short gear ratio question?


EKandrew

EKandrew

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Joined
Aug 11, 2012
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212
have my gearbox out to install a 4.9 final drive into my s80.. was a 4.4 in it, thinkin when the gearbox is out I might put a short gear kit in it.. would I be beter buying a full kit or just buying individual gears.. and if so what gears would be best... or would I just be better to by a 1.5 way diff?
 
Just make sure you don't end up with a gearbox that is too short. 1.5 way diff is awesome in a purpose built rally / track car, worth every penny. If you go for a gear set then the basic standard is: longer 1st, OEM 2nd, shorter 3rd, 4th, 5th. You did the same thing I did - went for a 4.9 fd. Now I wish I'd gone for 4.7 and a gear set. I might still do it but I'll have to stop pouring money into the 9 at some point. I will never buy the NSX if I keep spending thousands on the 9.
 
Your car looks like a rally car, which is about the only use I think a 4.9 AND a close ratio kit would be desirable, for anything else, it would be too short.

LSD instead I say.
 
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4.9 and a gearset would be good as Kozy said for a rally car or likes.

I put an Mfactory gear set in my EK4 SiR with a 4.4.

3rd - 78
4th - 99
5th - 125 ish.

Video of it, ran a 14.7 which I was very impressed with for a B16A with just simple bolt on's and full road trim, spare wheel the lot.

http://www.youtube.com/watch?v=OJChzepgODs

Was awesome to drive and the best thing I did to my B16A, the thing about a gear set is that it reduces the rev drop between each gear, where as a final drive just brings all the gears closer together. If I were you, I would sell the f.d, buy a gear set and 1.5 way if money is an issue, LSD's can crop up used for good prices at times, Would be an awesome setup! My SiR had an OEM LSD but if I could justify spending more on it a 1.5 way would have been my next project, My dad's DC2 has a Cusco 1.5 way and a spoon gear set and it drives/goes very well on track.
 
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Kipper said:
the thing about a gear set is that it reduces the rev drop between each gear, where as a final drive just brings all the gears closer together.
Click to expand...

[pedant mode]

Reducing the rev drop is bringing the gears closer together.

The final drive gears down every ratio by the same amount, but technically they are no closer together.

[/pedant mode]
 
Kozy said:
[pedant mode]

Reducing the rev drop is bringing the gears closer together.

The final drive gears down every ratio by the same amount, but technically they are no closer together.

[/pedant mode]
Click to expand...

I understand :nice:. I by no means understand the whole topic on transmissions. But I know working on them can make an NA B series much more enjoyable to drive and potentially faster in some area's.
 
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4.9 + Gear set will essentially turn your 5th into your current 4th, or even slightly "slower"... Your maximum theoretical speed with 195/55/15 tyres would be around 120 mph. In the diagram below the red lines represent a standard box with 4.4 FD, the blue lines 4.9 FD and shorter 3rd, 4th and 5th. Both with 195/55/15 tyres.

Gearset.png
 
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Blaady 'orrible that chart is!



:D
 
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well hat il be doin in the car is timeattack in mondello park , bishopscourt , kirkistown and the likes. il be looking at doin hillclimbs this incomeing year to. 120 mph top speed would be grand , as long as im getting proper ratios .. what ima buy now is either a longer first and shorter 3rd 4th and 5th or else a 1.5 diff.. horrible decision to make not knowing just.. alota money to
 
I agree that yours is better Kozy and I thought about using it - but the MFactory one has all the ratios preset so you just select your option from a drop down menu, and I couldn't be bothered re-typing it all ;)

EKandrew: To me this is a no brainer - go for the diff!
 
Yea I need to get that sorted. I had a go, but it wouldn't auto update properly so I ended up scrapping it.

I've not got access to the machine with all the scripting gear on it at the moment and haven't done for a while. Lot of updates to do once I'm able to!
 
oifovo said:
I agree that yours is better Kozy and I thought about using it - but the MFactory one has all the ratios preset so you just select your option from a drop down menu, and I couldn't be bothered re-typing it all ;)

EKandrew: To me this is a no brainer - go for the diff!
Click to expand...

and if some magical reason I was able to get both a diff and gearset , was that be better again?
 
Is a gear set going to make you that much faster to warrant the expense?
 
anything would be a bonus.. if it would make a good job of the gearbox id always have it like. Getting sponsorship in the new year so could possibly use the sponsorship for one or the other..
 
Well take what I say with a pinch of salt, but I'd be inclined to say it wouldn't offer anywhere near enough of a gain to be worth the expense.

I made up this tool specifically for this purpose, to see whether gearing and engine improvements offer decent value for money.

Black Art Dynamics - Honda Thrust Curve Calculator

Put your current setup in on the left and the proposed one on the right, and see how they stack up on the stats and weigh that against the costs.

The 4.9 vs the stock 4.4 looks great, but the 4.9 + gearset vs 4.9 and stock ratios does not.
 
Little video of my car round Kirkistown with the mfactory gearing:

Honda Civic EK4 SiR 18/08/2013 Kirkistown - YouTube

A video before the gearing:

14/4/2013 Kirkistown Circuit Honda Civic EK4 SiR - YouTube

On that track I would say I was performing on average about 1.5 secs quicker with the new gearing, the power was much more usable in the lower speed section and it kept me nice and high in the powerband.

I suppose you already have a 4.9, but if you didn't and had to choose between gearing and an LSD around Kirkistown, it would be gearing for me. Ever thought about an OEM DC2 LSD even? Can be had cheap at times.
 
yeah I have a lsd in the box.. its a 96spec s80 4.4 lsd I have. have the 4.9 to go in now..
 
Get the LSD, you'll wonder why you even asked this question once your driving it,
With 4.9fd and 1.5way LSD in my b18 ek9 I was lapping the ring in 8:30's consistantly and could go faster if I wasn't a pansy
 
Thanks for all the replies. Been on the lookout for a lsd since. they are mega money but hopefully worth it. thanks for the replys!
 
Yeah they are worth it if you get the plate type. When I was looking there was afew about cheapest was a Cusco at 300 ended up with a ats at 500ish, lee on here with the b20ek9 was selling his ats. Not sure if that's still going on though?
 
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