Overdrive unit for our Tranny's
07-26-04, 10:08 PM
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Overdrive unit for our Tranny's
I was watching horsepower TV, or Trucks, forgot which, and saw they had an overdrive unit from some manufacturer.
I don't want to push the top speed of the gs, just lower the cruising RPM's at around 95 from 4000 to somewhere in the range of 2500 so my engine will last a long time.
Is this possible? Anyone done it? Anyone know any manufacturers of this?
I don't want to push the top speed of the gs, just lower the cruising RPM's at around 95 from 4000 to somewhere in the range of 2500 so my engine will last a long time.
Is this possible? Anyone done it? Anyone know any manufacturers of this?
07-27-04, 12:54 AM
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The kinds of units I've seen are designed for very low-geared trucks and 4 wheelers that have the room in the drivetrain for transfer cases and other devices like that. No way anything like that would work on the GS (or just about any car I'd guess).
Also, my car was at about 3350 rpm at 100 mph when I had stock gearing. Is the GS3 geared that much lower? I know the rear diff ratio is pretty low...
Maybe you could swap in a GS4 diff, but then you would have gearing that was not appropriate for your engine (i.e. too high ratio). It would be difficult to do 95 mph at only 2500 rpm with this car and engine even if you could change the gearing IMO. The power required to maintain that speed under most conditions would not be available at that lower rpm and the trans would want to be downshifting every chance it got. The gearing and power band of the engine need to be matched well for balanced performance.
BTW, the size wheels/tires you have already have raised your effective gear ratio somewhat due to they're being about 1" larger diameter than stock, so that helped a little...
Also, my car was at about 3350 rpm at 100 mph when I had stock gearing. Is the GS3 geared that much lower? I know the rear diff ratio is pretty low...
Maybe you could swap in a GS4 diff, but then you would have gearing that was not appropriate for your engine (i.e. too high ratio). It would be difficult to do 95 mph at only 2500 rpm with this car and engine even if you could change the gearing IMO. The power required to maintain that speed under most conditions would not be available at that lower rpm and the trans would want to be downshifting every chance it got. The gearing and power band of the engine need to be matched well for balanced performance.
BTW, the size wheels/tires you have already have raised your effective gear ratio somewhat due to they're being about 1" larger diameter than stock, so that helped a little...
Last edited by FutureGS400; 07-27-04 at 12:59 AM.
07-27-04, 09:04 AM
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I'm not sure if it was exaclty 3500, just guesstamating.
Yeah I thought about the power the car needed to stay up at that speed....... huh....oh well.......It cant be that bad on the engine to run at that high rpm's if the factory set it that way.
Yeah I thought about the power the car needed to stay up at that speed....... huh....oh well.......It cant be that bad on the engine to run at that high rpm's if the factory set it that way.
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