Deener Posted June 9, 2009 Share Posted June 9, 2009 Hey guys, I just got my 88 GL back from a Tranny rebuild (couldn't find another one within 2000km) as well as a new front differential. I am stoked...It's as smooth as glass in 2 wheel but I am getting a grind-ish/growly sound out of the rear differential now(may have been there before but I am not sure), but only in 4 wheel. We had it up and there is no noise when it's up, only when it's on the ground and in 4 wheel. I have a new drivers side wheel bearing in there (thanks to this wonderful website) and the other side is nice and tight so I would suspect it isn't the wheel bearings. The drive shaft is tight and aligned nicely as well. I understand that the rear diff's rarely go on these machines but all evidence so far points to the rear diff being the culprit. Here are my questions: 1. Is there a sure fire way to know if the rear diff is bad without cracking it open? Shake the axles? 2. I have found another differential near me for fairly cheap (I have yet to check what ratio mine is but they have both ratio's if needed). The process doesn't seem too difficult to swap. If I was to attempt this, are there any seals or bearings or anything else I should buy so I don't end up replacing them in a couple days? Link to comment Share on other sites More sharing options...
Turbone Posted June 9, 2009 Share Posted June 9, 2009 First off, what was the tranny that got rebuilt? 5spd D/R? 5spd Fulltime? 4EAT? All of these depend on what you run in the rear for a diff. The Dual Range will use a 3.9 diff, the others use a 3.7 diff. A 3.9 diff is easy to find, at least here in the PNW. Link to comment Share on other sites More sharing options...
The Beast I Drive Posted June 9, 2009 Share Posted June 9, 2009 Are the rear axles in good shape, no torn boots? the rear DOJs on the Beast are shot, but it only makes noise if Im in 4wd going backwards, and I just get a clicking like a bad CV. Mabye your rear diff bearings inside the unit are bad, I know the ones in my Brat are, I can wiggle the stub shafts like a shifter stick Maybe pull the drain plug (lower one on the back cover, 13mm square head) and see what the rear diff fluid looks like, it very well may have never been changed, a lot of people forget that gear oil breaks down too. -Bill Link to comment Share on other sites More sharing options...
Deener Posted June 9, 2009 Author Share Posted June 9, 2009 Sorry, that was a 3 spd automatic with on demand 4 wheel. Sounds like I would need the 3.7...? I guess I should run my VIN through the dealer to be sure. Link to comment Share on other sites More sharing options...
Deener Posted June 9, 2009 Author Share Posted June 9, 2009 Yup, the rear axles are really sturdy actually, boots are sealed and I don't get any clicking. The sound happens both forward and reverse but only under load and in 4 wheel. Link to comment Share on other sites More sharing options...
The Beast I Drive Posted June 9, 2009 Share Posted June 9, 2009 Yeah check the fluid, if there is something wrong inside the diff it should tell the story. -Bill Link to comment Share on other sites More sharing options...
Deener Posted June 9, 2009 Author Share Posted June 9, 2009 On that note...what color is good and what color is bad? Also...is there a prefered weight I should use? If I only had a proper manual...the haynes I have is good if you like jokes. Link to comment Share on other sites More sharing options...
Turbone Posted June 9, 2009 Share Posted June 9, 2009 It should be a 3.7 diff, theres a tag on the back cover where it should say. The fluid might be a little dark, depending on how old it is. Otherwise it should be gold in color. Remove the top plug on the back cover and put your finger in the hole. It fluid should be up to the bottom of the hole. Use 80-90 weight gear oil. Link to comment Share on other sites More sharing options...
bratman18 Posted June 9, 2009 Share Posted June 9, 2009 Make sure the tires are the same size as well Link to comment Share on other sites More sharing options...
NorthWet Posted June 9, 2009 Share Posted June 9, 2009 (edited) It should be a 3.7 diff... Unless my mind skipped over mention of it being a turbo, I believe it should be a 3.9 ratio. Oh, also, you should probably pull the top (fill) plug first, as it may not want to come out. If you pull the drain first and can't remove the fill plug, things get a little complicated. (Guess how I know?!) Edited June 9, 2009 by NorthWet Link to comment Share on other sites More sharing options...
Turbone Posted June 9, 2009 Share Posted June 9, 2009 Last time I checked, all 3AT's were 3.7 The Fulltime 5spd's(except XT6) and 4EAT are also 3.7 Link to comment Share on other sites More sharing options...
NorthWet Posted June 10, 2009 Share Posted June 10, 2009 Last time I checked, all 3AT's were 3.7... Well, I was REALLY hoping to give Turbone a :-p by taking a pic of Christine's diff sticker, but it is too crusty to read and she is the only NA 3AT I have. So, I guess that I will have to trust Rob more than my memory. (Gosh, I HATE when that happens!!! ) Link to comment Share on other sites More sharing options...
Niku-Sama Posted June 10, 2009 Share Posted June 10, 2009 vancouver is only 100 miles away from where i am at, i take it if you didnt find a tranny in vancouver your odds of finding a rear end are pretty slim. if there are yards up there you should check out bellingham or mount vernon, if any thing there are old school subaru nuts up there who probally have a stock pile of rear ends and trannys for when they break off roading. i am in arlington and i remember seeing a 3.90 and a d/r 5spd here. probally somre more by now. sorta off topic, so 3.70 and a 4eat turbo is normal? Link to comment Share on other sites More sharing options...
