It runs, but have a speedo question

[NISMO_RB25]

I got my RB25DET powered S13 running this weekend. I want to thank everyone in this forum who helped me. I will try to get pictures up soon.

I don't know squat about the transmission connectors on the RB25(or any car for that matter) I want to hook up the speedo but I have to extend/splice some wires, and I don't even know what plug it is. Could someone tell me, starting from the motor going back what the connectors are. I assume one is reverse lights, and one is speedo, but have know idea what the others are.

Anyway thanks again to everyone. I will try to help out the new people the way you guys helped me.

For everyone thinking about this swap, It's better than I expected. The engine purrs like a kitten and I left dual 12 foot stripes without trying

[PROJECTRB240SX]

YOU SHOULD HAVE A NEUTRAL SWITCH, REVERSE SWITCH, AND THE ELECTRIC SPEEDO (THIS YOU WILL HAVE TO SWAP SENSORS).

[NISMO_RB25]

I owe you a lot. Question on the speedo sensor. Is it the one with the little spiral wheel? Do I just pull it out of the KA's transmission and put it in the RB's?

[PROJECTRB240SX]

YES JUST PULL THE KA SENSOR OUT AND PUT IT IN THE transmission. I DEFINATELY KNOW THE RB20 transmission ACCEPTS THIS SPEEDO SENSOR NOT POSITIVE ON THE RB25.

[NISMO_RB25]

You the man. I will try it out, thanks.

[Nameless EJ6]

Please report back on whether it fits or not.

[Joe]

all the 5 speed speed sensors are interchangable. the Ka will work with RB20 or 25 transmissions.

a auto sensor will not work in a manual transmission, and vice versa

[NISMO_RB25]

Because I have realized that I should have done this before I mounted the transmission/Engine in the car, I had another question.The location of the sensor once it is in the car, makes it difficult to remove without unbolting the engine/transmission mounts and lowering the transmission.

Would it be possible to just rewire the connector and use the RB's sensor?

Once you did the switch, has your speedo been pretty accurate?

[NISMO_RB25]

So I pulled the sensor out of the RB25 transmission,(assuming it is the sensor with the red shafte and gear)It does not match the 240's. It is longer and a little wider than the one from the 240. Any ideas?

And yes I realize I said, shaft, longer, wider.

[PROJECTRB240SX]

DOES IT BOLT IN? IF IT DOES THE SPEEDO IS PROGRAMMED TO THAT GEAR RATIO ON THE SENSOR SO IT WILL STILL READ CORRECTLY.

[NISMO_RB25]

no the housing is a little smaller on the KA's sensor and the shaft with the gear is probably 2 inches shorter. Basicall it slides in but wouldn't make contact. I think I may just have to run an aftermarket speedo and run directly to the sensor. Making my own gauge cluster is starting to seem like a possible solution. That way I solve the Tach and Speedo with one step. I think this weekend I may just take the lower harness from both Cars and start making my own. I was just kiddn' about you needing to answer this question. I am sure someone out here has done the swap and had this same problem.

[PROJECTRB240SX]

TRY WIRING THE RB25 SENSOR TO THE KA HARNESS AND SEE IF IT READS THE SPEED.

[NISMO_RB25]

That is what I am thinking. To add confustion the two wires are both green and neither have a stripe. I am just going to cut it and extend them. I will let everyone know if it works or if the car catches fire

[PROJECTRB240SX]

LOL, YEAH FILM IT TO SO WE CAN MORUN THE STUPIDITY.

[Nameless EJ6]

Hey do you have a camera? If so can you take a picture of both speed sensors beside each other? I'd like to see them..

[NISMO_RB25]

I do and I would but it was so hard to get the sensor out of the RB's transmission while it is in the car, that I really don't want to do it again. I will see if I can get a pic of it installed if that will help. Basically they are very similar, but the RB's is a couple of inches longer. I am begining to think that most people with RB's have the 20 and not the 25. The 20 transmission is smaller, and I think that is why they were able to swap sensors. If the weather holds up, I will probably try to wire directly to the RB sensor and see if that works. You have a place I can dump the pics? I don't mind taking a bunch of pictures, but I don't have a place to upload them.

