Porsche 911UK Forum

Welcome to the @Porsche911UK website. Register a free account today to become a member! Sign up is quick and easy, then you can view, participate in topics and posts across the site that covers all things Porsche.

Already registered and looking to recovery your account, select 'login in' and then the 'forget your password' option.

996 gearbox strip down and rebuild?

ELA

Well-known member
Joined
30 Aug 2011
Messages
1,423
Has anyone here tried. I'm thinking about giving mine an overhaul with some trick bearings... just wondered if the likes of Infrasilver or Demort have been down this road.
 
I'm no mechanic, but I'd say its no easy job to dismantle and put back together this box having seen the myriad of bits that come out of one at Sports & Classic (see his website).

Aside from skill and competency it needs specialist equipment to remove bearings and apply the correct pre-loads on assembly.

But you are the one to know your confidence and the equipment you have.
 
Theres apparently a really big press needed for one bearing, and you only get a couple of chances with it in the life of the casting. Also theres some unknowns around sourcing parts for the boxes.

Have a search of the US Porsche forums as more people have documented work on them.

Mike at sports and classic is apparently the UK expert on these having invested in tooling and many indies send boxes there.

So you can take your chances - if you have the tools and presses then go for it. Personally I would look for a used low mileage box.

Would a 997 box fit?!
 
It was originally suggested that the 996 box couldn't be cracked open and serviced.... but there are a number of specialist gearbox rebuilders that now do so relatively routinely.....
- on balance I would definitely send to a specialist and save yourself some grey hair!

My rebuilder preferred me to source the parts i.e. the various bearings and syncros they identified after the strip down, but otherwise didn't seem concerned about the logistics
(pinon gear height is apparently a bit of a big deal with these gearboxes, along with a few casing peculiarities)

I still remember picking up that rather small £1,300 box of parts from the OPC a few years ago........!

I wouldn't play with it myself, but you've already shown yourself to be "braver" that most : )

....not sure about compatibility offhand, but I think I'm right that the 996.2 GT3 had "strengthened"/toughened 2nd and 3rd syncros...?
 
As stated by wasz, the main bearing needs a few ton to press it out. Personally I'd have thought some decent heat around the casing would lower the tonnage required. Any 'arf decent mechanical Engineer shouldn't have a problem with it.
 
I had my 'box done by Mike at Sports & Classic. It'd started doing the dreaded 2nd gear syncro pop-out. There were a few other bits that, one closer inspection, warranted replacement whilst the thing was dismantled.

Every time I visit for a service there's another 996 or 997 (normally GT3 or turbo) in there, minus a gearbox, so he certainly knows the job well. From his description, there are a few tricks to getting the parts replaced and put back together in optimum alignment - this latter, the assembly technique, is what caused a lot of premature failures, as opposed to component or manufacturing failures.
 
Guys thank you for all the ideas. I did a bit of testing today and think it is the diff pinion bearing. I then phoned up Mike at SC and he has confirmed that this is a common issue, usually around the 70-80k miles mark. I was considering cancelling the upcoming UK trip for the Simply Porsche event, but think I will risk it, then drop the box when I get back home. Whilst in there I'm thinking of also throwing in a different diff. It has the Porsche Sports diff from factory (M220 I think it is) but I hear these are likely to be pretty tired in short order.
So any ideas on a good replacement. Nothing too crazy (Fast road rather than Track)?
 
Above jobs can be done in situ. I knarled all the teeth off my diff. pinion (sun) gears ages ago. My man rebuilt the diff. with new gears, bearings, seals, etc. with the gearbox still in the car. Takes about an hour to get the diff. out.

Read hear for more info:

http://911uk.com/viewtopic.php?t=101970

:thumb:

EDIT: Scratch that mate, I was getting mixed up with your diff bearings. Worth checking them first though.
 
I pop around to have a coffee with Mike when I'm out and about and I agree - he nearly always has a Turbo or GT3 gearbox strip and rebuild - and shows me the general state if its dismantled.

He does a series of mods when assembling the gearbox with new parts that he doesnt disclose but in short he claims they extend the life of the gearbox.

He also shows me examples of gearboxes sent to him by another dealer, invariably a non-specialist (courier on a palette) from within the UK as well as abroad and I see first hand some examples of the total c&ck up someone else has made and in desperation they send it to him to sort. That's twice the gearbox is dropped, stripped and rebuilt! Imagine the cost of that!
 
demon said:
....not sure about compatibility offhand, but I think I'm right that the 996.2 GT3 had "strengthened"/toughened 2nd and 3rd syncros...?

That is drifting out of context - the gearbox in the GT3 is a completely different item to that in the Carreras and is completely serviceable to a good gearbox builder. Porsche will rebuild a GT3 gearbox, however they will always exchange a 996 Carrera one.

But your point is in the right area - brass synchros in the 996.1 GT3 gearbox were replaced by steel in the 996.2 equivalent (which IIRC also added an extra gearbox oil cooler). :thumb:
 
Demort said:
@ ELA i think your question has been answered already :D

With any box you need a press .. various pullers , heat and some Paracetamol ;)

:thumb:
 
Demort said:
@ ELA i think your question has been answered already :D

With any box you need a press .. various pullers , heat and a manual ;)

I like the idea of a challenge, but having read a few stories about potential to damage and even established gearbox outfits struggling with the 6speed Getrag unit, I think I'll just do the Beaulieu thing, keep my fingers crossed that the box holds up for the 1200mile journey, then send it to Mike at SC when I get back. In the mean time, I'll drop the oil and check for debris on the mag pick-up before driving over.
Also a 2nd hand unit is no good as it could be worse. I may just be being hyper-sensitive but I think balancing the LWFW/clutch, refreshing/upgrading the GB and throwing in a trick diff will mean worry free motoring for another 100000miles (well the gearbox atleast) :)

Alex/Cheshire911 thanks for all your input :thumb:
 
I agree with your remark about a used gearbox - it could be needing work or it could be worse than your example. If your box is rebuilt, you know where you stand versus an unknown gearbox.
 
Sorry one other thing. What Gearbox oil are people using? I know it's 75W90, I am currently running Motul, but just wondered what brands people recommend? I've heard good things about Redline...
 

New Threads

Forum statistics

Threads
124,353
Messages
1,439,439
Members
48,708
Latest member
JLav211
Back
Top