dizzle Posted August 18, 2009 Share Posted August 18, 2009 Does anyone know what ratio rear end originally came in the skyline with the rb20? I am changing my rear end gears and hoping that my speedo might be somewhat close. I Need to do some more searching on what car I can cross ref the correct one. But crossing my fingers that the rb20 trans came with a 3:71 Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted August 19, 2009 Share Posted August 19, 2009 I don't mess with that until I actually drive the car. You're also swapping that drivetrain over to a car that probably has different tire diameter than the car it came from. I would drive the car, see how far it is off, and then start with the speedo drive swaps. Quote Link to comment Share on other sites More sharing options...
260zman Posted August 19, 2009 Share Posted August 19, 2009 There were several different ratios. It depends on model of skyline, and if it came out of an automatic vehicle, as what i've found is they are quite a bit different. i found on these forums once upon a time, a list of all the ratios, and the speedo drive gears (colour of the drive gear is different for each ratio). for the ratio you're looking at, its the same as mine, which came out of an R31 rb20det (old red top motor), it had the longnose r200 LSD, and i think the plastic speedo drive was blue. not sure if i've helped?!! Quote Link to comment Share on other sites More sharing options...
dizzle Posted August 19, 2009 Author Share Posted August 19, 2009 So then what cars speedo gear will fit into my rb20det trans?? I read about some austrailian market stuff that might fit, but not much help here. Or am I just stuck getting an aftermarket?? Quote Link to comment Share on other sites More sharing options...
260zman Posted August 20, 2009 Share Posted August 20, 2009 whoops, sorry- i didnt tell you what car that diff came out of!! It was an 1988 R31 GTS skyline, japanese spec. (so had the rb20det, independant rear end, r200lsd, 4ws, and the front struts you can directly bolt 4 pot skyline brakes onto). it has to be jap spec as Australian ones dont have the same diff, but have a solid rear axle. You should be able to still buy the drive unit from Nissan. hope this helps. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted August 21, 2009 Share Posted August 21, 2009 Isn't the RB20 tranny a FS5W71 tranny? If so, you have dozens of choices for mechanical speedo drive and only a few if you want to use a sensor. If the car you are putting it into originally had a nissan digital dash, you might need a short speedo cable that goes to a pulse unit that mounts in the engine compartment and sends the signal to the digital speedo head. If your car has a nissan analog speedo of a certain year that uses a sensor, then you might need a sensor that screws to the speedo drive from a 1987-1989 300zx (analog dash car). If your car uses the later style of sensor on the tranny, you have many choices of sensor and gear sizes from the 240sx and possibly the nissan trucks and pathfinders that came with a FS5W71 family tranny. Quote Link to comment Share on other sites More sharing options...
zedman240 Posted August 21, 2009 Share Posted August 21, 2009 When I ran the Rb25 and non turbo trans, I had a 3.9 LSD but a 4.1 would've been better suited. As for the speedo drive, I found a unit out of an Australian market Nissan Gazelle (84-85) that went straight in and speedo worked fine. Was about 4-5 mph slower but I usualy had my gps with me to use as a more accurate speedo. I do have a speedo drive unit new from Nissan if you can't locate one easily. Quote Link to comment Share on other sites More sharing options...
dizzle Posted August 21, 2009 Author Share Posted August 21, 2009 Well my s30 still has the mechanical speedo. And the rb20 still has the cable style speedo drive. The cable fits up perfect but with the 3.34 rear end, was aprox 20% off. So there are z31's that had this style speedo drive?? On a side note, do you think I chose the right gearing?? A friend swore up and down that the 3.7 would be best for a rb25det street car. I still have another 3.9 r200 in the garage I can use if it is still going to be too long of gears. Just would like to know what others are running in their rb powered z cars?? Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted August 22, 2009 Share Posted August 22, 2009 The Z31 runs 3.9 with the 5 speed from the factory and I never noticed too high a rpm on highway but it does have 215/60 tires which does change things a bit. Many S130s ran 3.54 and I believe a few even ran the 3.36 but I could be mistaken. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.