: Diagnosing Differential and Driveline Noises


lanceygto
05-29-2008, 07:25 AM
Found this writeup and thought useful to post:

"Diagnosing Differential and Driveline Noises

We don’t know which sounds worse—us singing show tunes in the shower or a howling differential. While there is no help for our singing, we can help you diagnose the sounds coming from a differential gone bad.

A clunk, whine, or howl can signal a worn-out pinion gear, bad bearings, or a faulty gear installation. Sometimes, the noise is not differential-related, but is caused by other driveline or axle components. The guide below will help you match up the noise you’re hearing with the differential or axle component making it—or at least get you in the ballpark.

Noise: Howl while decelerating (gears previously quiet)
Cause: Loose pinion bearing preload

Noise: Howl with whir or rumble while accelerating at any speed (gears previously quiet)
Cause: Worn rear pinion bearing or worn gear set

Noise: Howl without whir or rumble while accelerating at any speed (gears previously quiet)
Cause: Worn gear set due to lack of lubrication or overloading

Noise: Howling while accelerating over a small speed range (gears previously quiet)
Cause: Worn gear set due to lack of lubrication or overloading


Noise: Howling after gear set installation
Cause: Faulty gears or improper installation

Noise: Low-pitch rumble at all speeds over 20 miles per hour
Cause: Worn carrier bearings

Noise: Whirring during acceleration/deceleration at about 10 miles per hour
Cause: Worn pinion bearings

Noise: Banging or clunking while making a turn, backing up, or rapid deceleration (like on a freeway off-ramp). Noise gets worse in warmer weather
Cause: Posi chatter due to improper lubrication; worn clutches or spider gears; improper assembly


Noise: Banging, crunching, or popping while making a turn. Noise not affected by temperature
Cause: Badly worn or broken spider gears

Noise: Banging or heavy clicking every 2-3 feet during acceleration and deceleration
Cause: Damaged or broken pinion gear tooth or teeth


Noise: Banging or heavy clicking every 2-3 feet during acceleration or deceleration, but not both
Cause: High spot or heavy chip on pinion gear tooth

Noise: Banging or heavy clicking every 8 feet during acceleration and deceleration
Cause: Damaged or broken ring gear tooth or teeth

Noise: Banging or heavy clicking every 8 feet during acceleration or deceleration, but not both
Cause: High spot or heavy chip on ring gear tooth

Noise: Clicking while decelerating from 20 miles per hour to a complete stop
Cause: Worn carrier case-side gear bores

Noise: Rumble or clicking that gets worse during hard turns
Cause: Bad wheel bearings

Noise: Driveline squeaking or grinding at any speed
Cause: Worn or damaged U-joints

Noise: Clunking when depressing the throttle pedal (takeoff)
Cause: Worn U-joints; worn spider gears; worn axle splines; excessive gear backlash; loose yoke splines; worn slip yoke splines

Noise: Clunk immediately after taking off from a stop
Cause: Worn slip yoke splines

Noise: Steady vibration that increases with speed
Cause: Worn U-joint or out-of-balance driveshaft

Noise: Cyclic vibration that varies in intensity. Intensity increases at a specific speed range, worsens during deceleration
Cause: Pinion angle too low (not parallel with front yoke on driveshaft)"

Scyry
05-29-2008, 07:52 AM
Mine clunks everytime when you roll back into the throttle after coasting a few seconds or more at 70-80mph. Clunk is worse if you are coasting down or up hill. It also does it after down shifting from 6th to 5th or 5th to 4th. It is a dull, thud/clunk from the rear of the car.

So far the dealer is claiming they can't do anything because they can't diagnos it, because they can't open up the diff, being it is a non servicable part.

mach5288
05-29-2008, 11:40 AM
I was going to start a new thread but this seems like a good place to ask about the problem I'm having.
3 weeks ago I changed out my diff fluid because at 32k I was still running the stock fluid and was just beginning to get a slight whine at high speeds, I replaced it with Mobil1 75-140. Everything was great until about a week ago when I started getting a little clunk from the rear end when engaging the clutch in reverse, this has progressively gotten more noticeable and today I'm getting some clunking at low speeds such as rolling through parking lots, etc... I'm thinking it's fluid related because today is the warmest it has been here so far and it seems to get worse as the temp goes up. I'm hoping that's all it is because I'm out of warranty and really don't want to have to replace the rearend right now.

