Please explain the differences in the G50 box
Discussion
I am new to this Ultima stuff and need clarification on the various G50 boxes.
1)I am told there are long and short, but the chassis accomodates both. What are the differences, is the long box better for cooling the oil, as bigger, or does the long box take the 6 gears and the short the 5 gears?
2)What I am looking for is a box that gives good acceleration in all gears. I am not interested in 200mph, but really topping out around 150-160mph, as this is mainly useful for uk roads and short blasts. I prefer low down speed, low down generally to 120mph, so is a 6 speeder better for and not use the other top two gears or a 5 speeder with low gearing. My friend has a Diablo, so roughly the same power output, around the 600bhp figure, but obviously heavier, he rarely uses first and generally won`t drop below 3rd unless in slow moving traffic.
3)There has been a lot of talk about changing the gear ratios, but is this needed for road use, I understand for track use, you want it suited to the track.
4)Which box keeps the driveshafts as straight as possible, so no chance of snapping driveshafts, as they maybe at a different angle?
5)Are the long boxes used for the higher bhp engines as stronger or what. Sorry to ask so many questions in one hit, but I need to understand, so I don`t opt for the wrong box?
Any advice greatly appreciated.
Dave
1)I am told there are long and short, but the chassis accomodates both. What are the differences, is the long box better for cooling the oil, as bigger, or does the long box take the 6 gears and the short the 5 gears?
2)What I am looking for is a box that gives good acceleration in all gears. I am not interested in 200mph, but really topping out around 150-160mph, as this is mainly useful for uk roads and short blasts. I prefer low down speed, low down generally to 120mph, so is a 6 speeder better for and not use the other top two gears or a 5 speeder with low gearing. My friend has a Diablo, so roughly the same power output, around the 600bhp figure, but obviously heavier, he rarely uses first and generally won`t drop below 3rd unless in slow moving traffic.
3)There has been a lot of talk about changing the gear ratios, but is this needed for road use, I understand for track use, you want it suited to the track.
4)Which box keeps the driveshafts as straight as possible, so no chance of snapping driveshafts, as they maybe at a different angle?
5)Are the long boxes used for the higher bhp engines as stronger or what. Sorry to ask so many questions in one hit, but I need to understand, so I don`t opt for the wrong box?
Any advice greatly appreciated.
Dave
Dave,
1)I am told there are long and short, but the chassis accomodates both. What are the differences, is the long box better for cooling the oil, as bigger, or does the long box take the 6 gears and the short the 5 gears?
There are long and short boxes - both G50s, the . A short box looks like this There are 4 speed boxes (they're the long ones and have a cable operated clutch so require you to fabricate your own operation mechanism - avoid these) and 5 speeds (the most popular). The G50 gearchange mechanism can be centre or driver side mounted although, the central rod linkage takes a more protracted route to the gearbox which personally put me off a bit.
The 6 speed is the Getrag 'box which is more expensive, but is short (quite a bit shorter than a short G50 in fact) and uses a neat cable shifter (centrally mounted in the cockpit). I believe that the factory make a neat cowel for the gearchange too which looks the business. The 6 speed obviously uses shorter ratios as there are more gears to play with. General feeling seems to be that the G50 ratios are better suited to the Ultima, but that's down to your personal preference.
2)What I am looking for is a box that gives good acceleration in all gears. I am not interested in 200mph, but really topping out around 150-160mph, as this is mainly useful for uk roads and short blasts. I prefer low down speed, low down generally to 120mph, so is a 6 speeder better for and not use the other top two gears or a 5 speeder with low gearing. My friend has a Diablo, so roughly the same power output, around the 600bhp figure, but obviously heavier, he rarely uses first and generally won`t drop below 3rd unless in slow moving traffic.
Right, there are a couple of variants of the G50 in terms of ratio and LSD. Here's the info to tell what's what:
1987 911 G50s have an 8 digit code stamped in the bottom, for example 'G50/0073H'_'12/00050'
G50/00 = G50 trans
7 = trans for 6 cylinder
3 = 5-speed Rest of World; 4= 5-speed USA/Japan/M298)
H = 1987 model
00050 = serial number
A 1988-89 trans has a 12 digit code, such as 'G5000 1 J 00903'
G5000 = trans type (see below)
1 = normal differential (0= no diff, 2= ZF ltd. slip diff)
J = 1988 model (K= 1989)
00903 = serial number
Transmission types:
G50/00 = 911 Carrera, R.o.W.
