Differentials

[gtsfirefighter]

Ok, time for me to ask another question I'm sure has been addressed numerous times, but cannot find what I really want to know.

Which cars have which differentials? Which one is best for just cruising. My car is an 89 NA, where on the car do I find the code to determine which one I have? My speedo is off exactly 10 miles per hour (shows faster than what I'm doing) and was wondering if maybe one of the previous owners swapped them.
Ken

 

[Tearlessj]

My 89 n/a has the 4.10 open diff.

 

[tsuper92]

4.30 open if non-sport package.
4.30 lsd if it is a sport package n/a
do you have a taller tire or a different tran's?

 

[gtsfirefighter]

4.30 open if non-sport package.
4.30 lsd if it is a sport package n/a
do you have a taller tire or a different tran's?

Is there not a 3.90?

The tires are the correct size. The previous owner had a JDM auto put into it earlier this year.

 

[jdub]

All you want to know:
http://www.mkiiitech.com/forums/viewtopic.php?t=40

 

[BorHor]

4.30 open if non-sport package.
4.30 lsd if it is a sport package n/a
do you have a taller tire or a different tran's?

I was also an option for the N/A

 

[gtsfirefighter]

All you want to know:
http://www.mkiiitech.com/forums/viewtopic.php?t=40

'89+ MA70 turbo MKIIIs have a 3.73 clutch-pack LSD differential.
'87 - '88 MA70 turbo MKIIIs have a 3.91 clutch-pack LSD differential.

Can someone explain the pro/cons? What I want is to cruise at 70-80+mph without my rpms being over 4k. I'm not looking for 0-60mph in 3 seconds or anything like that.
Can these be easily swapped into my 89 N/A non sports package Supra?

 

[jdub]

'89+ MA70 turbo MKIIIs have a 3.73 clutch-pack LSD differential.
'87 - '88 MA70 turbo MKIIIs have a 3.91 clutch-pack LSD differential.

Can someone explain the pro/cons? What I want is to cruise at 70-80+mph without my rpms being over 4k. I'm not looking for 0-60mph in 3 seconds or anything like that.
Can these be easily swapped into my 89 N/A non sports package Supra?

Either will work and can be dropped right in to your NA. The 3.73 ratio LSD will give you a little lower (100-200) rpm at highway cruise with your auto tranny. However, since you have an NA, I'd go with the 3.91 LSD so you keep some acceleration ability.

I also have an auto...I swapped my original '89 3.73 LSD for an earlier 3.91 LSD that I re-built. I did it for a little more off the line ability. At 80 mph, I cruise at 2900 rpm...not bad at all.

 

[JustAnotherVictim]

With a w58 and a 3.91 I cruise at 70mph at about 3k.

 

[phoenix6]

86.5 Sports Package for me

4.30 LSD NA FTW

 

[ma71supraturbo]

W58 4.30 (5spd NA)

5th gear
RPM MPH
750 15.89181475
1000 21.18908633
1250 26.48635791
1500 31.78362949
1750 37.08090107
2000 42.37817266
2250 47.67544424
2500 52.97271582
2750 58.2699874
3000 63.56725898
3250 68.86453056
3500 74.16180215
3750 79.45907373
4000 84.75634531
4250 90.05361689
4500 95.35088847
4750 100.6481601
5000 105.9454316
5250 111.2427032
5500 116.5399748
5750 121.8372464
6000 127.134518
6250 132.4317895
6500 137.7290611
6750 143.0263327
7000 148.3236043



R154 4.30 (5spd turbo with 5spd NA diff)
5th gear

RPM MPH
750 16.52495478
1000 22.03327303
1250 27.54159129
1500 33.04990955
1750 38.55822781
2000 44.06654607
2250 49.57486433
2500 55.08318258
2750 60.59150084
3000 66.0998191
3250 71.60813736
3500 77.11645562
3750 82.62477388
4000 88.13309214
4250 93.64141039
4500 99.14972865
4750 104.6580469
5000 110.1663652
5250 115.6746834
5500 121.1830017
5750 126.6913199
6000 132.1996382
6250 137.7079565
6500 143.2162747
6750 148.724593
7000 154.2329112



R154 3.91 (87-88 5spd turbo)
5th gear

RPM MPH
750 18.17322392
1000 24.23096523
1250 30.28870654
1500 36.34644784
1750 42.40418915
2000 48.46193046
2250 54.51967177
2500 60.57741307
2750 66.63515438
3000 72.69289569
3250 78.75063699
3500 84.8083783
3750 90.86611961
4000 96.92386092
4250 102.9816022
4500 109.0393435
4750 115.0970848
5000 121.1548261
5250 127.2125675
5500 133.2703088
5750 139.3280501
6000 145.3857914
6250 151.4435327
6500 157.501274
6750 163.5590153
7000 169.6167566



R154 3.73 (89-92 Turbo 5spd)
5th gear

RPM MPH
750 19.05021596
1000 25.40028795
1250 31.75035993
1500 38.10043192
1750 44.45050391
2000 50.8005759
2250 57.15064788
2500 63.50071987
2750 69.85079186
3000 76.20086384
3250 82.55093583
3500 88.90100782
3750 95.2510798
4000 101.6011518
4250 107.9512238
4500 114.3012958
4750 120.6513678
5000 127.0014397
5250 133.3515117
5500 139.7015837
5750 146.0516557
6000 152.4017277
6250 158.7517997
6500 165.1018717
6750 171.4519436
7000 177.8020156



A340E @ 3.91 (86.5-88 MK3 Auto)
4th gear

RPM MPH
750 19.41054981
1000 25.88073307
1250 32.35091634
1500 38.82109961
1750 45.29128288
2000 51.76146615
2250 58.23164942
2500 64.70183269
2750 71.17201595
3000 77.64219922
3250 84.11238249
3500 90.58256576
3750 97.05274903
4000 103.5229323
4250 109.9931156
4500 116.4632988
4750 122.9334821
5000 129.4036654
5250 135.8738486
5500 142.3440319
5750 148.8142152
6000 155.2843984
6250 161.7545817
6500 168.224765
6750 174.6949483
7000 181.1651315


A340E 3.73 (89-92 Auto)
4th gear

RPM MPH
750 20.34725194
1000 27.12966925
1250 33.91208657
1500 40.69450388
1750 47.4769212
2000 54.25933851
2250 61.04175582
2500 67.82417314
2750 74.60659045
3000 81.38900776
3250 88.17142508
3500 94.95384239
3750 101.7362597
4000 108.518677
4250 115.3010943
4500 122.0835116
4750 128.865929
5000 135.6483463
5250 142.4307636
5500 149.2131809
5750 155.9955982
6000 162.7780155
6250 169.5604328
6500 176.3428502
6750 183.1252675
7000 189.9076848