968 gearbox in a 944
- Thread starter dodgydal
- Start date
Peter Empson
PCGB Member
I'm all muscle you know (apart form the 99% of me that's pure fat) [
]We have a few speakers, turntables and amps at the shop that are in the 40-60 kg range, so you get quite used to lugging those brutes about. Not fun when most of them have to go upstairs, I really must try to sell more headphones [
] 
pauljmcnulty
Active member
ORIGINAL: Peter Empson
I'm all muscle you know (apart form the 99% of me that's pure fat) [
We have a few speakers, turntables and amps at the shop that are in the 40-60 kg range, so you get quite used to lugging those brutes about. Not fun when most of them have to go upstairs, I really must try to sell more headphones [
Or, get a downstairs shop? [:-][:-]
Peter Empson
PCGB Member
[
] Can't argue with that logic! []
This is my understanding following a discussion with one of the Clubs foremost technical Gurus. As explained to me, the issue is the sixth gear which is housed in an appendage to the 944 casting. This appendage is the size of a couple of beer glasses (guess where he discussion was taking place) so would require some fairly enthusiastic panel work to the boot floor.
sawood12
New member
From reading on Rennlist from guys who have done this I thought the 968 box was a straight swap. The only difference is one of the driveshafts as they are unequal lengths and the speedo is different in that on the 968 it is an electronic pick-up and on the 944 it is a mechanical pick-up - but there are ways around this. In fact I think the Audi S2 basically used an S2 gearbox with an electronic speedo pickup so I think you can buy a pick-up module from an Audi S2 and use that. Also if you've got the plastic fuel tank you're OK, but if you've got the earlier metal one you'll need to replace with the plastic one. There certainly wasn't any mention of panel modifications. I've also read an article a while back in Porsche 911 world mag where a guy transplanted a complete 968 engine and transmission into his S2 which required no modifications to the car whatsoever, just a straight replacement of the relevent parts.
I really think that this would be a waste of time on a turbo unless you installed some major engine mods i.e. increased capacity etc.. I think the ratio's on a turbo box are already pretty good. When on it and changing from near the red line you are dropped right into the start of the powerband for the next gear therefore wasting virtually none of the enigne's power band. And at 70 - 80 mph motorway cruise you are sat right at the lower end of the powerband so have instant on-boost power available at your right foot. With a 968 box you'd either be dropping out of the on-boost power band at gearchanges or picking up the next gear well into the powerband thus wasting good powerband. Lots of gears are the solution to a narrow powerband engine - changing gear often doesn't result in a quicker drive as you're not laying power down when changing gear.
I guess if you changed the ratio's such that the first 5 gears are the same and the 6th can be used for an ultra-economy cruising gear (like the 7th gear on the new PDK 997's) then that would be useful for long motorway journeys, though you'd be cruising out of boost.
I really think that this would be a waste of time on a turbo unless you installed some major engine mods i.e. increased capacity etc.. I think the ratio's on a turbo box are already pretty good. When on it and changing from near the red line you are dropped right into the start of the powerband for the next gear therefore wasting virtually none of the enigne's power band. And at 70 - 80 mph motorway cruise you are sat right at the lower end of the powerband so have instant on-boost power available at your right foot. With a 968 box you'd either be dropping out of the on-boost power band at gearchanges or picking up the next gear well into the powerband thus wasting good powerband. Lots of gears are the solution to a narrow powerband engine - changing gear often doesn't result in a quicker drive as you're not laying power down when changing gear.
I guess if you changed the ratio's such that the first 5 gears are the same and the 6th can be used for an ultra-economy cruising gear (like the 7th gear on the new PDK 997's) then that would be useful for long motorway journeys, though you'd be cruising out of boost.
Peter Empson
PCGB Member
I'm probably wrong, but I thought that all cars after the oval dash had electronic pick up for the speedo?
sawood12
New member
Well most the vast majority of what i've read on this have been in relation to transplanting a 968 box into a turbo which were all oval dash models, and the only issue which required a solution was the speedo pickup.
