rb25 transmission swap on r32 speedometer

[jonask]

Hi,

Maybe it's a stupid question...
when you swap a rb20 transmission for an rb25, you have the issue of the speedometer.

does it affect only the speedometer or it affects other things, like the rpm ?

thank you

[Skym]

Speedo only.

Would need to check with an expert or search the forum, as the information is here, but I think a R32 GTR gearbox speedo cable works (gearbox side), as the gearboxes are nearly identical internally, but one is rwd and the other 4wd (transfercase, etc).

CAS on front of exhaust cam > ECU > dash is for rpm.

The other is the gearbox mount, crossmember (custom) with R32 manual chassis. With a R32 auto chassis it bolts in with I think a manual 240sx crossmember or similar factory crossmember (search the forum, as there are photo's of the difference in chassis, crossmembers).

[jonask]

Do you know this modification ?

http://www.jdmlegion.com/Projects/R32%20Skyline%20GTSt/RB25-conversion-Stage-13---Installing-the-gearbox-and-modifying-the-speedo-sender-780d0e8e-cfd4-4006-8cb3-db2db119a53f

seems pretty easy to do.

[Skym]

Yes, usually for a change in final ratio or I think wheel diameter (what you need to check).