Front diff
11-07-2009, 11:45 PM
#1
Pro
Thread Starter
Front diff
Front end crunching getting worse. Wifey gettin worried and scared to drive.
Been trying to do a little research since the final diagnosis is scheduled for monday when i can get some lift time. The crunching in the front end is prolly gonna be wheel bearings ($40) or the front diff ($2300). if u knew my luck its an even money bet which one its gonna be. After checking alldata which says the unit can be removed without taking down the cradle with a R&R in 4.2 hrs. Seems a little short. Has anyone done this job? With or with dropping the cradle? Any info greatly appreciated.
TIA,
Scott
Been trying to do a little research since the final diagnosis is scheduled for monday when i can get some lift time. The crunching in the front end is prolly gonna be wheel bearings ($40) or the front diff ($2300). if u knew my luck its an even money bet which one its gonna be. After checking alldata which says the unit can be removed without taking down the cradle with a R&R in 4.2 hrs. Seems a little short. Has anyone done this job? With or with dropping the cradle? Any info greatly appreciated.
TIA,
Scott
11-08-2009, 12:25 PM
#2
Board Certified Porsche Trauma Surgeon
Cayenne Grief Counselor
Rennlist Member
Cayenne Grief Counselor
Rennlist Member
Front Diff R&R can be a pain in the ***. First thing is make damn sure you get the correct diff from your parts source. There is 3 different final drive ratios, (v-6, S, and Turbo). V48/00 is the "S" 4.1 ratio, V48/50 is the Turbo, 3.7 ratio. I don't have the v-6 numbers in front of me, but I think it is a ratio of 4.5. You know how "Parts personnel" are!! There ego is far superior to there parts knowledge in most cases. 
If you can get the WM instructions that would be a big help. Be carefull with the inner C.V. joints. If you over extend them, they will come apart!! NOT a good day!!!
I have never seen a front diff cause a "crunching noise" per se, I have only done a few for moaning type noises, probably a pinon bearing. But we do not tear them down, out with old, in with the new. Under what conditions does the car make the crunching noise? I have seen 16mm sockets that techs have dropped when doing coils/plugs on bank 1 passenger side. The socket gets wedged between the engine cradle and engine (or front diff housing). It makes all sorts of racket, grinding, crunching etc. Lower control arm bushings fail too. At low speeds, less than 10mph, apply fast, quick stabs to the brake pedal, if you get a big clunk, then your lower control arm bushings are junk. If your are convinced that it is the front diff, then I will post some of the key points from the WM on the R&R procedure. OR someone else with that capablity can do the same.
If you can get the WM instructions that would be a big help. Be carefull with the inner C.V. joints. If you over extend them, they will come apart!! NOT a good day!!!
I have never seen a front diff cause a "crunching noise" per se, I have only done a few for moaning type noises, probably a pinon bearing. But we do not tear them down, out with old, in with the new. Under what conditions does the car make the crunching noise? I have seen 16mm sockets that techs have dropped when doing coils/plugs on bank 1 passenger side. The socket gets wedged between the engine cradle and engine (or front diff housing). It makes all sorts of racket, grinding, crunching etc. Lower control arm bushings fail too. At low speeds, less than 10mph, apply fast, quick stabs to the brake pedal, if you get a big clunk, then your lower control arm bushings are junk. If your are convinced that it is the front diff, then I will post some of the key points from the WM on the R&R procedure. OR someone else with that capablity can do the same.
11-09-2009, 11:59 PM
#3
Pro
Thread Starter
Drove her car to the shop today. Ran it all over the parking lot for the slow stuff she has reported. the worst noise is backing with a lot of steering lock. I also found a heavy thumping under full accel . you can feel it across the front axle. She didnt tell me bout that one. Put it in the air and the noise is coming from the diff. Used a Steelman and no noise from either upright. checked the control arms and they look good. No low speed clunks. Looked for socket surprises with no luck. Pulled the PSM fuses, put her in drive and held either wheel. The noise sounds bad, even worse with the headphones on. Definitely the diff. Now the search goes on for one. Thanx for the help.
01-14-2010, 09:47 AM
#7
Pro
Thread Starter
what a PITA. possibly the worst job I have ever done with little gratification. Yea the noise is gone, but there is no smile and happiness afterward. Like replacing the boiler in your house. No fun but has to be done. We tried a partial drop of the cradle and we were able to get it out. Did i say it was a PITA? I opened the box but could not see any definitive answer for the noise. The bearings were intact but I am no pro when it comes to diagnosing tranny's. We did see some markings on the ring gear but they looked manufactured as opposed to misalignemt from the pinion. I still believe the passenger side bearing was the culprit. As a precaution, since I am going to need a full brake job soon, I am going to replace the wheel bearings. I have to almost strip the uprights anyway. This way there are all new bearings everywhere on the front end. Just another addition to the p!g list.
Last edited by SCOTITUDE; 04-04-2010 at 01:48 AM.
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01-14-2010, 11:17 AM
#8
Board Certified Porsche Trauma Surgeon
Cayenne Grief Counselor
Rennlist Member
Cayenne Grief Counselor
Rennlist Member
what a PITA. possibly the worst job I have ever done with little gratification.
I told ya so
, good job on getiing it done.
01-14-2010, 10:21 PM
#9
Pro
Thread Starter
the more I dig on this p!g the more I wanna find a VW engineer and beat the snot out of him. I made a joke during the job that I bet it takes 2 bolts and 2 minutes to drop the same part out of my yukon. I was under the Yukon today and I wasnt far off.
01-22-2010, 08:02 PM
#11
Pro
Thread Starter
spent about 9 hours on it. I was in no rush plus didn't want to screw anything up.
the engine needs to be supported as the bottom engine crossmember needs to be moved out of the way.
the engine needs to be supported as the bottom engine crossmember needs to be moved out of the way.
09-24-2010, 01:42 PM
#14
Burning Brakes
Scott.......still stuck in Austin so I cannot find a weekend yet to try the brake job...........
I have a question on this old thread........when i drive down the high way, I feel a wobble and I am pretty sure its not alignment......when I go to park, there is a heavy grinding/rubbing noise when i turn into the spot.
wondering if these is CV joints or pinion....or does that mean the same thing
....
My jeep was the thing I always cursed and had as a back, looks like they might flip flop for a week!
I have a question on this old thread........when i drive down the high way, I feel a wobble and I am pretty sure its not alignment......when I go to park, there is a heavy grinding/rubbing noise when i turn into the spot.
wondering if these is CV joints or pinion....or does that mean the same thing
....My jeep was the thing I always cursed and had as a back, looks like they might flip flop for a week!
09-24-2010, 04:07 PM
#15
Pro
Thread Starter
i think you have 2 different issues there. The tight turning into the parking spot I found to be the CV's in the axles. Dealer price for new was not an option,$800 ea, vertex around $500 ea, so I had them rebuilt by a local shop for $100 each. I just saw one on ebay new for just over $200 so there are plenty of options. As far as the highway wobble I would rebalance the tires first. Then check the wheels for bearing movement. I changed out the bearings as a while i was in there.