SOLVED: Why is our 99 Forester drivetrain louder than our 97 Legacy?

[uniberp]

Lots louder it seems. Both have 170k miles, both auto, (ed. both wagons), both had replaced wheel bearings, struts, balljoints,brakes, good tires regularly rotated, sound exhaust, run just fine.

 

But the Forester has a distinctly loud drivetrain noise. After the last rear wheel bearing, it hasn't changed much. Regular and no change while turning.

 

I just removed the driveshaft, fully expecting to find a grindy center bearing, but it all appears fine. I may try a different driveshaft form the boneyard. No leaks in the diff seals, diff fluid is clear.

 

Can I drive the car without the driveshaft if I pull (or put in) the FWD fuse?

 

The only thing I noticed when underneath is a slight rust scraping as the pinion flange turned. Rear brakes are drum, and have just been cleaned and the wheels turn without any scraping.

 

I just don't get it. Is this maybe front output shaft bearings?

Edited October 20, 2011 by uniberp

[idosubaru]

legacy a sedan so the noise is more isolated in the trunk or both wagons?

 

have someone sit in the rear or outside the vehicle and try to determine if it favors one side or is centrally located?

 

if you're hearing rust scraping, that's probably it. did it sit for any length of time? 2000 forester i worked on last year was a real pain to keep the rust from rubbing - finally wire brushed the rotors and cleared it up.

[uniberp]

This is Michigan, so you can practically watch rust form.

Legacy is a wagon, with rear discs.

I'll clean that pinion rust up tomorrow, and maybe change the front diff fluid also.

 

legacy a sedan so the noise is more isolated in the trunk or both wagons?

 

have someone sit in the rear or outside the vehicle and try to determine if it favors one side or is centrally located?

 

if you're hearing rust scraping, that's probably it. did it sit for any length of time? 2000 forester i worked on last year was a real pain to keep the rust from rubbing - finally wire brushed the rotors and cleared it up.

[jarl]

There was a thread not long ago that mentioned an electronic "chassis ear". It could prove very useful in isolating the noise. I don't know if you can rent one at Autozone or O'Reillys, though...

[bheinen74]

wow. Okay to start off, one is a sedan with a trunk lid / deckklid covering most of the back wheel wells. The Forester has basically in comparison, open rear wells to the cabin.

 

I doubt you have the same make brand age of tires on both; Tires are a factor.

 

 

What I have done, is to put a sound deadener in the panels of the Forester, and sound deadening blankets installed under both of the makes rear seats. Spray the wheel wells on the compartment area and the underside area with some 3m undercoating. Etc.

 

So many factors at play here i cannot go further into detail. But you are talking open wheel wells vs trunk.

 

You never said if your Legacy is a wagon or a sedan so i made some assumptions.

[nipper]

Tires can make a hige difference to start with.

The amount of sound insulation may be more in the Lego then the Forester.

 

When was the last time the diff lubrication wa schanged?

 

Are the tires cupped ?

[john40iowa]

wow. Okay to start off, one is a sedan with a trunk lid / deckklid covering most of the back wheel wells. The Forester has basically in comparison, open rear wells to the cabin.

 

I doubt you have the same make brand age of tires on both; Tires are a factor.

 

 

What I have done, is to put a sound deadener in the panels of the Forester, and sound deadening blankets installed under both of the makes rear seats. Spray the wheel wells on the compartment area and the underside area with some 3m undercoating. Etc.

 

So many factors at play here i cannot go further into detail. But you are talking open wheel wells vs trunk.

 

You never said if your Legacy is a wagon or a sedan so i made some assumptions.

 

Having the '99 myself the Forester is noisy! I took out the carpet and put sound deadner as well as all the doors and as much of the fire wall as reachable. Also I bought special sound deadner for the engine side of the firewall. All of this really helped a lot in terms of noise; only thing left is the

head liner if I get the gumption to do it. I must say it was a joke what passed as insulation for this model and year. It gets cold here and I noticed

a dramatic improvement in heat retention. Much work yes...

[nipper]

Yes they are not the quietest subaru cars, rather loud compared to a leggo or outback.

[bheinen74]

Yes they are not the quietest subaru cars, rather loud compared to a leggo or outback.

 

impreza is the budget low end car Subaru makes, yes not much for sound deadening in comparison to a Legacy or Outback. Forester is an impreza, lifted, it shared that same chassis.

 

 

Cheap, and loud and built to stay that way......errr.

[john40iowa]

are the newer Foresters improved in this area? I hear the steering isn't as

tight in terms of handling.

[jarl]

Ok... after playing the detective, it looks like the OP's '97 Legacy is a Wagon. Back to your drawing tables, gentlemen

 

One thing I saw while looking for this is that the OP had replaced the Forester bearings. Did he (you!) use the (original) ball bearings, or the (recommended) tapered bearings? Have you replaced suspension bushings?

 

Something else comes to mind: the geometry of the suspension may be slightly different. Old Citroens had to have a subchassis attached with very soft rubber mounts because of the steep angle of the suspension travel... which in turn was very steep to compensate for the amazingly soft suspensions.

 

PD: now that you mention increasing the sound deadening material... what is normally used? I need to replace the carpet on my OBW and would like to increase the sound insulation if possible while at it.

Edited October 5, 2011 by jarl

[john40iowa]

I can't remember what the product name was I used. It was similar to

Dynamat but from a company in Oregon- really nice owner as well. The product I used is two part, in that you place a layer or more of covered tar paper

over the surface and then a spray it with adheasive to be followed by a layer

of thin accousticle foam. It worked out well.

[uniberp]

Hanger bushings are ok. Diff fluids ok. Axles seem to have no play. Boots are good. The one axle I loosened when I did the bearing was fine.

