Getrag Gearbox
Discussion
There have been several discussions on gearboxes but can anyone offer advice on the Getrag.
I got my GTR on the road in June and have done over 6000 miles since then with the Getrag transaxle. I like the gearbox but as mentioned in other posts it is geared for higher revving engines. 1st gear is a waste of time and I now find 165mph top speed too slow
I would like to increase the final drive thus bringing 1st gear into play and increasing the top speed.
Does anyone know what options are available (if any) for this gearbox or any companies in the UK who could help?
ulitimacz - I know your not in the UK but I read your post in which you state you are changing the final drive on your getrag box from 3.44 to 3.07 is this a standard part or are you adapting gears from another box.
I got my GTR on the road in June and have done over 6000 miles since then with the Getrag transaxle. I like the gearbox but as mentioned in other posts it is geared for higher revving engines. 1st gear is a waste of time and I now find 165mph top speed too slow
I would like to increase the final drive thus bringing 1st gear into play and increasing the top speed.
Does anyone know what options are available (if any) for this gearbox or any companies in the UK who could help?
ulitimacz - I know your not in the UK but I read your post in which you state you are changing the final drive on your getrag box from 3.44 to 3.07 is this a standard part or are you adapting gears from another box.
The major player in modding Porsche boxs seems to be Powerhaus in the States, I know they can provide final drives to increase the gearing on my box.
It won't be cheap though... assuming they do a bigger diff for your box.
Don't forget though that you can get different cogs and could change the gearing that way at around $600 a cog, and 3to4 and 5to6 usually interchange (I think first comes on the final drive though).
I do have a few number you can try over here and I will dig them out.
It won't be cheap though... assuming they do a bigger diff for your box.
Don't forget though that you can get different cogs and could change the gearing that way at around $600 a cog, and 3to4 and 5to6 usually interchange (I think first comes on the final drive though).
I do have a few number you can try over here and I will dig them out.
Chewy,
This conversion will be done by a specialised company in Austria (Porsche specialists). We have taken the gearbox there just now and they will make an offer. For sure it will not be cheap - Getrag is obviously charging a lot for these parts. I will inform once everything is clarified. If the conversion is not possible (or reasonable) we will have to go for a new gearbox. The current gear ratios are a threat for the live expectation of the SB - these engines are not designed to be revved like a Porsche and suffer accordingly (own experience)...
This conversion will be done by a specialised company in Austria (Porsche specialists). We have taken the gearbox there just now and they will make an offer. For sure it will not be cheap - Getrag is obviously charging a lot for these parts. I will inform once everything is clarified. If the conversion is not possible (or reasonable) we will have to go for a new gearbox. The current gear ratios are a threat for the live expectation of the SB - these engines are not designed to be revved like a Porsche and suffer accordingly (own experience)...
Is there any place you can get Parts for these Getrac boxes, as have been tring to find a 2nd gear Sycro for a Spare box I have. But so far no one can get spares, stating that neather Porsche nor Getrac will suply them. Also have another box coming soon, that needs a rebuild, but aparently there are also some one-off bearings in them as well, so may just end up with a bag of bits.
G50's do seem to be the most modifieable gearbox !!
G50's do seem to be the most modifieable gearbox !!
Clive,
The Porsche dealerships do not supply parts for these boxes? Seems odd. I don't normally buy my G50 parts from a dealership b/c of the high cost, but it was always pretty simple to purchase the G50 parts before from them. Have you tried PowerHausII in the states or Patrick Motorsports or any specialist rebuilders in the UK? What car does the Getrag come from(I was thinking it came from a Porsche boxster)? I'm curious if any of the internal parts are the same as the G50(gears, synchros, sleeves, needle rollers, etc...). I have opened up and rebuilt my G50, and I have a spare set of gears, synchros, sleeves, etc..that I could take measurements from.
Cheers!
-Mack
The Porsche dealerships do not supply parts for these boxes? Seems odd. I don't normally buy my G50 parts from a dealership b/c of the high cost, but it was always pretty simple to purchase the G50 parts before from them. Have you tried PowerHausII in the states or Patrick Motorsports or any specialist rebuilders in the UK? What car does the Getrag come from(I was thinking it came from a Porsche boxster)? I'm curious if any of the internal parts are the same as the G50(gears, synchros, sleeves, needle rollers, etc...). I have opened up and rebuilt my G50, and I have a spare set of gears, synchros, sleeves, etc..that I could take measurements from.
Cheers!
-Mack
Glyn - Just thinking aloud here. If you know what model your 'box came from. C2, C4, Turbo etc. You may be able to find out if any of the other models have a higher final drive and try and source/swap the diff or whole box for the one you preffer?
I'm thinking a C2 may have a lower f/d than a C4 or turbo.
Paul.
I'm thinking a C2 may have a lower f/d than a C4 or turbo.
Paul.
I have made note of all the serial and casting numbers I can find on the box but am struggling to find any references that may identify these markings and point to which model it is from and indeed if there is any difference between them. I believe Ultima has supplied a couple of different variants of the box (Some with LSD and others without dependant on availability) but I don’t think they have much information as to the internals of the box.
