G50 refurb advice
Discussion
having a few minor issues with a leak from my G50 5 speed which looks to be the seal between the diff/main section, having had a chat on impact bumpers forum it looks like to change that seal the box needs splitting down fully.
while i'm doing that much work i might as well get the bearings checked/replaced etc, any suggestions who might be willing to do this and wont rip my eyes out at the same time?
box would be removed and drained ready for inspection/overhaul etc.
cheers
while i'm doing that much work i might as well get the bearings checked/replaced etc, any suggestions who might be willing to do this and wont rip my eyes out at the same time?
box would be removed and drained ready for inspection/overhaul etc.
cheers
To replace the diff housing to centre gear casing gasket requires the end casing and gears to come off before the centre case so a 'partial strip' is minimum; the input and output shafts essentially remain 'built'. A full strip/inspection and rebuild will be more expensive but gives peace of mind and better performance.
Sportsandclassic - Mike's on here and a transmission specialist
I'd do it @ PC Swindon try us for a price to compare?
Sportsandclassic - Mike's on here and a transmission specialist
I'd do it @ PC Swindon try us for a price to compare?
Unit 11 www.unit11.co.uk know these well - they rebuilt mine in my 964 race car at very reasonable cost.
Sports and Classic can do it too (labour rates slightly higher) www.sportsandclassic.com
Hartech www.hartech.org may do it too (they will certainly be able to, but tend to be very busy with later cars now).
These are places I know and have used but there will be plenty of others around the country too. I think I'd choose Unit 11 because, besides their low labour rates and experience of these boxes, if any parts are worn there's more chance of them having good used parts available on the shelf as an alternative to new parts (which are sometimes eye-wateringly expensive for these 'boxes). HTH
Sports and Classic can do it too (labour rates slightly higher) www.sportsandclassic.com
Hartech www.hartech.org may do it too (they will certainly be able to, but tend to be very busy with later cars now).
These are places I know and have used but there will be plenty of others around the country too. I think I'd choose Unit 11 because, besides their low labour rates and experience of these boxes, if any parts are worn there's more chance of them having good used parts available on the shelf as an alternative to new parts (which are sometimes eye-wateringly expensive for these 'boxes). HTH
G50 does not have an internal pressure pump, so no oil pressure.
Clean the seam with brake cleaner and smear with RTV sealant before taking the box out.
The diff housing is bolted to the main gear housing by the ring of M8 nuts that you can see. If you are good enough to get the box out, you could probably do the rest. The oil seal on the input shaft is the most difficult bit, but not if you have a piece of tube the right size to press in a new one.
Time to take diff out, lift off diff housing, replace oil seal, clean faces, fit new gasket and reassemble is less than an hour.
Replace the clutch if anything, if the bearings/synchros aren't broke don't fix them.
Clean the seam with brake cleaner and smear with RTV sealant before taking the box out.
The diff housing is bolted to the main gear housing by the ring of M8 nuts that you can see. If you are good enough to get the box out, you could probably do the rest. The oil seal on the input shaft is the most difficult bit, but not if you have a piece of tube the right size to press in a new one.
Time to take diff out, lift off diff housing, replace oil seal, clean faces, fit new gasket and reassemble is less than an hour.
Replace the clutch if anything, if the bearings/synchros aren't broke don't fix them.
thanks for the replies, just to clarify its the main body seal by the look of it ie the mid section. apparently the rear section is easily removeable after dropping the oil to do that seal which i would attempt, but this one is where the main gear section mates to the front of the box/bellhousing, so assuming thats the one requiring a full strip with the main shafts out. its not the diff housing seal, thats bone dry.
the mention of sealant is an interesting one as its only a very minor weep, when the box gets very warm on trackdays. i can remove the mount and get to the faces i reckon, it might be worth a try.
the box is mounted upside down in a t70 replica, so the breather is now the sump and the sump is a breather, its worked very well for 3 yrs and still had almost the full amount of oil in it so it hasnt lost much, it just gets messy under the box after a while.
i can get the box out fairly easily, (half days work) any ideas of what sort of cost i'd be into to have it stripped and sorted with new seals (and any bearings etc). its not noisy at all, i run a quaife diff i fitted a long time back and the clutch was new last season, so hoping to keep costs down.
my only real issue is the trackday season starts for me in april, and i'd need to make a decision soon to remove it or not, or take a slight chance on some external sealant holding it back.
its not peeing out and i ran it like this for the last 2 trackdays of last season with no issues, other than a wipe down clean afterward, but obviously its not great to keep doing this.
i have nipped some of the bolts up that had worked slightly loose on that section, the gearbox mount picks up on 3 of them so they had slackened slightly, i'm also hoping that helps a bit.
