Jump to content
Ultimate Subaru Message Board
Sign in to follow this  
CNY_Dave

Welcome me to the 'noisy front diff' club

Recommended Posts

So if the front diff pinion bearings are getting noisy, any thoughts on if there is any lube or additive choice that can stretch out the time to repair?

Share this post


Link to post
Share on other sites

Generally I put some lucas in diff's.

 

A super product (and reflects that in it's price) is MT-10 from Muscle Products. It's an additive.

 

It seems the viscosity doesn't change with temperature.

 

A friend and I got a gallon some years back - I wanna say lit was like 150/gal then or more.

 

I know if I'm in the garage when it's cold the already thick Lucas is incredibly thick. So much so that I have an old crock pot to warm it up.

 

But the MT-10 seems to have the same thickness as it does when it's 90 degrees. They probably have a website. They used to have a location close to me but after it being there many years they closed it a few years back. They so still have it at the dealer car auctions, and my local transmission shop has it too.

 

Nothing will overcome damage/wear though.

Share this post


Link to post
Share on other sites

I recently used some Redline Lightweight Shockproof (smurf blood!) in diffs and transmissions in our 2 soobs and it seemed to cut the 'normal' front diff whine in our H6 Outback approx in half. Slightly improved 'speed shifting' in my WRX 5spd. It has some kinda particles in suspension so, maybe it's quieter because it works in a slightly different way? Not for any system with a pump or filter.(STI 6 speed for example)

 

 

expensive to try very many lubes but, that's the only suggestion I have.

 

 

chances are, if a well maintained diff has sustained some kinda damage, oil is not gonna fix it.

Share this post


Link to post
Share on other sites

Auto or manual? If it's an auto then it's likely pinion bearings and there's nothing that will help but replacement. If it's a manual then it's most like the rear input shaft bearing. Either way you need to repair it.

 

GD

Share this post


Link to post
Share on other sites

H6, so an auto. Typical pinion bearing whine, disappears when there's no load.

 

Just under 200k miles, fluid has always been at the proper level, always looked clear and smelled nice and fresh, was even changed a few times.

 

No goop is going to cure it, but I'd like to see how long I can put off major trans work.

Share this post


Link to post
Share on other sites

Crack Dave, sorry to hear that.

 

It's a pain job that no one knows how to do but could readjusting the backlash help at all...mitigate the slack created by the excessive wear?

Share this post


Link to post
Share on other sites

I've changed out the front fluid for lucas with 50% lucas additive, no change in the noise.

 

Took the crud off the magnet, the flakes here are incredibly thin and might just be tiny particles held together because they are magnetized, no solid pieces at all.

post-22963-136027661854_thumb.jpg

Share this post


Link to post
Share on other sites
I've changed out the front fluid for lucas with 50% lucas additive, no change in the noise.

 

Took the crud off the magnet, the flakes here are incredibly thin and might just be tiny particles held together because they are magnetized, no solid pieces at all.

 

assuming the total mass in that pic is 1/4 - 1/2 teaspoon or so, it fairly well matches the stuff I've wiped off the diff magnets on my cars. FWIW

Share this post


Link to post
Share on other sites

Most shops will probably recommend a new transmission to fix the issue but it's not too hard to tear it apart and o it yourself. Done a few of them myself and major tools needed would be a 1/2"drive impact gun, a 35mm socket, a press and some bearing clamshells.

Share this post


Link to post
Share on other sites

Posted a vid of the noise, the persistent rumble is a wheel bearing, pinion noise is the one that comes and goes as I add/reduce throttle.

 

Share this post


Link to post
Share on other sites

audio pick up is such that I can't distinguish the pinion bearing from the wheel bearing.

 

not timing chain noise, you'd surely know that?

Share this post


Link to post
Share on other sites

any i see that the pinion bering is going out its the berring cage that wreaks it the cage breaks up and gets into the berring and eats it up and allows the pinion to shuttle back and fourth. Witch can take out the awd end of trans to by chewing up the output drums and gears. if you can hear it i bett the pinions done.Have had 3 thiss year had smoked pinions lucky i have many good cores with good diffs.

Share this post


Link to post
Share on other sites

Noise with rear wheels on the ground and not moving:

 

 

I think this is definitive, front pinion bearing.

 

I also confirmed even in 1, there is NO drive to the rear wheels until you step on the gas (whern I had all 4 off the ground, heh)

Share this post


Link to post
Share on other sites

Trans is in the hatch, $860, 96k on it, out of a 2004 LL bean.

 

Came with the converter and I asked them to leave the mounts on.

Share this post


Link to post
Share on other sites

I am wondering if it's worth bothering changing either trans filter (internal or external) if the fluid in my orig trans looks clean.

 

I do know a slight dent in the incoming trans means the pickup might be blocked by the pan.

Share this post


Link to post
Share on other sites

I'd replace the external one while it's easier, it's old.

 

The only compelling reason to replace the internal one is due to the oring on it, the filter itself as you know is just a screen and doesn't clog. If it has debris in it then your issues are far more ominous than a dirty filter. Whether that oring ever causes a problem I have no idea, seems I've heard of it once, but most orings do have the capacity to cause issues.

Share this post


Link to post
Share on other sites
That's a pretty sweet deal!

 

Next best in driving distance was $930 for one with a few thou more.

 

There were cheaper ones, but these were both 'A grade' condition rating.

Share this post


Link to post
Share on other sites
I'd replace the external one while it's easier, it's old.

 

The only compelling reason to replace the internal one is due to the oring on it, the filter itself as you know is just a screen and doesn't clog. If it has debris in it then your issues are far more ominous than a dirty filter. Whether that oring ever causes a problem I have no idea, seems I've heard of it once, but most orings do have the capacity to cause issues.

 

External one is just wire mesh, isn't it?

 

Part of my decision will be based on what the fluid coming out looks like.

Share this post


Link to post
Share on other sites

On the way home last night I thought I may have smelled gear lube.

 

Pulled the car in the garage last night, am starting the trans swap.

 

There's oil under the car.

 

I'm goin' in.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×