b tranny gear swap ?

j954drgsr

Member
i have my b18c1 tranny apart and now i want to extend my 5th gear ratio to an ls. does anyone know if the 5th gear from an ls will fit and go in gear along with my b18c1 guts and will it affect my 1st o 4th and final drive gear ratio. im sure if it works, i will have to get the input and output 5th gear ls set.
 

nfn15037

Senior Member
Yes it works and is about the worst mod you could do to your tranny. The few hundred RPM difference @ cruise makes ZERO difference in fuel consumption. Hell, you could use USDM ITR 5th gear and a JDM 4.7 FD and your fuel mileage will be exactly the same. The fact that the car will fall on its face from 4th to 5th is not worth whetever percieved benefits you may thing the LS 5th gear will give you.
 

wanderinman

Senior Member
Originally posted by nfn15037@Jul 7 2005, 04:08 PM
Yes it works and is about the worst mod you could do to your tranny.  The few hundred RPM difference @ cruise makes ZERO difference in fuel consumption.  Hell, you could use USDM ITR 5th gear and a JDM 4.7 FD and your fuel mileage will be exactly the same.  The fact that the car will fall on its face from 4th to 5th is not worth whetever percieved benefits you may thing the LS 5th gear will give you.
[post=522257]Quoted post[/post]​



You can't say it makes zero difference in fuel consumption. The sheer fact that its a few thousand less explosions a minute proves that. It just might not be a big enough difference to make it worth it. I know the LS are rated at 25/31mpg, anybody got the GSR numbers off the top of their head? I'm pretty sure its just about the same.

The boldface is a big no... you would notice a drop is gas mileage, but like I said earlier, it might not be big enough to really matter (2-3mpg).

I would say the biggest advantage to the LS 5th as opposed to the more agressive 5th gears out there would be reduced wear on the engine, especially if your primarily on the highway like I am. Hell 400 R/minute, times how ever many HOURS/DAYS a year I'm on the highway, thats a lot less spinnin of my motor.
 

xj0hnx

I wanna be sedated
VIP
Originally posted by nfn15037@Jul 7 2005, 10:08 PM
Yes it works and is about the worst mod you could do to your tranny. The few hundred RPM difference @ cruise makes ZERO difference in fuel consumption. Hell, you could use USDM ITR 5th gear and a JDM 4.7 FD and your fuel mileage will be exactly the same. The fact that the car will fall on its face from 4th to 5th is not worth whetever percieved benefits you may thing the LS 5th gear will give you.
[post=522257]Quoted post[/post]​

You ever think the guy wants to do it so he isn't revving at 4000 rpms on the freeway going to work? And yes, less rpms, means less fuel consumption.
 

j954drgsr

Member
thanks a bunch for the input but yes im always traveling hwy miles and at 60mph im at 3100 rpm and at 80 which i usually go it over 4000 rpm and my vtec comes in at 4100 or 4200 rpm so thats why im looking to sway out the gsr 5th gear to a ls 5th gear. on the drag strip i wont be needing to switch to 5th anyways so im going to get the ls 5th gear but before i do that i will see what i need from the ls 5th and guts to do the 5th gear complete conversion.
 
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