Don't know if it's been covered but I couldn't find it in a search.

A little background first. It's a daily driven EM1, internally stock B16A, stock 8000 rpm redline, plan to stay all motor. Occasional track day car. Rebulding the transmission at the moment and was thinking of getting a GS-R fifth and maybe fourth gear set.

Calculations show that with the stock trans:

1-2 shift @ 38.65 mph, drops to 5214 rpm
2-3 shift @59.31 mph, drops to 5541 rpm
3-4 shift @ 85.62 mph, drops to 6074 rpm
4-5 shift @ 112.77 mph, drops to 6128 rpm

With GS-R fifth only:
4-5 shift @ 112.77 mph, drops to 5687 rpm

With GS-R fourth and fifth:
3-4 shift @ 85.62 mph, drops to 5673 rpm
4-5 shift @ 120.73 mph, drops to 6089 rpm

Question is, do I need the GS-R fourth to keep me in the powerband for the shift into the GS-R fifth? Or will the GS-R fifth suffice? I know shorter ratios are better for the track but realistically it's a daily driven car and I'd like that extra overdrive the GS-R fifth gives me on the freeway. I'm borrowing a friends GS-R trans right now and I like the more relaxed freeeway cruise.

Any and all advice is greatly appreciated. Experience with this setup would be helpful too. Thanks in advance.

 

I think the tracks you run may determine what way you should go. On my GSR, there is not very much acceleration going up the back straight at Watkins Glen when I hit 5th. I have more torque than a B16 but the car is heavier too. At those speeds, aero differences between the body styles may matter as much as the weight. If you don't regularly get into 5th, the taller gear will help more on the highway than it hurts on the track. I find most tracks near me I run most of the time in third and fourth. Having a gap between 3 and 4 would hurt much more than between 4 and 5 since I only need fifth on a few tracks. If all that makes sense, I hope it helps you decide.

 

Good point. Since it will be primarily be a commuter car, the taller fifth would help a lot more. So you're saying that a 500 rpm or so defecit starting off the fourth gear pull would not be worth switching out the taller GS-R fourth.

I was going to get the fifth for sure but I forgot about "stretching out" the B16A third gear to compensate for the taller fourth. And like you said, fifth is hardly used depending on the track.

 

Why do you want the gsr 5th / or 4+5 combo?

 

I see NO reason to put the GSR gears in there.. Your going to loose performance if you swap them in..

 

As stated, he is looking at a compromise between street and track driving. The stock fifth gear is awfully short on the highway. Of course the taller fifth would hurt on track, if the tracks he runs are fast enough to top out fourth. If not, it does not hurt anything. Changing out both fourth and fifth will hurt much more since there is now a gap between 3 and 4 and most tracks use lots of fourth gear.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Honda318dx &raquo;</TD></TR><TR><TD CLASS="quote">I see NO reason to put the GSR gears in there.. Your going to loose performance if you swap them in..

</TD></TR></TABLE>


DO NOT CHANGE ANY GEAR IN YOUR B16 TRANNY......

especially if it is a b16 engine

if you do anything add a 4.785 or a 4.9 final drive and LSD

that is the only thing you should do to any b16 powered car!!!

you are retarding your gearbox if you put gsr or ls gears in it!!!

 

I tend to agree with Chad.

There's nothing to gain except maybe a slight noise decrease, and possibly an unmeasurable amount of engine wear.

Considering many exhausts actually tend to get quieter as revs increase it's possible that you're not even helping the sound issue. If I got the parts for free, and the transmission already out of the car and apart I still wouldn't change the gears - even if the car was solely a daily driver.

 

Maybe I posted in the wrong forum. This car is NOT a track car, only for occasional track days.

I fully understand that taller gears (even if only a taller fifth) would hurt accceleration. And that a shorter final drive would keep me in the powerband or at least in a better part of it, after the shifts.

I posted here to get feedback on whether the 4-5 shift would put me outside the useable part of the powerband (112 mph @ 5700 rpm). It will definitely affect acceleration at that point but outright acceleration is not my priority.

Don't get me wrong, I appreciate the feedback because you all seem to have a lot of track experience. But even if it is "solely a daily driver" is this not recommended?

And yes, an LSD is going in before I put it back together. Suggestions while we're on the subject?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by L8apex &raquo;</TD></TR><TR><TD CLASS="quote">Suggestions while we're on the subject?</TD></TR></TABLE>

OEM ITR

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .RJ &raquo;</TD></TR><TR><TD CLASS="quote">OEM ITR</TD></TR></TABLE>


Personally, I'd put in the ITR LSD (as mentioned above) along with the ITR 4.79 final drive - along with an LS or GS-R 5th gear. I honestly don't see any reason to worry about your 5th gear for track events! Use that 5th soley for highway cruising and road trips. Also, if you end up running out of rpms in 4th gear for track events, then upgrade the valvetrain on your B16 for more room.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MrTodd &raquo;</TD></TR><TR><TD CLASS="quote">I honestly don't see any reason to worry about your 5th gear for track events! </TD></TR></TABLE>

Because with a b16 box, you will be using 5th on track. Especially with a shorter FD... if you put one in, then go 4.9 or leave it stock.

 

EDIT: My mistake, sorry.

 

My friend had this idea in mind a few years back. He had an ITR and he put the JDM final drive in with a GS-R 5th gear to keep the revs lower on the highway. He liked it a lot at first, more power in the lower gears while keeping the revs down on the highway.

After a few HPDE's he found he wanted the ITR 5th back badly. He could care less about crusing because he hated the way the 5th gear would bog down at the track.

 

Thanks for the input. But like I said, my car would spend a whole lot less time on the track and it is a sacrifice I'm willing to make. Plus I'm still keeping the stock 5th gear sets in case I change my mind.

Speaking of your friend's ITR, what did he do with the stock ring and pinion/countershaft?