Turbone Posted June 10, 2009 Share Posted June 10, 2009 Well, I was REALLY hoping to give Turbone a :-p by taking a pic of Christine's diff sticker, but it is too crusty to read and she is the only NA 3AT I have. So, I guess that I will have to trust Rob more than my memory. (Gosh, I HATE when that happens!!! ) Hah, I looked in 2 different FSM's to make sure :-p Nik, the 4EAT FT will be 3.7, even the turbo's. Heres a weird one tho - the XT GL 4WD with 5spd S/R is 3.7 :-\ Link to comment Share on other sites More sharing options...
GeneralDisorder Posted June 10, 2009 Share Posted June 10, 2009 Last time I checked, all 3AT's were 3.7 I though that as well - till I parted out a 3AT wagon - a 93 Loyale if I'm not mistaken... it was a 3.9 and I drove it home so I know it wasn't swapped at some point. I remember specifically because SoobGoob and I swapped in a 5 speed D/R and we were assuming we would have to swap the diff but were pleasantly surprised that it was also a 3.9. And that's how I ended up with a spare 3.9 open diff in my shed..... not something I would ever buy but I can't throw away free parts. IIRC that FT4WD Turbo sedan you and I parted out was a 3.7 though so I think you are right there - at least as far as the EA bell-housing 4EAT's go. GD Link to comment Share on other sites More sharing options...
Turbone Posted June 10, 2009 Share Posted June 10, 2009 I though that as well - till I parted out a 3AT wagon - a 93 Loyale if I'm not mistaken... it was a 3.9 and I drove it home so I know it wasn't swapped at some point. I remember specifically because SoobGoob and I swapped in a 5 speed D/R and we were assuming we would have to swap the diff but were pleasantly surprised that it was also a 3.9. And that's how I ended up with a spare 3.9 open diff in my shed..... not something I would ever buy but I can't throw away free parts. IIRC that FT4WD Turbo sedan you and I parted out was a 3.7 though so I think you are right there - at least as far as the EA bell-housing 4EAT's go. GD There is nothing in the FSM's from 86 to 89 that show a 4wd 3AT thats 3.9. My 88 parts book also shows all the 3AT's as a 3.7 final drive. Personally, I have never seen one. So if there is a 3AT out there thats a 3.9, its a freak of Subaru nature Link to comment Share on other sites More sharing options...
The Beast I Drive Posted June 10, 2009 Share Posted June 10, 2009 There is nothing in the FSM's from 86 to 89 that show a 4wd 3AT thats 3.9.My 88 parts book also shows all the 3AT's as a 3.7 final drive. Personally, I have never seen one. So if there is a 3AT out there thats a 3.9, its a freak of Subaru nature Not so fast hot rod, GD's case makes at least 2, I have a 87 4wd with 3.9 ratios and a 3at... So maybe your FSM is missing a section or something... Or you need thicker glasses :-p Jk Rob, your's not that old... Yet... -Bill Link to comment Share on other sites More sharing options...
Turbone Posted June 10, 2009 Share Posted June 10, 2009 I'll believe it when I see it Link to comment Share on other sites More sharing options...
Niku-Sama Posted June 10, 2009 Share Posted June 10, 2009 i am sure some where there have been 3.70's replaced with 3.90's Link to comment Share on other sites More sharing options...
Gloyale Posted June 10, 2009 Share Posted June 10, 2009 Sorry, that was a 3 spd automatic with on demand 4 wheel. Sounds like I would need the 3.7...? I guess I should run my VIN through the dealer to be sure. NO, 87 and after, all the Non-turbo 3spds are a 3.9 diff as well Yours should be 3.9. Look at the sticker on rear diff, it may be covered in grease. Pull the protective film off and you will have a clear view. Link to comment Share on other sites More sharing options...
Gloyale Posted June 10, 2009 Share Posted June 10, 2009 There is nothing in the FSM's from 86 to 89 that show a 4wd 3AT thats 3.9. Damn, I wish my scanner worked. I am staring at the 88 FSM, 4WD System Section, and it lists all NON-Turbo 4wd as 3.9 Look harder, it's there. Link to comment Share on other sites More sharing options...
edrach Posted June 10, 2009 Share Posted June 10, 2009 Are you trying to drive in 4WD on pavement or dirt? I'm not sure about the automatics, but my old 5MT did not drive well in 4WD on pavement even with matched tires. If you really need another diff, it might be worth your while to drive down to Smokey Point PAP. Rear diffs are $25 plus tax and a small core charge there. Link to comment Share on other sites More sharing options...
Deener Posted June 10, 2009 Author Share Posted June 10, 2009 Wow. Thanks everyone. To be completely honest, this site is so invaluable to me because of all the help I get when I ask questions. I am learning how to wrench bit by bit with every post and reply. Seriously...you folks rule!!! The car is an 88 GL Wagon, with on demand 4 wheel drive, non-turbo, 3 spd tranny. The tires are matched and the sound is happening on pavement but I haven't had a chance to test it on any of the slippy stuff. I will slide under the car and take a look at the sticker tonight and let you folks know what ratio the rear diff is reporting. The wrecker that I called is one of 2 in the area that house Subaru's, it's called Aldergrove Auto Wrecking and they quoted me $175 for the the rear diff. I saw the post about the 25 dollar diff... and here I thought I was getting a deal. Link to comment Share on other sites More sharing options...
Deener Posted June 11, 2009 Author Share Posted June 11, 2009 So the tag says the rear diff is a 3.9 ratio. I would imagine that I should take the driveshaft off first then the hanger bolts and then the axle pins. Jack the old one out, then reverse the process with the replacement diff? Any other tips that I should be aware of? Link to comment Share on other sites More sharing options...
Turbone Posted June 11, 2009 Share Posted June 11, 2009 Wow, guess I cant always be right eh? And I blame it partially on my library. My 88 FSM is for XT's Damn Subaru and their inconsistencies Link to comment Share on other sites More sharing options...
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