Gearbox inversion - Precisely!
Discussion
There was a thread on the gt40s forum where a small length of plastic tube had been installed in the lowest drain bung, of the inverted g50 box. This allowed the oil level to be monitored while the car was in motion. Can’t remember how far it dropped ones the gears were turning, suffice to saw it was considerable, indicating that a large amount of the oil would be coating the internal components of the gearbox. Other threads on the site have also stated things like trying to avoid having a spray bar spraying onto the input side of a gear as this would encourage hydraulic pitting of the gear tooth surface due to the high pressure film of oil between the to teeth paces. Where the truth lies between these too statements I’m not entirely sure.
Does the oil pump in the GT2 and GT3 boxes work when you invert the box?
Where does the GT2 and GT3 boxes spray the oil inside the box?
Does the oil pump in the GT2 and GT3 boxes work when you invert the box?
Where does the GT2 and GT3 boxes spray the oil inside the box?
ezakimak said:
Does the oil pump in the GT2 and GT3 boxes work when you invert the box?
Where does the GT2 and GT3 boxes spray the oil inside the box?
Thanks Ezakimak ....the question very succintly put! ...and VERY relevent to me in particular...Where does the GT2 and GT3 boxes spray the oil inside the box?
..Anyone actually KNOW the answer to the above?
Cheers
keith
V8 Vum said:
ezakimak said:
Does the oil pump in the GT2 and GT3 boxes work when you invert the box?
Where does the GT2 and GT3 boxes spray the oil inside the box?
Thanks Ezakimak ....the question very succintly put! ...and VERY relevent to me in particular...Where does the GT2 and GT3 boxes spray the oil inside the box?
..Anyone actually KNOW the answer to the above?
Cheers
keith
Found em, from the 911 gt2 transmission service information – 2002 year I think!
General:
The six-speed manual transmission of the 911 GT3 is used as the basic transmission for the 911 GT2
(G96/88).
The principal features of this transmission are:
• Dual-mass flywheel
• Cable shift mechanism
• Transmission-oil cooling
• Oil pump for oil-spray lubrication
• Asymmetric limited-slip differential
• Adapted transmission ratios with improved strength and acoustic characteristics of gearwheel sets
• Use of steel synchronising rings
1360 dual mass flywheel clutch
The working cycles and firing order of the engine cause speed fluctuations resulting in irregularities which lead to torsional vibrations along the entire drive train. These torsional vibrations may cause all loose, non-driven parts with play to rattle, chatter or bounce (loose gearwheels, parts of the
synchronisation system). This may result in annoying transmission noise, especially at low
engine speeds and high transmission oil temperatures. As with previous Porsche vehicles, the 911 GT2 has a dual-mass flywheel (DMF) to prevent these noises.
Transmission lubrication
A separate oil pump (1) is used in the 911 GT2 transmission to ensure optimum lubrication even at critical locations, uniform oil distribution, reduced churning losses and a drop in transmission oil
temperature. The gear pump (1) driven by a drive pinion mounted on the drive shaft draws the oil out of the differential housing. It pumps the oil through the oil-to-water heat exchanger (2) and then feeds it to the various lubricating points.
The differential housing is divided into two sections by a partition wall to ensure that the oil can be drawn in reliably without air pockets. One section contains the crown wheel and the other the settled oil and the suction pipe (3).
In the front transmission cover (the rearmost cover on an Ultima), the cooled transmission oil is pumped into the transmission (4) and passes through the hollow-drilled input and output shaft to lubricate the loose gear bearings. The shafts have cross bores at the loose gear bearings. This ensures that oil is supplied directly to the loose gear bearings.
An oil-spray pipe (5) also supplies oil to the 3rd – 6th gear mesh as well as to the bevel gear and crown wheel.
The oil pump has a delivery rate of approx. 8 litres at 6,000 rpm. The oil pressure is limited to 2.7 – 3 bar by means of a ball valve.
General:
The six-speed manual transmission of the 911 GT3 is used as the basic transmission for the 911 GT2
(G96/88).
