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Front diff pinion bearing toasted?


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After reading this thread:

http://www.ultimatesubaru.org/forum/showthread.php?t=94774&highlight=transmission+pinion

 

1995 impreza wagon awd 5-speed 1.8l

 

What i thought was a wheel bearing i'm starting to think is something serious in my tranny.

 

Noise started as a high piched harmonic noise from 60 to 70 mph. when i accelerated or decelerated the noise would go away. car has new tires (balanced), new MW axles. The right front has 2 new wheel bearings in the last 2000 miles. SO, i assumed when this noise first appeared that it was just that, a bad hub.

 

However, driving 70 on the highway to work the other day i start hearing more and more of gear/grinding/bad noise. i pull over and call AAA not wanting to damage my vehicle anymore. get towed home. go to work, come home and start investigating. i take the front right rotor off and feel with tire on. feel just fine. Put her all back together and took her for a drive around the block with my buddies head on the floor listening to the noise.

 

On the drive took a few minutes for noise to start showing up. When it would show up it would sound like loud gear noises coming perceivably from the gear box.

 

Noise is associated with vehicle speed.

 

I'm thinking pinion bearing front diff.

 

I did have this tranny out about 2k ago and put new input shaft bearing and seals, any way that i could have put the diff together wrong. It all seemed to fit back together nicely.

 

just got acl surgery on thursday. and now prolly have to pull a tranny. F my life.

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probably simpler to throw a used trans in it, i wouldn't bother repairing it. subaru transmissions can be had for cheap often if you look around.

 

that is - after you verify it's not exhaust shields, axles, driveshaft or something else.

 

good luck. stick with that PT after the surgery too, that stuff is huge.

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any good tips for the verification.

 

Thinking i'm gonna put it on 4 stands and let it run in the air with s stethascope on the tranny.

 

the noise is stuck in my mind and 98% sure its not exaust shieds.:mad:

 

atleast i get to sit and ponder it for a week or two. source a tranny.

no biggie.

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Closest I can come is since wheel bearings turn fairly slowly, they tend to make a 'droning' sound, pinions turn 3-4x faster, so they make more of a 'whining' sound.

 

If you do run it suspended in the air, attach a long metal piece to the trans so you can listen to it without getting under or in front of the car.

 

 

Dave

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Did you split the case to replace the seals? Or did you just unscrew the retainers?

 

If you undid the retainers, you may have not gotten the backlash/tension adjustment correct.

 

If you split the case, then you already know how to do it to remove and replace the diff bearings anyhow.

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is there a chance he could just readjust those retaining screws if they're out of adjustment?

 

If you split the case, then you already know how to do it to remove and replace the diff bearings anyhow.
one guy I know that did this with his XT6 ended up with blown diff after blown diff. i was under the assumption that the first time the diff went bad (not sure what failed though), it made other things "out of spec" and ruined what ever new parts he put in there later, which ended up failing shortly afterwards.

 

anything he can check to avoid that or was that just a bad experience/workmanship?

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is there a chance he could just readjust those retaining screws if they're out of adjustment?

 

 

Yeah, but to do it proper you have to remove the tranny and set it on it's side and use a dial indicator to check backlash (through the drain plug hole)

 

When you've done a few, you can do them with it in the car by feel.

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so how long do you think i could drive it before the tranny blew up.

I split the case when i did everything.

planning on putting a new(to me) trann and swaping it out.

 

What years subi and model tranny will do.

where is the diff ratio marked also?

-zack

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The diff ratio isn't marked. I'm almost positive yours is a 3.9.

 

There's a manual transmission gear chart that has the final drives all spelled out in intricate detail, you should find that thread. maybe it's int he USRM or somethign?

 

Quick look and I didn't see any cheap ones in your area. Good luck finding one. Maybe a pull it yourself yard if you have time or craiglist?

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  • 7 years later...

I currently have problem with the Pinion bearing on my Subaru Brumby, The pinion shaft that comes out of the side of gearbox to connect with cv drive shaft is rattling and noisy.  I have screwed out the circular plate (turn anti clockwise to release) that covers the bearing . I marked the position of the circular plate prior to removing it and counted the number of turns required to release it so it can be returned in the same position. I now have the huge job of finding a bearing extractor  for this particular job.  I obtained the pinion bearings from BSC. Bearing  is NSK HR 30207J  and the seal is AHI513F. Bearing cost $17  and seal $15.20. I am now racking my brain on how to remove the bearing. I know that to replace the bearing it must be  heated to 200 degrees  and then placed on the pinion shaft.  The job is tricky but taking the gearbox out and replacing it is a job of very last resort. All I need is an appropriate  bearing extractor.

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The shafts that come out the side of the transmission ate not pinion shafts. Those are axle stubs. The bearings that support them and the differential are on screw in carriers that are used to adjust the mesh of the pinion and ring gear. The pinion shaft and it's bearings are inside the transmission, and major case disassembley is required to get to them.

