Aftermarket Final Drive Acceleration....

[Stylesa]

I have considered changing the final drive but after a brief search, i havent really found the answer to my questions.

Right..... Final drive from CRX or FD2 would be the way to go.... This would apparently improve acceleration and decrease top speed.

My question is, would it actually increase acceleration as you are going flat out through the gears....?

If you are on WOT up through the gears and you change up from 2nd to 3rd at 58mph (rough guess), would you actually be going any faster if you had a final drive? With the final drive your shift point will decrease through each gear, ie you will be changing up into 3rd at 51/52mph (again, a rough guess), but surely in that window the OEM ratios will catch up. 2nd gear OEM ratio at 52mph will be accelerating faster than a shortened ratio in 3rd at the same speed? So you would get like a yo-yo effect as you went up thorugh the gears.....or is is the case that the aftermarket FD will cause the car to rev up fast enough to 'outrun' the OEM ratios?

I realise that in a set gear at a set speed the shortened FD will accelerate faster... and at cruising speed it will accelerate faster...but thats not what im asking.

Surely the way to go would be a whole new gear set.....i understand that is a huge expense.

 

[sinbad]

in simple terms, yes it will accelrate quicker.

 

[leejw87]

The car will feel more torquey too.... For example if in 6th gear with a final drive it will be like being in 5th gear.

I may consider the spoon final drive when I supercharge mine, that if I put another LSD in though.

Edit: I think there's a few you tube vids of people with EP3s with the final drive in and show the Instrument cluster and how quick it revs...... 1-2 looks too short for my liking but I bet the other gears are awesome with a FD.

 

[rascal69]

Al get you a video of my car when it's back.
Just simple bolts ons. But have a 5.48 fd installed.
Just of the dials? 1st and 2nd are really short. Lol

 

[pulpmelon_r]

Do 1st and 2nd become an utter spin fest with a 5.46FD?

 

[rascal69]

In the wet yeah. I run semi slicks so helps in the dry.
Havnt launched it. Isn't too bad will post a video when I get my car back.

 

[blueguy]

Acceleration definitely is quicker. Although the 5.1 FD does feel noticeable, it's not a huge difference. Remember it's only 6.3% difference over the OEM FD.

 

[VT-Doo]

The car will feel more torquey too.... For example if in 6th gear with a final drive it will be like being in 5th gear.

This is probably the simplest way to think about it.





[font="arial][size="2"]

Yes, and the Civic FD2 has the same final drive of 5.062


Yes.



Standard Y2M3 @ 8,400rpm

1st - 39.6mph - 63.7km/h
2nd - 60.7mph - 97.7km/h
3rd - 85.2mph - 137.1km/h
4th - 115.2mph - 185.4km/h
5th - 132.9mph - 213.9km/h
6th - 165.6mph - 266.5km/h

70mph - 112.7km/h = 3,550rpm


Standard Y2M3 with CRV/FD2 final drive @ 8,400rpm

1st - 37.2mph - 59.9km/h
2nd - 57.1mph - 91.9km/h
3rd - 80.1mph - 128.9km/h
4th - 108.5mph - 174.6km/h
5th - 125.1mph - 201.3km/h
6th - 155.9mph - 250.9km/h

70mph - 112.7km/h = 3,772rpm


P.S. 120km/h = 74.56mph = 3,781rpm on a standard gearbox & 4,018rpm with the CRV/FD final drive.



HTH

[/size][/font]

 

[VT-Doo]

Ok here goes, I hope I'm right with my calculations

By increasing the final drive from 4.764 to 5.062 you are affecting the ratios of EVERY gear.
Increasing the final drive from 4.764 to 5.062 the toque (at the wheels) is increased by 6.255% in EVERY gear. As you know, if you increase toque the car will go faster.

Get it now?

 

[Stylesa]

Cheers guys. i was just curious. its one of many routes that im considering.

I know that Buddyclub are now offering a shorter 5th and 6th gear as an option too.

 

[Dan2020]

Ok here goes, I hope I'm right with my calculations

By increasing the final drive from 4.764 to 5.062 you are affecting the ratios of EVERY gear.
Increasing the final drive from 4.764 to 5.062 the toque (at the wheels) is increased by 6.255% in EVERY gear. As you know, if you increase toque the car will go faster.

Get it now?

I'm getting intrigued now!!

