Buying transmission... How to manually engage gears?

[huzilulu]

Hi guys

I am just about to purchase a used G97 (997 C2) transmission and have been told to check that it engages all forward and reverse gears - how do I do that manually (using the levers on the side where the shifter cables attach)? What should I look out for? And what should I walk away from?

Thanks

[Storer]

No knowledge about the shift levers/cables but I would have a chat with the Factory as I am not sure that is the right box to go for.
I think you will run out of revs at about 175mph with a LS/SBC engine.
You would either need to change the final drive or top ratio for relaxed crusing.

A turbo box is a better choice as the Porsche turbo has similar red lines to our V8.


Paul

[JohnMcL]

Hi Huzi,

The big lever selects the gears and the small lever is the cross-gate selector. Just push the big lever forwards and then backwards to select 3 & 4. Press and hold the small lever towards the drive flange and push the big lever forwards and back to select 1 & 2, press and hold further (quite hard) to get reverse, press and hold away from the drive flange to get 5 & 6.

When in gear, turn the drive flanges or input shaft to check smooth engagement all round the gear set and the ring/pinion. Gears will probably stay in (it’s a tough box) but that is no guarantee they will stay in under load. Can you check with the previous user? Also, check all over the outside for damage or cracks. Not expensive to have it checked internally by a specialist.

As Paul said above, any C2 box is not so good for use with a high torque low revving V8. You need a GT2 or turbo box to get the bigger ring gear and right ratios. A turbo box needs the front drive removing and a G96-50 from a 996 T has marginally better (longer) ratios than a 997 T.

Depending on driving use, 5 gears may be a better option in an Ultima, so an earlier 5 speeder could be good if you can find one.

Hope that helps and best of luck.

Edited by JohnMcL on Sunday 8th February 12:15

[huzilulu]

Thanks for the tips.

Much appreciated!

[ezakimak]

there is potentially 0.026 in it in terms of the overall final drive ratio 0.88 verses 0.85
both are 3.44 final drive.
no much different to the rest of the G50/01/02/03 range either.

http://californiamotorsports.net/pages/porsche-997...

Type: G97/01 (Manufactured by Aisin)
Original equipment for: Porsche 997 Carrera 2 2005-2008
Description: H Pattern 6 speed manual transaxle with cone synchromesh and synchronized reverse
Limited Slip Differential: LSD standard equipment (S model only)
Weight (approx): 170 lbs
Oil Capacity (approx): API classification GL5 75/90
Speedometer: None
Trans controls: Shift cables
Clutch: Hydraulically assisted push clutch, single plate
1st gear 3.91
2nd gear 2.32
3rd gear 1.61
4th gear 1.28 (1.31 S model)
5th gear 1.08
6th gear 0.88
Final drive 3.44

verses
http://californiamotorsports.net/pages/porsche-996...

Type: G96/96
Original equipment for: Porsche 996 GT3, 2004+
Description: H Pattern 6 speed manual transaxle with Borg Warner synchromesh w/synchronized reverse
Limited Slip Differential: 40/65% LSD standard equipment
Drive flange size/CV overall diameter: 110mm
Weight: approx 175lbs
Oil Capacity: approx 3.8L API classification GL5 75/90
Speedometer: None
Trans controls: Shift cables
Clutch: Hydraulically assisted pull clutch, 240mm single plate
Remarks: First and second use triple cone synchros. Steel synchros 3rd-5th standard equipment. Oiling/cooling system standard equipment.
1st gear 3.82
2nd gear 2.15
3rd gear 1.56
4th gear 1.21
5th gear 1.00
6th gear 0.854
Final drive 3.44, 9”

the G50/50 is a different animal though
http://californiamotorsports.net/pages/porsche-g50...

[F.C.]

ezakimak said:

there is potentially 0.026 in it in terms of the overall final drive ratio 0.88 verses 0.85
both are 3.44 final drive.
no much different to the rest of the G50/01/02/03 range either.

http://californiamotorsports.net/pages/porsche-997...

