27 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCH2003 4s Front Diff replacement/repair
Reported or suspected cause
pinion bearing in the transmission
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that report identifying a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Reported cause
Still had the whine and it turned out to be the pinion bearing in the transmission which I had rebuilt by Gbox.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion · Original poster
Took my car in for oil change and post-cat O2 sensor replacement, asked indy to check on new whining/drone sound coming from front end at high speeds whenever off the throttle.
Leading evidence: 'pinion bearing in the transmission' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'pinion bearing in the transmission' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check on new whining/drone sound coming' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed
Precision Motion in Colton, CA rebuilt my diffs and replaced my seals.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed · Original poster
I ended up picking up a 40k mile used differential from a local RL member, taken from a 996tt, for $300.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed · Original poster
This isn�t a problem that will total the car by any means and luckily many used differentials are available due to all the AWD to RWD conversions.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion · Original poster
Took my car in for oil change and post-cat O2 sensor replacement, asked indy to check on new whining/drone sound coming from front end at high speeds whenever off the throttle.
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
Check on new whining/drone sound coming
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion · Original poster
Took my car in for oil change and post-cat O2 sensor replacement, asked indy to check on new whining/drone sound coming from front end at high speeds whenever off the throttle.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
27 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
2 acknowledgements have no verified action link; they do not establish a repair result.
Took my car in for oil change and post-cat O2 sensor replacement, asked indy to check on new whining/drone sound coming from front end at high speeds whenever off the throttle. Car now has 52,750 miles with 31,000 in the past 24 months alone. Sound disappears as soon as throttle is engaged. Report back that front differential needs rebuild or replacement. Did a quick RL search and see some old posts but nothing very recent. Anyone have any info on shops that can rebuild? Can a used one be trusted? Anyone selling one? Appreciate any helpful comments/suggestions.
Am I limited to just the 996 version or would a 997.1 4s front diff work as well?
Thanks
Also interested in this subject. By the description it seems to rule out front wheel bearings and axles. And the description of the sound is similar to transmission bearing failures. Might be worth a call to Rancho Transaxles in Fullerton, CA. They are well known in the Vanagon Syncro world which has a front diff with a VC very similar to the 4S.
Indy was positive of his diagnosis and there was even a small leak noted. Mentioned carrier bearing issue. When i got home i noticed a small stain on the garage floor that i hadnt noticed previously corresponding to front diff area.
Are you a DIY type? The front diff isn't very complicated. Where in the differential is the sound coming from?
997.1 diff will physically swap in, but the gear ratio is different. You'd want to run 997 spec tire sizes.
I believe the sound is coming from the carrier bearing if I understood my indy. He made a suggestion of buying a used diff off ebay and sending it off for rebuild since (1) you never know how good a used one is and (2) it would allow me to keep driving until the newly acquired diff is back from rebuild and ready for installation. New ones are about $5k, trying to avoid that if less expensive alternatives are practical.
I would have guessed yes, but checked, and looks like the same part numbers..
Here is the PET for the 996 (inc. C4S).
http://www.autoatlanta.com/porsche-p...section=305-10
and the Turbo:
http://www.autoatlanta.com/porsche-p...section=305-10
A couple of years ago I had a whine that I thought might be the front differential so I bought another used one and installed it. Still had the whine and it turned out to be the pinion bearing in the transmission which I had rebuilt by Gbox. I still have the original differential that I would sell if you are interested.
FYI, CMS (CaliforniaMotorSports) charges $1,100 to refurbish 996 front differential, turn around time of less than 2 weeks. Spoke with Roger who was very informative and helpful. Will update as things develop. Still waiting to hear back from Precision Motion as recommended above.
Just wanted to update this thread. I ended up picking up a 40k mile used differential from a local RL member, taken from a 996tt, for $300. Showed no signs of leakage and had the flanges intact. Decided to have my indy do a straight swap rather than sending it or my existing one out for refurbishment. Picked my 4s up today in the pouring rain, drove home 15 minutes, but already can hear/feel the difference ....no more whining sound when off throttle and overall significant reduction in NVH. Can't wait for better weather to take it on a longer drive with windows down and confirm success.
Went for a longer ride this morning and the difference is night & day. Not only are all whining sounds gone, but all front end harshness I had been feeling/hearing, especially a slight rubbing sensation I've been complaining about for over a year through the steering wheel, is gone! Car feels like it day Day 1 again. Super happy.
I saw many for sale on ebay at various prices. Shop I consulted with mentioned they had good luck with straight swaps of low mileage ones vs spending $1,100 for refurbishment of seals and bearings. Obviously recommended finding lower mileage one and possibly one from a non turbo since turbos tend to get driven harder. Told me to avoid any with leaks or missing flanges.
From what i've learned it starts with a leak. Then noise comes from carrier bearings. I was told it was safe to drive until i picked up the replacement but I assume if the leak is large (mine was very light, hadn't even really noticed any stains on my garage floor) that the gears can fail and cause more significant issues. My indy seemed to indicate this was a known issue (maybe more on 996tt models) and many got replaced under warranty. Seen posts where people replace seals and bearings as DIY project. Not something I was comfortable trying. One shop I consulted recommended examining the diff fluid if you have a leak. If no metal particles are present then a rebuild of seals and bearings should work, whereas metal showing up in the fluid would be a sign the gears had suffered damage and most likely the part is toast.
Glad this worked out for OP -
Curious where these "leak" from. Where the axle enters the box? I have a slight whine, hard to tell if it decreases on throttle but it is there coasting in neutral. I don't have any leak as far as I can tell but want to take a closer look.
Thanks!
I believe the leak is at that spot, yes. the flange? I had the coasting sound as well. Might suggest a flush, change, and examination of differential fluid. Might be a cheap fix.
Oh man, just another thing to worry about now! First I'm hearing/reading of this issue. Of course I'm reading about it after a week and 2 days of picking up my C4S. Glad it worked out for you.
I push my car hard but dont track it. Assume that puts added stress on the differential. This isn�t a problem that will total the car by any means and luckily many used differentials are available due to all the AWD to RWD conversions. Even the parts to fix it DIY aren�t expensive. In my case labor was the majority of the cost, but worth every penny as the car feels refreshed.
I doubt tracking has anything to do with it. The diff only allows 2-5% power going to the front and it takes a whole lot of rear tires slipping for the fluid to heat up and send more power to the front. I'd guess that it never actually does send more power to the front. Even with rear slipping the PSM will then come on and brake the slipping wheels, preventing and power to be transferred to the front. I think that the age is why this happens the seals don't last forever.
This is a source reference. Confirm exact model applicability in the original material.
