Final Drive 4.4 or 4.7?

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Final Drive 4.4 or 4.7?

Postby Cotomeus » Thu Mar 17, 2011 8:32 am

I have plans to get the OS Giken LSD from Goodwin soon and was thinking since I am going to do that, I should also have the final drive changed from the current 4.1 to perhaps 4.4 or 4.7 while I am at it.

Can anyone share their views or experiences with this?

Cheers!

Currently, I am running on 205/45/17 tires but having seen so many ppl here using 235 or higher, I kinda wonder... Wouldn't a wider tire cause the car to be slower in acceleration and thus making it more sluggish? What are the benefit of running such wide tires? As here in Singapore it's quite rare to see anyone going higher than 225.

Finally, would changing the final drive help compensate the wider tires sluggishness? I am confused as you can see :p

Some info of my car, which is a 08 NC 6 speed manual sports with Ohlins, racing beat sways front and rear. Using this car as my daily drive, monthly track events and occasional drift.

Thanks in advance!
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Re: Final Drive 4.4 or 4.7?

Postby matthew-m » Fri Mar 18, 2011 12:16 am

I did some research prior to purchasing a 3.636 ring/pinion gear set. Here are a couple things I learned:

A 235/40/17 tire is only 0.5% slower than the tire you are using now, and a 245/40/17 is only 1.8% slower. (1.8% is roughly equivalent to 1 mph at 60 mph.) I think the extra weight of the tire/wheels will have more effect than reduced/increased tire diameter. Someone else will have to comment on the advantage of the wider tire, though I suspect it is useless on the street.

When I asked for advice on the gear ratio, I was interested in better fuel economy and lower noise on the freeway. You should consider that a 4.4 will theoretically reduce top speed in first gear to 28 mph, and the 4.7 to 26 mph, at 6700 rpm. Also, it will be really hard to find the gears.

Since I haven't installed the gear set, I can only give you the theoretical top speed in first of 34 mph for the 3.636. I hope it will make first gear more useful on really tight corners, and lower rpm's/better fuel economy on the highway. Here are some of the links I found for final drive calculator http://www.car-videos.net/tools/speedrpm.asp and tire size calculator http://www.1010tires.com/tiresizecalculator.asp.

Good luck with your search!
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Re: Final Drive 4.4 or 4.7?

Postby Cotomeus » Fri Mar 18, 2011 3:10 am

Thanks, I have been doing some reading up as well...and I must say you brought quite a few insight into this, and thanks for the link to the gear ratio calculator, it was very helpful indeed.

While I was working on the calculator however, something interesting was that with a wider tires, you seems to be able to get higher speed per gear, (with no regards to weight). However, just changed from 215 to 205 lately while keeping the same sets of rims, the feel I got was that the 215 is more stable but felt a little sluggish, while the 205 was feeling really zippy and Fuel Consumption improved with the 205 as well.

Anyway, that aside...what I realized that what FD you choose depends on what kind of modification road map you have. For those going/planning for an SC or Turbo, would probably want a FD of 3.7. While for those who are going the NA route would want to move up to 4.44 or to as high as 4.7.

Sadly, with Singapore's anal regulations, SC and Turbo is out of the question for me, which means going the higher FD ratio is the only route. So I will most probably settle for the 4.44 FD with 215/45-17 tires as my main but would need to do more research to see if it would be a good match-up to my 6 speed manual gear box.
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Re: Final Drive 4.4 or 4.7?

Postby jboemler » Fri Mar 18, 2011 12:13 pm

I can't think of a worse combination than 4.77 gears with a 6-speed. First gear will be usable only for plowing fields, and second gear for when you can get up to parking speed. Seriously, the 6-speed gears are too low and too closely spaced even with the 4.1 -- anything higher (numerically) would be just ridiculous.
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Re: Final Drive 4.4 or 4.7?

Postby Cotomeus » Fri Mar 18, 2011 9:15 pm

Thanks for the input Jim!

That's the part that I need to research on, I have a friend who got the 4.7 FD on his car and is in the midst of changing it back to 4.1 as 4.7 is not highway friendly, though he making good time in the Sepang F1 Circuit in Malaysia, the track that we usually track on.

