911sc Gear Box rebuild
Discussion
It depends where you are. I use Carrera Perormance for all my gearbox work, they are near Horshem. Cost depends on how much needs replacing, some parts are expensive, but with removal, refit and a couple of synchros and dogs budget above £1000. It may well be a lot more if the clutch needs replacing. Are you sure it needs rebuilding? A lot of gearbox issues can be cured by replacing a coupling of gear linkage bushes and careful setting up of the linkage itself.
Edited by nick-moss on Tuesday 25th September 18:19
The problem with this gearbox is in the synchro ring design.
It has a large C shaped spring which is compressed by a selector ring being forced over it and then it does its stuff to slow down or speed up the engaging gear to shaft speed.
From new they are not precision ground but just black hardened spring steel. The black rough surface makes it difficult to slide the ring over it and hence the difficulty from new.
As they wear they get smoother and the gearchange actually gets better until they wear to a size when the ring eventually slides over without gripping anymore and the dog teeth hit each other and fall off.
As a result of this - a rebuilt gearbox can often feel stiffer and awkward compared to the old one just before it failed - although some smoothing of a new spring before assembly - does improve things.
For this reason - when you are buying a car - finding a nice smooth gearbox in it does not mean it will have years of life left - more often that it is at the end of the cycle and will fail quite soon.
Baz
It has a large C shaped spring which is compressed by a selector ring being forced over it and then it does its stuff to slow down or speed up the engaging gear to shaft speed.
From new they are not precision ground but just black hardened spring steel. The black rough surface makes it difficult to slide the ring over it and hence the difficulty from new.
As they wear they get smoother and the gearchange actually gets better until they wear to a size when the ring eventually slides over without gripping anymore and the dog teeth hit each other and fall off.
As a result of this - a rebuilt gearbox can often feel stiffer and awkward compared to the old one just before it failed - although some smoothing of a new spring before assembly - does improve things.
For this reason - when you are buying a car - finding a nice smooth gearbox in it does not mean it will have years of life left - more often that it is at the end of the cycle and will fail quite soon.
Baz
Just had my g/box out of a '73 car , admittedly only a couple of synchros , basically trying to save some leakage , however inc clutch center plate, £145 , covered in oil,bill less than £1000 ............until u get into full gear sets +++ or pay £100+ per hour labour u wud be very unlucky to spend more than £2k and on normal indy rates more like £1500 max ...............wish rthat were the same for the GT2 !
997GT3 said:
Hespereus - that what happens when you use a car - it wears. Much better leavin it in the garage like I do then nothing wears out!! 
Thats cos' you cant afford the petrol after speccing that beast of yours up with so many extras for the next owner !!!!Edited by Hespereus on Tuesday 25th September 09:02
Hespereus said:
997GT3 said:
Hespereus - that what happens when you use a car - it wears. Much better leavin it in the garage like I do then nothing wears out!!
Thats cos' you cant afford the petrol after speccing that beast of yours up with so many extras for the next owner !!!!Edited by Hespereus on Tuesday 25th September 09:02
Many a true word spoken in jest
give Mike Bainbridge a call. He's one of the best in the business & won't charge you a fortune.
http://www.mbporsche-engineering.co.uk/
http://www.mbporsche-engineering.co.uk/
Edited by hot66 on Tuesday 25th September 14:26
0
Hespereus said:
Thanks for that ... JUst been told it might cost upto £4500 ... I may be an ex-porsche owner if it is that much!
Join the club pal....I'm feeling it for you....having my 964 gearbox totally rebuilt at Ninemeister and been told it will cost just over 4K !!!....Had minor work done before (previous owner) at a very famous independent in the southern area who apparently made mess of the job...now I'm paying the price so be carefull who you choose!Gassing Station | Porsche General | Top of Page | What's New | My Stuff