S2 Transaxle in a Turbo
- Thread starter 944 man
- Start date
PSH
PCGB Member
Hi Simon
I have no direct experience but I can tell you about a road test carried out on a Turbo S back in 1988 that had a lower final drive fitted as per customers request. Can't remember who wrote it, may have been 'What Car' or perhaps 'Auto Car', I can find out if you wish. Anyway I do recall reading that it had little if any effect on the cars acceleration with the 0-60 time basically the same as a car with the correct final drive, reason being that whereas our cars hit 60+ in second gear, when you use the lower drive ratio you need to shift up to third at 56mph which adds up to a time the same as the standard gearbox. so no gain there but a big setback in top speed that was reduced to around 140mph.
I'd leave alone unless your only going to race up to 50mph...
Pete
Neil Haughey
New member
Very popular mod stateside for racing to put the S2 ring and pinion in the turbo box. Lower gearing = more torque at the rear wheels per rpm = faster acceleration. The negatives come from being in the wrong gear for certain corners etc. however I find in my S2 that 3rd and 4th are pretty much perfect for a lot of corners on UK tracks.
Pete is correct though on the 0-60, for starters I get enough traction problems in my S2 off the line couldn't imagine how it would be with loads more power. Once up and moving though it would be great if 2nd was longer, 3rd the same and 4th and 5th progressively shorter. This would be ideal rather than a crude drop in final drive ratio.
Pete is correct though on the 0-60, for starters I get enough traction problems in my S2 off the line couldn't imagine how it would be with loads more power. Once up and moving though it would be great if 2nd was longer, 3rd the same and 4th and 5th progressively shorter. This would be ideal rather than a crude drop in final drive ratio.
944 man
Active member
Thanks Pete - Id be interested in reading it, if thats possible.
I too thought that this would be an issue, so Ive spent the evening half watching the television and working out the practical differences as a result of the lower final drive and higher 5th gear.
With the original transaxle fitted, and confirmed by the gear/speed charts in the handbook, the Turbo will redline at 69.23mph and with the S2 transaxle it will redline at 60.32mph. This said, 0-60 races arent what Im interested in, particularly.
If Id watched less television then Id have plotted the drops, but with only the top gear differing Im hoping that it wont really make any difference... Im hoping that the lower overall ratio will make a big difference to useability, though.
Simon
I too thought that this would be an issue, so Ive spent the evening half watching the television and working out the practical differences as a result of the lower final drive and higher 5th gear.
With the original transaxle fitted, and confirmed by the gear/speed charts in the handbook, the Turbo will redline at 69.23mph and with the S2 transaxle it will redline at 60.32mph. This said, 0-60 races arent what Im interested in, particularly.
If Id watched less television then Id have plotted the drops, but with only the top gear differing Im hoping that it wont really make any difference... Im hoping that the lower overall ratio will make a big difference to useability, though.
Simon
PSH
PCGB Member
Simon I've done a little reading of my old road tests to help you make an informed decision. The road test with the Turbo S was done by 'Car and Driver' June 1988, the car tested had a final drive of 3.89:1 that was a special order. For the S2 I have conflicting final ratio's given between different write ups so not sure which is correct however they are both very close to the Turbo S test at 3.875:1 and 3.889:1 so I guess the speeds would be very close to the Turbo S test. A standard Turbo box has a final drive of 3.375:1 although some tests report 3.38:1.
Hope this helps a little
regards
Pete
Hope this helps a little
regards
Pete
944 man
Active member
Being certain of your figures is extremely difficult, certainly. I have used ratios from Clark's Garage, because Clark was the only source who acknowledged the existence of markets other than North America.
I have used:
944-T: 1st-3.500, 2nd-2.059, 3rd-1.400, 4th-1.034, 5th-0.829, FDR-3.375:1
944S2: 1st-3.500, 2nd-2.059, 3rd-1.400, 4th-1.034, 5th-0.778, FDR-3.875:1
All of my working out is available. []
I have used:
944-T: 1st-3.500, 2nd-2.059, 3rd-1.400, 4th-1.034, 5th-0.829, FDR-3.375:1
944S2: 1st-3.500, 2nd-2.059, 3rd-1.400, 4th-1.034, 5th-0.778, FDR-3.875:1
All of my working out is available. [
]al@broadway
New member
I agree with Neil, I'm running 285's on the rear but with no LSD it spins them up like a dragster so a lower final drive wouldn't be for me, horses for courses!
Fat Albert
New member
Interesting as when the gearbox went on my modified SAAB 9000 Aero, the specialist accidentally put the gearbox from a 2.0t in. It made the car absolutely useless as it felt like the engine had nothing to 'bite' against so acceleration felt very lame and it revved out at around 135 leptons in top.