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  • 4 weeks later...

The shafts that come out the side of the transmission ate not pinion shafts. Those are axle stubs. The bearings that support them and the differential are on screw in carriers that are used to adjust the mesh of the pinion and ring gear. The pinion shaft and it's bearings are inside the transmission, and major case disassembley is required to get to them.

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Yes I have removed the front Axle Shaft Oil seal holder and behind that is a roller bearing on the Axle drive shaft  which has been rattling bad as I drive under acceleration. It was badly worn very loose. I have removed the outer race and the race bearings (17_bearings) and have the inner race left which is pressed on to the Axle drive shaft. I need a bearing puller to extract that inner race. Once removed Im told that heat the new bearing to 200 degrees at it should fit on.  Trying to get out of dropping the gearbox which apart from this fault operates perfectly.  Having a few problems extracting that inner race. Have a slim bearing extractor which I will have to modify to get grip on the rear of the back of the race and a stopper metal pipe on front of  Axle shaft to  hold in place while extracting this race. Any views on this crazy project.

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  • 5 months later...

Yes I have removed the front Axle Shaft Oil seal holder and behind that is a roller bearing on the Axle drive shaft  which has been rattling bad as I drive under acceleration. It was badly worn very loose. I have removed the outer race and the race bearings (17_bearings) and have the inner race left which is pressed on to the Axle drive shaft. I need a bearing puller to extract that inner race. Once removed Im told that heat the new bearing to 200 degrees at it should fit on.  Trying to get out of dropping the gearbox which apart from this fault operates perfectly.  Having a few problems extracting that inner race. Have a slim bearing extractor which I will have to modify to get grip on the rear of the back of the race and a stopper metal pipe on front of  Axle shaft to  hold in place while extracting this race. Any views on this crazy project.

I have read all this articles about how to  get a pinion bearing on a pinion  shaft. Microwave oven , stove tops, ovens etc u name it. All these electric appliances cut out at 230 degrees and some start retracting. The ONLY one on YOU TUBE that really makes sense is where a guy heats a pinion bearing up to 1200F which is round about 500C in Aus using a oxy actelyene torch with the pinion bearing on a steel plate. This guy heated the bearing on the plate to 1200F and it dropped straight on.  Ive tried these 200degrees and above to 300 and NO GO they are a TIGHT  fit bearing. Also I have check the map of the front gearbox Diff on the Brumby and it only shows ONE  bearing and that is on the pinion shaft which is part of the Diff case.

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I would be very concerned about heating bearing above a couple hundred F. It could ruin the hardness, and lead to very quick failure.

 

Typically bearing races are pretty tight press on and off. Meaning it needs to be dissasembled enough to get at everything with big tooling.

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Yes I have removed the front Axle Shaft Oil seal holder and behind that is a roller bearing on the Axle drive shaft  which has been rattling bad as I drive under acceleration. It was badly worn very loose. I have removed the outer race and the race bearings (17_bearings) and have the inner race left which is pressed on to the Axle drive shaft. I need a bearing puller to extract that inner race. Once removed Im told that heat the new bearing to 200 degrees at it should fit on.  Trying to get out of dropping the gearbox which apart from this fault operates perfectly.  Having a few problems extracting that inner race. Have a slim bearing extractor which I will have to modify to get grip on the rear of the back of the race and a stopper metal pipe on front of  Axle shaft to  hold in place while extracting this race. Any views on this crazy project.

 

Well, theres your problem.  The thing you unscrewed is responsible for adjusting your pinion/ring backlash, now you've removed it, you must readjust the setup, frankly I don't know how well this will work on a box with a long-established wear pattern, even if you can figure out how to re-set it..

Edited by briankk
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The diff ratio isn't marked. I'm almost positive yours is a 3.9.

 

There's a manual transmission gear chart that has the final drives all spelled out in intricate detail, you should find that thread. maybe it's int he USRM or somethign?

 

Quick look and I didn't see any cheap ones in your area. Good luck finding one. Maybe a pull it yourself yard if you have time or craiglist?

If you have the dif case off the pinion, figuring the ratio is trivial.  Count the teeth on the ring gear, write it down, count the teeth on the pinion, write it down, get calculator, divide the ring gear number by the pinion number, presto, there's your ratio.  For instance, on my SVX  I have 11 teeth on the pinion, 39 teeth on the crown gear, =3.545...

You may not need to count the crown wheel teeth, my pinion had the number 39 etched in it, I presume to indicate it should go with a 39 tooth crownwheel.   

This makes me wonder a bit, back in the day R&Ps were machined as a set, if one replaced so should be the other.  But that was when gears were milled, perhaps no longer with hobbed set, as long as tooth count is correct.  But that's just speculation, don't quote me on that...

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