Is there a chance of doing any damage to the diff with this going on? Should I try not to drive it until I can get the fluid changed out to something other than the Mobil1?

Scyry
05-29-2008, 01:08 PM
Mach5288, did you put a friction modifier in with the new fluid? If not, that may be your issue.

ebae
05-29-2008, 03:36 PM
I was going to start a new thread but this seems like a good place to ask about the problem I'm having.
3 weeks ago I changed out my diff fluid because at 32k I was still running the stock fluid and was just beginning to get a slight whine at high speeds, I replaced it with Mobil1 75-140. Everything was great until about a week ago when I started getting a little clunk from the rear end when engaging the clutch in reverse, this has progressively gotten more noticeable and today I'm getting some clunking at low speeds such as rolling through parking lots, etc... I'm thinking it's fluid related because today is the warmest it has been here so far and it seems to get worse as the temp goes up. I'm hoping that's all it is because I'm out of warranty and really don't want to have to replace the rearend right now.

Is there a chance of doing any damage to the diff with this going on? Should I try not to drive it until I can get the fluid changed out to something other than the Mobil1?

If you did remember the friction modifier, than it may just be the Mobil 1. I tried both Amsoil and Redline in my differential and I noticed that it was quietest by far with the OEM stuff - which is what I went back to and it is still completely silent. I also noticed that the OEM stuff is like 30 bucks a quart; I don't know if it's because it's GM or if it's because of a superior additive package. The OEM gear oil is fully synthetic and made from 100% group 4 basestocks (PAO - PolyAlphaOlefin - Esters), so it's a lot better than you would think. Perhaps GM really does know what's best for this one. If I'm not mistaken, that guy JET had the same experience with the aftermarket vs. OEM gear oils. One thing is for sure, the GM friction modifier worked WAY better than the Amsoil or Redline FM's (yes I changed my gear oil like 6-7 times before I found the best combo).

StreetSleepR
05-29-2008, 04:38 PM
I have a clunking when slowly rolling away from a dead stop..I mean, extremely slow. It almost feels like the trans shifts (A4) and then the rear end catches up a second later. If I roll away with normal throttle or aggressive, nothing.

What do you think it is?

Also, has anyone experienced a noise almost like birds chirping? I thought it was my breaks, then I changed the diff fluid and it went away for a day..now it's back..

mach5288
05-30-2008, 05:15 AM
Thanks for the replies guys, I DID NOT use any friction modifier with the M1 fluid, it is fully synthetic and says it is formulated with FM for use in LSDs, like Royal Purple I suppose. Should I try to add some factory FM to the M1 fluid or completely change out the fluid again for stock and see what happens?

StreetSleepR, that is basically the kind of clunking I have as well, allthough I have a 6 speed, when I engage the clutch I can feel it grab but the rear end seems to catch and clunk a split second later, and it will clunk around at slow speeds like idling through a parking lot etc...

Scyry
05-30-2008, 06:03 AM
Thanks for the replies guys, I DID NOT use any friction modifier with the M1 fluid, it is fully synthetic and says it is formulated with FM for use in LSDs, like Royal Purple I suppose. Should I try to add some factory FM to the M1 fluid or completely change out the fluid again for stock and see what happens?

Just pick up some friction modifier to add to the Mobile 1. I threw in Mobile 1 without the FM and it made noises almost immediately. Just drove to the parts store and got FM. Issue went away after that.

SJFGTO
05-30-2008, 08:23 PM
I think you need FM with Mobile 1, I have never heard that it has FM in it already. Even the factory synthetic requires FM. Mobile 1 and GM FM seems to work for me.

mach5288
06-01-2008, 02:50 PM
Well I picked up some generic FM at Napa over the weekend because the dealer didn't have any stock fluid and said they couldn't order just one bottle for me, I'd have to buy a case of 12.... Anyway, the clunking has not gotten any better, I'm almost 100% positive it's fluid related because I was not having problems before the fluid change. I guess my differential just doesn't like the M1, should I order some stock fluids and see if that takes care of it, and where is the best place to order them, because the local dealer obviously isn't very helpful when it comes to the GTO specific issues.