QUAIFE as suggested look like they may be well worth a phone call when I have got the serial numbers in front of me as looking at their web site they offer several direct replacements for the Porsche 996 gearbox and have some internals for the GT3 gearbox.
QUAIFE as suggested look like they may be well worth a phone call when I have got the serial numbers in front of me as looking at their web site they offer several direct replacements for the Porsche 996 gearbox and have some internals for the GT3 gearbox.
Quaife were a waste of time when I contacted them, I have their booklet and it clearly says parts for the GT3 are available.
I phoned them up and they said they have never done any parts to the GT3 box as if I was totally stupid, so I pointed out their clear advertising to the contrary...'Oh we thought about it once but it never got past the drawing board'
I phoned them up and they said they have never done any parts to the GT3 box as if I was totally stupid, so I pointed out their clear advertising to the contrary...'Oh we thought about it once but it never got past the drawing board'
I thought the same as you and when the gearbox died (G50-03 available for rebuild) I fitted a G50-52 which takes the final gearing to about 30mph/1000revs.
There are some issues with this conversion - the box is about an inch longer at the tail which required support mods (linkage had enough adjustment to work ok)but the real issue is in the bell housing itself as it's designed to run with the later flywheel and clutch assembly which has the starter ring gear on the flywheel and not on the clutch cover.
It took me 16 hours to hand machine (remove metal) from the inside of the housing to make the opening parallel to accomodate the existing clutch. It was not fun nor easy as I didn't have a machine shop and any 'normal' grinding tools don't work on the aluminium without clogging up! It was finished as I recall at 7.30 one evening last June in time for us to drive through the night to arrive at the Nurburgring at about 5 in the morning!
It has transformed the long distance cruising ability and 1st gear is now usable. The only trade off is the extra length of the other gears which some might say reduces the 'urgency' of the Ultima acceleration but I reckon there's enough torque for that not to be an issue.
Cheers,
Dave
There are some issues with this conversion - the box is about an inch longer at the tail which required support mods (linkage had enough adjustment to work ok)but the real issue is in the bell housing itself as it's designed to run with the later flywheel and clutch assembly which has the starter ring gear on the flywheel and not on the clutch cover.
It took me 16 hours to hand machine (remove metal) from the inside of the housing to make the opening parallel to accomodate the existing clutch. It was not fun nor easy as I didn't have a machine shop and any 'normal' grinding tools don't work on the aluminium without clogging up! It was finished as I recall at 7.30 one evening last June in time for us to drive through the night to arrive at the Nurburgring at about 5 in the morning!
It has transformed the long distance cruising ability and 1st gear is now usable. The only trade off is the extra length of the other gears which some might say reduces the 'urgency' of the Ultima acceleration but I reckon there's enough torque for that not to be an issue.
Cheers,
Dave
davejw said:
...It took me 16 hours to hand machine (remove metal) from the inside of the housing to make the opening parallel to accomodate the existing clutch. It was not fun nor easy as I didn't have a machine shop and any 'normal' grinding tools don't work on the aluminium without clogging up!
I'm sort of glad to hear that I wasn't the one that had to go through this process... I seem to remember it took me even longer (I lost count of the hours in the end...)
Some news on my Getrag:
Not possible to change final drive, unfortunately. We are now changing the 6th gear ratio only, to allow for a drop of approx. 600 to 900 rpm at speed 120km/h, i.e. reducing from currently 3.000 rpm to approx. 2.200. This should assure much better comfort, fuel consumption and less wear with longer highway driving. We will have the new gears manufactured by a specialised company in Austria, as Porsche or Getrag do not offer any suitable spares.
The gearbox specialist stated that he found already quite some wear, more than usual. This after 5000 miles and no racing. He was not surprised though, because this Getrag is designed for 300HP max. Looks like a complete replacement in one year or two.
Peter
Not possible to change final drive, unfortunately. We are now changing the 6th gear ratio only, to allow for a drop of approx. 600 to 900 rpm at speed 120km/h, i.e. reducing from currently 3.000 rpm to approx. 2.200. This should assure much better comfort, fuel consumption and less wear with longer highway driving. We will have the new gears manufactured by a specialised company in Austria, as Porsche or Getrag do not offer any suitable spares.
The gearbox specialist stated that he found already quite some wear, more than usual. This after 5000 miles and no racing. He was not surprised though, because this Getrag is designed for 300HP max. Looks like a complete replacement in one year or two.
Peter
doc_fudge said:
Peter,
What make you think that the Getrag is limited to 300hp?
I mean, doesnt every current Porsche fitted with this box produce more power than this?
Maybe youve used the wrong oil or something?
