yourself. If your lucky you will drop 0.1 second, otherwise it won't even register a difference.

[edw-R]

Different final drive suit for different track. The lower final drive will not give you any power but it can acceralate faster. Why i said that? I don't sell any final drive. I don't need to advertise the lower final drive. That's what i know and i tell. It is a fact. Lower final drive is a 'bang for buck' mod for the 4.4 final drive.

[Hondavirgin]

The AUSDM type R final drive is only a 4.4, same as for VTiR, i'm fairly sure anyways.

[lerroy]

dam lot of posts

been looking a mit more into it ots gonna coast me a lot of money which in the end my car has done 190000kms might as well sell it and get a R hahah

but yeah thanks for the input guys

[wynode]

The AUSDM type R final drive is only a 4.4, same as for VTiR, i'm fairly sure anyways.
AUDM ITR is 4.7x

[Chi]

The AUSDM type R final drive is only a 4.4, same as for VTiR, i'm fairly sure anyways.

4.7xx

[00dc2]

higher final drive WILL improve acceleration in all gears at all revs.

sacrafices top speed and having to change gears more often for better iin gear acceleration.

yes it is 4.7 for typeR. eventhough a lot of places (incl motor mag) has it as 4.4 like vtir. Someone at honda must have overlooked this when putting this info together for the journo's back in 99.

[00dc2]

to prove it, one of you guys with a vtir check what speed your going in 2nd gear at 5000rpm.. i am at just over 50.. maybe 52km/hr.. i bet your doing close to 60 at those revs.

EDIT - Actually I assume here that the 2nd gear ratio of the typeR and the vtir are the same and that might not be the case.. ??

[string]

to prove it, one of you guys with a vtir check what speed your going in 2nd gear at 5000rpm.. i am at just over 50.. maybe 52km/hr.. i bet your doing close to 60 at those revs.

EDIT - Actually I assume here that the 2nd gear ratio of the typeR and the vtir are the same and that might not be the case.. ??
Speed in different gears doesn't mean shit to acceleration, you havn't proved a thing.

Acceleration is proportional to power, changing final drive doesn't change the ammount of power you put to the ground.

[kOncept]

Selecting the right final drive will improve acceleration.

[string]

Selecting the right final drive will improve acceleration.
Yes, selecting the right final drive.

Bang for buck performance increase, this mod rates about the same level as a body kit.

[bennjamin]

Speed in different gears doesn't mean shit to acceleration, you havn't proved a thing.

Acceleration is proportional to power, changing final drive doesn't change the ammount of power you put to the ground.

For all us non-informed - we already know changing a final drive doesnt change the amount of power put to the ground. Get over this point and stop repeating :)

But - acceleration is not just relative to "power" - what about weight ? Resistance ? (wind/road/element) gearing ? driver ?

[kOncept]

Yes, selecting the right final drive.

Bang for buck performance increase, this mod rates about the same level as a body kit.

LOL

:rolleyes:

[kousoku]

Yes, selecting the right final drive.

Bang for buck performance increase, this mod rates about the same level as a body kit.

i agree with benjamin on this point,
acceleration is more then just pure power figures,
for example, if you compared a type r and a type r with a vtir gear box in it (ie, higher final drive) you would find 100%of the time the stock type r would win.

not to sure how good body kits are, but i'm betting at street legal speeds having a lower final drive will improve your performance to a higher degree then a body kit.

[wynode]

I'm sure Honda threw in a higher FD (heck they went from 4.4 in the 96 spec JDM ITR to a 4.7 FD in the 98 Spec) just for the hell of it eh? :rolleyes:

Should have just improved the styling of the bodykit instead :thumbsup:

[_CiVIC_]

what is FD ???

[lerroy]

final drive

[Mooro]

Digging up old post but in regards to Strings comments that changing FD will not change acceleration because it is not increasing power to the ground. I agree that it does not increase power to the ground but it does increase torque which will give better acceleration.

By your logic if you drag two identical cars one who must start in 4th gear and stay in 4th and the other can start in 1st and accelerate through the gear - are you saying these cars will be equal because they are putting the same amount of power to the ground, the only difference is gear ratios? I know which car I would put my money on.

[bennjamin]

Bang for buck performance increase, this mod rates about the same level as a body kit.