Edited October 5, 2011 by uniberp

[uniberp]

OK, I've been through everything now, and I guess I can live with it. Rust inside the pinion flange may have been scraping, but the noise is mostly still there.

 

What I think is, the rear diff side bearings are worn, but not enough to warrant a job.

There is a tiny bit more movement on the 99 than on the 08, maybe.

Diff side bearing preload settings are a wizards art. Not me.

 

The seals are not leaking, so I'm not messing with it.

 

If I were to correct this, it would take a driveshaft, axles, diff rebuild and then probably work on the front end as well.

 

Nah. It runs nice. I'll look into dynamat, or maybe use that rubberized torchdown roofing stuff if I got it lying around.

[Fairtax4me]

I'd lean more towards tire noise than a drivetrain issue. What kind of tires are on your cars?

Also your Legacy has more insulation to keep sound out than the Forester does.

[uniberp]

I'd lean more towards tire noise than a drivetrain issue. What kind of tires are on your cars?

Also your Legacy has more insulation to keep sound out than the Forester does.

 

Pirelli P3000, good tires about 3 years old. Balanced and evenly worn.

 

I really think it's the rear diff. It howls like a diff. There's 4 in the pickapart place here. I may pull one for fun. Better than disabling a running vehicle for research purposes.

 

The 2.2 Legacy Auto Wagon has noticeably less power, which to me would explain why that diff is not as worn at the same mileage. (It's named "The Legato" for that reason) That little Forester still gets up and moves with traffic at 85 no problem. That's pushing it for the Legato.

 

BTW: who knows if Legacy and Forester/Impreza auto diffs are all 4.11:1?

[uniberp]

It appears to be the OTHER (Left) rear wheel bearing that was making the noise.

 

I had replaced the right rear bearing when it was obvious that it had play in it when shaking the wheel. The left rear bearing seemed OK from shaking and spinning the wheel and hub with the axle in it, and I couldn't sense any roughness, AND I had replaced it about 5 years ago, so I didn't suspect it.

 

HOWEVER, when I removed the left rear hub, as I was preparing to remove the differential, when I got it down to only the hub and knuckle (axle out), it was rough, and had obviously heated up enough to melt all the grease out and mix it with the antisieze on the splines. The inner seal was shot too.

 

The bearing felt rough only then, with the axle removed.

 

SO, it is possible to have a noisy bad rear bearing that makes no change in sound when turning, has no play, and is otherwise undetectable except for the loud noise.

 

I will confirm this afternoon when the hub is back from the shop

 

I even have a driveshaft to swap in, which has a slightly smoother center support bearing.

Edited October 20, 2011 by uniberp

[hohieu]

Rear wheel bearings can make noise for tens of thousands of miles and still not show any play or roughness. Mine did for 40K miles. By the time there's play, you're facing potentially catastrophic failure.

 

One way to check them is to put one hand on the suspension coil while turning the wheel with your other hand. Any roughness will be transmitted to the coil.

[uniberp]

It is fixed and now as quiet as the "Legato".

 

The left rear bearing was bad, but the only symptom was general increased noise, no change when turning, no play at the hub, no detectable roughness through the hub or suspension until the wheel, drum and axle were removed. I only got it disassembled that far because I was going to remove the differential, and decided to start on that side. Then I could feel just the bearing in the hub and it was notchy.

 

Removing the rear hubs on a 12 year old rustbelt car is not without trickery, especially on those that use that 250mm long bolt that goes through the 2 lateral links and 2 holes in the knuckle. So it's a bit of ordeal even to diagnose correctly.

 

I suppose you could put it on stands and run it in gear, and feel/probe to locate noise, but I don't like that safety factor, working alone.

 

I swore it was the differential or driveshaft. It wasn't. I even took the driveshaft out AGAIN and inserted the FWD fuse to test that. BTW, the trans will leak a little fluid if you do that.

 

Live and learn.

Edited October 19, 2011 by uniberp

[edrach]

It is fixed and now as quiet as the "Legato".

 

The left rear bearing was bad, but the only symptom was general increased noise, no change when turning, no play at the hub, no detectable roughness through the hub or suspension until the wheel, drum and axle were removed. I only got it disassembled that far because I was going to remove the differential, and decided to start on that side. Then I could feel just the bearing in the hub and it was notchy.

 

Removing the rear hubs on a 12 year old rustbelt car is not without trickery, especially on those that use that 250mm long bolt that goes through the 2 lateral links and 2 holes in the knuckle. So it's a bit of ordeal even to diagnose correctly.

 

I suppose you could put it on stands and run it in gear, and feel/probe to locate noise, but I don't like that safety factor, working alone.

 

I swore it was the differential or driveshaft. It wasn't. I even took the driveshaft out AGAIN and inserted the FWD fuse to test that. BTW, the trans will leak a little fluid if you do that.

 

Live and learn.

Good job. That long bolt is a bugger even here in the relatively rust-free NW. Thanks for posting the resolution. I hate it with threads like this when they suddenly die without any mention of a resolution.

[Rooster2]

are the newer Foresters improved in this area? I hear the steering isn't as

tight in terms of handling.

 

A friend bought a 10 Forester. I have ridden in and drove it. Seems quiet enough, so Subaru must have added good sound absorbing material, when this vehicle was redesigned.

[uniberp]

Good job. That long bolt is a bugger even here in the relatively rust-free NW. Thanks for posting the resolution. I hate it with threads like this when they suddenly die without any mention of a resolution.

 

Here's my pics for a way to remove the frozen-in-bushing bolt after cutting the head off.

 

http://www.ultimatesubaru.org/forum/album.php?albumid=304