Type: G97/01 (Manufactured by Aisin)
Original equipment for: Porsche 997 Carrera 2 2005-2008
Description: H Pattern 6 speed manual transaxle with cone synchromesh and synchronized reverse
Limited Slip Differential: LSD standard equipment (S model only)
Weight (approx): 170 lbs
Oil Capacity (approx): API classification GL5 75/90
Speedometer: None
Trans controls: Shift cables
Clutch: Hydraulically assisted push clutch, single plate
1st gear 3.91
2nd gear 2.32
3rd gear 1.61
4th gear 1.28 (1.31 S model)
5th gear 1.08
6th gear 0.88
Final drive 3.44

verses
http://californiamotorsports.net/pages/porsche-996...

Type: G96/96
Original equipment for: Porsche 996 GT3, 2004+
Description: H Pattern 6 speed manual transaxle with Borg Warner synchromesh w/synchronized reverse
Limited Slip Differential: 40/65% LSD standard equipment
Drive flange size/CV overall diameter: 110mm
Weight: approx 175lbs
Oil Capacity: approx 3.8L API classification GL5 75/90
Speedometer: None
Trans controls: Shift cables
Clutch: Hydraulically assisted pull clutch, 240mm single plate
Remarks: First and second use triple cone synchros. Steel synchros 3rd-5th standard equipment. Oiling/cooling system standard equipment.
1st gear 3.82
2nd gear 2.15
3rd gear 1.56
4th gear 1.21
5th gear 1.00
6th gear 0.854
Final drive 3.44, 9”

the G50/50 is a different animal though
http://californiamotorsports.net/pages/porsche-g50...

The Aisin box is reputably a difficult box to work on and re-builds appear to be more expensive compared to the Getrag.
The G50/50 was produced for about a year and dropped in favour of the G50/52.
Though they are ostensibly the same, sharing the same ratios and synchro set up.
The 50/50 had the cross-member mounted shorter rear, speedo drive and an optional 40% LSD.
The 50/52 has the later longer "nose mount" no speedo drive and a 20/100% LSD fitted standard.
They both share what is arguably one of the strongest final drives in the business a 9" crown wheel and pinion as opposed to 7.5" in the N/A range.
They are a little agricultural by todays standards (IMO) but none the less a very desirable option (and all the more expensive to buy).

[ezakimak]

Thanks F.C.

much appreciated.

the G50/50 and the G50/52 are both shown in this link and appear to match the descriptions you describe
http://californiamotorsports.net/pages/porsche-g50...

I know after marked gear sets are available for the G50, from Albins here Australia.
http://retro-sport.com/products/911--930-74-89/tra...

so it would be posible to spec the higher top gear that is available in the G50/50 and G50/52 and install in a base spec G50, so that leaves the main difference as the smaller ring and pinion.

there are alternate pinions available for the 996 range (G96) at the moment which would give a lower cruising speed (that's right isn't it?). presume it is only a matter of time before they are available for G97
http://retro-sport.com/products/porsche-gears.html
they are pricey though

[ezakimak]

interesting?

http://www.gboxweb.com/996shimtip.html

[Storer]

It might be useful to resurrect Dom's gearbox calculator spreadsheet.

It can be found about 1/3 of the way down this thread which is in the Stickies

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

I think Spatz is hosting it.


Paul

[mt308]

Does anyone have a similar level of knowledge of the G50/20 gearbox?

Purely selfishly, as I have one, and I have been struggling to find out much about it (other than the fact is has 6 gears and quite nice ratios that seem to suit the car).

Mark

[JohnMcL]

The key comparison is between the turbo and other long ratio boxes and the C2 type transmissions. e.g.

G97/01 997 C2/C4
1 3.91
2 2.32
3 1.61
4 1.28
5 1.08
6 0.88
Final drive 3.44

G96/50 996 Turbo
1 3.818
2 2.048
3 1.407
4 1.118
5 0.919
6 0.750

That's over 17% higher revs in 6th compared to the turbo box when using the same diff ratio and tyre circumference. Ultimas with LS engines can easily pull the turbo top gear and cruising is so much more relaxed. Then there is also the higher top speed or better fuel consumption.