So would the torque show on the rollers as an increase? i.e. my car is 174 lbft so would this make it 180 lbft on the dyno? Not chasing figures but curious to how/if it would be measured? :xconfused:

 

[Stoo]

Something to note

With a lower ratio final drive, your acceleration will be quicker, but your in-gear top speeds will be less and overall your top speed will be reduced.

Ie If you currently stay in 2nd to accelerate to 60MPH, you may need to change to 3rd to get 60MPH.....

Think of it as gears on your bike.....
Lower gear you can accelerate faster but cant go as fast as you would in a higher gear

 

[haitch]

Cheers guys. i was just curious. its one of many routes that im considering.

I know that Buddyclub are now offering a shorter 5th and 6th gear as an option too.

I run these, very good, got a couple of vids kicking around, along with my BC gearset review.

I'm getting intrigued now!!

So would the torque show on the rollers as an increase? i.e. my car is 174 lbft so would this make it 180 lbft on the dyno? Not chasing figures but curious to how/if it would be measured? :xconfused:

You wont see the difference in dyno figures.

The K series gearsets seem to use longer ratios than oem with a short final drive, like the 5.46, MFactorys is circa £1600 + post/import/fitting, add in a fd to go with it and its real pricey, a fd on its own is in reach of most peoples pockets, just dont go too short for your usage, that or the BC 5/6 combo.

With a fd change only, the acceleration to the next gear is quicker, revs quicker, but as you change up the rev drop remains the same (approx 2k oem), with one of the shorter final drives, because it accelerates so quickly it seems like the rev drop has changed giving 'an effect' of closer ratios, although you have not physically changed the gear ratios.

With a gearset, you get the best of both, quick acceleration and a lower rev drop as you change up, say 1k or 1.5k depending on the ratios & car.

 

[VT-Doo]

IMO you'd only want a shorter 5th & 6th gear for the track.

 

[haitch]

IMO you'd only want a shorter 5th & 6th gear for the track.

Have to disagree, they work very well on the road with the oem final drive, 6th is like 5th and a half, gives it plenty of punch, especially for those not running big power, great for overtaking on carriageway/motorway.

 

[VT-Doo]

Have to disagree, they work very well on the road with the oem final drive, 6th is like 5th and a half, gives it plenty of punch, especially for those not running big power, great for overtaking on carriageway/motorway.

I stand by what I said about the aftermarket 5th & 6th gear.
On a road car you do not need the acceleration that the 5th & 6th gear offers that the first 4 can not deal with...not to mention the side effect of less MPG...

Like I said, track yes, road no.

 

[haitch]

MPG is hardly noticeable, and those who worry about it should not modify their car, people dont 'need' a supercharger, a big brake kit or plenty else that is on offer either..

 

[dave c]

I considered this route too but I thought for me (95% road driving) the thought of a shorter 3rd & 4th is the most appealing. 5th and 6th (you shouldn't be doing that on the road anyway)

1st and 2nd are perfect as they are (imo) then the thought of even higher revs on the motorway would put me off a 6th gear change.

In short, I couldn't decide what was best so havent done anything yet. When my clutch goes I may consider a new 3rd, 4th, 5th if such a kit exists?

Having said that I've been out in Justin's (blueguy) and the "short ratio" ratio affect described above is very satisfying. Always in the juicy part of the power band on gear change. :twisted:

 

[blueguy]

For me (I realise every gear is shortened), the most useful is the shortened 3rd (followed by 4th and 5th) as it gives you the flexibililty to take a hairpin in the powerband (within reason) if you have not been able to balance the car in time to shift down to 2nd. Additionally, I tend to take most fast corners on track (at entry) in 3rd.

However in saying all of the above, the shortened 2nd is savage and I absolutely love it!

 

[haitch]

The only kits seem to be a full 1-6 (MFactory/Gear X), or BCUK 5/6 kit (not sure if they plan others), its that or mixing up ratios from different Hondas, if you have a shorter 5th and the oem 6th, the change up into 6th from 5th will leave things feeling a bit flat, even if it is just for cruising, tried this on the B series, wasted more cash to open the box and do it all over again.

I rarley travel above 70 on the motorway, only to overtake or get out of a tight spot, its effortless with the close 6th. Most worry about the extra noise from the revs but will have no hesitation putting up with the drone of a loud exhaust system instead..