The principal features of this transmission are:
• Dual-mass flywheel
• Cable shift mechanism
• Transmission-oil cooling
• Oil pump for oil-spray lubrication
• Asymmetric limited-slip differential
• Adapted transmission ratios with improved strength and acoustic characteristics of gearwheel sets
• Use of steel synchronising rings
1360 dual mass flywheel clutch
The working cycles and firing order of the engine cause speed fluctuations resulting in irregularities which lead to torsional vibrations along the entire drive train. These torsional vibrations may cause all loose, non-driven parts with play to rattle, chatter or bounce (loose gearwheels, parts of the
synchronisation system). This may result in annoying transmission noise, especially at low
engine speeds and high transmission oil temperatures. As with previous Porsche vehicles, the 911 GT2 has a dual-mass flywheel (DMF) to prevent these noises.
Transmission lubrication
A separate oil pump (1) is used in the 911 GT2 transmission to ensure optimum lubrication even at critical locations, uniform oil distribution, reduced churning losses and a drop in transmission oil
temperature. The gear pump (1) driven by a drive pinion mounted on the drive shaft draws the oil out of the differential housing. It pumps the oil through the oil-to-water heat exchanger (2) and then feeds it to the various lubricating points.
The differential housing is divided into two sections by a partition wall to ensure that the oil can be drawn in reliably without air pockets. One section contains the crown wheel and the other the settled oil and the suction pipe (3).
In the front transmission cover (the rearmost cover on an Ultima), the cooled transmission oil is pumped into the transmission (4) and passes through the hollow-drilled input and output shaft to lubricate the loose gear bearings. The shafts have cross bores at the loose gear bearings. This ensures that oil is supplied directly to the loose gear bearings.
An oil-spray pipe (5) also supplies oil to the 3rd – 6th gear mesh as well as to the bevel gear and crown wheel.
The oil pump has a delivery rate of approx. 8 litres at 6,000 rpm. The oil pressure is limited to 2.7 – 3 bar by means of a ball valve.
Great stuff!
Thanks - I am somewhat impressed!
...only problem is mine!!..... errrr....I am totally out-of-my-depth in understanding the implications
and need this put into context with turning the thing upside-down? 
Anyone care to comment, elaborate or add to the discussion?
Keith
Thanks - I am somewhat impressed!
...only problem is mine!!..... errrr....I am totally out-of-my-depth in understanding the implications
and need this put into context with turning the thing upside-down? Anyone care to comment, elaborate or add to the discussion?
Keith
Edited by V8 Vum on Friday 12th September 14:07
Disclaimer - Based on the fact that what i’m about to say is gleaned from looking at a few photos, spare parts catalogues and considering an Ultima engine bay, I’m hardly an expert.
The oil pump in the box, which appears to be driven off one of the shafts, sucks up oil from a sump that is cast into the bottom of the differential housing, and located adjacent to the crown wheel. This will now be at the top of the box once it has been inverted. I would imagine that you need to re-route the oil pump pickup so that it is now in the lower part of the box. You could possibly create another sump and splashguard in the inverted differential housing or create some other external oil reservoir for the oil to drain to and settle in, hopefully loosing any air bubbles in the process.
Given that the rotation of the gear shafts has not changed direction. The internal spray point for the 3rd – 6th gear mesh as well as to the bevel gear and crown wheel will probably be in the right place to avoid hydraulic pitting of the gears, as it will be hopefully spraying on the output side of the gear. However as the boxes is inverted, this may be submerged and in the remaining oil that is not being churned up by the gear shafts and cog sets. This is hard to tell in the photos and images that i have. Looks like it has an internal attachment point on the opposite side of the front cover to where the oil supply line goes back into the gear box (rear cover in an Ultima – oil line would go in on right side of rear cover, spray bar would be internal to box and on the left side in an Ultima install) does it look like there is an internal oil gallery cast into the rear cover of the box?
The hollow internal shaft lubrication system will probably still work fingers crossed.
The oil pump in the box, which appears to be driven off one of the shafts, sucks up oil from a sump that is cast into the bottom of the differential housing, and located adjacent to the crown wheel. This will now be at the top of the box once it has been inverted. I would imagine that you need to re-route the oil pump pickup so that it is now in the lower part of the box. You could possibly create another sump and splashguard in the inverted differential housing or create some other external oil reservoir for the oil to drain to and settle in, hopefully loosing any air bubbles in the process.