Traction control off the line is all in the left and right feet. After that the shorter final drive is fantastic in most applications. We ran the S2 ring and pinion in the stock 5 speed gearbox and it REALLY wakes the car up. Fine on the street Great on the track. The only downside is on the motorway you feel like an extra gear when cruising so it depends on your criteria.
edh
New member
Sounds like a good idea - and Patrick has been there & done it, so he should know. People don't find the S2 engine speed an issue when cruising, so I can't see revs going up by 10% being a big deal, apart from using a bit more fuel maybe. (my last track car cruised at 5-6k rpm, and topped out at 8500/~130mph [])
I was surprised how easy it was to spin the inside rear of the exit of the S2 on the two 2nd gear corners at Anglesey - on a hot, dry track. I wouldn't have expected my old turbo (with LSD) to do that at all, & that was with the same width tyres (225) as well. What options do you have to put an LSD in there at the same time? (I don't know whether yours has a turbo/LSD box or not)
])I was surprised how easy it was to spin the inside rear of the exit of the S2 on the two 2nd gear corners at Anglesey - on a hot, dry track. I wouldn't have expected my old turbo (with LSD) to do that at all, & that was with the same width tyres (225) as well. What options do you have to put an LSD in there at the same time? (I don't know whether yours has a turbo/LSD box or not)
944 man
Active member
Unfortunately the original box is a UY, bereft of cooler and LSD. People are presuming that this is a performance upgrade, and whilst I do have my eye on this, its also an expedient solution, as my original transaxle has a leaking driveshaft and a porous rear, so it needs work.
Edited to add: having just read my opening post - people are presuming that its a performance upgrade because of what I said. Sorry.
Edited to add: having just read my opening post - people are presuming that its a performance upgrade because of what I said. Sorry.
944 man
Active member
A 3.889:1 FDR will have come out of an S or an 8v car, although the difference between this and an S2 is very small. Im surprised at their results though, because even allowing for a lower rev limit (they state 6,400rpm but my calculations assume a 6,500rpm limit), Id still expect to reach 59.3mph, but they claim 54mph.
PSH
PCGB Member
happy it got to you ok then Simon, well I guess there can be a number of reasons for differences when testing a car, head wind, tyre pressure, air pressure etc etc... still it's an interesting read and back then the 944 was held in very high esteem as it should still be today.
Pete
Neil Haughey
New member
Simon all your numbers tally with what I see from my S2. On the 0-60 they probably didn't rev out 2nd.
Edd my car is even worse than yours as lighter and very stiff on the rear end. You can see and hear the traction problems I had in the loop at Silverstone and that was with leaving it in 3rd when its really a 2nd gear corner. The 968's such as Paul F killed me massively in that section.
The thing with the LSD is I don't really think the ZF unit is much cop and I know EMC feel exactly the same. Ben Eacock described it to me in the terms that an LSD in an S2 is like understeer/understeer/oh bugger I'm sideways, whereas the KAAZ unit they use in the 968 is much more progressive. Certainly driving my car with the LSD at Brands it was shocking just how prophetic Ben's description was because that is exactly what the car was like, arms and shoulders killing understeer like I have never experienced before followed by snap oversteer once the limit is broached. Kills the enjoyment of the car for me thus I feel unless someone can get a Guards diff or something or just doesn't care and is chasing tenths of seconds then IMHE steer clear of the factory LSD.
Having said all that I am also convinced that the LSD is only an issue in an S2 for 2nd gear corners. The rest of the time the suspension can and should be tuned to fix other issues. As an example the inside rear wheel lifting problem I had last year was a suspension issue, trying to fix it with an LSD is bad engineering as its using something to fix the symptom and not the cause.
Edd my car is even worse than yours as lighter and very stiff on the rear end. You can see and hear the traction problems I had in the loop at Silverstone and that was with leaving it in 3rd when its really a 2nd gear corner. The 968's such as Paul F killed me massively in that section.
The thing with the LSD is I don't really think the ZF unit is much cop and I know EMC feel exactly the same. Ben Eacock described it to me in the terms that an LSD in an S2 is like understeer/understeer/oh bugger I'm sideways, whereas the KAAZ unit they use in the 968 is much more progressive. Certainly driving my car with the LSD at Brands it was shocking just how prophetic Ben's description was because that is exactly what the car was like, arms and shoulders killing understeer like I have never experienced before followed by snap oversteer once the limit is broached. Kills the enjoyment of the car for me thus I feel unless someone can get a Guards diff or something or just doesn't care and is chasing tenths of seconds then IMHE steer clear of the factory LSD.
Having said all that I am also convinced that the LSD is only an issue in an S2 for 2nd gear corners. The rest of the time the suspension can and should be tuned to fix other issues. As an example the inside rear wheel lifting problem I had last year was a suspension issue, trying to fix it with an LSD is bad engineering as its using something to fix the symptom and not the cause.
I'd agree with what Neil says here. The Guards ones ex USA are probably still the best option out there from what I've read. I have a KAAZ in the 6 speed but can't give any real feedback as of yet. Not sure if KAAZ has one for the 5 speed? I have a spare 5 speed with the S2 r&p and a Mondena Motorsport LSD sitting in the workshop. It's always had a little whine but works perfectly. New syncros put in recently. Fly over and take it home Simon. [
] Neil, ot, but interested to hear of your inside rear wheel lift and what you found caused it and cured it? This is why I had my crash but still haven't determined why this situation exists. I suspect ride height is set too high due to the front wheel clearance needed.
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