flyer23 Posted November 24, 2009 Share Posted November 24, 2009 How do I replace the small black gear located on the bottom of the VSS inside the front diff. I have a 1995 Legacy L automatic AWD. I had to replace the axle seal on the right side and in removing the RUSTED SOLID side cove that holds the seal I accidentally damaged the gear on the bottom of the VSS. It worked for about a week and then the speedo stopped working and I got an extra code for the VSS. I have the gear and upon removal of the VSS there is a slotted drive that it fits into. The gear is bigger than the hole so I imagine I need to remove the side cover again any help would be great. Thanks in advance. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted November 25, 2009 Share Posted November 25, 2009 The tranny has to be removed from the car and opened up, the VSS drive gear shaft removed from the tranny, gear and seal replaced, and tranny reassembled. Additionally, you can't just pop the side cover's off, replace the seal, and put them back. Those cover's set the front ring & pinion clearances and should never be removed without splitting the transmission and resetting the clearances. If you are VERY careful you might be able to count the number of turns on the cover plate, marking start and end posistions but did you? If not start looking for another transmission - bad front diff clearances and a shot VSS drive gear? No Bueno. GD Link to comment Share on other sites More sharing options...
flyer23 Posted November 25, 2009 Author Share Posted November 25, 2009 Well I did not count the turns since it was siezed and te seal was damaged as well. I wad to actually break the cover upon removal. I have had enough transmission and diffs apart to realize the carrier bearing was help by this cover. So you mean to tell me since it was not removed and measured there is going to be an issue? I screwed the cover in all the way and backed it off slightly before locking it down with the lock nut. I have been driving it for several hundred miles and have not heard anything out of the ordinary or any vibrations. It has 120,000 miles on it and I don't have the cash for a new diff, even if it comes from the junkyard. Also upon further investigation the gear seems to be intact and I am guessing that just the speed sensor has failed. I am going to replace the sensor and see what happens. There is no other way to set the carrier bearing clearance? For example screw the cover all the way tight and then back off 1/4 or some thing like that? Thanks again for your input. Link to comment Share on other sites More sharing options...
lostinthe202 Posted November 25, 2009 Share Posted November 25, 2009 Sadly, no. The diff backlash is set by painting a layout die on the diff and looking for a specific wear pattern between the ring and pinion gears, so you have to have things apart to see this. The tolerances are very tight, too tight for production so there is no single amount of "backing off" that will work for every diff. You may not be hearing noise yet, but you will if that adjustment isn't correct. It will probably last several thousand miles before it fails, and you should hear some warning signs before it happens, but fail it will. You might be able to find a board member with an auto trans with torque bind and pick it up for cheap then swap on your center diff section. Good luck! Will- Link to comment Share on other sites More sharing options...
johnceggleston Posted November 25, 2009 Share Posted November 25, 2009 (edited) Well I did not count the turns since it was siezed and te seal was damaged as well. I wad to actually break the cover upon removal. I have had enough transmission and diffs apart to realize the carrier bearing was help by this cover. So you mean to tell me since it was not removed and measured there is going to be an issue? I screwed the cover in all the way and backed it off slightly before locking it down with the lock nut. I have been driving it for several hundred miles and have not heard anything out of the ordinary or any vibrations. It has 120,000 miles on it and I don't have the cash for a new diff, even if it comes from the junkyard. Also upon further investigation the gear seems to be intact and I am guessing that just the speed sensor has failed. I am going to replace the sensor and see what happens. There is no other way to set the carrier bearing clearance? For example screw the cover all the way tight and then back off 1/4 or some thing like that? Thanks again for your input. the primary issue for setting a new carrier bearing is position. the fsm describes it being done with the diff off of the trans, auto any way, and then attaching the diff to the trans to test how the ring gear and pinion gear teeth mesh. apparently it can take several tries to get right. once the you have it right you can bolt the 2 together and move on. when replacing the bearings, if you count the number of turns when removing the keepers so you can put it back together EACTLY the way it was and if you do one side at a time you have a real good chance of not screwing it up. the way you have done it sounds pretty good to me considering what you had too work with, but only time will tell. but if you didn't move the diff while the seal was out you have a shot. there are only 3 possibilities, too tight, too loose, or just right. Edited November 25, 2009 by johnceggleston Link to comment Share on other sites More sharing options...
flyer23 Posted November 25, 2009 Author Share Posted November 25, 2009 Well that really is bad. I guess I will keep an ear out for any noise from the bearing. What seemed to be an easy seal replacement has now turned out to be a possible problem for my only car. Trying to fix the leaking seal before it lost all the fluid in the diff has turned out to be a reall issue. Why are the axle seals not servicable without removing that side cover? Is it different on the newer models? Well I will pray that I got the backlash pretty close to where it was before I took it apart and just listen if the noise gets louder. I'm really bummed about this now. Been working on cars, race cars, engines for over 20 years and never saw anything like this before. Thanks for all your input guys....... Link to comment Share on other sites More sharing options...
bheinen74 Posted November 25, 2009 Share Posted November 25, 2009 (edited) My dad helped me replace the speedo drive gear inside the front diff. We left the tranny in the car, pulled off the right side axle, marked the retaining ring on the tranny, counted number of turns in until firm bottom, counted number turns back out for removal, pulled the seal cover, pulled out bearing, removed the small driven gear via snap ring, that has to come out to pull off the BIG drive gear, pulled out the speedo drive gear (big yellow plastic ring that was stripped) replaced with new drive gear, replaced seal with new (that part is mandatory), put back together, counted number turns in til firm bottom, and counted number turns back out to keep it the same. I have pics of all this, and yes it was done with tranny still in the car. So some of you guys have it wrong, I for one, have done this repair, was done when car had 159k on it, and now the last i heard, car had 195k plus miles on it and still going I would hope. Edited November 25, 2009 by bheinen74 Link to comment Share on other sites More sharing options...
lostinthe202 Posted November 25, 2009 Share Posted November 25, 2009 Didn't mean to say it couldn't be done without pulling the trans, I'm not qualified to so say one way or the other. My only comment was on the "tightened the ring all the way then backed it of a little" approach. What's "a little" 1/4 turn, 1/2 turn 2 full turns? I understand the OP didn't have much choice since the ring was seized, but still it's hardly accurate. Perhaps you could do the "turn counting until firm" on the other side and make this one the same? I really don't know how far off from each other they would be. Also, I don't think it'll be bearing noise that you'll hear but the gears whining instead. Link to comment Share on other sites More sharing options...
bheinen74 Posted November 25, 2009 Share Posted November 25, 2009 also, before tearing it apart, you can measure the tolerance somewhat by grabbing and shaking axle cup near the transmission (on both left and right side) and measuring movement. Then set it the same. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted November 25, 2009 Share Posted November 25, 2009 The real problem isn't the R&P contact, as that is set by BOTH the side rings - the problem at this point is the bearing clearance - being it's a timken roller bearing it has a fairly tight tollerance that is supposed to be set with a specified amount of weight on the end of the stub (transmission on it's side, etc). As to why they aren't easily serviceable - they rarely fail - especially if the axles have the dust sheilds in place. I've seen plenty of transmissions make it their entire lives without a leak here. In fact most Subaru tranaxles make 250k without a leak *anywhere*. GD Link to comment Share on other sites More sharing options...
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