mmm. what to do!
the mention of sealant is an interesting one as its only a very minor weep, when the box gets very warm on trackdays. i can remove the mount and get to the faces i reckon, it might be worth a try.
the box is mounted upside down in a t70 replica, so the breather is now the sump and the sump is a breather, its worked very well for 3 yrs and still had almost the full amount of oil in it so it hasnt lost much, it just gets messy under the box after a while.
i can get the box out fairly easily, (half days work) any ideas of what sort of cost i'd be into to have it stripped and sorted with new seals (and any bearings etc). its not noisy at all, i run a quaife diff i fitted a long time back and the clutch was new last season, so hoping to keep costs down.
my only real issue is the trackday season starts for me in april, and i'd need to make a decision soon to remove it or not, or take a slight chance on some external sealant holding it back.
its not peeing out and i ran it like this for the last 2 trackdays of last season with no issues, other than a wipe down clean afterward, but obviously its not great to keep doing this.
i have nipped some of the bolts up that had worked slightly loose on that section, the gearbox mount picks up on 3 of them so they had slackened slightly, i'm also hoping that helps a bit.
mmm. what to do!
Edited by 200Plus Club on Saturday 21st January 22:44
Pope said:
To replace the diff housing to centre gear casing gasket requires the end casing and gears to come off before the centre case so a 'partial strip' is minimum; the input and output shafts essentially remain 'built'. A full strip/inspection and rebuild will be more expensive but gives peace of mind and better performance.
Sportsandclassic - Mike's on here and a transmission specialist
I'd do it @ PC Swindon try us for a price to compare?
any parts diagrams online that show this seal clearly?Sportsandclassic - Mike's on here and a transmission specialist
I'd do it @ PC Swindon try us for a price to compare?
It is a shim that spaces the ring gear off the pinion shaft between the mainhousing and the diff housing. I just looked in my Porsche G50 workshop manual.
The main shafts are carried in the main casing and the rear housing accesses the main and secondary shaft collared nuts, but you don't need to go there.
The main shafts are carried in the main casing and the rear housing accesses the main and secondary shaft collared nuts, but you don't need to go there.
1point7bar said:
It is a shim that spaces the ring gear off the pinion shaft between the mainhousing and the diff housing. I just looked in my Porsche G50 workshop manual.
The main shafts are carried in the main casing and the rear housing accesses the main and secondary shaft collared nuts, but you don't need to go there.
do you mean thats causing the leak do you think? not sure what you mean with regard to the shim?The main shafts are carried in the main casing and the rear housing accesses the main and secondary shaft collared nuts, but you don't need to go there.
cheers
looking at the parts diagram there it does indeed look like the shim3 is the joint between the 2 sections.
just had a call back from Nick at Redtek as i'd emailed him last night and he was good enough to chat about it today ,so i have a good idea of whats needed if it is just seals/shims etc.
still got to decide if the box should come out or not, its about half a day work and a mate to lift it with but Nick mentioned it was unusual to get that leak from that spot.
just had a call back from Nick at Redtek as i'd emailed him last night and he was good enough to chat about it today ,so i have a good idea of whats needed if it is just seals/shims etc.
still got to decide if the box should come out or not, its about half a day work and a mate to lift it with but Nick mentioned it was unusual to get that leak from that spot.
Hi,
There seems to be a lot of confusion here over what is actually leaking and the place you describe as
leaking is the diff/ bell housing to gearbox centre casing. Those two casings are sealed together with a paper gasket. Not a shim. The shim sits on the bell housing/ diff housing and sets the pinion height not the ring gear height as someone pointed out. They do not form any seal between the casings.
This type of repair is a straight forward repair as no re shimming is required unless you are replacing bearings.
Just bear in mind that not all companies have the required and essential tooling to carry out the pinion height or diff setup.
We have done gearboxes for a lot of Porsche specialist companies and main dealers as they do not have the know how or tooling to repair the boxes. (including names mentioned already)
I would estimate that that repair would cost in the region of £450 plus vat. This would include new gasket set and labour.
This would not how ever cover any inspection of internal bearings or synchro rings/hubs and forks. As this is used in a track car I personally would be upgrading a few componets and then you can put it to the back of your mind as its been sorted and less chance of giving trouble in the track season.
Mike
There seems to be a lot of confusion here over what is actually leaking and the place you describe as
leaking is the diff/ bell housing to gearbox centre casing. Those two casings are sealed together with a paper gasket. Not a shim. The shim sits on the bell housing/ diff housing and sets the pinion height not the ring gear height as someone pointed out. They do not form any seal between the casings.