The actual speedo gauge has an electronic input so there must be a mechanical to electric transducer somewhere in the 944 system so I don't see why you can't simply covert the electronic signal from the 968 to the electronic signal the 944 speedo needs rather than trying to solve the problem at the gearbox end.
The actual speedo gauge has an electronic input so there must be a mechanical to electric transducer somewhere in the 944 system so I don't see why you can't simply covert the electronic signal from the 968 to the electronic signal the 944 speedo needs rather than trying to solve the problem at the gearbox end.
TTM
Well-known member
When we fitted the 968 gearbox on my friend's '91 turbo, we used the following parts :
- 968 gearbox
- 968 gearshift
- 968 gear linkage
- 968 right driveshaft
- 968 ABS control unit
- 968 relay G16 "Frequency Control Unit"
The 968 differential is less wide than the 944's and is slightly offset to the left, whence the need for the right 968 driveshaft that is longer. The left 944 driveshaft can be reused.
The 944 gearknob fits on the 968 gearshift.
The 968 ABS control unit and the G16 relay are needed to convert the signal taken from the ABS to the speedometer. There is no slot in the relay box of the 944 for the G16 relay since the 944 wiring loom and the 968's are different, meaning some thinking has to be done when looking at both wiring diagrams in order to insert the G16 relay in the 944 wiring (my friend located the relay in the dashboard behind the central air vents).
Lastly the connector for the backwards lights (the white ones that light up when you drive backwards, don't know the term in English for these! [8|]) doesn't connect directly. Can't remember how we got through this one.
- 968 gearbox
- 968 gearshift
- 968 gear linkage
- 968 right driveshaft
- 968 ABS control unit
- 968 relay G16 "Frequency Control Unit"
The 968 differential is less wide than the 944's and is slightly offset to the left, whence the need for the right 968 driveshaft that is longer. The left 944 driveshaft can be reused.
The 944 gearknob fits on the 968 gearshift.
The 968 ABS control unit and the G16 relay are needed to convert the signal taken from the ABS to the speedometer. There is no slot in the relay box of the 944 for the G16 relay since the 944 wiring loom and the 968's are different, meaning some thinking has to be done when looking at both wiring diagrams in order to insert the G16 relay in the 944 wiring (my friend located the relay in the dashboard behind the central air vents).
Lastly the connector for the backwards lights (the white ones that light up when you drive backwards, don't know the term in English for these! [8|]) doesn't connect directly. Can't remember how we got through this one.
Peter Empson
PCGB Member
Thanks for clearing that up Scott. I do wonder why they changed it on the 968?
Thom, they're called reverse lights.
Did your friend like the 968 box? I have a friend that did the same conversion and likes it.
I sort of agree with Scott re the ratios suiting a high revving n/a motor for example, but having the S2 crown wheel & pinion in mine, I have to say that this is a great modification and you get to use the 'meat of power' just fine. You do shift more, but I don't feel like I'm wasting the powerband. If ever any of you guys come down to Sydney be sure to look me up and try it for yourself.
Did your friend like the 968 box? I have a friend that did the same conversion and likes it.
I sort of agree with Scott re the ratios suiting a high revving n/a motor for example, but having the S2 crown wheel & pinion in mine, I have to say that this is a great modification and you get to use the 'meat of power' just fine. You do shift more, but I don't feel like I'm wasting the powerband. If ever any of you guys come down to Sydney be sure to look me up and try it for yourself.
sawood12
New member
Funnily enough i've been keeping track of a thread on Rennlist about retrofitting early Boxster ABS into a 951 which is apparently the same as the 968 ABS system. Apparently the main difference is that the DME takes it's speed reference from one of the rear ABS sensors and ties in with the ABS somehow and obviously they thought they may as well take the speedo input from there also. In a 951 the ABS is completely stand alone from the ECU. Later Boxster ABS systems are more complex as they are 5 channel and are hooked into the ECU moreso due to traction and stability control.
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