TheSubaruJunkie Posted January 21, 2008 Share Posted January 21, 2008 Will it only mess up the diff if it is driven on pavement? or only offroad? It will only mess up the diff if you drive it in 4WD. Rule of thumb is to NEVER (EVER EVER EVER EVER.... EVER!!!) drive your car in 4WD on pavement. The new RX Trans you just got. It CAN be driven on Pavement because its a true AWD box with an open center diff. The diff lock on the trans will lock the center diff, and you want to only do that on dirt/mud/snow. Quote Link to comment Share on other sites More sharing options...
slideshow86 Posted January 21, 2008 Author Share Posted January 21, 2008 Can someone please help me? Any Ideas because I just dont know Are there any numbers on these to determine what they are? Quote Link to comment Share on other sites More sharing options...
edrach Posted January 21, 2008 Share Posted January 21, 2008 Can someone please help me? Any Ideas because I just dont know Are there any numbers on these to determine what they are? The only diff we're sure of is the rear LSD 3.700). If the car was having difficulty in 4WD with your original rear diff (3.900) you might have lucked out and gotten a 3.700 front diff which will match the LSD now in it. I don't believe that any of the earlier transmissions had a label on them to indicate a part number. Three things that might help. 1) Go back to Pull a Part and yank the transmission out of the car that had the LSD in it. If it's a d/r you should be okay with it. 2) Go back to the car that had the transmission that you now have in your car and look for the transmission part number on the VIN # plate in the engine compartment. Armed with that part number you might be able to confirm what ratio gearbox you have. Do this very carefully (i.e. don't be under the car while you're trying to count turns): 3)Drive your current car up onto one ramp to raise that side off the ground. Except for the AWD tranny, all the front diffs are Open. Put wheel chocks on the rear wheel as the ramp side to keep the car from moving. Jack up the other front wheel until it's off the ground. Mark the wheel with chalk at the 12 o'clock postion and turn the wheel and count turns. Now here's where theory runs into reality. Turning either the front wheel 3.7 revolutions (or 3.9) will result in one revolution of the driveshaft.....or the other way around....one revolution of the front wheel will result in either 3.7 or 3.9 turns of the driveshaft depending on the front diff ratio. I've never had to try method 3 before (and that's why I'm confused about the turns), but it should tell you something if methods 1 & 2 fail to get you the information you need. Lastly, try to meet up with XSNRG. He's reasonably local to you and might be able to figure out what you have there. A lot of information may have been mixed up in all these posts and speaking with someone in person who's pretty much an expert might resolve this dilemna. Good luck. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted January 21, 2008 Share Posted January 21, 2008 Almost all D/R's were 3.9 - which is made more likely by the 23 spline axles. The only D/R's that were 3.7 were on the turbo RX's. But they have 25 spline axles, so your's isn't one of those. Another way to tell is with the ratio of the low range gear. The RX's low range was only 1.2:1 instead of 1.5:1. There ARE part time and Full Time RX's tranny's out there - 86's had the part time, and 87+ had the full time. Best thing to do is to put the car up with two wheels on the same side off the ground. Put the car in 5th gear and turn the engine over by hand. See if the wheels rotate a different amount. GD Quote Link to comment Share on other sites More sharing options...
TeamCF Posted January 21, 2008 Share Posted January 21, 2008 $26 LSD........ Awsome. Now I just need to find a deal like that. Never seem to see one down here though. Quote Link to comment Share on other sites More sharing options...
slideshow86 Posted January 21, 2008 Author Share Posted January 21, 2008 So then the 3.9, 23 spline count at 1.5:1 would be the choice trans for offroading? If all turbo cars had 3.7 and my rearend was 3.9 then the p/o had changed the rearend. I ran that with the incorrect rear end in it for 2 1/5 years and since someone told me I could drive it on the pavement in 4wd, I drove it on pavement in 4wd for the past 8 mo. Ive never owned a d/r trans and It in itself feels weird. I just ran the new d/r at Im guessing 3.9? w/ my 3.9 open diff. It felt great offroad, just kinda binding, felt weird but good. I finaly just kinda tested my new lsd a few mins ago. I feels the same except grip from both rears. Would I be able to feel it doing any thing weird? I have the trans but dont know if if its worth the swap to 3.7 and getting a 1.2:1 low range :-\ wouldnt this be bad for wheeling? I now have a (from what Im told) 3.7 single range trans 25 spline count, 3.7 dual range from rx coupe 25 spline count ( bought it today), 3.9 open diff (came in the car), and 3.7. lsd ( just swapped in car). Im confused now and its been a long day. Correct me if im wrong but isnt the 3.9 gearing better for wheeling? woulndt 1.2:1 be worse along with being lower geared? Jess Quote Link to comment Share on other sites More sharing options...
edrach Posted January 21, 2008 Share Posted January 21, 2008 $26 LSD........ Awsome. Now I just need to find a deal like that. Never seem to see one down here though. They are pretty scarce here too. I've only snagged two in over 5 years of pretty consistent PAP addiction. Quote Link to comment Share on other sites More sharing options...
Gloyale Posted January 24, 2008 Share Posted January 24, 2008 So then the 3.9, 23 spline count at 1.5:1 would be the choice trans for offroading? Im confused now and its been a long day. Correct me if im wrong but isnt the 3.9 gearing better for wheeling? woulndt 1.2:1 be worse along with being lower geared? 3.7 is Higher geared, and has a higher LO range as well. In reference to manual trans, all 3.7 will have 25 spline and all 25 spline are 3.7. Better for offroading would be the 3.9, 1.5 reduction LO, Part time 4wd D/R box. 23 spline. DO NOT USE ANY DIFF THAT DOESN"T MATCH THE TRANS!! To plug and play with you're LSD, you need to use the 25 spline Fulltime 3.7 box. This would give you the benefit of fulltime AWD as well If you want to use the Part time 3.9, 23 spline box, you'll need to swap the LSD carrier into you're 3.9 Diff. Quote Link to comment Share on other sites More sharing options...
slideshow86 Posted January 24, 2008 Author Share Posted January 24, 2008 If you want to use the Part time 3.9, 23 spline box, you'll need to swap the LSD carrier into you're 3.9 Diff. This is exactly what I will be doing. Where are you guys getting the cap seals and O rings? Subaru doenst offer the O rings anymore and the cap seals (which match the same as Datsun 510 rear diff cap seals) are 5 days out from subaru. I will be calling a few nissan dealers tomorrow for cap seals. What is the propper term for this "cap seal"? And what are torque spec's? Quote Link to comment Share on other sites More sharing options...
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