2015 Audi s3: Front Bevel Box failing?

[Thewheelm4n]

Hey guys,
I had created a thread last week with no luck regarding a howling/grinding noise, quiet but noticeable and constant from 10mph+. Noise does not change with turning like a bad wheel bearing, brakes have plenty of life left. I'd originally brought it to my preferred local Audi indy shop as I thought my front driver axle was failing and asked them to replace that and diag the howling noise if they had time; heard back, was told axles were fine but howling noise was from a bad rear diff that needed replacement. I found a used lower mileage diff at a local salvage yard, supposed to be delivered to the shop today. However, I stumbled on this thread (https://www.audizine.com/forum/showt...l-Box-failures) and one of the posters mentioned that a bad front Bevel Box can cause both a howling noise while driving AND a "binding"/"clicking" type noise/sensation while turning. Months ago I had a random issue that only occurred for about 20min, car refused to go over like 20mph and when I tried to push it, just felt like when you're running out of fuel, but the traction control light kept flashing; if I backed off throttle it'd stop, but trying to give it throttle did nothing. This disappeared a half hour or so later and hasn't returned, freaked me out good though.

So, basically, wondering if all my above symptoms could be explained by a failing front Bevel Box (before I go and have them do the rear diff!). I can't seem to find the location on a diagram, a part #, or a photo of it though. All I can find on Audi's parts catalog is the rear "AWD coupling unit" which on ECS comes up as a Haldex Control Unit but says it doesn't fit my car ).

Thoughts? Screenshot_20230327-115708_Brave.jpg

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2015 Audi S3

[MikTip]

https://www.audizine.com/forum/showt...1#post14777158

[Thewheelm4n]

https://www.audizine.com/forum/showt...1#post14777158

Oddly enough this was what I was looking for when I stumbled on the thread I linked with the guy with the same symptoms as me and Bevel Box failure.

Do you think a fluid change and that LM addative would solve the issue? The reason I ask is you said you only had a howl/whine and it got rid of that, I'm also getting binding/clicking while turning which doesn't look like an axle issue so I'd assume it's Bevel Box-related. Obviously don't want to go replacing the Bevel Box if I don't have to but I just am skeptical the fluid change and addative will solve the issue.

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2015 Audi S3

[MikTip]

Oddly enough this was what I was looking for when I stumbled on the thread I linked with the guy with the same symptoms as me and Bevel Box failure.

Do you think a fluid change and that LM addative would solve the issue? The reason I ask is you said you only had a howl/whine and it got rid of that, I'm also getting binding/clicking while turning which doesn't look like an axle issue so I'd assume it's Bevel Box-related. Obviously don't want to go replacing the Bevel Box if I don't have to but I just am skeptical the fluid change and addative will solve the issue.

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2015 Audi S3

The bevel box oil change and LM additive is the easiest and lowest cost attempt to remedy thing you can do. Why not try it?

How much oil is in your bevel box? You know it vents to atmosphere? Audi had an issue number of years ago with their rear diff oils evaporating! Hello!

Did you know the bevel box is "air-cooled"? Funny as it sits right behind the hot engine block and its tiny cooling fins barely get any air-flow...

What have you got to lose? $35...an hour of your time?

Binding clicking while turning...my guess...outer CV joints...or upper strut bearing.

How many miles on this car? Mods? Springs? Shocks? Stock?

The bevel box is simply a 90 degree diff. No LS(limited-slip)



Allows the DSG(designed for Front wheel drive) to drive a rearward drive shaft for the VW 4-motion drive system.

Its not even a real Audi Quattro drive setup!

I highly recommend to change the bevel box oil.

For the simple reason you will KNOW its got good oil now at the proper amount and if the issue goes away your a hero!

[Thewheelm4n]

The bevel box oil change and LM additive is the easiest and lowest cost attempt to remedy thing you can do. Why not try it?

How much oil is in your bevel box? You know it vents to atmosphere? Audi had an issue number of years ago with their rear diff oils evaporating! Hello!

