Quick question on rear diff ratios

[Chris]

Guys, been asked a question about my axle on e-bay. I think some of this is in a recent post somewhere, but could anyone give a me a simple table / run down on standard issue rear ratios for diesel auto and manual please? I guess pre 92 and post 92 if there is a difference. It's just not data that I have in my head like many of you chaps as you have played with them for so long.

Ta

Chris

 

[Andrew Prince]

Autos are 4.1:1 for all 80 series AFAIK and manual I believe are 3.7:1 but I don't know if that is common throughout the "range".

Cheers,

 

[Chris]

Cheers Andrew. Just went out and turned the pinion counting one rev of wheel to drive flange and it looked more like 4.5 - 1
Now I am confused

Chris

 

[Jon Wildsmith]

There were no changes in ratios, Andrew gave the right numbers, so yours is 4.1 Did you hold one hub still while you rotated the diff pinion and counted the turns of the other side?

 

[Chris]

Jon that's good enough for me. Answer is that man and auto are different.

Chris

 

[Toby]

Hi Chris,

I concur with Jon and Andrew; AFAIK UK/European spec 80s had 4.1s in the automatics and 3.7s in the manuals. I think some 'rest of world' spec 80s had 4.1s and manual boxes, not sure about the JDM models.

Of course, that's if your car hasn't been re-geared in the past...

All the best,
Toby
1990 HDJ80
1994 HDJ80

 

[Chris]

Thanks lads. That's all clear. This is the rear diff from GW which JW built the front diff for. He'd have spotted that! And the potential buyer is in a uk manual. Safe to say my rear diff is same as JW front one or it would have been an interesting drive!

Chris

 

[Jon Wildsmith]

Putting diffs from an auto into a manual is quite a good upgrade if the manual has big tyres but you need to do both ends of course

 

[frank rabbets]

Just to change the subject slightly my 100 auto seems to rev more in top gear than my manual 80 at the same road speed or is this difficult to compare because of the torque converter? Or, even worse, is there something wrong as it only seams to have 3 gears! Lets put it this way compared with the 80 the hundred is a bit disapointing as it seams a bit low geared.

Frank

 

[Jon Wildsmith]

depends on the road speed, above 40mph on light throttle the torque converter should be locked and the revs be quite low. On medium to high throttle then the TC will be unlocked and the engine revs will be higher.

 

[wongtsenhin]

What is your rpm at 100km/h?? Auto and manual,please!