G50/01 = 911 Carrera, USA/CND/J/AUS
G50/02 = 911 Switzerland (very short gear ratios)
G50/50 = 911 Turbo world wide, 1989 only
G50/52 = later Porsche turbo boxes ZF ltd. slip
I've got a G50/02 which is a short ratio box with LSD. This means that whilst I can't do 200mph (or I don't think I can
to my mind it's more usable day to day and has the benefit of having LSD fitted as standard. To retrofit something like the quiaffe ATB is more than 800 quid for the diff alone!. The G50/52 from the Turbo has LSD, but is the other end of the ratio spectrum using very long ratio's which will give you less 'urge' on acceleration (if that's possible with 614 ft/lbs of torque!).
3)There has been a lot of talk about changing the gear ratios, but is this needed for road use, I understand for track use, you want it suited to the track.
The G50/00 ratio's are fine. In fact, you could live with any of them but see comments above.
4)Which box keeps the driveshafts as straight as possible, so no chance of snapping driveshafts, as they maybe at a different angle?
Good question. But the differences between them are marginal and don't have a significant effect on the driveshafts. The only exception is (wait for it) supercharger installations. The engine has to move back a little to clear the bulkhead (for which the factory supply an adaptor kit) which offsets the drive flanges a little - but again, not enough to be a problem.
5)Are the long boxes used for the higher bhp engines as stronger or what. Sorry to ask so many questions in one hit, but I need to understand, so I don`t opt for the wrong box?
Nope. All G50's are the same strengthwise (Turbo included). The tyres will spin/clutch will slip before gearbox gives in anyway (he says
1)I am told there are long and short, but the chassis accomodates both. What are the differences, is the long box better for cooling the oil, as bigger, or does the long box take the 6 gears and the short the 5 gears?
There are long and short boxes - both G50s, the . A short box looks like this There are 4 speed boxes (they're the long ones and have a cable operated clutch so require you to fabricate your own operation mechanism - avoid these) and 5 speeds (the most popular). The G50 gearchange mechanism can be centre or driver side mounted although, the central rod linkage takes a more protracted route to the gearbox which personally put me off a bit.
The 6 speed is the Getrag 'box which is more expensive, but is short (quite a bit shorter than a short G50 in fact) and uses a neat cable shifter (centrally mounted in the cockpit). I believe that the factory make a neat cowel for the gearchange too which looks the business. The 6 speed obviously uses shorter ratios as there are more gears to play with. General feeling seems to be that the G50 ratios are better suited to the Ultima, but that's down to your personal preference.
2)What I am looking for is a box that gives good acceleration in all gears. I am not interested in 200mph, but really topping out around 150-160mph, as this is mainly useful for uk roads and short blasts. I prefer low down speed, low down generally to 120mph, so is a 6 speeder better for and not use the other top two gears or a 5 speeder with low gearing. My friend has a Diablo, so roughly the same power output, around the 600bhp figure, but obviously heavier, he rarely uses first and generally won`t drop below 3rd unless in slow moving traffic.
Right, there are a couple of variants of the G50 in terms of ratio and LSD. Here's the info to tell what's what:
1987 911 G50s have an 8 digit code stamped in the bottom, for example 'G50/0073H'_'12/00050'
G50/00 = G50 trans
7 = trans for 6 cylinder
3 = 5-speed Rest of World; 4= 5-speed USA/Japan/M298)
H = 1987 model
00050 = serial number
A 1988-89 trans has a 12 digit code, such as 'G5000 1 J 00903'
G5000 = trans type (see below)
1 = normal differential (0= no diff, 2= ZF ltd. slip diff)
J = 1988 model (K= 1989)
00903 = serial number
Transmission types:
G50/00 = 911 Carrera, R.o.W.
