I have an open diff right now with the standard 4.636 gear but I picked up a used LSD. Don't know if it matters but it's a 33 spline axle.

My question is, will my current ring gear work with/bolt on to the OEM LSD ? Nissan won't give me any info because my truck wasn't originally equipped with it. They say I need a vin for one that was equipped with the lsd.

Thanks ahead of time for any info.

If yours is 33 spline and the 3rd member that you picked up has the same gearing then you should be able to swap in the LSD unit without modifications. Even if you just picked up the carrier with the ring gear installed that should drop into your diff.

The LSD I picked up dosen't have the ring gear installed. I was Going to re-use the ring gear on my current 3rd member. Wasn't sure if my current ring gear will bolt on to the new LSD.

The new LSD is the proper 33 spline HB233B part. I don't know how to check to see if it's the same gearing though. Only way I know how to check gearing is when its installed on the truck with the rear off the ground.
I just don't want to disassemble my axle then find out my ring gear wont bolt on to the lsd for some reason.

Would you know how I can I.D. the diff gearing ?

EDIT: I re-read the last post. In your case, the LSD will bolt to any H233B ring gear from 1987 on with no problem. There's nothing gear-wise to confirm.

I'll leave the rest below for future reference should anyone come across it.

If you have the complete third-member with the ring and pinion already installed with the LSD, you should be able to swap it wholesale. To ID the gearing, rotate the ring gear and look for the stamping on the outward-facing edge of the ring gear, it'll be something like 48:11 (4.363) or 51:11 (4.636) or 49:10 (4.90) and you just divide the numbers to find the ratio. If course, you can't swap it wholesale if your front diff doesn't have the same ratio...

If all you have is the LSD carrier w/ no ring gear, you can just stick your ring gear on it and put it back in, just need to double-check backlash/preload.

If you just have an LSD with a ring gear on it, that ring gear is junk. A ring and pinion are always a matched set and you never install a random ring gear in your current third member with your current pinion.

Hey now, Thanks for confirming and that's some good info there.
I currently have the 51:11 (4.636) gear in my open diff. I'm going to re-use my current ring and pinion on the new (used) LSD carrier. The last thing I wanted to do is to crack my axle open to find out they won't mate.
I'd like to change my gearing when I move up to 32" tires.
Looks like I will have to match the front gears when I do that upgrade ?

your stock gearing will be just fine with 32s.

I've got 4.6ish with 32s. It's fine.

Thanks guys. My rpm's seem high to me as is. 3100 RPM @ 70mph seems a bit high to me but this is my first V6 in a while. Both my jeep 4.0 and my old trailblazer ran way lower rpm's.

It will drop with larger tires.

But your speedo might be a little off.

RPMs will not appear to change for a given indicated speed no matter what gears or tires you run. If you read 2500 RPM at 60 MPH now, you'll read 2500 at "60" regardless. However, the "60" indicated may be more like 65 or so actual speed with the same gears and bigger tires. However, if you were to slow down to a true 60 MPH you would see your engine RPMs lower as a result (along with your indicated speed.)

Changing the gears can bring the indicated speed back close to accurate, I'm pretty much dead on after going from 4.636 to 4.90 while running 32" tires.

The only way to change the correlation between indicated speed and RPM is to change the gear and/or signal from the sensor on the transmission, or change the actual gear ratios themselves inside the transmission.

Ahhh. It's all a little clearer now. I knew bout the speedo being off. That would affect one's true mileage on the odometer too, wouldn't it ? If so, then one couldn't properly calculate fuel economy with larger tires without changing gearing to compensate.

I don't remember what vehicle I was driving at the time but I remember on this particular transmission, to correct the speedo, you had to Take a bolt off of the bracket that held on the speedo cable at the trans and re position the little gear to the proper ratio. Wish I remembered what vehicle that was.

Yeah, your miles recorded will be lower if you have bigger tires, and you'll have to compensate by the % change in tire size when computing fuel mileage.

Time to break out the ol' calculator. I had a feeling that the odometer wouldn't reflect true mileage.

Offroad X, did you change the front and rear ring and pinions from 4.636 to 4.90 to match gearing ?

quote:

Originally posted by Black flag:
Offroad X, did you change the front and rear ring and pinions from 4.636 to 4.90 to match gearing ?

Yes, I swapped the 4.90 gears front and rear in place of the 4.636 my truck was built with. Not so much to "get back to normal" as far as RPM/odometer-wise as to get some more power back to make up for the larger tires.

I will be looking for 4.90s then for the same reason. Do you mind me asking where you found them ?

quote:

Originally posted by OffroadX:

quote:

Originally posted by Black flag:
Offroad X, did you change the front and rear ring and pinions from 4.636 to 4.90 to match gearing ?

Yes, I swapped the 4.90 gears front and rear in place of the 4.636 my truck was built with. Not so much to "get back to normal" as far as RPM/odometer-wise as to get some more power back to make up for the larger tires.