[87supramario]

Im looking to purchess a diff from a friend. He has both pre 89 and 89+ diffs available. Just wondering what are the RPM's you guys are at highway speeds.

86-88 Turbos 3.91 LSD

89-92 Turbos 3.73 LSD

 

[jonahs_supra]

i have a 87 turbo...at 60mph im at 2,300-2,400rpms and at 65mph im at 2,500rpms

 

[Miiike]

In my '90 turbo I was at 2500 at 100 km/h (62mph)

 

[matt666]

you want the 3.73 if your going bigger power.

 

[Supra NA-T]

im not turbo im about 3500 - 3700 at 60-65

 

[KingCobra]

Depends on what you want, gas mileage or power ...

the 4.30 gearing will make you quicker, but you will burn a bit more gas @ highway speeds > 65 (and yes you can get or make a 4.30 LSD unit).

If you want best gas mileage, you want the 3.73 because it will produce the lowest RPM's at highway speeds ... and the 3.91 gearing is a nice middle of the road option ... (all the MX83 Cressidas are 3.91 from the factory too just like the early MK3's).

Also remember, if you change your rear end gear ratio, you also should replace the gear for the speedo cable in the tailshaft of your tranny to match the chassis the diff came from so that your speedo is accurate!

 

[87supramario]

Sorry for the double thread obviously something whent wrong while posting. And again I cant delete even this one since the delete option is not there.

Anyways I have a 1986.5 sport package LSD 4.30 diff with W58 drivetrain all original with 7mge. High RPM's on the highway about 3200RPM at 62MPH. I hate this gear reduction and how it eats away at my gas on the highway. Also my universal axels are going, you feel alot of play when you ease off the clutch.

Question - Am I able to keep my driveshaft for this particular swap?

 

[Fonz87]

Auto or 5 speed ?? i think i m at like 2 ish k or so at 60 mph in my turbo 5 speed 1989.

 

[87supramario]

Depends on what you want, gas mileage or power ...

the 4.30 gearing will make you quicker, but you will burn a bit more gas @ highway speeds > 65 (and yes you can get or make a 4.30 LSD unit).

If you want best gas mileage, you want the 3.73 because it will produce the lowest RPM's at highway speeds ... and the 3.91 gearing is a nice middle of the road option ... (all the MX83 Cressidas are 3.91 from the factory too just like the early MK3's).

Also remember, if you change your rear end gear ratio, you also should replace the gear for the speedo cable in the tailshaft of your tranny to match the chassis the diff came from so that your speedo is accurate!

Now with 18inch rims my speedo reads 10km/h over what im actually moving. I think this swap will make the speedo read alot worse.

 

[87supramario]

Can anybody running a turbo diff and W58 tranny let me know how fast there going at highway speeds? Also, witch diff they are using?