Gearbox Choice

[leem5]

Firstly I gather this has been covered many times but pistonheads search function is no good!

Basically looking at what choices there are, I see the G50? has the gear stick on the right of the driver, I've seen a few photos where it is in the centre of the car. Can anyone educate me what 'box this is, turbo maybe? Modified? If so, where can these be sourced and where do they go to be modified too two wheel drive?

Cheers

[356Speedster]

You're right, this does get discussed a lot and everyone has their own view on each option.... each to their own, there is now right answer to the 'box question.

With that out of the way, there are a lot of G50 variations out there and you can get a cable conversion for the rod change mechanism. I don't know if there are any G50s with cable change out of the box, I'm sure someone on here with more knowledge than me will be able to advise...

Generally when folks talk about centre change cable boxes, they're talking about the 996/997 Porsche 'boxes (all 6-speed). In a nutshell..... G96/00, G95/01 & G97/01 came from Carrera 2 models and are generally regarded as weaker, shorter geared and harder to rebuild.

G96/30, G96/31 & G97/31 are Carrera 4 versions of the above. Same comments as above apply, I can't see why you'd consider one of these.

G96/50 & G97/50 are the twin turbo 4WD boxes. These are easily converted to 2WD and are long geared, strong and easy to maintain boxes. This is what I've gone for as for me it represented the best box for strength & gearing.

Then you have the GT2/GT3 boxes.... G96/80, G96/90 & G96/96. These command big money, from what I've seen 2x even upto 4x what a G96/50 costs. GT3 gearsets are the same as the TT, but I think the GT2 uses slightly longer gearing.

My advise to anyone building a 500bhp+ LS Ultima wanting centre change is to go for a TT 'box and have it converted to 2WD by someone like Auto Bionics. Just my thoughts

[F.C.]

leem5 said:

Firstly I gather this has been covered many times but pistonheads search function is no good!

Basically looking at what choices there are, I see the G50? has the gear stick on the right of the driver, I've seen a few photos where it is in the centre of the car. Can anyone educate me what 'box this is, turbo maybe? Modified? If so, where can these be sourced and where do they go to be modified too two wheel drive?

Cheers

G50/50 and G50/52 probably one of the "best geared" boxes for road use they are both availble as centre shift by means of a simple cable conversion.
I have a G50/52 cable centre shift with 9" crownwheel and LSD (G50/50 has this too) from a Turbo variant and are generally accepted as one of the strongest boxes available (though scarce).
The G50 boxes mentionrd above are two wheel drive.
Later boxes can have the 4 w/d blanked off.
Be sure of your gearing!! It can make or break the feel and drive of the car.
To give you an idea the G50/52 is 5 speed and good for 210 MPH at 7,200 RPM. my car will pull 5th gear at 30MPH without issue.
A 6 speed box MAY be better on track with the right ratios but with the torque these big V8's produce it's a bit academic on road.
Avoid the later 2w/d carrera boxes would be my advice with turbo variant boxes being better able to cope with the torque loads involved.

ETS Went out in the car today and it actually pulls top from rolling tickover = 22mph, got to love the torque produced by these engines!

Edited by F.C. on Wednesday 14th November 23:28

Edited by F.C. on Thursday 15th November 19:15

[MarkWebb]

I have a G50/00 With an Autobionics centre change conversion. It all works well and has lasted 10000 miles with 550hp. Trouble is my gearing is very low with 70mph being about 3000rpm. What does it cost to change the final drive ratio?

[356Speedster]

Wise words from F.C..... with regards to gearing, I'd just add:

On std TT gearing @ 6,600rpm my car is theoretically good for 197mph. With a 7,200rpm limit, that rises to 215mph. More than enough!

The key difference between the 2 boxes (with all other things being equal) with the gearing will come in shifting thru' the gears. At comparable shift points (6,600rpm for the sake of my ready-made spreadsheet!!):

TT - 1st = 39mph, 2nd = 72mph, 3rd = 105mph, 4th = 132mph, 5th = 161mph, 6th = 197mph
G50/52 - 1st = 47mph, 2nd = 83mph, 3rd = 116mph, 4th = 153mph, 5th = 193mph

My humble is that the longer 1st & 2nd will help traction a wee bit just by pulling the slightly longer gears, but other than that, it'll be swings & roundabouts really.