Edited by JohnMcL on Wednesday 11th February 15:16

[ezakimak]

well, using Dom/Spaz gear box calculator, it would be fair to assume that the Factory GTR720 is running either a G50/50 or a G50/52 with a 7900 rpm rev limit to achieve the final top speed of 231MPH.
its defiantly a right hand rod shift so its not one of the later 6 speeds.

from memory they start in second for the 0-100mph-0 record runs and to achieve the 2.6 second 0 - 60mph time.

http://www.ultimasports.co.uk/Content.aspx?f=recor...

if Ultima Factory are reading this, can they confirm what gear box is in the GTR720?

[ezakimak]

mt308 said:

Does anyone have a similar level of knowledge of the G50/20 gearbox?

Purely selfishly, as I have one, and I have been struggling to find out much about it (other than the fact is has 6 gears and quite nice ratios that seem to suit the car).

Mark

see here
http://californiamotorsports.net/pages/porsche-g50...
an LSD was an option.

[huzilulu]

If I were to go the 996/997 Turbo box route, what all would need to be done to the box to prep it for the Ultima? ie - convert AWD to 2WD, invert(needs to be done anyway), anything else(with slave cylinder? cable/shifter? mounts?)

[mt308]

ezakimak said:

mt308 said:

Does anyone have a similar level of knowledge of the G50/20 gearbox?

Purely selfishly, as I have one, and I have been struggling to find out much about it (other than the fact is has 6 gears and quite nice ratios that seem to suit the car).

Mark

see here
http://californiamotorsports.net/pages/porsche-g50...
an LSD was an option.

Great thanks for that. How can I tell if it has an LSD (I have heard conflicting reports about jacking up, spinning one wheel in gear and the other wheel spinning backwards for example - someone told me this would tell me it had one, someone else said it means it doesn't!)

[ezakimak]

ezakimak said:

well, using Dom/Spaz gear box calculator, it would be fair to assume that the Factory GTR720 is running either a G50/50 or a G50/52 with a 7900 rpm rev limit to achieve the final top speed of 231MPH.
its defiantly a right hand rod shift so its not one of the later 6 speeds.

from memory they start in second for the 0-100mph-0 record runs and to achieve the 2.6 second 0 - 60mph time.

http://www.ultimasports.co.uk/Content.aspx?f=recor...

if Ultima Factory are reading this, can they confirm what gear box is in the GTR720?

never mind

http://www.ultimasports.co.uk/Content.aspx?f=recor...

The Ultima GTR720 is a fully road going car and is often used as a daily driver. The car is equipped with e-marked road tyres and fitted with our standard production 720bhp Chevrolet V8 engine option built by our OE engine suppliers American Speed. A standard G50-03 transmission was used with a taller 5th gear ratio (the taller 5th gear ratio is now a new option on our pricelist at £540) to suit the prolonged 200mph plus requirement for a successful lap record of the Nurburgring in an Ultima.
We would very much like to take this opportunity to thank our record attempt sponsors AP Brakes, Goodridge, Intrax Suspension, Kumho Tyres and Titan for their valuable support.

[ezakimak]

huzilulu said:

If I were to go the 996/997 Turbo box route, what all would need to be done to the box to prep it for the Ultima? ie - convert AWD to 2WD, invert(needs to be done anyway), anything else(with slave cylinder? cable/shifter? mounts?)

this shows some details of the oil system inside the box.
http://www.gboxweb.com/oilsystem.html

cms can do the inversion
http://californiamotorsports.net/products/cms-gt2-...

I believe that the oil system sump pick up will need to be inverted so that it picks up oil from the bottom of the diff housing. other wise when inverted it will be sitting at the top of the diff housing and not in the oil.

im not sure where the spray bar sits and if it would be submerged when inverted.

factory position at the top


cms inverted position at the bottom

[ezakimak]

Thread regarding rebuilding GT3 diff plates

http://www.pistonheads.com/gassing/topic.asp?h=0&a...