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Discussion Starter #1
Hey all of you speedfreaks & gearheads everywhere...I just joined, but have been visiting this site since may when i bought my 'lude.

I was wondering if anyone has ever reduced the final drive or the 5th gear in the trans so that the rev's would come down a bit when your makin' "good time" on a long hiway?

Does an overdrive kit exist for these cars?
Is there a way i can maintain a "somewhat high" speed while getting decent fuel mileage?
Or is this something i should resolve with a full Hondata300 chip & fuel map/ dyno tune.?

You've already given me guidance into the taillight leak issue, and i've checked over my block for oiling issues. Thanks all for reading...

A Northern Speedfreak
 

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IBTK!!! :D

No, no overdrive kits. Technically in a stock 5th gen transmission both 4th and 5th gears are considered overdrive as they have a gear ratio that is less than one. If you're looking for highway fuel economy, some would suggest having an accord 5th gear installed in lieu of your prelude 5th gear. This of course involves having the transmission pulled apart completely. There are other alternatives, such as a transmission swap using the transmission of a specific model of accord, in which the gear ratios of the accord 1-4 closely match those of a 5th gen prelude transmission, but the 5th gear is set for highway fuel economy. Both options will be pricey.

Honestly your best bet: cruise at 70mph.
 

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Since Fal encouraged me to post, I will. The 5th from an F-series transmission would be your ultimate answer. But there's more to it than just swapping. Some machining is required. So it's not very common.

As for your gas mileage: Cruising at 80mph isn't that bad on fuel despite sitting at 4k the whole time. You'll notice little difference if you spent the whole tank only cruising at 70mph or even 60mph. The key is more of how you get to 80mph.

But, before we open that box of worms, what's your actual mpg? Knowing that will determine good or bad.
 

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There's a thread on HT about it. Basically the Accord 5th is a little wider than the Prelude 5th. So you have to shave it (sorta like resurfacing a flywheel or rotor) down like 2mm.

I think the thread is in the FAQ over there.
 

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I'm looking at a transmission rebuild at the moment so I was considering this myself. I ultimatley decided that it's not worth it due to the machining involved, and then who's to say it won't blow up 200 miles down the road.

I know gearspeed makes a 4.64 Final drive set, which would definatley make for an interesting daily driver but wouldn't solve your problem. You'd almost want a 4.022 Final drive like alot of the accord transmissions. That might make your gears realllllly long. That said, from the research I've done they're pretty much the be-all-end-all of Honda transmission shops. If you really were to pursue either changing your final drive or using an accord 5th gear, They'd be the people I'd call to do it. I'm sure they'd know whats involved.

They actually do advertise custom gear sets on thier webpage. A phone call would find out if they'd be willing to find you an accord 5th gear and do the homework to make it work. You may even want to refrence this thread, the thread on H-T, and any other of the 5000 accord 5th gear threads on here. It might even make sense for them to offer it as a product, which might save you some cash compared to just buying a one off custom part.

Edit: Fun calculator for those who want to play around with the concept http://www.zealautowerks.com/transcalc.php
 

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Discussion Starter #8
Transmission gearing

Hey guys, thanks for the replies.
I kind of assumed that it would be pricey (probably so much so that it will negate any savings in fuel over the next year or so) to get a better hiway cruising mileage. I have access to machining equipment, so shaving a few thousanths off the width of an accord cog gear wouldn't be a challenge.

Thanks for the help guys

I guess in the meantime, saving fuel means easing off on the vtec.
Cheers all
 

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You could always get a slightly taller tire, too.
I know you know, but in case the OP or someone else doesn't realize:

Getting a taller tire will definitely have that effect, however, it's basically like changing the final drive of the entire transmission, not just 5th. So you'll cruise at a lower RPM for the same speed, but you'll have a loss of acceleration through the entire spectrum.
 

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I know you know, but in case the OP or someone else doesn't realize:

Getting a taller tire will definitely have that effect, however, it's basically like changing the final drive of the entire transmission, not just 5th. So you'll cruise at a lower RPM for the same speed, but you'll have a loss of acceleration through the entire spectrum.
Not the entire spectrum. Sometimes more acceleration, sometimes less.
 

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Discussion Starter #13
Not the entire spectrum. Sometimes more acceleration, sometimes less.
Hey Blue01,
I see you're running an accord trans. in your ride. How long have you had that in there? And more importantly, how do you like it? Is there a noticeable difference in the lower gears as well?
And I assume if were to go with an accord trans, I would need one from roughly the same year car right?

Cheers man
________
'01 Prelude
AEM cold air kit
Tanabe upper/lower F/R susp. brace
NGK blue
 

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Couple years. It's fun.

Keep in mind, though, this is an Accord transmission out of a JDM DOHC Accord. It's not what you're thinking of. 1st and 5th are the same as stock and 2, 3, 4 are shorter.

A normal Accord trans would probably feel totally lame.

For what it's worth I wouldn't bother messing around with the gearing like you want. Don't worry so much about the RPMs. Putting a longer 5th gear in there is just going to put a big gap between 4th and 5th which you'd really feel in the 85-100km/h range and isn't worth the effort imo.
 

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Yea most accord transmissions are no fun, they'll get you much better gas mileage, but when you want to haul ass they will drop you out of VTEC in your 1-2 and 2-3 shifts. It will help make you that much slower.

That's based on the stock VTEC crossover.
 
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