Did you know the bevel box is "air-cooled"? Funny as it sits right behind the hot engine block and its tiny cooling fins barely get any air-flow...

What have you got to lose? $35...an hour of your time?

Binding clicking while turning...my guess...outer CV joints...or upper strut bearing.

How many miles on this car? Mods? Springs? Shocks? Stock?

The bevel box is simply a 90 degree diff. No LS(limited-slip)



Allows the DSG(designed for Front wheel drive) to drive a rearward drive shaft for the VW 4-motion drive system.

Its not even a real Audi Quattro drive setup!

I highly recommend to change the bevel box oil.

For the simple reason you will KNOW its got good oil now at the proper amount and if the issue goes away your a hero!

I do agree, problem is I have no way to change it myself. Otw to the shop now, they have it on the lift, gonna just see if they'll let me/do it while it's there before they close.

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2015 Audi S3

[Thewheelm4n]

No dice doing it today, but they're willing to drain and change fluids on the rear diff and Bevel Box using the Mos2 addative in both and see if it solves the issue (praying it does). Unfortunately couldn't get a second tube of the Mos2 locally so hoping FCP can ship it quick and get it to me by Wednesday, car will be down a week and counting at that point.

I feel it also worth noting that they had the car running on the lift today, could not hear any noise at all/feel any vibration from the Bevel Box, but could from the rear diff. Still going to have them replace gear oil in both along with a tube of the Mos2 and see what happens, but worried the rear diff may be shot.

I'm not sure if an outer cv join or strut mount would be the cause of the clicking/binding as it also occurs when I'm driving straight, just isn't quite as noticeable. It feels almost exactly like if you get a large enough bolt or something stuck in your tire and can feel it being "ran over" over and over again as you drive, but in my case it's not a uniform feeling, it's random "clicks/clunks" and there's nothing stuck in the tire. Makes me feel it could be the Bevel Box, reminds me of a 2014 328d msport xdrive I had with a common transfer case failure, had severe binding while turning but was a similar feel/noise.

Thoughts?

Will report back.

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2015 Audi S3

[Thewheelm4n]

The bevel box oil change and LM additive is the easiest and lowest cost attempt to remedy thing you can do. Why not try it?

How much oil is in your bevel box? You know it vents to atmosphere? Audi had an issue number of years ago with their rear diff oils evaporating! Hello!

Did you know the bevel box is "air-cooled"? Funny as it sits right behind the hot engine block and its tiny cooling fins barely get any air-flow...

What have you got to lose? $35...an hour of your time?

Binding clicking while turning...my guess...outer CV joints...or upper strut bearing.

How many miles on this car? Mods? Springs? Shocks? Stock?

The bevel box is simply a 90 degree diff. No LS(limited-slip)



Allows the DSG(designed for Front wheel drive) to drive a rearward drive shaft for the VW 4-motion drive system.

Its not even a real Audi Quattro drive setup!

I highly recommend to change the bevel box oil.

For the simple reason you will KNOW its got good oil now at the proper amount and if the issue goes away your a hero!

Sorry, forgot to mention, car is stock, no mods of any kind.

179k on it.

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2015 Audi S3

[MikTip]

Sorry, forgot to mention, car is stock, no mods of any kind.

179k on it.

Well...your right up there with my 2015 S3 at 180k!

[Thewheelm4n]

UPDATE:
Well, the shop was able to change the fluid in both the front and rear differentials today with liqui moly gear oil and add the liqui moly Mos2 to both and do the Haldex fluid service, etc. Said the old fluid was dark and smelt burnt in both which I expected. Said there was no metal shavings or anything from the Bevel Box coming out in the old fluid, so that's good, but said he checked the Haldex pump screen/rear diff filter, whatever is back there, and there was some crap/metal shavings in it... Hoping and praying the fluid change/mos2 will let me get more life out of the rear and if the binding/clicking I was getting in the front on turning was from the Bevel Box, have cured that, but I'm still concerned that the rear diff may be toast.

Thoughts?