Given that the rotation of the gear shafts has not changed direction. The internal spray point for the 3rd – 6th gear mesh as well as to the bevel gear and crown wheel will probably be in the right place to avoid hydraulic pitting of the gears, as it will be hopefully spraying on the output side of the gear. However as the boxes is inverted, this may be submerged and in the remaining oil that is not being churned up by the gear shafts and cog sets. This is hard to tell in the photos and images that i have. Looks like it has an internal attachment point on the opposite side of the front cover to where the oil supply line goes back into the gear box (rear cover in an Ultima – oil line would go in on right side of rear cover, spray bar would be internal to box and on the left side in an Ultima install) does it look like there is an internal oil gallery cast into the rear cover of the box?
The hollow internal shaft lubrication system will probably still work fingers crossed.
Edited by ezakimak on Friday 12th September 14:29
Keith, I have a G96-88 (GT2) box for my GTR. I have not installed it yet. Roger Brown California Motor Sports (CMS) provided. Roger can give you the details for the Ultima setup. The spray oilier was moved, taller first gear installed, oil fill hole was moved, and so on. I have found Roger to be a wealth of information. Roger can be reached at:
California Motorsports
2175 North Kiowa Blvd. Ste 108
Lake Havasu City, AZ 86403 USA
928-855-5755 voice/928-855-6021 fax
He can be reached directly at 303-530-0660.
roger@californiamotorsports.net
Send him an email I am sure he would be happy to help.
Randy
California Motorsports
2175 North Kiowa Blvd. Ste 108
Lake Havasu City, AZ 86403 USA
928-855-5755 voice/928-855-6021 fax
He can be reached directly at 303-530-0660.
roger@californiamotorsports.net
Send him an email I am sure he would be happy to help.
Randy
Great topic guys,
But ....I don't get it.
Do I have to change the adapterpoint of the oilpump?
I have the ricaro GT2 (seq/dog/etc) one like Xavier,
maybe he knows what is going on inside the gearbox?
Xavier?? help wanted.....
PS: I should have some drawings of my gearbox somewhere, but where?.
But ....I don't get it.
Do I have to change the adapterpoint of the oilpump?
I have the ricaro GT2 (seq/dog/etc) one like Xavier,
maybe he knows what is going on inside the gearbox?
Xavier?? help wanted.....
PS: I should have some drawings of my gearbox somewhere, but where?.
Edited by donkeasy on Friday 12th September 22:48
https://techinfo.porsche.com/techinfo/index.jsp
i think that is the link. you might be able to download some of the parts manuals,they generally have exploded diagrams so you can see what will be affected by the inversion and where parts sit in the boxes.
i think that is the link. you might be able to download some of the parts manuals,they generally have exploded diagrams so you can see what will be affected by the inversion and where parts sit in the boxes.
YIIHAA said:
Stig said:
Was that before or after 14FC was written off during a customer demo (heralding the end of customer driven test drives!) 
Failure was before being written off, me acquiring it was after (circling overhead like a vulture).V8 Vum said:
(Sigh!)
You see...
..the situation is far from clear-cut...
...The factory bless-them, have already suggested my choice of box is not recommended
, so asking them for advice on the oiling is somewhat superfluous.
The third-gear thing is useful to know...
Pity I don't live in the states as GBOX would be worth talking to, but I don't.
Not sure who in the UK?
Then there is the sticky subject in whether the advice I would be getting is somewhate bias towards spending dosh I can ill-afford on a mod that actually does nothing to enhance longlevity. I have no problem contributing to someones profits, provided their service is beneficial to me in equal proportion.
More comments please!
cheers
Did you ever get to the bottom of this V8??You see...
..the situation is far from clear-cut...
...The factory bless-them, have already suggested my choice of box is not recommended
, so asking them for advice on the oiling is somewhat superfluous. The third-gear thing is useful to know...
Pity I don't live in the states as GBOX would be worth talking to, but I don't.
Not sure who in the UK?
Then there is the sticky subject in whether the advice I would be getting is somewhate bias towards spending dosh I can ill-afford on a mod that actually does nothing to enhance longlevity. I have no problem contributing to someones profits, provided their service is beneficial to me in equal proportion.
More comments please!
cheers
I have just inverted the 996 turbo box , after cutting new oil ways, adding an OS Giken LSD and a cooler thinking i had all angles covered but now the cables are struggling with the force I have to put through it to change gear. Reverse is basically impossible.
Did you resolve all the issues??
Cheers,
J
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