I guess this is the point he is trying to make...as a cost vs performance increase. Still , for the amount of monet invested (maybe $2k all up including parts and labour) a lower final drive IS a acceleration increase. It will also decrease top end speed as the car will be geared shorter :)

[Sexc86]

If your car is boosted? will a lower final drive give you more turbo lag? ie will boost hit later ? or the same?

[T-onedc2]

If the car is boosted the car will have a little less lag but only slightly, turbo lag or response will mostly come down to the turbocharger specs and how well it's suited to a given application (ie, street/track/drag).

If a boosted car has trouble with traction in lower gears then changing to a lower final drive will make it even worse.

[Sexc86]

so basically the lower you make your final drive the more turbo lag you will have, gears get shorter and boost will come on later

[aaronng]

FD does not affect turbo lag. Turbo lag is when you lift your foot off the throttle (And lose boost pressure) and you then reapply the throttle. Because the exhaust gases have to be produced again to spool up the turbo, the engine runs at the lowered compression ratio for a short while before positive pressure is restored at the intake manifold. Even if you are at 6000rpm, there will be turbo lag if the turbo is designed as such that it has inherent lag. Think of turbo lag as a super slow defective electronic throttle.

Having a turbo set to come on boost at 3000rpm and your engine being at 2000rpm, leaving having to wait 1000rpm does not constitute turbo lag. That just means that you are not at the right RPM for power.

[Mooro]

But if you consider turbo lag as being the time it takes to restore positive pressure to manifold after a gear change, which will be proportional to turbine speed, which will be proportional to exhaust gas flow which will be proportional to engine revs then lag may decrease slightly as for a given road speed the engine revs will be higher...although I agree it's not really worth worrying about.

[T-onedc2]

But if you consider turbo lag as being the time it takes to restore positive pressure to manifold after a gear change, which will be proportional to turbine speed, which will be proportional to exhaust gas flow which will be proportional to engine revs then lag may decrease slightly as for a given road speed the engine revs will be higher...although I agree it's not really worth worrying about.
Yeah I was about to say the same, and yes it's such a small difference it's not worth worrying about.

[Sexc86]

excellent!

[aaronng]

But if you consider turbo lag as being the time it takes to restore positive pressure to manifold after a gear change, which will be proportional to turbine speed, which will be proportional to exhaust gas flow which will be proportional to engine revs then lag may decrease slightly as for a given road speed the engine revs will be higher...although I agree it's not really worth worrying about.
I get what you mean, that a higher revving engine can restore positive pressure quicker. And that's right when you are in the same gear as an identical car with a stock FD (your RPM is higher at the same road speed because of the lower FD).

But a lower FD does not change the RPM you get when you change gear. So if you shift at 8000rpm and land at 5500rpm with the stock FD, changing it to a lower one will still give you the same 5500rpm after shifting.

[T-onedc2]

Wouldn't you agree though that the revs would build just that little bit faster therefore increasing the gas flow and spinning the turbine earlier (depending also on the tubine's inherent response capability), but so slightly it really could only be seen on a dyno graph?

I know I'm being picky but that's just me...lol

[Mooro]

Sexc86, in your original post you also referred to two different things, boost hitting earlier and turbo lag. Turbo lag has been addresses above but in regards to boost hitting earlier, relative to rpm it wont (this is dependant on turbo spec, and basically engines ability to flow air) however relative to road speed then yes it will hit earlier again because for a givn road speed you will be reving harder and hence boosting harder.

However for a turbo a shorter final drive is not necessarily a good thing because the benefit of a turbo is mountains of torque and a good torque spread hence why turbo cars are often geared longer to make use of the torque and keep them in the powerband longer. COmpared to a highly stung NA which will have closly geared short ratios to keep the revs up and make use of the high rpm power band.

[string]

At any given speed, acceleration will be directly proportional to power, and since speed (i.e. wheel rpm) is constant, acceleration will be directly proportional to wheel torque.

If we are keeping the same maximum engine rpm, you are wasting your time. Final drives ratios are setup for you to decide at what speeds you want to be at your peak power at. Shortening them just for "acceleration" is silly unless you are absolute moneybags, without also increasing maximum rpm (and therefore power, assuming torque continues). First gear is the only gear you will really benefit as you must go through it entirely, not just in your high-rpm bracket where the difference between the final drives will be negligible.