TR GTO
06-01-2008, 02:56 PM
To get the 7098 fluid recommended by GM for the GTO it is best to order it from GMpartsdirect. I just switched my car over to Mobil 1 after Torco. It was quieter than stock with Torco, but Mobil 1 made mine almost whisper quiet with 1oz of 7098.

2QWK4RU 06 GOAT
06-01-2008, 03:11 PM
I Used Several Fluids Rp And Lucas With Poor Results. I Then Used The Thicker 75w140 Rp With Some Gm Fm And It's Much Better Now. I Think I Need A Lil More Though...

Amsoil Fm Did Not Work And Neither Did Torco Fm. These Fric. Mods. Made The Diff Too Tight Or Loose.

TR GTO
06-01-2008, 03:23 PM
I Used Several Fluids Rp And Lucas With Poor Results. I Then Used The Thicker 75w140 Rp With Some Gm Fm And It's Much Better Now. I Think I Need A Lil More Though...

Amsoil Fm Did Not Work And Neither Did Torco Fm. These Fric. Mods. Made The Diff Too Tight Or Loose.

I noticed mine was a bit loose with the Torco. When you used a different grade, did you end up using the 90 instead of the 140?

SRMjoe
07-02-2008, 06:10 AM
Noise: Howl while decelerating (gears previously quiet)
Cause: Loose pinion bearing preload

I am definitely experiencing this, and I'm sure others have. The dealer will probably be 'unable to reproduce' it, but it's worth a shot. Thanks for the info!

JoeyElbows
07-09-2008, 06:46 PM
I got one of the last two. i get a vibration thru my clutch pedal then it'll go away. I just put 700 miles on the new clutch and slave cylinder. I'm thinking it may be my driveshaft. what do u guys think?

04Goatboy
02-01-2009, 06:19 PM
OK, I have question along this topic... I have an '04 with a little over 70K on the clock. When the goat is cold, there are no odd sounds from the rear - but when it is hot (30 miles or so of driving) I get clunks at low speeds, only when the clutch is engaged, and a weird growl during slow turns, again only when the clutch is engaged. I am gonna change out the diff fluid, but I am thinking this could be something bad...

wrp
02-01-2009, 06:54 PM
That is a pretty comprehensive list and most likely should be in the KB. I've been through a lot of this though mostly with performance parts. The clunking sure seems like it is from the LSD. Every new differential I put in I spend the 75 for the LSD spring kit which is money well spent.

I have tried several of the oils mentioned here with different results than some of the posted experience. In general I have been very satisfied with Torco RGO 85-145 and Ford FM. The synthetics seemed to break down and lead to more howling noise.

I am firmly convinced that twice a year the following should be checked:


Torque of pinion flange bolts and Driveshaft
Torque of central carrirer bearing
joint just behind carrier bearing between two DS to look for wear or signs of damage
Front Yoke bolts to driveshaft
rubber donuts for wear and cracking
mounting bolts for differential to body mounting
Hex bolts mounting CVS to stubs and hubs (24 of them)
Subframe connector bolts
shock mounts
swaybar bolts and mounts and bushings
Front struts for rub
front suspension fo leaks, wear, bent components
Transimssion fluid levels
Differential fluid leves (I flush and refiull mine twice a year.


That is just the way I do it, had to break a lot of chit to get this anal about it.

genoliver
02-09-2009, 08:43 AM
I just went to advanced and go Mobil 1 75-145 for the rear and asked the manager if it needed friction modifier and he said no. From what I am reading here, I should put friction mod in. Where is the best place to locate FM if not from the dealer. I seen someone said NAPA??

SJFGTO
02-09-2009, 04:18 PM
Some people use Trans-X which is available from most auto chain stores.

wrp
02-09-2009, 04:49 PM
I just went to advanced and go Mobil 1 75-145 for the rear and asked the manager if it needed friction modifier and he said no. From what I am reading here, I should put friction mod in. Where is the best place to locate FM if not from the dealer. I seen someone said NAPA??I can just about get Torco shipped to me by calling them faster than driving to the local autoparts store, especially during the week when I need to often work late. You can also get FM from them.

