I've noticed that's theres quite a few threads describing *how* do do an LS 5th gear in a b-series transmission, but few describing what it actually feels like on the street. I just completed installing my LS 5th gear, and wanted to describe how it's affected my car.

Its easy to plug in numbers and figure out that the LS 5th drops highway RPM @ 70 from about 4000 to about 3200, on a b16 transmission, but raw numbers don't give driveability. My b16 handles the lower RPMs just fine; acceleration obviously isn't as good as before, but I can accelerate without much problem. I now have to downshift to 4th on some hills that I made it up in 5th before, but that's expected. What's nice is that the LS 5th works for almost all of the situations where I used 5th before - even driving around town at 45. RPMs are waaaay low there, but as long as I don't want to accelerate there's no problem.

I haven't had the gear long enough to compare mileage, but I'll be making a reasonable length road trip this weekend, and figure out what I get. I got 30-33 driving at 70 before; hopefully I can get that up to 35, but I really have no idea where it will go to.

I also installed a Fidanza aluminum flywheel - the thing's great. Revmatching is easier; the engine revs much more freely. Taking off from a start isn't difficult, just unforgiving of less than perfect clutch technique. And there's a bit more vibration at idle; but that's not a big deal.

 

cool, this something i was wanting todo on my car, expecially with a jdm lsd with the short gears i rev 4000 at 110 kms i'd like to get it down to about 3200 or so, as soon as i can afford it i'm building a b20 vtec so power shouldnt be a problem

 

Definitely a good idea for getting better highway MPG and still having aggressive gearing for the street

 

so you had to buy the ls 5th counter shaft and main shaft gears in this swap correct? I read on HT a while ago that you need both gears. If their are any other parts you had to buy can you list them? I have a JDM 2nd gen b16a tranny, with a 4.785 FD and it sucks on the highway.

 

That's correct. Mainshaft 5th gear, part 23581-P80-000, and the countershaft 5th, part 23461-P80-000. The mainshaft came apart by hand, but I had to bring the countershaft into a transmission place and have them install the gear there.

Edit: Part numbers are for a hydro b-series transmission. You can't buy the cable 5th gears directly anymore; you'll have to find a cable ls tranny and scavenge parts.

 

are those the ONLY parts u needed? You didnt need to do the entire mainshaft itself? I'm planning on doing a GSR 5th gear in a '97 Spec JDM ITR transmission. All i need is the mainshaft 5th gear and countershaft 5th gear from a GSR?

 

No you dont need the mainshaft, just the matching 5th gear set


I have an ls 5th in my gsr transmission. I thought it was really easy to install, didnt take it to a shop either (just bought a bearing separator from harbor freight)
The absolute hardest part about the whole thing was getting the two casings back together....f-ing pita

btw...why would you want gsr 5th?

 

well i have a '97 JDM ITR Tranny, and the Fourth and Fifth are shorter then any other B-Series ratios. But it has a 4.4 FD. Well i bought a 98+ 4.7 Final Drive and it will make my 4th and 5th extremely short. I dont have a problem with 4th being short but i want my fifth to be more like stock. I also dont want a HUGE difference between 4th and 5th. With the GSR 5th gear and 4.7 FD my 5th will equate to a regular B16 5th gear. which will be just fine for my CRX. Just imagine if i kept the shorter 5th...

This should show you more what i'm talkin about:

 

understood
I just wouldnt want to bother with swapping if it were me. Not really worth it imo

 

well the difference it will make is 4000 RPMs in 5th gear will be 75 mph instead of 68 mph.

 

Been thinking bout doing this lately, U need LS tranny case with LS 5th gear, and your B16 1-4th, great acceleration and LS 5th gas mileage

 

Good info.

BTW, if you were getting 30-33mpg on the hwy before, you will probably get better than 35mpg with the LS 5th.

 

you dont need an ls transmission case......

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dann6968 &raquo;</TD></TR><TR><TD CLASS="quote">Good info.

BTW, if you were getting 30-33mpg on the hwy before, you will probably get better than 35mpg with the LS 5th.</TD></TR></TABLE>

Depends on the speed.

If he was getting 35mpg before w/ a B16 trans - he doesn't exactly speed - he drives pretty damn slow - so if you're at a significantly lower RPM your throttle will have to be depressed harder.

He'll probably get 35-37. Most D series Hondas around here pull 36 or so on the highway @ about 75-80mph.

EDIT:
Although I've never driven in a car w/ an B16/LS 5th I definitely decided awhile back that if I did do a swap (and if it wasn't H/F) it'd probably be the LS or GSR (torque motors) and that I'd go with a B16 trans/LS 5th.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pdiggitydogg &raquo;</TD></TR><TR><TD CLASS="quote">you dont need an ls transmission case......</TD></TR></TABLE>
thats what i was gonna say.