Andy
Andy,
This is the information which I got from a Porsche gearbox specialist. I personally understand nothing about it. The Getrag box we have is designed for basic 911 (not for the latest models I think!) and good for around 300HP to go through it. Same applies for the clutch which is also Porsche std. We bought now a stronger clutch. Bigger problem than HP is the torque, as I understand. I am told that the better box would be from a GT2, i.e. for around 450 turbo HP with rear wheel drive. Also the gear ratios are more suitable, i.e. 0.72 for the 6th gear, compared to 0.84 on my std. Getrag, should run 305kph (190mph) at around 6300rpm, whereas current one does "only" 165mph when it hits the rev limiter. But a GT2 box is far more expensive, of course. Oil is original as supplied from Ultima factory, never changed.
I would be interested whether anybody has put a GT2 box into an Ultima GTR/CanAm and what modifications would be necessary. I can still re-think the modification of the gears in my current box and replace it alltogether.
Cheers,
Peter
Advice I had from a Porsche gear box specialist was that you take the torque of the car it was designed for and the box would be officially rated for torque just a few % higher. Double that to get the real maximum operating torque though. This may of course apply only to G50, Getrag box may have less safety margin.
This 2 x rating is the maximum before possible destruction of components. Quite likely that higher torque than box rated for might increase wear rate but wouldn't expect it to be that bad with synthetic oil and clean internals.
This 2 x rating is the maximum before possible destruction of components. Quite likely that higher torque than box rated for might increase wear rate but wouldn't expect it to be that bad with synthetic oil and clean internals.
gdr said:
Advice I had from a Porsche gear box specialist was that you take the torque of the car it was designed for and the box would be officially rated for torque just a few % higher. Double that to get the real maximum operating torque though. This may of course apply only to G50, Getrag box may have less safety margin.
This 2 x rating is the maximum before possible destruction of components. Quite likely that higher torque than box rated for might increase wear rate but wouldn't expect it to be that bad with synthetic oil and clean internals.
I was also told that Porsche boxes have a big safety margin, so it should not be that critical. On the other hand there are signs of wear after 5000mls which should not be. The specialist said that it is no problem to run it now but that I should avoid quick starts (or drag races). Or the box would not last too long. Now, this is a problem for me - biggest fun is accelerating, not cruising.
As said before, oil was ok and I treated the box pretty well (only 5 track days since new). A friend of mine who bought the Ultima GTR at the same time in spring this year(550BHP and identical box) complained from the beginning about problems with switching gears and when his box was dismantled now it was found that a bearing was totally destroyed. Seems like a Getrag manufacturing issue in this case, not too much torque.
These Getrag boxes are not too expensive, so it would be an economical solution to run them some years and then to re-build them. Problem is that there are no spare parts available and due to the way the internals are pressed together it is quite risky to take it apart and put again together. This box is really for complete replacement only, not for repairs.
At this point Peter, I am guessing that you are just trying to salvage and use your getrag box without having to go through the expense of purchasing something new. Don't let this thing be a "money pit" for you though. I've seen prices on rebuilt G50/20 6-speed transaxles fall dramatically since the Getrag has come out(cut in half). www.phii.net/new/sale.cfm
I'm a G50 man personally. I like the fact that the G50,G50/50,G50/20, etc... all have many spare parts and modifications available. I can get custom gears in just about any ratios, Porsche has special racing parts available, and there are a variety of LSD options. Not to mention they all share similar parts and gears. A friend of mine is running a GTR with 1000hp/625ft.lbs of torque with a G50/20 and hasn't had any problems.
On this subject of gearboxes. Has anyone thought about a 1960's Hewland LG500 or LG600(6-speed)? Those canam cars ran 700hp and loads of torque. I saw an LG500 advertised for about $5800 US.
I can understand your frustration Peter. I got so pissed off after receiving my rebuilt G50 that didn't shift into 1st or 2nd gear(rebuilder used non porsche parts with a synchro hub that was not precisely machined) that I dropped $6000 on 5 new gears and synchros. Then dropped another $700 on Porsche factory tools and factory service manual to rebuild the damn thing myself! Fortunately, I was able to get a factory manual off of EBAY for $25 bucks on microfiche. The hardcopy of course costs $600 just in itself. I can understand your frustration Peter...bigtime!
Cheers!
-Mack
I'm a G50 man personally. I like the fact that the G50,G50/50,G50/20, etc... all have many spare parts and modifications available. I can get custom gears in just about any ratios, Porsche has special racing parts available, and there are a variety of LSD options. Not to mention they all share similar parts and gears. A friend of mine is running a GTR with 1000hp/625ft.lbs of torque with a G50/20 and hasn't had any problems.
On this subject of gearboxes. Has anyone thought about a 1960's Hewland LG500 or LG600(6-speed)? Those canam cars ran 700hp and loads of torque. I saw an LG500 advertised for about $5800 US.
I can understand your frustration Peter. I got so pissed off after receiving my rebuilt G50 that didn't shift into 1st or 2nd gear(rebuilder used non porsche parts with a synchro hub that was not precisely machined) that I dropped $6000 on 5 new gears and synchros. Then dropped another $700 on Porsche factory tools and factory service manual to rebuild the damn thing myself! Fortunately, I was able to get a factory manual off of EBAY for $25 bucks on microfiche. The hardcopy of course costs $600 just in itself. I can understand your frustration Peter...bigtime!
Cheers!
-Mack
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