JoeyElbows
02-17-2009, 10:02 PM
i think its time to upgrade for me. taking a turn uber slow or backing out of a parking spot i get a popping clunking sound and it feels like something is binding up. I guess its time to put the spare rear in and take this one out and investigate.

mungtor
02-18-2009, 09:17 AM
I have a clunking when slowly rolling away from a dead stop..I mean, extremely slow. It almost feels like the trans shifts (A4) and then the rear end catches up a second later. If I roll away with normal throttle or aggressive, nothing.

What do you think it is?

Also, has anyone experienced a noise almost like birds chirping? I thought it was my breaks, then I changed the diff fluid and it went away for a day..now it's back..

Did you ever solve this? I've got it now, but I've got an '04 M6.

The noises seem worse when it's cold, chirping birds goes away when warm. I thought it was an idler pulley but it only happens when I'm moving. I'm suspecting the driveshaft carrier bearing, since I've also got a minor vibration in the shifter at about 75mph in 6th.

SloNlo_350
03-01-2009, 09:08 AM
Did you ever solve this? I've got it now, but I've got an '04 M6.

The noises seem worse when it's cold, chirping birds goes away when warm. I thought it was an idler pulley but it only happens when I'm moving. I'm suspecting the driveshaft carrier bearing, since I've also got a minor vibration in the shifter at about 75mph in 6th.
I've got both of those!! My vibration is very very minor while on the gas, but if I disengage the clutch the vibration is pretty pronounced. Doesn't do it until after about 70 though. I have another driveshaft that I want to try but it's at my parent's house 2 hours away. My chirping comes only when decelerating from about 40, while OFF the brakes, and without using any sort of engine braking.

NewImpulse
04-29-2009, 08:04 AM
I am experiencing the clunck when maneuvering when I first begin driving while the fluid is at ambient. The symptom goes away after the fluid heats up. I just had the fluid changed at the local shop who confirmed that they used 75W140 full synthetic Pensoil with an added friction modifier. Could it be that there isn't enough FM in there? Would that clunk indicate that there is too much or too little? I am no longer under warranty and I want to go to a dealer about as much as I want a root canal but it may come to that...

Atlantalion
07-08-2009, 04:04 PM
I am experiencing the clunck when maneuvering when I first begin driving while the fluid is at ambient. The symptom goes away after the fluid heats up. I just had the fluid changed at the local shop who confirmed that they used 75W140 full synthetic Pensoil with an added friction modifier. Could it be that there isn't enough FM in there? Would that clunk indicate that there is too much or too little? I am no longer under warranty and I want to go to a dealer about as much as I want a root canal but it may come to that...

NewImpulse, I'm in the same boat; just noticed the 'clunck' a couple of weeks ago? Did you take yours to the dealer? What happened?

Beach Goat
07-08-2009, 06:05 PM
Sticky.

Atlantalion
07-08-2009, 06:33 PM
<message deleted>

Beach Goat
07-12-2009, 08:52 AM
Bump to the front page.

Mods, please sticky:judge:

CrAzYGOAT
07-12-2009, 09:12 AM
my differential has a symphony of chirps, cluncks, knocks, and whines... but that all dosnt matter cuz im getting a eaton trutrac and 3.91 gears on thursday FACE:turbonaug

RitcheyRch
07-13-2009, 03:19 PM
My diff is making noises on deceleration. Took it into the dealer this morning and a new diff is on its way. Thank gawd for warranty. Hoping this will also eliminate some of the clunking at low speeds.