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2015 Audi S3

[MikTip]

UPDATE:but said he checked the Haldex pump screen/rear diff filter, whatever is back there, and there was some crap/metal shavings in it...
Thoughts?
[/URL]

2015 Audi S3

Haldex pump screen...its separate from the rear diff. They are not the same. The Haldex pump screen debris will be from the Haldex clutchs...

Depending on how much...probably no need for alarm...especially if you are not experiencing any sort of haldex issues.



The rear diff uses a different(75w-90) and separate oil from the Haldex.

[MikTip]

https://www.jcr-leeds.com/haldex-servicing-gen5/

[Thewheelm4n]

Haldex pump screen...its separate from the rear diff. They are not the same. The Haldex pump screen debris will be from the Haldex clutchs...

Depending on how much...probably no need for alarm...especially if you are not experiencing any sort of haldex issues.



The rear diff uses a different(75w-90) and separate oil from the Haldex.

Is there a separate filter or screen to check for the rear diff? I'm wondering if since they diagnosed it as needing a rear diff, they're assuming the debris in the screen are from that and maybe don't realize that the screen inside the Haldex pump housing is only for the Haldex? I don't know though as I wasn't there. I know the Haldex is separate and takes it's own fluid, I got the service kit from FCP for them to use to service it. I don't *believe* I have any Haldex issues, awd seems to work fine, no issues with putting down power or getting around in the snow, can kick the rear end out fine in the corners if there's enough snow on the ground. What issues specifically would be present if I had a failing Haldex?

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2015 Audi S3

[MikTip]

https://www.audizine.com/forum/showt...failure-thread

[Thewheelm4n]

Is there a separate screen or filter for the rear diff vs the Haldex screen? Or no?

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2015 Audi S3

[MikTip]

Is there a separate screen or filter for the rear diff vs the Haldex screen? Or no?

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2015 Audi S3

There is no "screen/filter" for the rear diff. The haldex pump has a screen...

[Thewheelm4n]

There is no "screen/filter" for the rear diff. The haldex pump has a screen...

Okay, so they were definitely talking about the screen for the Haldex then. Hopefully they cleaned it off, I'll have to bring this up when I pick it up.

So the only way to tell if there is debris/metal shavings from the diff itself would be when the fluid is drained?

Would a grinding/vibration from the rear end possibly be caused by a failing Haldex and just seem like it's coming from the diff?



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2015 Audi S3

[MikTip]

The haldex is a hydro-mechanical switch that turns on or off the rear diff. It either works or it doesnt. When it doesn't there are codes. You never mentioned any haldex codes or rear wheel drive issues so apparently yours is working fine....

The rear diff is like any typical rear diff.

Im not sure what sounds/grinding/vibrations your hearing, they could be caused by anything...

Its rare the rear diff fails. Because there really is nothing to them.

I could be one of your rear wheel bearings????

I cannot say here cause I physically need the car to properly diagnose.

You take it to a shop for work so take it to the shop and say you have grinding/vibrations coming from the back.

You car has 179k...its gonna have some wear...

[Thewheelm4n]

The haldex is a hydro-mechanical switch that turns on or off the rear diff. It either works or it doesnt. When it doesn't there are codes. You never mentioned any haldex codes or rear wheel drive issues so apparently yours is working fine....

The rear diff is like any typical rear diff.

Im not sure what sounds/grinding/vibrations your hearing, they could be caused by anything...

Its rare the rear diff fails. Because there really is nothing to them.

I could be one of your rear wheel bearings????

I cannot say here cause I physically need the car to properly diagnose.

You take it to a shop for work so take it to the shop and say you have grinding/vibrations coming from the back.

You car has 179k...its gonna have some wear...

Okay, that makes sense, doubt I have a Haldex failure on my hands then.

