Bad diff?

[Timing]

Ive been having a clunk in my front end for awhile now and keep thinking i find the problem, fix it then hear it again.
I have,
Replaced both cv axles twice.
Both front wheel bearings.
Both inner and outer tie rods.
Sway bar links/ bushings
Control arms/ ball joints
Strut mounts
Tranny mount/ motor mount
Calipers/ rotors/ pads

This is driving me nuts.Today i put the car on jack stands and had my dad put the car in drive and brake, reverse and brake. I could hear the clunking clear as day from under the car but i cant tell where it is coming from. Seems like the differential. My other thought was the cradle bushings but didnt sound like it was coming from there but it was hard to tell crawling around on my back.

Anyone have any ideas?

[BillBoost37]

Do it again with a screwdriver in hand to use as a stethescope. Although I'd doubt a diff. When diffs make noise, they poke their diff pin through the cover in short time.

[Timing]

Ima try to get it on a lift and check, much easier.

Btw car has 97k and is clean as hell underneath, couldn't imagine the sub frame bushings being bad.

[BillBoost37]

When diff's go bad, you have trouble getting the car to move (worse than open diff) and usually there's a nice trans fluid leak where the aluminum diff cover took a hit from the diff pin or gear etc.

[Explicit_Spade]

My 04 made a clunk when I was shifting from a stop and ocassionally when accelerating. It was caused by my Pacesetter downpipe hitting the firewall or floorboard.

[Timing]

Explicit you bring up a very valid point that i didnt really think of. I did notice the rear is very close to my firewall, like basicly touching. Ima jack it up this afternoon again and find out for sure. I cant go much longer with this clunk.

[BillBoost37]

Driving ...is driving you nuts eh?

[Timing]

Its worse than having a squeeling belt. Everytime i take off or stop at a stop sign or light everyone looks at me like im some hack that doesnt take care of his ****.

[BillBoost37]

Meanwhile, you're the retentive guy who works on the car til 3am to try and cure this clunk for the last 3 months. lol

[Timing]

Meanwhile, you're the retentive guy who works on the car til 3am to try and cure this clunk for the last 3 months. lol

Spot on fml

[BillBoost37]

Well...what did you come up with last night?

[Timing]

Well...what did you come up with last night?

Meh didnt have a chance to get to it. As soon as the miss got home i got a call from my dad to go grab his truck out fo town cus he had the tranny rebuilt and by the time i got back it was dark and its getting a little to chilly at night to be sitting outside undernieth the car.Maby tomarrow morning after i get back from hunting.

[Timing]

Well finnally got under thee yesterday and rechecked all my bolts and everything was good cept for the tranny mount i put in was a little loose so i retightened those. Rear header was close but not hitting. Im pretty sure its the subframe bushings even though the car has only 97k. I ordered the bushings but the only ones i can seem to get are the ones rockauto lists and i believe they are the fronts. So if anyone has a partnumber for the rear ones through dorman or something that would be great. Im goign to drop the subframe on wends and check them and see how they are and also while im at it make sure its not my rack bushings. I also thought about possibly just making them out of polly but unsure untill i look at them and get an idea.

[BillBoost37]

There is only one bushing for the rack, on the pass side.

[Mr D]

OP, I have 03 GTP, and similar issues. At about 125k, I got a progressively bad shift bang into 1st. Did a zzp shift kit, then a TEP shift kit. Then noticed a "hum" from front right. All along I have a clunk from front right/underneath when engaging gear from stop, or reverse. Did a bunch of reading, and found hum is symptom of bad diff and bad water pump. Within weeks of noticing hum, I got a LOT of right wheel spin, all the time. It was fun to chirp it at 30, but I knew it was wrong. So I replaced the diff and hum, and right wheel spin were fixed. It never leaked and the case, and everything else was still good, from what I could see. Still had shift-bang and clunk. I recently replaced the shift solenoids and shift bang is gone. I intended to change the subframe bushings too, but couldn't come up with a way/don't have the tools to get oe out and they didn't appear bad, so I left oe in. 04 is different design, but when I bought my subframe bushings I found that Dorman and Napa have fronts, but rear subframe bushings are not as readily available, got them from gmpartsgiant.com. Use the diagram. Enter your vehicle info, select from "section": body mnt'g, a/c, ..., select from "component": body mnt'g, select view info, select view. Not cheap and slow shipping, but IMO better than the stealership.

Let us know when you get it right!

[Timing]

OP, I have 03 GTP, and similar issues. At about 125k, I got a progressively bad shift bang into 1st. Did a zzp shift kit, then a TEP shift kit. Then noticed a "hum" from front right. All along I have a clunk from front right/underneath when engaging gear from stop, or reverse. Did a bunch of reading, and found hum is symptom of bad diff and bad water pump. Within weeks of noticing hum, I got a LOT of right wheel spin, all the time. It was fun to chirp it at 30, but I knew it was wrong. So I replaced the diff and hum, and right wheel spin were fixed. It never leaked and the case, and everything else was still good, from what I could see. Still had shift-bang and clunk. I recently replaced the shift solenoids and shift bang is gone. I intended to change the subframe bushings too, but couldn't come up with a way/don't have the tools to get oe out and they didn't appear bad, so I left oe in. 04 is different design, but when I bought my subframe bushings I found that Dorman and Napa have fronts, but rear subframe bushings are not as readily available, got them from gmpartsgiant.com. Use the diagram. Enter your vehicle info, select from "section": body mnt'g, a/c, ..., select from "component": body mnt'g, select view info, select view. Not cheap and slow shipping, but IMO better than the stealership.

Let us know when you get it right!

Well then thankyou. I am going to get under there after work and remove the subframe bolts to check bushings and check if rack is tight. But now that your saying that about the wheel wpin on one side i did notice that when taking off quick the car seems to pull to one side a bit, motor trans mount are good, brakes are good, ect. Also when i had jacked it up and was having my brother in law put it in drive/brake reverse/brake to immitate the sound i noticed the left wheel would spin but the right wouldnt with it. Idk how these diffs are setup. If there is no weight on the vehicle will only one side spin?

[Mr D]

Sorry, but I have no idea what is supposed to happen when its on a lift/jacks.

The diff is at the right, very end of the transaxle. These cars are innately 1-wheel wonders and, as designed, torque steer (pulling when under load) is inevitable. The left side should get more power to the ground, that's why when I had right wheel spin, I knew something was wrong. Seriously, in my case, it was dumb luck that nothing else was wrong.

The diff has a bunch of interlocking gears, which is why I THINK, it hums when it starts to get sloppy--loose gears spinning fast=hum. Seems to me, if something in there (diff/trans side cover) is clunking, then the diff is not sloppy, its broken, its in pieces--then you get the leaks, broken case, lose parts grinding away your internals.... Seems like with what Explicit and Bill said, and what I experienced, I would keep looking before I opened up the trans. IDK

[BillBoost37]

Don't get me wrong, I've seen a few diffs that started to self destruct and were caught in time. It's not typical though. Usually the roll pin pops/breaks and the main pin in the diff will start to move.

Here's one that blew enough stuff into the trans (Intense LSD) that the filter plugged.


This one was about to poke through the casing


Luck of the draw..I pulled the cover to move something over and the pin nearly hit me in the forehead


Once in a while, you'll tear up the planetaries with shrapnel, this started as a bad diff pin

[Timing]

So I finally corrected the clunk. Anyone care to bet what it was?

[rodguezsciii]

So I finally corrected the clunk. Anyone care to bet what it was?

diagonal braces?