[Run Forrest]

Hi all, newbie here looking for a little advice.
Gotta '17 GSW 4motion that's completely stock and needs a new rear diff at 87K.
Gonna keep the car 5 more years most likely, but wondering about a few things before I decide to fix this.
First off, I'm not going to attempt this myself. I'm very handy and do a lot of other items on the car (did my haldex and DSG fluid changes), but this is beyond me.

My questions are:

Go with new or used diff?
New diff $2,500-$3000. Used begin at $300 with 80K on them.
If installing used, is this something that should get new seals beforehand or just go with it? Are there any seals?

Been driving on the bad diff for many months already. The AWD still works fine. Had dealer assess the noise back there this week. They said it's the diff. Bearings and brakes are fine. They changed the fluid in the diff. It was all "glittery with metal." (great ). New fluid didn't quiet it any. It's not making a really loud noise, more like brake noise that's only discernable at low speeds. No vibration, etc.

Wondering what I can expect if I keep driving it. Hoping to have more time to save $ for this. Already drove 10K with it making noise.
So... what will happen if I keep driving? Will it vibrate eventually and let me know it's time to stop driving like this? Or will it just lock up unexpectedly? Will driving it longer hurt my tires, bearings, brakes and suspension much?

Appreciate the advice.
Thanks in advance.

 

[KarstGeo]

Did this happen after you did the DIY Haldex service? Some have mistakenly drained/filled the r. diff with the Haldex fluid or drained one and filled the other. R. diff going is a bit odd.

Driving it...I guess? Noisy is about all you will get and at some point it goes which could lock things up back there...I'd be concerned about possible repurcussions to the Haldex.

I would use a used diff personally to save some money and replace it.

 

[Run Forrest]

Thanks for the advice.
I did the haldex fluid before this happened, about 4 months prior...But I researched the procedure thoroughly beforehand and was aware of the mistake of draining the wrong fluid, etc.
I feel confident that I got it right because the dealer said the AWD still works fine and the diff and haldex were not low on fluid, it hadn't been leaking, etc, and I think the haldex and diff are different in terms of fluid capacities. I think the diff is larger.

Anyway, yeah I was hoping I got the haldex service right. I feel that i did. It is kinda odd for the diff to go. I mentioned to the dealer that people tune these cars and put a lot more HP through the drivetrain... so why is my stock Sportwagen shredding the diff? He said the diffs aren't all that tough and are the weakest part of the drivetrain. The DSGs don't fail, it's the diffs, he said. He mentioned the red Alltrack that DAP modded (seen on YouTube) and supposedly they wrecked the diff on that car. He asked me if I drove mine hard.
I did a few times, but not often, and never "off road" where the diff would get hard use. I live in Maine and do drive in snow a lot, but that's usually in traffic where I'm being safe, not winding it up. But a car in Maine gets a diff excercised more than California I suppose.

Thanks for the advice on buying a used diff. I am leaning towards that approach.

Wondering if it makes sense to have the seals done before installing a used diff
??

 

[jjvincent]

If my diff took a dump, I'd buy a used one and install it. All a failing diff will do is get noiser and finally self destruct leaving you stuck somewhere. For a used diff, I'd just claen it up and change the oil. Then install.

 

[jjvincent]

Did this happen after you did the DIY Haldex service? Some have mistakenly drained/filled the r. diff with the Haldex fluid or drained one and filled the other. R. diff going is a bit odd.

Driving it...I guess? Noisy is about all you will get and at some point it goes which could lock things up back there...I'd be concerned about possible repurcussions to the Haldex.

I would use a used diff personally to save some money and replace it.

VW diffs do fail. Same for all other vehicles. It's not common but does happen. Since it's similar to other VAG diffs, it's mass produced and thus a certain percentage will fail.

 

[Run Forrest]

If my diff took a dump, I'd buy a used one and install it. All a failing diff will do is get noiser and finally self destruct leaving you stuck somewhere. For a used diff, I'd just claen it up and change the oil. Then install.

Thanks for the info.
Looks like I'll be shopping for used diff. Appreciate the advice about skipping the seals. We'll see what other thoughts might come...
So sounds like if the diff does lock up I won't wreck my axles. I hope...

 

[CanuckBird]

VW diffs do fail. Same for all other vehicles. It's not common but does happen. Since it's similar to other VAG diffs, it's mass produced and thus a certain percentage will fail.

jjvincent-
What's the owners manual (or wise owners own) recommended maintenance interval on rear diff?
How about the front bezel?
As I recall they use the same gear oil.

Which is NOT the same gear oil as the
Haldex
or
6MT
which are two different oils and P/Ns

but easily confused, can be incorrectly issued by parts guys at the dealership, who reportedly rely on the techs to verify correct P/Ns. Same grey bottle with VW on it, "gear oil" but different oils, P/N.

Caveat Emptor

 

[KarstGeo]

jjvincent-
What's the owners manual (or wise owners own) recommended maintenance interval on rear diff?
How about the front bezel?
As I recall they use the same gear oil.

Which is NOT the same gear oil as the
Haldex
or
6MT
which are two different oils and P/Ns

but easily confused, can be incorrectly issued by parts guys at the dealership, who reportedly rely on the techs to verify correct P/Ns. Same grey bottle with VW on it, "gear oil" but different oils, P/N.

Caveat Emptor

R. diff and f. bevel box both use a 75W90 gear oil - I use Redline MT90 but Liquimoly etc. all make one that works. There is not maint. interval listed for these two. I did mine at ~70K when I did my DSG/Haldex for the second time.

 

[CanuckBird]

R. diff and f. bevel box both use a 75W90 gear oil - I use Redline MT90 but Liquimoly etc. all make one that works. There is not maint. interval listed for these two. I did mine at ~70K when I did my DSG/Haldex for the second time.

Thanks Karst. Have you done a Blackstone on it?
Considering it for second oil change on both bezel and r.diff, last done at 50k with VW oil, when 100K rolls around.
Did a Blackstone on second haldex (@ 80K on 40k interval); was clean: reassuring.

 

[KarstGeo]

Thanks Karst. Have you done a Blackstone on it?
Considering it for second oil change on both bezel and r.diff, last done at 50k with VW oil, when 100K rolls around.
Did a Blackstone on second haldex (@ 80K on 40k interval); was clean: reassuring.

No - it's just going to show lots of metal b/c it's a gear on gear system. You keep popping back up.....

 

[CanuckBird]

No - it's just going to show lots of metal b/c it's a gear on gear system.

Gotcha, thanks.