MB05gto
07-15-2009, 11:34 PM
I noticed my diff. started making noise around 30k, now at 37k acceleration or decel. same howl. I changed the fluid with valvoline synthetic and some fm. within 1500 of the fluid change I now have very loud clunks every time I let out the clutch when I shift.
Got under the car and grabbed an axle shaft and the pinion, turned back and forth to see if any play, there was very little, nothing unusual.
The tranny was in gear, rotated just the drive shaft.. geez it turned almost a quarter turn either direction and made a clanking noise at the tranny..
whats the deal with that?

aquariussuperman
07-16-2009, 12:52 PM
Try putting jacking the rear end up in the air and grab the tire and spin back and forth. That's the clunking sound you're hearing at low speeds. It's scary.

goat1964-2004
07-24-2009, 08:28 AM
I installed a Harrop Diff cover along with Pedders 0 drop springs / shocks last month and have noticed allot of clunking from the back of the car only after I drive and get it warmed up. The car will make these noises when I go from reverse to drive (A4) or when I make really slow turns and go over a few bumps. I also tried the "figure 8's" trick in a parking lot and the posi clutches seem fine.

I have checked for broken welds, loose bolts, loose suspension components, shock mounts, and have added another 1 oz of type "F" friction modifier (total 4 oz) to my Torco fluid just to make sure.

Any suggestions ????

plautz
07-25-2009, 09:52 AM
ever since i installed a hendrix 2 piece I have had a clunk as soon as I shift into R. and then when I shift in to D. and also when it down shifts hard.

2QWK4RU 06 GOAT
08-01-2009, 07:38 PM
I noticed mine was a bit loose with the Torco. When you used a different grade, did you end up using the 90 instead of the 140?No, the thicker fluid worked best. The 75w90 was loud and clunky. The 140 took care of most of the noise.

LETHAL06GTO
08-03-2009, 04:40 PM
I have a slight whine, like a bad bearing, whenever I accelerate the first couple of seconds of each gear. If I let off and the RPMs are low enough and I accelerate again it will make the noise again. It seems like it's coming from the transmission but I'm not 100% sure. Any ideas? I'm going to replacing the tranny fluid tomorrow night and I've already replaced the rear diff fluid. It was making this noise before and after I changed the rear diff fluid.

cblandin
09-05-2009, 04:01 PM
Why do I have a bad feeling we are all in for new diffs...amazing, after all these years, GM just refuses to get it right. It's amazing they haven't gone bankru...oh wait, never mind.

genoliver
04-25-2011, 08:52 AM
I am having problem with driveline noise. a little background, about a year ago I had the 3rd gear sycro fixed and since then I would notice a little unusual vibration coming from trans, but nothing severe and not very often.

About a month ago I replaced the gear shift lever with LSS and found it to get a little noisery but still not dramatic enough to warrant investigation.

Last week I put new shocks on the back along with the differential bushings. Everything went smooth. Most of my driving is short jaunts so I never noticed anything, well yesteday I went for a longer trip and after about 10-15 miles of highway driving 65-70 mph, I started getting a progressively loaded hum and vibration that seem to go through the whole car driveline.

I noticed that when I applied the brakes as I was coming to a stop it would diminish.(my belief is that the brake being applier diminished the sound transfer)

After I let the car sit a while when I started again it would not make the noise but as soon as it appeared that things got up to operating temp the noise would return. done this several times. When first starting no issue, the longer I drive the sounds comes on.

I removed the diff bushing and found that 90% of the noise is gone but I am thinking this is just masking a problem that is there but the diff bushing brought it more to the fore front.

any suggestions.

10kGTO
04-25-2011, 09:55 AM
My 04 GTO A4 has a whine from the rear also.

When I first got the car it sounded exactly like a Eaton supercharger. It was comical but I knew it wasn't a good noise. I made mostly short trips and it was cool out for the first few months.

In warm weather the rear whines really bad above 50mph, only when holding a constant speed or decelerating. Never makes the noise on accelleration. No clunks, no bangs, no crunch.

I changed the fluid and used some Redline, it was ALMOST silent for about 2 months. Now it's getting loud again...but no where NEAR as loud as before. I'm going to do another fluid change after the car comes back from the body shop and see what happens.

On some short 5-15 mile trips it'll never make a noise, other trips especially in warm temps it'll howl at me like a dying dog.

northern_goat
07-12-2011, 11:58 AM
Hey guys, sorry if this has been mentioned/asked before but I'm on the road and have to do this from my phone. Just noticed there is a whirring noise coming from driveline?? Its always there no matter what speed. Does get faster with speed. Any help would be awesome! Oh and its a 6 speed.