Speedometer reads incorrectly after lsd swap

[theboz]

I have a 90' 240 coupe, 5 speed, with the hud. I still have the stock KA24E and just installed an r32 VLSD. My speedometer was working fine and read right on the money until I swapped the rear end. Now when it is at idle it reads 7mph and if I rev the engine the speed goes up even though the car is not moving. I understand that I cahnged my rear end ratio when I put in the VLSD. It should now be a 4.4 rear end gearing. How would I go about correcting this problem. Does the speedo read off of the rear end or the transmission? I did a search and couldn't find any results that matched my problem. If anybody has any info that would be appreciated. Thanks.

[Rosco]

Mine does the same thing but it is only every now and then....It did it with the opend diff and still does since I swapped in my VLSD (also has the 4.4 gearing). I really haven't even bothered to figure it out yet.

[theboz]

I am in the military and have to drive onbase everyday. The military police are SUPER ANAL about driving the speed limit. I would just like to know how fast I am going.

I love the VLSD!! it is great and now I can break loose the rear end so much easier. I am getting my car ready for an RB20DET swap after the new years. I will keep everyone posted.

[naed240sx]

I have a 90' 240 coupe, 5 speed, with the hud. I still have the stock KA24E and just installed an r32 VLSD. My speedometer was working fine and read right on the money until I swapped the rear end. Now when it is at idle it reads 7mph and if I rev the engine the speed goes up even though the car is not moving. I understand that I cahnged my rear end ratio when I put in the VLSD. It should now be a 4.4 rear end gearing. How would I go about correcting this problem. Does the speedo read off of the rear end or the transmission? I did a search and couldn't find any results that matched my problem. If anybody has any info that would be appreciated. Thanks.

I have a 4.4 r32 diff too. First of all, you speedometer is guaranteed to be put off my the different ratio, becasause you driveshaft will have to spin at a higher rate of speed at a given mph than before. The difference will not be that bad, just realize that you are going slightly slower than it reads. As far as the idle mph, and revving, that has absolutely nothing to do with the diff, because you diff is not even moving, or being affected at that point. If your car is moving, your diff is turning, if not, then it is motionless. Your speedo problem is completely unrelated to your diff swap.

[theboz]

That is kinda what I figured. The speedo sensor should be on the transmission. I have never had a problem until I put on the VLSD so I was just wondering. I guess it is time to troubleshoot. Is there any way to get the speedo to read correctly? Can you change sensors or something? Thanks.

[cdlong]

you can get new gears for the speedo from http://www.courtesyparts.com i think.

found it, it's called the speedometer pinion.http://www.courtesyparts.com/nms/s13/s13_4.html

[Badfish]

Nice find cdlong!

Just bought an r32 vlsd so I figured the speedo would read faster than I was actually going after I install it.

[theboz]

Now I just need to figure out which speedo pinion gear I need to get. Thanks for the help. By the way are you an Lt.? Saw the butter bar and was wondering.

[theboz]

Badfish - At 60mph my speedo reads 63. At 70 it reads 74. At 40 it reads 41. I have the 4.4 geared VLSD. I had my buddy pace me in his turbo MR2.

My problem with my speedo was at idle. It would read 7mph. I revved the engine and the speedo went up to 20mph. I was still parked under my carport with the e-brake on and not moving. HEHEHE. Just trying to figure it out.

Good luck with the install. Not too hard should only take a few hours. You will need some help dropping the diff though. It was kinda heavy.

[cdlong]

i don't know what the stock pinion has so i'm not sure what you need to make it work right. just give them a call, they are very helpful and can probably tell you what you need. if not, just find out what stock is and we'll figure it out.

yep, i'm an Lt in the Air Force at Dyess, not too far away from you. i've thought about changing my avatar but it's so easy to pick out my posts.

[Rosco]

Seems like we have alot of military/ex-military in this thread. [RANT MODE] I've been out (army) for about 2 years and a half and I have a year and a half left on my IRR. What really sucks about that is they are trying to call me back because the recruiting numbers are bad.[RANT MODE]

[theboz]

I feel you. I will be on my third trip to Iraq this coming year. The up side is when I get back with some money in the bank turbo upgrades etc, etc. They are giving great enlistment bonuses............great way to upgrade car......HEHEHE.

[S-14boy]

I was about to install my LSD and I was gonna use this to recalibrate my speedo.

http://yellr.com/yb_home.htm

[Rosco]

What's your MOS? I'm pretty much screwed since I'm an 11B (infantry)...I have sniper training at BN level so I think I'm stuck with going back. I was told that combat mos's are pretty much being called up from IRR and the only way out of it is if you have some kind of injury or a broken bone. My bro is EOD (explosive ordinance disposal) and was injured over in Iraq and I was told that has no bearing on wether or not I have to go back....talk about freakin' BS!! srr for thread jacking....

[flohtingPoint]

Air Force has "AFSC's" instead of "MOS's".

Anyway, back on topic, I've never had a correct speed on any of my Nissans. Back at Goodfellow AFB (near both of you folks) and here in Ramstein, I just drive slower than normal until I see another car, then I travel at their speed.

[theboz]

My MOS is 15R. Apache crewchief. I know I will be going back. No problem though. They upped the hazardous duty pay and the family seperation pay. Looking forward to going and putting some money in the bank.

[theboz]

My Nissan speedo was spot on until the VLSD swap. Now it is only a few miles off at highway speeds. No problem I just drive with traffic and I should be ok. I figured the speeds out so when I drive on post I won't get stopped. Did you look at the speedometer pinion from courtesy nissan? The url is in one fo the posts. They are not too expensive and should solve the speedo reading problem. Take a look and tell me what you think.

Boz

[tyrannix]

if you do a search for the 180mph mod, theres a screw on the back of the cluster you can adjust for fine tuning the speedo

[Darius]

I installed the J30 VLSD and I thought that had a 4.4 final drive. If that is the case with the R32, then the speedometer is off by 4%. Someone calculated it out and I can't remember where I found it. I just know that's what it is. In fact, I got a speeding ticket for going 75 (clocked), when my speedometer read 72. Cop dropped it to 70 though. Still a wang for pulling me over on a deserted highway.

[onosqv]

Your problem w/ idle & rev is not diff related.

I have the same problem sometimes. It is caused by either your ecu or transmission wires or one of the wires coming/from one of these doesn't know you are in neutral, and thinks you are in gear.

Soooo, that's why when you are at idle, it thinks you are moving along slowly, and when you rev, it thinks you are speeding up.

Another way to correct it is to get smaller tires if your speedo is reading too fast, hehehe.

[cdlong]

I installed the J30 VLSD and I thought that had a 4.4 final drive. If that is the case with the R32, then the speedometer is off by 4%. Someone calculated it out and I can't remember where I found it. I just know that's what it is. In fact, I got a speeding ticket for going 75 (clocked), when my speedometer read 72. Cop dropped it to 70 though. Still a wang for pulling me over on a deserted highway.

the J30 diff is 3.96 or something, but i bet you figured that out already.

[Darius]

Found it...

The stock 240 diff has a ratio of 4.0836363636 and the J30 VLSD has a ratio of 3.9166666. Therefore, if you take the difference between them divided by the original ratio, you get your percent error on your speedometer.

(4.083636-3.91666)/4.083636=.04088, so about 4.1% slow like I stated above.

(4.083636-~4.4)/4.08363636=.0775, so about 7.8% fast for the R32 that you said you installed.