Lewis Maudlin Posted February 13, 2006 Share Posted February 13, 2006 OK, I have never gone with a LSD, but I am currently putting down 260hp and looking at switching fuel injectors, MAF, and engine management to put down 350rwhp. I think I need LSD. I have not done the research, however, a guy near my hometown has a Viscous LSD rear end. I asked him gearing and he said it has 40 big teeth. Does anyone know anything good or bad about these? Is there anything I should look for in regards to wear and tear? Any help would be appreciated. Thanks. Lewis http://album.hybridz.org/showgallery.php?cat=618 Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 13, 2006 Share Posted February 13, 2006 The LSD doesn't determine the gear ratio. There should be a stamp on the ring gear that says the number of teeth on the ring and the number on the pinion. The number is about 10 characters long IIRC, but its the part with the colon that is the important bit. My 4.11 says 37:9. Divide 37 by 9, 4.1111111 is the result. 37:10 is a 3.70, 37:11 is a 3.36. 39/11 is 3.54, etc. Quote Link to comment Share on other sites More sharing options...
Lewis Maudlin Posted February 14, 2006 Author Share Posted February 14, 2006 OK, the guy now says it is 39:10 and he does not know if it is a VLSD and does not know how to tell. How do I tell if it is a VLSD as opposed to just a regular R200? The gearing is correct for a 1988 VLSD, I believe. Please help, I intend to pick this up on Wednesday if it is a VLSD. Quote Link to comment Share on other sites More sharing options...
Z-TARD Posted February 14, 2006 Share Posted February 14, 2006 If it's a VLSD, the output shafts will be really hard t turn against eachother. It will feel like trying to twist apart a big lump of clay (Best way I can describe it...) You also wont see any spider gears inside it when it's opened up either. This is an R-200 VLSD short nosed diff out of a J-30, but it should look similar: Mike Quote Link to comment Share on other sites More sharing options...
Top Fuel ZX Posted February 14, 2006 Share Posted February 14, 2006 Similar to what Z-Tard said but you can tell if it's a LSD by turning the input shaft of the differential. Both output shafts will rotate together in the same direction. If its an open differential the output shafts will rotate in different directions. Sean Quote Link to comment Share on other sites More sharing options...
zgeezer Posted February 21, 2006 Share Posted February 21, 2006 The JYs I frequent usually have the cars sitting on the ground and usually without stands or concrete. One or the other of the wheels don't turn b/c they are mired in sand or dragging some bent piece. Often, the best I can do is elevate one wheel a few inches above the deck. Here's a rough guide and process with which i've had luck. 1. Elevate one wheel off the ground, 2. Check that parking brake is off, 3. Place transmission in neutral or remove drive shaft, 4. With a permanent marker, mark a vertical line at 12:00 o' clock on the brake drum, or tire that is elevated, 5. Mark one horizonal line that begins on the u joint and crosses over to the differential case. Chose a place on the side of the ujoint where you can see if from the side of the car. Rotate the tire 360 degrees in the direction of travel and count pinion rotations, estimate the last turns and multiple by 2. For example, I found my 3.36 R200 in a 280zx with a/t. The check was slightly over 1.5 turns, but not 1.75, which would be a 3.50 or 3.54. I'm sure others use this, but it has allowed me to really fly through JYs when looking for other ratios. g Quote Link to comment Share on other sites More sharing options...
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