C4S front diff issue?

Hi everyone, I'm looking for some reassurance on a front diff issue. Long story short, I've been doing some front suspension work over the last couple of days. In doing all of this I accidentally managed to pull the drive pinion from the front diff (major panic) I removed the drive shaft to the road wheel on that side and by some gentle turning of the connected front wheel I managed to get the drive pinion re engaged on it's internal splines and it went back in. Can this happen? Any chance of internal diff damage? It just seems a bit strange that the diff pinion can become disengaged like this. TIA for any wise words of reassurance!

Hopefully this will give a bit more information. Front diff 1 - Left nearside output shaft from front differential the side I haven't worked on. Front diff 2 and 3 - Right offside (drivers side) output shaft from front diff after reassembly. Coffin arm and suspension strut replaced and all back as should be. Thanks for any help.

Photo 2

Photo 3

If pic 3 is it slotted back in it doesn't look correct, I have my front diff on the workbench replacing the nose cone seal and bearings atm.

Update. I removed the driveshaft to one side and got a block of wood and gently tapped it with a hammer and it went back in as per normal. Relief! A question for anyone that's had the front diff out, do the output shafts naturally slide in and out like this? I'm just a bit concerned that something internal may have come adrift (circlip) that is now loose inside the diff. As always thanks for any help.

There should be a circlip on either side to hold it in place. https://www.design911.co.uk/diagrams/d/40875/ 99633231100 circlip 2,5 X 20

Yep, I think my circlip on that side has broken (hopefully that's all at least). I tried the left hand diff output shaft and only moves a fraction. Obviously, this needs to be sorted as having a circlip AWOL in the diff could be disastrous. So, the decision is to whether I drop the front diff etc or get the car recovered to a local Porsche specialist for investigation. Thank you Nighttrain for your help.

Other option is you could just remove the AWD system for now. Run it as a RWD for a bit. 90% of those who have done this don't go back.

You HAVE to have that circlip on the end of that shaft or it will move in and out .. this will dump the diff fluid and do god knows what . The circlip also needs removing .. its toughened spring steel . You can .. remove the diff .. pull off the cover and remove it .. face up .. don't lose any shims . technically you don't have to set it back up . remove the dif and take to your local garage and let them do it .. If you remove the diff and driveshafts .. i'm out of my comfort zone here .. then i would have thought you need dummy shafts to hold the wheel bearing each side together .. basically turn it into a C2 .. Not sure but that's what i would suspect ... i can't see the wheel bearings staying in one piece otherwise . it won't help but working on our loan car .. a Jag the other week .. removed the driveshaft and the circlip fell off inside the box .. a long extendable magnet and we fished it out .. Turned out to be a previous bodge but the Extendable magnet worked wonders .

Yeah, you need to remove the axle stubs/cv joints from the end of the drive shaft. Or you can buy new ones from design911.com for around £140 the pair, many prefer this than the hassle of taking them apart. https://rennlist.com/forums/996-forum/762585-how-to-convert-your-awd-996-to-rwd.html

Thank you for your replies and advice. This forum is a great resource. My initial thoughts are to get the car recovered to a local Porsche specialist and get them to remove the diff and investigate. It's on axle stands at the moment whilst is was doing some front suspension refresh work, so for me to remove the diff assembly isn't easy... weight and access etc etc. Or am I over estimating the task? Thanks again.

Hi Mark, it's an easy job to remove the diff, mine is on front axel stands only. Tools... axle stand... trolley jack, I had a piece of 4x2 on mine to help. Undo the drive shaft bolts either side of the diff, remove the front and middle support brackets with a trolley Jack under the diff as you do this, then as you lower the diff slightly pull it forward to release the splined rear shaft making sure you have an axle stand in place to support the rear shaft. It's not heavy and can easily be done in your garage or taken to a specialist, if you have the tools you could remove an replace the circlip yourself, these diffs are very basic inside. Cheers, Mark

Hi Mark, it's an easy job to remove the diff, mine is on front axel stands only. Tools... axle stand... trolley jack, I had a piece of 4x2 on mine to help. Undo the drive shaft bolts either side of the diff, remove the front and middle support brackets with a trolley Jack under the diff as you do this, then as you lower the diff slightly pull it forward to release the splined rear shaft making sure you have an axle stand in place to support the rear shaft. It's not heavy and can easily be done in your garage or taken to a specialist, if you have the tools you could remove an replace the circlip yourself, these diffs are very basic inside. Cheers, Mark

Hi Mark, thanks for the advice. I'm pretty OK with mechanics. But haven't dropped a C4S front diff before. From what you say it's pretty simple as I have a trolley jack to hand and have all the necessary tools. As you say it's hopefully just a new circlip and finding the old one that's come adrift. Also a good excuse to replace the oil in the diff which was on my 'to do list'. Cheers Mark