I thought I adequately described the issue earlier, but I'll try to reiterate it again quickly. Basically, when I'm doing 10mph or more, regardless of going straight, turning, or speed, there is a constant quiet but noticeable "grinding/howling" type noise. Pitch never changes until I slow down to below 10mph, then it slowly goes away. Appears to get louder the longer I drive, I. E. As the car warms up. It's definitely not tire noise as I've had the same tires on it and it just came out of nowhere a couple weeks back, and tires only have like 10k miles on em max, probably not even. and I've had both rear wheel bearings replaced within the last 20-30k miles, and like I said, turning makes no difference in the noise so it's definitely not wheel bearings. Only time I can get the noise to seemingly go away is if i turn very sharply, like a 90 degree turn in a neighborhood or something, either direction and the noise will disappear until I'm driving straight again.

With the car on a lift and in gear, you can hear a quiet but noticeable "grinding" type noise from the rear diff like I describe but is amplified while actually driving, and can feel a slight vibration from the rear diff housing; for comparison, there's zero noise or vibration like this from the Bevel Box up front. Shop told me rear diff is bad and needs replacement, but did mention how surprised they were as it's rare and they've only done one and that was 5 years ago.

I wanted to, like you said, do fluid change with Mos2 added first as a diff is hard to come by used and not a cheap job before just going ahead with it.

Is that enough info for you to have any thoughts? Thanks again!

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2015 Audi S3

[Thewheelm4n]

Going to pick it up in a few so we'll see if the fluid flushes/mos2 solved any of the issues...

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2015 Audi S3

[Thewheelm4n]

UPDATE:
Well, nothings changed. Still getting the same exact quiet steady grinding sound while driving, and once the car warmed up after 50mi of driving or so still also getting the same binding/clicking type sensation/sound from the front (seemingly driver) side. So whatever is going on, fluid changes and MoS2 additives for the Bevel Box and rear diff made no difference.

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2015 Audi S3

[MikTip]

How old and in what condition is the transmission mount?

[Thewheelm4n]

How old and in what condition is the transmission mount?

Man, I have no idea, I'd assume it's original to the car. Is it somewhere I could easily view it myself using a floor jack? Getting sick of having to bring my car to the shop. Miss the days I had access to a private lift.

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2015 Audi S3

[WeldLife88]

Pretty easy to get to..mine was wasted at 58k.. a lot of clunking was going down lol. It's under the battery.. intake, battery and tray, ECU need to come out to access..( if memory serves me right) I think there's a wiring loom under there as well.. don't know if that gets moved over just to inspect or when replacing.

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[MikTip]

Youtube...

[Thewheelm4n]

Pretty easy to get to..mine was wasted at 58k.. a lot of clunking was going down lol. It's under the battery.. intake, battery and tray, ECU need to come out to access..( if memory serves me right) I think there's a wiring loom under there as well.. don't know if that gets moved over just to inspect or when replacing.

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What kind of clunking? I don't really have any issues I'd describe like clunking, I just get a random "clicking/binding" sort of sensation after driving for a while that seems to be coming from the front driver wheel area, like when an axle is going bad or a transfer case is going bad. That, and the constant low grinding/howling sort of noise while driving that I believe is the rear diff.

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2015 Audi S3

[WeldLife88]

Going into gear on a slight incline, reversing and takeoff, it was most noticeable.. I also developed an intermittent shake/ shimmy at highway speeds( not sure if this was related to the mount as I did coilovers the same weekend) but it did go away after. It was an audible usually single clunk coming from under my feet. Gear changes were like a rubber band,very very sloppy.. When I had the mount out, the rubber was so loose it was flopping around. I was actually nervous I did damage to the DSG.

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[Thewheelm4n]

Going into gear on a slight incline, reversing and takeoff, it was most noticeable.. I also developed an intermittent shake/ shimmy at highway speeds( not sure if this was related to the mount as I did coilovers the same weekend) but it did go away after. It was an audible usually single clunk coming from under my feet. Gear changes were like a rubber band,very very sloppy.. When I had the mount out, the rubber was so loose it was flopping around. I was actually nervous I did damage to the DSG.