This type of repair is a straight forward repair as no re shimming is required unless you are replacing bearings.
Just bear in mind that not all companies have the required and essential tooling to carry out the pinion height or diff setup.
We have done gearboxes for a lot of Porsche specialist companies and main dealers as they do not have the know how or tooling to repair the boxes. (including names mentioned already)
I would estimate that that repair would cost in the region of £450 plus vat. This would include new gasket set and labour.
This would not how ever cover any inspection of internal bearings or synchro rings/hubs and forks. As this is used in a track car I personally would be upgrading a few componets and then you can put it to the back of your mind as its been sorted and less chance of giving trouble in the track season.
Mike
Pope is right, the collared nuts do have to come off the shafts, it is a long time since I rebuilt a G50.
This is a 930, but it is similar. If you strip down your box look at the oil channels, running upside down might need an exterior pipe to connect the compartments so they act like a sump.
This is a 930, but it is similar. If you strip down your box look at the oil channels, running upside down might need an exterior pipe to connect the compartments so they act like a sump.
sportsandclassic said:
Hi,
There seems to be a lot of confusion here over what is actually leaking and the place you describe as
leaking is the diff/ bell housing to gearbox centre casing. Those two casings are sealed together with a paper gasket. Not a shim. The shim sits on the bell housing/ diff housing and sets the pinion height not the ring gear height as someone pointed out. They do not form any seal between the casings.
This type of repair is a straight forward repair as no re shimming is required unless you are replacing bearings.
Just bear in mind that not all companies have the required and essential tooling to carry out the pinion height or diff setup.
We have done gearboxes for a lot of Porsche specialist companies and main dealers as they do not have the know how or tooling to repair the boxes. (including names mentioned already)
I would estimate that that repair would cost in the region of £450 plus vat. This would include new gasket set and labour.
This would not how ever cover any inspection of internal bearings or synchro rings/hubs and forks. As this is used in a track car I personally would be upgrading a few componets and then you can put it to the back of your mind as its been sorted and less chance of giving trouble in the track season.
Mike
thanks MikeThere seems to be a lot of confusion here over what is actually leaking and the place you describe as
leaking is the diff/ bell housing to gearbox centre casing. Those two casings are sealed together with a paper gasket. Not a shim. The shim sits on the bell housing/ diff housing and sets the pinion height not the ring gear height as someone pointed out. They do not form any seal between the casings.
This type of repair is a straight forward repair as no re shimming is required unless you are replacing bearings.
Just bear in mind that not all companies have the required and essential tooling to carry out the pinion height or diff setup.
We have done gearboxes for a lot of Porsche specialist companies and main dealers as they do not have the know how or tooling to repair the boxes. (including names mentioned already)
I would estimate that that repair would cost in the region of £450 plus vat. This would include new gasket set and labour.
This would not how ever cover any inspection of internal bearings or synchro rings/hubs and forks. As this is used in a track car I personally would be upgrading a few componets and then you can put it to the back of your mind as its been sorted and less chance of giving trouble in the track season.
Mike
i've spent all afternoon messing about with it, have drained the box again and its definately coming out of the seal where the paper gasket would sit, but i have realised why. the gd t70 uses a support bracket that picks up 4 of the original M8 studs that hold the 2 sections together, i originally undid the nuts and fitted the bracket, then locked the nuts back up. over time 2 or 3 have worked the studs slightly loose and the bottom one was weeping a tiny amount of oil past the threads and out (not a blind hole).
i've attempted a repair by removing the studs fully, cleaning out the threads and drying it off with brake cleaner. i then applied some thread sealant and refitted the studs fully tight, and locked down some new nuts, its all pulled up tight so we'lll let the thread sealant cure and see if it works. it has 2 chances as they say, if not next step is box straight out and off to someone with nous like yourself to replace the gasket and any seals etc.
out of interest what mods would you look at with regard to this box? its running a quaife diff and (currently) seems to be coping quite well with 450bhp and 440ft/lb through it while running upside down!
i use redline shockproof gear oil that i was recommended and its lovely and clean still.
regards
chris
ps thanks to all for links and help, great stuff.
200Plus Club said:
cheers Mike
i'll probably fill it with oil later in the week and run the car on stands at the weekend up to temperature to see if it leaks. if it does i will give you a bell to discuss further.
thanks
I have a friend who worked for Porsche for over 10 years who has just purchased his own garage in the Potters Bar(North London) area so if you need help I can point you in the right direction.i'll probably fill it with oil later in the week and run the car on stands at the weekend up to temperature to see if it leaks. if it does i will give you a bell to discuss further.
thanks
I always let him work on my 997tt.
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