regearing the speedo?

[BaliLover]

I just installed the VLSD rear end from an R32 skyline into my S13. It has the 4.36:1 gearing instead of the stock 4.1, so as expected the Speedo is off. Using a handheld GPS to track my speed, I found that for me to do 60mph, my speedo needs to read 68mph. This isn't a huge deal, but its slightly annoying as the correction factor changes depending on speed and I don't want to have to think about how fast I'm going all the time.

I know you can buy different speedometer gears from Nissan, or maybe a gear for the speed sensor, but I don't know which one I would need to get close to normal readings. I think Courtesy Nissan can get the gears but they must have 15 different options.

Does anyone have any ideas?

[onosqv]

courtesy nissan doesn't carry them anymore (referencing old thread where someone tried to buy some).

The only thing I can think of, is get larger diameter tires .

Your gps is probably a little off too, unless you are running smaller than stock diameter tires also, cuz 60->68 is about a 12% difference... your gear ratio is only 6% difference... so when your speedo says 68, you "should" be going 63-64.

So get a tire that is 6% larger than stock in the rear, and you should be good again.

[BaliLover]

The GPS uses a satalite triangulation to determine speed and is a true measure of speed. Speedometers, even stock, can be off as much as 5mph, which is why most police won't write a ticket for 5 over or less.

I checked it in the gf's 240 and at 60mph on the GPS, her speedo reads 58-59 so the GPS isn't off.

I'm running a 235/40/17 in the rear on a 17x9" wheel so I'm sure the speedo was already off a bit, now its just REALLY off.

Anyone know if I could snag the speed sensor with gear from say, a CA powered 180sx and just snatch the gear, or is the gearing done behind the speedometer itself?

[guyaverage]

There is a variable resistor in the back of the speedo cluster that can be adjusted to change the reading. It requires driving with the cluster hanging out and the steering wheel cranked all the way down to make room for the cluster so you can steer. I drove next to someone who had a Cadillac with a digital speedo and I set it based on their speed. ( I HIGHLY recommend 2 people to do this, one to drive, one to adjust. You'll obviously also need a 3rd person for a pace car, and cell phones to talk back and forth). Mine was about 10 mph off at 70 mph. I had to drill a small hole in the top of the cluster case to put a small screwdriver in to adjust it as I drove, and TINY adjustments made a big difference in speed shown. Good luck, its not difficult, just awkward, and you need to drill a small hole, get small screwdriver, and a few friends and an open stretch of road.