G50/01 = 911 Carrera, USA/CND/J/AUS
G50/02 = 911 Switzerland (very short gear ratios)
G50/50 = 911 Turbo world wide, 1989 only
G50/52 = later Porsche turbo boxes ZF ltd. slip
I've got a G50/02 which is a short ratio box with LSD. This means that whilst I can't do 200mph (or I don't think I can
to my mind it's more usable day to day and has the benefit of having LSD fitted as standard. To retrofit something like the quiaffe ATB is more than 800 quid for the diff alone!. The G50/52 from the Turbo has LSD, but is the other end of the ratio spectrum using very long ratio's which will give you less 'urge' on acceleration (if that's possible with 614 ft/lbs of torque!). 3)There has been a lot of talk about changing the gear ratios, but is this needed for road use, I understand for track use, you want it suited to the track.
The G50/00 ratio's are fine. In fact, you could live with any of them but see comments above.
4)Which box keeps the driveshafts as straight as possible, so no chance of snapping driveshafts, as they maybe at a different angle?
Good question. But the differences between them are marginal and don't have a significant effect on the driveshafts. The only exception is (wait for it) supercharger installations. The engine has to move back a little to clear the bulkhead (for which the factory supply an adaptor kit) which offsets the drive flanges a little - but again, not enough to be a problem.
5)Are the long boxes used for the higher bhp engines as stronger or what. Sorry to ask so many questions in one hit, but I need to understand, so I don`t opt for the wrong box?
Nope. All G50's are the same strengthwise (Turbo included). The tyres will spin/clutch will slip before gearbox gives in anyway (he says
Stig,
Excellent response, you certainly know ya stuff. The G50/02 as you have, if I am correct, would suit my driving requirements, i.e. more urge lower down and good pull throughout all gears right up to the limit. By the way, are rev limiters on these engines?
I remember seeing some graph, but can`t find it, where you can move your cursor across it and it shows the speeds, revs, bhp, any clues where it is?
Maybe we can talk more about this on Saturday when I pop over.
Cheers for the info
Dave
Excellent response, you certainly know ya stuff. The G50/02 as you have, if I am correct, would suit my driving requirements, i.e. more urge lower down and good pull throughout all gears right up to the limit. By the way, are rev limiters on these engines?
I remember seeing some graph, but can`t find it, where you can move your cursor across it and it shows the speeds, revs, bhp, any clues where it is?
Maybe we can talk more about this on Saturday when I pop over.
Cheers for the info
Dave
Whoops!! Forgotto say that I`m sure it was Ted at the factory who said that a lower geared car, gave the equivalent of another 50bhp, as I`m looking at one of the Amerspeed engines around 500-540bhp, this will put mine equivalent to mid to high 500`s bhp and christ, it takes yours to high 600`s.
Scary stuff eh??
Dave
Scary stuff eh??
Dave
How much horsepower / torque can a stock g50/52 take. I had a long conversation with a guy at PHII www.phii.net/ and he said the limit was about 400HP before you need to start moding it.
Is anyone out there running more than 400HP on a stock g50/52? I believe the guy at PHII knows what he is talking about, but then again he is the one trying to get me to buy the upgraded internals $$$$$
mark
Is anyone out there running more than 400HP on a stock g50/52? I believe the guy at PHII knows what he is talking about, but then again he is the one trying to get me to buy the upgraded internals $$$$$
mark
The long box has a rubber donought on the end. The 6-speeds and G50/50 and G50/52 are considered long boxes. They're longer in length. The shorter boxes are the G50/(00,01,02,etc...) without the rubber donought. They're shorter in length. However, don't be confused a few companies sell a modified G50 short box that's been shortened even further. This confused me quite a bit at first. The factory has been running 500-550hp demonstrators for a while with the standard G50 and G50/50(52) boxes. Most people will tell you that this box can take up to about 600-650 ft. lbs of torque. I don't think you'll have a problem with a standard 500-550ft. lbs of torque with the standard internals. If you want to go with more power, then I think you'd get more use out of the box with lightened gears(which run cooler), a gearbox pump and cooler, and a billet diff cover. A race prepared G50/52 is going to cost you big bucks due to the rarity of the box $15k with all modifications. As a substitute, I'd consider a 6-speed Porsche G50/20. Kurt Dobson runs this gearbox with 600-650ft. lbs and 1000hp in his GTR. He hadn't had any problems with it the last time I spoke to him. It was blueprinted and race prepared by Patrick Motorsports. This looks like an interesting deal as well. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33733&item=1876758028
Bubbles, I can supply you a chart and gear ratios for the G50 and G50/50 (1987-1989) if you like. I've rebuilt these gearboxes and know them fairly well.