Hope that helps.

[F.C.]

356Speedster said:

Wise words from F.C..... with regards to gearing, I'd just add:

On std TT gearing @ 6,600rpm my car is theoretically good for 197mph. With a 7,200rpm limit, that rises to 215mph. More than enough!

The key difference between the 2 boxes (with all other things being equal) with the gearing will come in shifting thru' the gears. At comparable shift points (6,600rpm for the sake of my ready-made spreadsheet!!):

TT - 1st = 39mph, 2nd = 72mph, 3rd = 105mph, 4th = 132mph, 5th = 161mph, 6th = 197mph
G50/52 - 1st = 47mph, 2nd = 83mph, 3rd = 116mph, 4th = 153mph, 5th = 193mph

My humble is that the longer 1st & 2nd will help traction a wee bit just by pulling the slightly longer gears, but other than that, it'll be swings & roundabouts really.

Hope that helps.

Your target rpm of 6,600RPM gives lower than 47mph. For a G50/52. that figure is for 7,000RPM
To be honest the first gear figure of 47mph isn't long enough (for me), I find I short shift into second as soon as I'm rolling, a better bet would be a slight increase in the final drive, giving a useful first gear and in turn a bit more top end (as if its needed) and hopefully more mpg.
Your 2nd gear 72mph looks as though it would be right on the money for a good 1st gear giving 10 mph per thousand RPM.

[356Speedster]

F.C. said:

Your target rpm of 6,600RPM gives lower than 47mph. For a G50/52. that figure is for 7,000RPM

Maybe my spreadsheet is a bit out..... 6.79ft rear tyre rolling radius, 3.154:1 1st gear ratio with 3.444:1 final drive, shows 47mph. Oh well, it works for illustration purposes as if it's a little off for one, it's the same for the others

[leem5]

Great stuff, thanks for the info. Will go a look way in making a decision.

I've been on AB's website and can't seem to see anything? Maybe its the filters the company has?

Cheers

[macgtech]

There are plenty of gearbox options (not limited to Porsche) completely depending upon your intended use and budget. Is it an LS install?

[UltimaCH]

leem5 said:

Great stuff, thanks for the info. Will go a look way in making a decision.

I've been on AB's website and can't seem to see anything? Maybe its the filters the company has?

Cheers

They are a bit hush hush for obvious reasons..., but send them a mail and you'll certainly get a reply

[F.C.]

If you want to run really serious numbers then the Ricardo box made for the Ford GT fits with a bit of jigging around the rear subframe, but it HAS been done.

[macgtech]

UltimaCH said:

They are a bit hush hush for obvious reasons..., but send them a mail and you'll certainly get a reply

Agreed, the Steve and Jason at AutoBionics are very helpful. Big thumbs up.

[Storer]

F.C. said:

Your target rpm of 6,600RPM gives lower than 47mph. For a G50/52. that figure is for 7,000RPM
To be honest the first gear figure of 47mph isn't long enough (for me), I find I short shift into second as soon as I'm rolling, a better bet would be a slight increase in the final drive, giving a useful first gear and in turn a bit more top end (as if its needed) and hopefully more mpg.
Your 2nd gear 72mph looks as though it would be right on the money for a good 1st gear giving 10 mph per thousand RPM.

I think you will find this is too high for driving in town. In traffic you will end up slipping the clutch.

With all the torque of an LS engine you really only need 5 gears (you could get away with 4!) but the G50.52 is getting hard to find and expensive so one of the later turbo boxes are probably a more cost effective proposition.

If you read down to Dom's Gear Ratio Calculator you will find a very useful calculator.

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

For relaxed motorway driving opt for a box with ratios that will show over 200mph in top at full revs.


Paul

[khm]

got an elite txl300 sequential dog box in my car, seams to do what i want it to, not sure on how it would fit into an ultima? long first gear over 60 mph but will make gearing to suit you
oh quite expensive too

[leem5]

UltimaCH said:

They are a bit hush hush for obvious reasons..., but send them a mail and you'll certainly get a reply

Cheers, will do.

Power wise, we are looking at the LS3, so 500 bhp ish. This will be a car built between a few mate who already have a car or two each and fancy something different.

