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Discussion summary
YOUR RESEARCH996 C4 Transmission Issue
Leading reported evidence
Install when the car was relatively new
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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0
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1
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Performed · outcome unconfirmed · Original poster
A bit of history on the car: when I bought it, it had a supercharger installed when the car was relatively new.
Leading evidence: 'Install when the car was relatively new' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Install when the car was relatively new' (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.
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Suggestion · Original poster
Drained the fluid (less that 10000 miles since last change) and it was black but sparkling like black metallic paint.
Replace front pinion bearing, typically about 35 tons
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Suggestion
As noted, you need a 50 ton press to get the gears and one of the bushings off the pinion shaft, if your goal is to replace the front pinion bearing, typically about 35 tons on the gauge while pressing.
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Suggestion · Original poster
Or third solution, should I replace the transmission with a used one?
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Suggestion
But the one set I did, the fancy tool set made it a breeze..
Replace front pinion bearing, typically about 35 tons
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Suggestion
As noted, you need a 50 ton press to get the gears and one of the bushings off the pinion shaft, if your goal is to replace the front pinion bearing, typically about 35 tons on the gauge while pressing.
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13 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261026T052503Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Hi, my '99 996 C4 started developing a very nasty grinding noise especially when decelerating. We identified that the noise was coming from the transmission. Drained the fluid (less that 10000 miles since last change) and it was black but sparkling like black metallic paint. The oil was full of millions of tiny aluminum flakes.
A bit of history on the car: when I bought it, it had a supercharger installed when the car was relatively new. So I suspect that a good number of the 92000 miles it had when I got it were done under supercharger load. I removed the supercharger, not feeling the need for the extra 120hp, about 1500 miles ago. The car has now 102000miles. After doing some reading on the transmission (G96.30) it seems that the bearings may have been compromised by the extra load of the supercharger. I need to mention that the gears shift perfectly fine with no grinding.
My mechanic is about to take down the transmission and open it up to assess the damage.
If only the bearings are damaged, should just change the bearings and call it a day or should I rebuilt the transmission for peace of mind. Or third solution, should I replace the transmission with a used one? A friend told me that I should keep numbers matching but I'm not sure that's really necessary.
Any advice?
Thank you in advance.
Everything I can find on the Getrag, only guys who have bled hard can rebuild them, the parts are not readily available via Porsche,
they just want to sell the assembly, the trans shares a ton of its parts with other Getrag boxes, but its an Easter egg hunt to do a full rebuild.
GBOX gets about 5K for a rebuild assuming no real major things are ruined.
By the time you change the bearings you'll have spent a fair chunk of the rebuild
cost depending on which bearings your going in after.
In the 996 transmission, the gears are pressed onto the shafts. You need a 30 ton press, so this is not a job for the average DIY. If you are seeing a lot of aluminum flakes, do not drive it anymore and get it fixed before more housing components are ruined. The aluminum is coming from the transmission housing parts because all the other gears, shaft, bearing shift forks, etc are steel. You cold send a note to zbomb concerning costs, he just had his tranny rebuilt. Good luck with it.
Markl
The 30 ton press is the easy part, there also used to be a 4500 dollar set of accessories to grab the gears in the press.. Without them, you will break teeth... BTDT...
Thank you everyone for the very useful info. I've decided to go with trying to source a used one. So if you hear of one with under 100000 miles please ping me.
I have rebuilt a bunch of G96 (your 996) transmissions for my customers. Yes, they are difficult to work on. As noted, you need a 50 ton press to get the gears and one of the bushings off the pinion shaft, if your goal is to replace the front pinion bearing, typically about 35 tons on the gauge while pressing. You also frequently need about 20 tons of pressure to press apart the input shaft (aka. mainshaft). Just getting the gear housing on and off is a hassle because of how the roller on the longer shift selector sits in its collar on the central selector shaft!
(I don't know what the $4500 tool set is that pdx refers to. The gears are supported properly and safely with some generic steel blocks / shafts in the press while taking them off the pinion shaft. There were some long press tubes Porsche listed in the tools catalog for the G96 at some point in time, NLA, but other press tubes work just fine.)
Regardless of these details, given what you've seen, the transmission is going to have to come apart for service. I am not certain what the source of your noise is. The aluminum, if its that, in your fluid could be from a shift fork, or from some part of the case, dunno. Feel free to ping me if I can be helpful to you in getting this sorted.
Joe Cogbill has been racing and rebuilding Porsche gearboxes for over 40 years. Price was reasonable ($3,750 with your 996C4 core swap) with a two year warranty.
Just thought I would cast that out there for ya.
https://www.cogscogs.com/
Hey, thank you for the hint. I called them and spoke to a very nice lady. The owner will call me back tomorrow to discuss my options. They seem very professional.
Yes, Joe is a really good guy and he has a great collection of 996's in his Porsche Graveyard for parts.
I have not been disappointed working with him yet... he and Kim have got some pretty good racing stories too. 😁👍🏾
The few Getrags I've been in to, there were some very specific clamshells needed to part the gears while pressing them off, Now its entirely possible skill is the actual winner
LOL
But the one set I did, the fancy tool set made it a breeze.. They just held the gears right. It was a kit and called a getrag service pack back when I was fiddling with it.. (Blue box that had GETRAG molded in to it/
Toyota had a similar thing back in the M54 trans days, if you didn't use the kit, chipped teeth were pretty much a absolute.. But again,, Skill over my skills probably wins..
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