Cheers!
-Mack
Bubbles, I can supply you a chart and gear ratios for the G50 and G50/50 (1987-1989) if you like. I've rebuilt these gearboxes and know them fairly well.
Cheers!
-Mack
BigMack,
Thinking the G50/02, same as Stigs, as he states it is the short ratio box, so although not good for the 160mph plus speeds, can`t see myself getting there that often, so not needed for me, but low down torque/pull/accelleration is immportant to me.
So if you have the graphs e.t.c. for this, could you post them or e-mail them direct to me, but best to put on here for others to see as well please.
Used to have a Lotus Esprit V8-GT and have hit the limiter 3 times in 5th, i.e. 175-180mph, but very impractical for uk roads and I must point out was on a motorway at 4.30am in the morning, nothing about, knew the stretch of road, M3, junctions 5 to 4, a straight 2 mile run, no coppers and no cars, only me to blame if something went wrong!! so I can`t personally see the point of a box that will get me to 180-200mph, when all I will do is quite often the 120-130mph and occasionally the 150mph plus figures.
I have certain runs I go on, know the roads like the back of my hand, all low down stuff sub 120mph, but a real adrenalin rush and there are a group of bikers who also do the run most weekends and it is good fun!!
Dave
Thinking the G50/02, same as Stigs, as he states it is the short ratio box, so although not good for the 160mph plus speeds, can`t see myself getting there that often, so not needed for me, but low down torque/pull/accelleration is immportant to me.
So if you have the graphs e.t.c. for this, could you post them or e-mail them direct to me, but best to put on here for others to see as well please.
Used to have a Lotus Esprit V8-GT and have hit the limiter 3 times in 5th, i.e. 175-180mph, but very impractical for uk roads and I must point out was on a motorway at 4.30am in the morning, nothing about, knew the stretch of road, M3, junctions 5 to 4, a straight 2 mile run, no coppers and no cars, only me to blame if something went wrong!! so I can`t personally see the point of a box that will get me to 180-200mph, when all I will do is quite often the 120-130mph and occasionally the 150mph plus figures.
I have certain runs I go on, know the roads like the back of my hand, all low down stuff sub 120mph, but a real adrenalin rush and there are a group of bikers who also do the run most weekends and it is good fun!!
Dave
Bubbles,
No problemo. I don't know how to post the spreadsheet to the site, but I can send you a copy. I need your email address. I'll even adjust it for the 18" Eagle F1 tires. The G50/02 is a swiss variant of the box. Stig has a copy of these, but I've made a few new revisions. You can purchase the service manuals for these gearboxes on microfiche on Ebay. I got mine for about $30 U.S.. A terrific investment.
Cheers!
-Mack
No problemo. I don't know how to post the spreadsheet to the site, but I can send you a copy. I need your email address. I'll even adjust it for the 18" Eagle F1 tires. The G50/02 is a swiss variant of the box. Stig has a copy of these, but I've made a few new revisions. You can purchase the service manuals for these gearboxes on microfiche on Ebay. I got mine for about $30 U.S.. A terrific investment.
Cheers!
-Mack
I just bought a G50/52 from PHII. Found out the following: 1) it is 1" longer than the other G50 series long transaxles 2) it has a larger ring and pinion set.
The factory has an adapter plate kit to move the engine forward 1". I have the kit and it is well made.
I bought this transmission for the above reasons. The idea of having the motor 1" closer to the middle and a larger ring and pinion were the main reasons for the purchase.
ken
The factory has an adapter plate kit to move the engine forward 1". I have the kit and it is well made.