By fitting a higher ratio final drive, you are increasing wheel torque at every given operating engine rpm, not wheel rpm.

If you take two graphs of wheel torque vs speed for each gear, for each final drive, the shorter final drive will be putting more wheel torque for each gear until the shorter one runs out of gear, at which the higher final drive will still be producing far more wheel torque due to being in a lower gear.

Edit: On the first page there appears to be a graph. Look at the are under the 4.4 and 4.7 final drives. The 4.7 is a touch higher, but then it runs out of gear and all that extra area is made up by the rest of the gear that is missing.

Once you get up to say 40kph; The area under these curves between any two speeds will be virtually the same due to the above.

If you increase maximum rpm however, then your final drive gear has a purpose, to keep your gear vs speed the same as stock, while increasing wheel torque at every speed.

I dare you all to open car test and fiddle with the final drives. Don't be too disappointed when your fancy 4.7 final drive gets you a 0.1 second faster quater mile, if at all any gain noticable in cartest (i've done it before, but can't remember the results).

For boost, final drives can be a good way to reduce wheel torque to control traction problems. Once you get into steady 5000->8000rpm acceleration in each gear, final drive isn't going to matter, and you'll be able to get the power to the ground. Win, Win.



However for a turbo a shorter final drive is not necessarily a good thing because the benefit of a turbo is mountains of torque and a good torque spread hence why turbo cars are often geared longer to make use of the torque and keep them in the powerband longer. COmpared to a highly stung NA which will have closly geared short ratios to keep the revs up and make use of the high rpm power band.

The idea of boosted engines using longer final drives to "keep them in the powerband longer" is a silly myth. Any engine, regardless of it's induction method can be (for simple calculations) though of as simple a function where you stick in rpm and it spits out torque; With boost you just get a big bump in that curve. The same rules of acceleration = k.wheeltorque still applies.

People usually run longer ratio's with boost for a) traction problems; b) they (generally) don't rev as high as their n/a counterparts; and; c) so they don't have to change into 5th in the quater mile.

[string]

Real world not internet I changed my FD from a standard 3.08 to a higher 3.73and netted 3 tenths quicker ET on the 1/4 mile. This is cheap with just a ring gear and pinion change at $175.00 US. A very good cheap mod you don't need to change the whole gearbox/diff just the ring and pinion and it works very well. Rpms in 5th cruse went up from 2700 to 3000 too much I didn't think so.
Yes, but there is a huge difference between 3.08->3.73 and 4.4->4.7; Perhaps 3.08 was a poor choice for the engine in the first place. Also, did you do many many runs in similar conditions? You could get a 0.3s variance between runs even with the same final drive ratio.

I'm waiting for some pedantic internet hero to come and pick out everywhere I said that "final drive isn't going to matter", or argue that a minor gain is still a gain, it's all relative. Of course an integra with a 1:1 final drive is going to be a slug, but you'd have to be a real idiot to try to apply the logic i've given to a situation like that. It's the same argument with ignition timing, ignition timing is used to correctly get the right ammount of power from the air you put in; Just like final drives are setup to give you the gear speeds you want from your rev range. You don't do either for more power/acceleration, you choose the right one for the rev-range you've got/whatever gear speeds you want(for example if you are doing a tight course that has lower corner speeds, a shorter final drive will be better suited, so that you are in the top of second for example, whereas on a not so tight course, the same final drive would keep you in low-3rd gear, slowing you down; It's not a matter of one size fits all; You determine WHY you wan't a higher/lower final drive, then figure out exactally what ratio you want, then go ahead and do it. Just adding a shorter final drive straight expecting huge 'performance' incrases is silly)

[bennjamin]

Just adding a shorter final drive straight expecting huge 'performance' incrases is silly)

We need to implement a "Scale" of "performance increase" as per $ spent.
IMO a better way to desribe a "increase" is maybe the same feel as installing a new light flywheel or takign a bunch of weight out etc. Its not increasing power but reducing resistance to accelerate :)

[Mst_Mugen]

FINAL DRIVE FTW!!!!!!! :thumbsup:

[Mst_Mugen]

if final drive helps you rev faster by shorting your gears (ie, accelerate quicker)... then what would be the benefits of fitting a final drive as well as a light weight fly wheel??? would the 2 used in conjuction with eachother be more effective??