Any help ? Is the diff on a 1st generation Q the same as the 91 up 300TT ? Seen gears listed for the 300TT ,,,If so where to locate 3:90 or 4:08 gears
Thanks:D
R200 Diff in 300TT same as 1st gen Q?
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Q45tech
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- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Q without Active or TCS have only a single channel rear ABS sensor on the input of the differential since in theory the LSD will not allow more than a half to a full turn of slip in braking.
The 300zx had 2 sensors on the rear so there can be differences in the differential output /input shaft lengths between models.just as there is between the Q options.
The driveshaft speed sensor is located in the rear of the tranny and has a nylon reduction gear appropriate to the diff ratio so this gear must be changed to one from a 300 zx automatic so the speedo, steering boost, odo, dual trip meters, tranny shifts, and engine ecu will read the correct speed!
The 4.083 is 15.4% higher ratio so the rear wheel torque is multiplied by 15% [a little lost to extra friction]. So for acceleration purposes the car acts like you added 36 lb/ft to the 235 rear wheel lb/ft at the tire interface [road]................this increases acceleration by 4% at the expense of increasing rpms by 15% which decreases highway mileage by 15% at exactly the same cruising speed. The city mileage is less affected say 10% less.
19 vs 16.88 would be my guess for the overall reduction: about 100 more gallons per 15,000 miles in mixed driving.
From a longevity standpoint: if 300k is norm then expect an engine life reduction of 30,000 miles or so based purely on piston speed as 60 mph will increase from 2000 to 2310 rpm.
The biggest down side is the change in 2nd gear shift point [as 854 becomes the new rpm/10 mph so the shift will occur around 71-73 mph [in a 90-93Q]......not necessarily the best point in trying to pass a semi......the 94-96Q with its smaller 1st and 2nd gear ratios will regain significant acceleration lost and shift at an ideal 80 mph [45, 80, 112 mph shift respectively].
If you feel the performance is worth the extra ANNUAL gasoline cost this is an inexpensive enhancer and roughly equals the JWT in gains and the two together complement each other nicely as in 0-60 mph both can drop the time by at least 0.5 [probably more]seconds in 90-96Q.
When you look at the differences between an Audi A8 and a S8 you'll see this is just what they did. You just have to fill up 15% sooner.
It is possible that the engine efficiency curve likes 2300 better than 2000 so 60 mph might not be as bad as I portrayed but the ecu assumes anything above 2500 is not cruising so 66 mph might be the pivot point where the full 15% reduction starts vs the normal 75 mph [auto enrichment to cool engine]???????
If your going 75 mph you can't be concerned about squeezing the optimum mileage is the way the current ecu thinks -- to protect the engine from leaness!
The 300zx had 2 sensors on the rear so there can be differences in the differential output /input shaft lengths between models.just as there is between the Q options.
The driveshaft speed sensor is located in the rear of the tranny and has a nylon reduction gear appropriate to the diff ratio so this gear must be changed to one from a 300 zx automatic so the speedo, steering boost, odo, dual trip meters, tranny shifts, and engine ecu will read the correct speed!
The 4.083 is 15.4% higher ratio so the rear wheel torque is multiplied by 15% [a little lost to extra friction]. So for acceleration purposes the car acts like you added 36 lb/ft to the 235 rear wheel lb/ft at the tire interface [road]................this increases acceleration by 4% at the expense of increasing rpms by 15% which decreases highway mileage by 15% at exactly the same cruising speed. The city mileage is less affected say 10% less.
19 vs 16.88 would be my guess for the overall reduction: about 100 more gallons per 15,000 miles in mixed driving.
From a longevity standpoint: if 300k is norm then expect an engine life reduction of 30,000 miles or so based purely on piston speed as 60 mph will increase from 2000 to 2310 rpm.
The biggest down side is the change in 2nd gear shift point [as 854 becomes the new rpm/10 mph so the shift will occur around 71-73 mph [in a 90-93Q]......not necessarily the best point in trying to pass a semi......the 94-96Q with its smaller 1st and 2nd gear ratios will regain significant acceleration lost and shift at an ideal 80 mph [45, 80, 112 mph shift respectively].
If you feel the performance is worth the extra ANNUAL gasoline cost this is an inexpensive enhancer and roughly equals the JWT in gains and the two together complement each other nicely as in 0-60 mph both can drop the time by at least 0.5 [probably more]seconds in 90-96Q.
When you look at the differences between an Audi A8 and a S8 you'll see this is just what they did. You just have to fill up 15% sooner.
It is possible that the engine efficiency curve likes 2300 better than 2000 so 60 mph might not be as bad as I portrayed but the ecu assumes anything above 2500 is not cruising so 66 mph might be the pivot point where the full 15% reduction starts vs the normal 75 mph [auto enrichment to cool engine]???????
If your going 75 mph you can't be concerned about squeezing the optimum mileage is the way the current ecu thinks -- to protect the engine from leaness!
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