I bought this transmission for the above reasons. The idea of having the motor 1" closer to the middle and a larger ring and pinion were the main reasons for the purchase.
ken
Just a quick note regarding the rating of the G50 'box.
It's a little known fact (the even Porsche have been known to deny) that the G50 was actually designed to be used upside down when being developed in the Le Mans cars.
The 400bhp rating comes from the box installation in a 911 where it's the right (read wrong) way up. This puts the gear cluster at the top of the 'box out of the oil.
By inverting it, the gear clusters are bathed in the oil sump as they're now at the bottom of the gearbox thus, increasing the abuse they can take.
So, by installing it upside down, it's acutally right side up!
It's a little known fact (the even Porsche have been known to deny) that the G50 was actually designed to be used upside down when being developed in the Le Mans cars.
The 400bhp rating comes from the box installation in a 911 where it's the right (read wrong) way up. This puts the gear cluster at the top of the 'box out of the oil.
By inverting it, the gear clusters are bathed in the oil sump as they're now at the bottom of the gearbox thus, increasing the abuse they can take.
So, by installing it upside down, it's acutally right side up!
for info on porsche boxes check out this site it gives a lot of useful facts and figureswww.rennsportsystems.com/2d.html
Not wishing to confuse things to much, I had the G50 02 "Swiss Tony" that i bought new from the factory, it actually has longer gears, due to the 3.33-1 final drive. This was the element that failed on my box, which I subsequently rebuilt using a new (Quaife) and more usable 1st& 2nd gear and the more standard 3.44-1 final drive it now sits lanquishing on my workbench.
I bought a secondhand box as an interim, which is still in the car and given very good service, as i only do track-days 3rd 4th and fifth are all the gears you'll need. (160mph is the best you'll see on U.K. tracks IMHO) for Spa you can stretch a little further!
If I were building a user friendly road car I would definitley use a taller and closer 1st and 2nd gear ratio!
I bought a secondhand box as an interim, which is still in the car and given very good service, as i only do track-days 3rd 4th and fifth are all the gears you'll need. (160mph is the best you'll see on U.K. tracks IMHO) for Spa you can stretch a little further!
If I were building a user friendly road car I would definitley use a taller and closer 1st and 2nd gear ratio!
As I start becoming an expert on the G50 transmissions here some new infos.
I bought a brand new G50 04 with LSD (yes that is hardly believable isn't it), did not even know that there is one, but this is the swiss version with longer 1st and 4th which is the perfect gear box for installing a longer 5th gear withou avoiding a too large drop from 4th to fith.
Thrust tube guide (Führungsrohr):
If you buy a clutch from the factory (Sachs) or from a Porsche dealer it will require a thrust guide with 32mm instead of the 34 mm that can be found on the boxes.
Removing this is quite a task as the screws are very tight. I had to drill them out and once the heads are gone and the guide is off, it was possible to remove the remainders. So when you order this new guide tube (90 EUROs here in Germany from Porsche) be sure to order the screws as well.
G50 ratios
911 Transaxles overview
911 G50 Road Speeds
Dom's Gear ratio calculator (EXCEL file)
I bought a brand new G50 04 with LSD (yes that is hardly believable isn't it), did not even know that there is one, but this is the swiss version with longer 1st and 4th which is the perfect gear box for installing a longer 5th gear withou avoiding a too large drop from 4th to fith.
Thrust tube guide (Führungsrohr):
If you buy a clutch from the factory (Sachs) or from a Porsche dealer it will require a thrust guide with 32mm instead of the 34 mm that can be found on the boxes.
Removing this is quite a task as the screws are very tight. I had to drill them out and once the heads are gone and the guide is off, it was possible to remove the remainders. So when you order this new guide tube (90 EUROs here in Germany from Porsche) be sure to order the screws as well.
Here some helpful links
G50 ratios
911 Transaxles overview
911 G50 Road Speeds
Here the Link to Dom's gear ratio calculator
Dom's Gear ratio calculator (EXCEL file)
Edited by spatz on Wednesday 3rd March 14:05
Gassing Station | Ultima | Top of Page | What's New | My Stuff