My buddy dropped his transmission off at our shop (transmission shop). It's a 98 GSR manual transmission, and he wants me to install the LS 5th gear so he can get a higher top speed, and better gas mileage on the highway. The 5th gear ratio for the GSR is something like 0.785 while the LS is something like 0.718.

What will I need to install this gear into the GSR transmission? I already have the case cracked open, and it's clean inside, so I don't have to worry about worn parts. I just did a lot of searching, and I keep finding somebody that says "I heard of somebody that installed an LS 5th gear into a GSR transmission" but nothing from a person that's actually done it.

Yes, I'm a lurker here, but any help is appreciated.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mike Diaz &raquo;</TD></TR><TR><TD CLASS="quote">My buddy dropped his transmission off at our shop (transmission shop). It's a 98 GSR manual transmission, and he wants me to install the LS 5th gear so he can get a higher top speed, and better gas mileage on the highway. The 5th gear ratio for the GSR is something like 0.785 while the LS is something like 0.718.

What will I need to install this gear into the GSR transmission? I already have the case cracked open, and it's clean inside, so I don't have to worry about worn parts. I just did a lot of searching, and I keep finding somebody that says "I heard of somebody that installed an LS 5th gear into a GSR transmission" but nothing from a person that's actually done it.

Yes, I'm a lurker here, but any help is appreciated.</TD></TR></TABLE>

There is a thread in the faq that has a walkthrough of a tranny overhaul. Might wanna refer to that. In addition the gas mileage isn't going to make any differance between the trannies. I have an LS tranny and the differance at speed on the freeway is 500rpm or so going 70 or 80. Its not so much rpm that uses gas as it is throttle position. but for the sake of helping...

https://honda-tech.com/zerothread?id=795700

 

You have to buy a P80 countershaft 5th gear and a P80 mainshaft 5th gear from a '94+ LS.

The '90 to '93 P21 5th gears might work too, but I haven't checked to see if the countershaft and mainshaft spline diameters are the same for both.

Regardless, the cost is the same for P21 and P80, so get the corresponding year to avoid any possible hassles until one of us figures it out.

CHeapest source for the gears:
http://www.barancoacuraparts.com
Enter Honda-tech and your H-T username in the comments when you check out to receive the revised shipping cost.

 

Oh, you'll need a countershaft locknut too and some specialty tools (or a press) to remove the countershaft bearings.

 

IN VTEC: Thanks for the info. Very informative.

So, just to be clear, I need the following:

94+ LS P80 mainshaft 5th gear
94+ LS P80 countershaft 5th gear
94+ LS P80 Locknut

Correct?

 

Refer to write-up for the specialty tools required.

You need a 32mm socket, large 2-jaw puller, and a large enough bearing splitter to remove the lock nut and bearings. Then you need a small sledgehammer and 2"x6" section of PVC piping to hammer the gear and bearings back down on the countershaft (if you don't have a press).

An impact gun and bench vise help as well. Use cardboard or wood as soft jaws for the bench vise.