So where are these gearboxes hiding then? Any tips/ heads up where to go looking?
Can they be sourced from the factory? Will send an email!

Cheers

[356Speedster]

leem5 said:

Cheers, will do.

Power wise, we are looking at the LS3, so 500 bhp ish. This will be a car built between a few mate who already have a car or two each and fancy something different.

So where are these gearboxes hiding then? Any tips/ heads up where to go looking?
Can they be sourced from the factory? Will send an email!

Cheers

When you mail Steve & Jason, ask if they have a TT box in stock, they often do, sometimes even pre-converted to 2WD ready to go

The factory don't support the TT box and will only sell you 996 C2 units (I think this is still the case). As such, you'll also need the necessary mounting hardware from AB. Basically, you should be able to get a ready to go TT package off AB... if not, get a copy of GT Purely Porsche and call the many part breakers in there and you should turn one up. If after that you still struggle drop me a PM and I might be able to help get a box.

[JohnMcL]

Hi Leem5,

All the guys have been talking about Porsche boxes that need a good bit of work to be a solution and to get really suitable ratios is quite expensive. As an alternative, take a look at https://griffingearboxes.com/Mid-Engine_Transaxles...

There is a huge choice of gear and final drive ratios, 5 or 6 speeds, no need for adapter plates as they bolt straight onto an LSx, come complete with a LONG shifter for cables, choice of LSD units, easy available clutch / flywheel / starter motor. All in all - significant advantages.

John McL.

[356Speedster]

JohnMcL said:

Hi Leem5,

All the guys have been talking about Porsche boxes that need a good bit of work to be a solution and to get really suitable ratios is quite expensive. As an alternative, take a look at https://griffingearboxes.com/Mid-Engine_Transaxles...

There is a huge choice of gear and final drive ratios, 5 or 6 speeds, no need for adapter plates as they bolt straight onto an LSx, come complete with a LONG shifter for cables, choice of LSD units, easy available clutch / flywheel / starter motor. All in all - significant advantages.

John McL.

I looked at these some time ago, but the price was horrendous..... I seem to recall about £8,000 for a basic 6-speeder before options, ancillaries, shift mechanism and then you need a custom rear mount. Basically, well over twice the price of a TT box, full installed with all parts. It's a great looking product, but not cheap and you'll still need custom parts to finish the install.

You do make a good point that other 'boxes are out there (a few guys on here use Quaife, Albins and one or two others), but people do need to bear in mind the complete package and all costs when making comparisons. The Porsche boxes are generally plug & play and do 99% of what most owners want, so yes, are often seen as the default choice.

[F.C.]

MarkWebb said:

I have a G50/00 With an Autobionics centre change conversion. It all works well and has lasted 10000 miles with 550hp. Trouble is my gearing is very low with 70mph being about 3000rpm. What does it cost to change the final drive ratio?

Your box has the same final drive ratio as my 50/52 but top is as follows:

G50/00 5th gear 0.861

Final drive 3.44, 7.5” Crownwheel

G50/52 5th gear 0.767

Final drive 3.44, 9” Crownwheel

I looked into final drives and some aftermarket crownwheel and pinions are available, but none (so far) to make overall gearing taller only shorter (for track and autocross).
Allbins may have a solution but last I looked a CW&P set was over $3000.00 US.
It may be more prudent to get a specialist builder in the UK to change your 4th/5th gear ratios, I haven't checked if this is even possible with your box but I know it can be done on some of the derivatives.
I know how you must feel, my car is taller geared and I still think top needs to be a bit longer for those m/way cruises.

[ROWDYRENAULT]

The post on the Griffin gear box is interesting. If I was building a car now, I think I would at least speak with Fran Hall at Race Car Replicas and ask his opinon of the gear box. Mr. Hall has an extensive background in race car fabrication and professional motor sports. I know this because a mutual friend who is in the motorsports proffesion complemeted Fran and my friend is not quick to do that. My input on your gearbox selection is make damn sure the thing has a limited slip in it. I have a quaife in my G50 -03 and it works great, when not if, the back end loses traction the car stays straight as a string. in 4 years with the car I have never had the car step out on mr. Lee