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Oh wow, I do have a little bit of a harsh slamming kind of feeling if I park the car on an incline like a steep driveway and shift back into reverse (got in the habit of using the ebrake to minimize this), I do have a slight vibration while driving, most noticeable around 40mph, thought it was probably the winter wheels as they're bent but I've had em road force balanced with new tires so I'm not sure. Was thinking it might be from a failing cv axle (as I've got that intermittent "clicking/binding" sound/sensation seeming to come from the front driver side), or from the Bevel Box. I had the shop drain the fluid (said it was burnt and dark) and refill adding the MoS2 additive), but that issue is still present so I'm wondering if my mount may be needing replacement based on what you've said and the mileage on the car.

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2015 Audi S3

[WeldLife88]

180k and if it happens to be original, there's a good chance its bad, especially if the previous owner liked to launch and drive aggressively. I did have all my tires road forced balance prior to the mount, thinking wheels were the problem.. I had a bent wheel, which I had repaired ( god damn pot holes in RI are more like sink holes!!!) and rebalanced perfectly and it still had a shimmy/ vibration.. until I did the Trans mount and coilovers

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[Thewheelm4n]

180k and if it happens to be original, there's a good chance its bad, especially if the previous owner liked to launch and drive aggressively. I did have all my tires road forced balance prior to the mount, thinking wheels were the problem.. I had a bent wheel, which I had repaired ( god damn pot holes in RI are more like sink holes!!!) and rebalanced perfectly and it still had a shimmy/ vibration.. until I did the Trans mount and coilovers

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Hmmm, interesting. I'll definitely have to check the trans mount then! Thanks. Potholes in Upstate NY are equally as horrendous, it's a miracle I have a car left at all at this point. Tax dollars hard at work!

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2015 Audi S3

[Thewheelm4n]

Youtube...

Thanks!

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2015 Audi S3

[Thewheelm4n]

Did you replace both these mounts or just the top one? Screenshot_20230402-173425_Brave.jpg

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2015 Audi S3

[WeldLife88]

Both..( I went aftermarket to get stiffer mounts ) I was going to mention the pendulum mount, but got stoned and forgot..sorry.. check the pendulum mount"pucks" as well. I put an aftermarket billet Alum 1 in, had it for a bit and decided against it. I just last week purchased an OEM pendulum mount and a yellow powerflex insert.. I'm running that now. Fyi pendulum mount bolts are, replace after removing.. I believe trans mount too??

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[Thewheelm4n]

Both..( I went aftermarket to get stiffer mounts ) I was going to mention the pendulum mount, but got stoned and forgot..sorry.. check the pendulum mount"pucks" as well. I put an aftermarket billet Alum 1 in, had it for a bit and decided against it. I just last week purchased an OEM pendulum mount and a yellow powerflex insert.. I'm running that now. Fyi pendulum mount bolts are, replace after removing.. I believe trans mount too??

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How did you determine your trans mounts were bad? Did you remove all that crap or could you tell beforehand? Appears my clicking/binding issue is an upper strut mount/bearing, not an axle, failing bevel box or trans mount, so trying to avoid the entire disassembly of the driver side battery area to check the trans mount only to find its just fine lol.

And what do you mean by pendulum mount pucks?

[rowlands57]

Taking out the battery box is not that bad. It's necessary to do the DSG maintenance and I have done it twice already and going back for number 3 soon. It only takes a few minutes and if it points to the issue you are having it's worth the time I'd say.

[Thewheelm4n]

So, brought it to a shop for an alignment (damn upstate NY potholes) and they said that my driver lower balljoint is bad, needs replacing before they can align it. I had finally thought I figured out what was causing my clicking/binding noise/sensation in the front driver area, bad upper strut mount/bearing, but they told me they think the ball joint may be causing the issues, and apparently with the magnetic suspension my car has, replacing the strut mounts is a big job.

Does it sound plausible the balljoint could be the cause (when car has been driven from cold for a few miles, get a clicking/binding type noise/sensation I can feel in the steering wheel and dummy pedal on the floor while driving straight at low speed or turning the wheel back and forth while parked or turning at low speed)? Gotta do it anyway but hoping so as with my rear diff still most likely needing replacement and chasing a fuel issue I still haven't solved, this car is quickly becoming a money pit...would love for a cheap, easy repair to solve something for once.

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2015 Audi S3