[dreamsOfSkylines]

I think the KA and RB20 trannys are essenially the same.

[HybridOne]

more like the 300zx and RB20 trannies are essentially the same...and SR20 too.

[NISMO_RB25]

So I wired using the RB25's speed sensor. I think it is at least 20 miles per hour lower than actual. Good news, I dug through all the hoses at Autozone and found a lower radiator hose that fit. From my earlier post, I could not get the stock hose on, and I still don't know anyone else was able to do it. I drove it yesterday for a while and man this thing is awsome. It would easily give my RX-7 TII a run for the money(I run 10 psi on my TII). I will see if I can take a few pics today. I don't have a way to make video, but I assure you it runs and runs well.

[Nameless EJ6]

Yah if you can get any pics email them to me and I'll upload and post them. thanks...

[email protected]

[undertaker]

based on a jdm silvia converted to rb25det with rb25 manual box you can calibrate the standard speedo to read correctly using the standard speed sensor. there are two tiny pots on the speedo pcb, the centremost one adjusts the reading (you may want to mark it before you adjust it). on mine i had to add more resistance to the resistor in the same circuit as the pot, i used a 10k pot and it gave me enough. it hepls to drill through the gauge cluster from the top so you can adjust the pot without disassembling the cluster.

[oreofreak]

I would try buying brand new Z32 300zx transmission sensor from the dealership. The sensor should not be to expensive. The SR20,KA24,VG30E,CA18,R20 all share the same transmission type that is a FS5W71C. The Z32 300zx and RB25 share the same transmission type that is FS5R30A which a bigger and beefer transmission. Thats most likely the reason why your sensor is not interchangeable with the RB25 transmission.

[NISMO_RB25]

based on a jdm silvia converted to rb25det with rb25 manual box you can calibrate the standard speedo to read correctly using the standard speed sensor. there are two tiny pots on the speedo pcb, the centremost one adjusts the reading (you may want to mark it before you adjust it). on mine i had to add more resistance to the resistor in the same circuit as the pot, i used a 10k pot and it gave me enough. it hepls to drill through the gauge cluster from the top so you can adjust the pot without disassembling the cluster.

You the man. I had the same idea this morning, and that is probably what I am going to try. I went ahead and ordered a Apexi Rev/Speed Meter, just so I can start driving it.

[NISMO_RB25]

Well I hooked up the Apexi Rev/Speed meter this weekend. I should have looked into it a little more as it only displays in Km/h(doh!)Anyway, it is reading exactly off as much as my 240's speedo? but the tack on the apexi is right.

I had another thought besides tweaking the 240's speedo, how about getting the speedo from a 300zx since the trannies are similar?

[IvoryJ30t]

i didnt know about the potentiometer on the speedo pcb, but for about $150, you can get a converter box for your speed sensor. it divide/multiplys the speed sensor signal by xx/xx. its adjustable from any range thereof. 01/99-99/01 so you can have any fraction you want.

i was thinking about using it so that i can use the gtr dash cluster with the proper redline, and converting the reading from0-180kph to 0-180 MPH.

[IvoryJ30t]

just have to put a little MPH sticker over the kph

[NISMO_RB25]

Interesting Idea. Not knowing how fast I am going is getting annoying.

[IvoryJ30t]

the great part about it is that you can adjust for different tire sizes, or gear ratios, and you speedo will still be accurate.

figure if you use the skyline cluster, you just figure the ratio of the difference between the skyline rear gear, its rear tires, and the difference between mph and kph, and what your car has now, and set the converter to that ratio. the speedometer will read accurately.

or even better, if you have a cop friend, have him clock you while your driving at a steady speed, and divide actual speed by gauge speed, and set the converter to that.

there only $150, and its a 4 wire connection. i want it so i can have the skyline cluster, and have it read 180 MPH.

http://www.terf.com/SpeedChangerPage.htm

[IvoryJ30t]

i almost forgot. if you use the 180 kph cluster, and use the converter to make it read in mph, your JDM tyte speed limiter gets moved to 180 MPH. [its true, there was a discussion about that on skylineowners.com] so you get the proper reading, and the speed cut gets moved in one nice easy step.

[kevy8up]

now yer starting to interest me....hehe