One of the few reason I am thinking of a 4.4 though is that with the 4.1, I realized that I am mostly cruising on the highway without hitting the 6th gear. On the Sepang track, I would probably need to rethink the gearing through the corners, guesstimate is that I will only need to drop to 2nd gear for 1 corner and go through most corners using the 3rd instead.

Ponders....
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Re: Final Drive 4.4 or 4.7?

Postby CHeavin_2006 » Fri Mar 18, 2011 10:28 pm

I wouldn't go above 4.1
Have you considered a lightweight flywheel?
If your NC is feeling 'sluggish' I'd imagine the lightweight flywheel would pep the car up quite a bit, increasing the throttle response making the car more 'zippy' through the gears.
Just a suggestion, if you couldn't tell I'm trying to talk myself into getting the flywheel soon. :wink:
I've heard nothing but great things so far, maybe someone who has a flywheel installed will chime in...

Anyways, good luck with whichever route you choose to go!
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Re: Final Drive 4.4 or 4.7?

Postby jboemler » Sat Mar 19, 2011 1:09 am

If it was me (and at one time it was), I'd switch to the 5-speed. Sixth gear on the 6-speed is actually lower (slower) than 5th gear on the 5-speed, which is part of why the ratios on the 5-speed are so much better. In my view (worth every penny you paid for it...), the 6-speed was strictly a marketing bullet on somebody's PowerPoint slide -- in the real world it's completely useless.

jim (never lacking for a contrary opinion)
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Re: Final Drive 4.4 or 4.7?

Postby Cotomeus » Sat Mar 19, 2011 3:32 am

CHeavin_2006 wrote:I wouldn't go above 4.1
Have you considered a lightweight flywheel?
If your NC is feeling 'sluggish' I'd imagine the lightweight flywheel would pep the car up quite a bit, increasing the throttle response making the car more 'zippy' through the gears.
Just a suggestion, if you couldn't tell I'm trying to talk myself into getting the flywheel soon. :wink:
I've heard nothing but great things so far, maybe someone who has a flywheel installed will chime in...

Anyways, good luck with whichever route you choose to go!



Well, look no further, I have the fidanza flywheel installed just a few months back :) It was a fantastic purchase which I have no regrets. Some of the concerns I had when I was getting the flywheel was that the fidanza might be too light, and makes daily driving a chore. Another would be the fly wheel chatters that some mentioned about.

After installation, this is what I find. The rev does goes up faster but it drops faster too, initially driving was pretty jerky but once you get used to it, the drive is so much better than before. One tip I can share is that you need to learn to blip the throttle during downshift (heel-toe) as well as upshift to make the transition smoother. PM me if ya need more details

As for the chatters, I have been driving for 3 months now, and I must say there are hardly any chatters except the sound of the engine rev-ing. It all boils down to the guy installing the flywheel, take note never to use pneumatic tools to tighten the flywheel, mine was installed by the old mechanics who tighten everything with a hand tool and was being very careful to ensure the alignment was right.



As for the changing of 6 speed to 5 speed, I think that's a little impossible for me, now that I know better. :P Reason why I gotten the six speed was due to the LSD and bilstein, but as you can see, i have changed both of them. I have also heard that the 6 speed gear box is better suited for track, but oh well.

I am also thinking it will be easier to sell my current FD 4.1 with Stock LSD as a package for all those guys running on 3.7 without LSD in Singapore, rather than just selling the stock LSD alone. Oh well, more guys to chip in on this topic please?

Ponders.....
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Re: Final Drive 4.4 or 4.7?

Postby CHeavin_2006 » Tue Mar 22, 2011 6:42 pm

Hmmm... I've heard good things about the Fidanza unit, but I'm still hesitant purchasing it. The guy that does all the work on my NC said he had problems with a Fidanza flywheel before and strongly suggested that I get the heavier billet steel flywheel. I guess I'll have to check around with more people's personal experiences with the Fidanza flywheel.
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Re: Final Drive 4.4 or 4.7?

Postby Brian » Tue Mar 22, 2011 6:48 pm

Near every weekend I smash about 300 hp onto my Fidanza flywheel in our supercharged 2007.....under the harshest race conditions (standing starts, etc). And not having any problems.....
Brian Goodwin
Good-Win Racing
www.good-win-racing.com
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