Ae71 Diff Advantages

[Gecko71]

G'Day all,

 

I'm running an AE71 with a 3.9:1 Differential on it, I have a rear axle with a 4.3:1 Diff on it and i was wondering if there is any advantage in putting

this 4.3:1 Diff into the car???

Known Advantages and Disadvantages would be appreciated.

 

Thanks.

[Sam_Q]

all your gears will be closer together which means you can keep your engine in the rev range much better and close the big chasm between 2nd and 3rd gear a bit. The catch is your revs will sit on 3300RPM at 100km/h.

 

By the way 4.3:1 diffs are very hard to come by

[Gecko71]

all your gears will be closer together which means you can keep your engine in the rev range much better and close the big chasm between 2nd and 3rd gear a bit. The catch is your revs will sit on 3300RPM at 100km/h.

 

By the way 4.3:1 diffs are very hard to come by

 

Thanks for the info. I reckon i'd valule acceleration over top speed, also, the engine has no overheating problems.

I have a 4.3 diff already (got it from an Auto AE71).

Thanks again.

[Sam_Q]

that being the case then chuck it in as it should help

[SLW42]

so if i was going for a higher top speed would the auto ae71 diff be better or would a manual diff be the go

[Sam_Q]

well if it was revs limiting the top speed then yes the auto one would be better as they are 3.7:1 or something yes? but its not the top speed so without knowing the power curve of your engine I can't say. You may well have a higher top speed.

[Gecko71]

well if it was revs limiting the top speed then yes the auto one would be better as they are 3.7:1 or something yes? but its not the top speed so without knowing the power curve of your engine I can't say. You may well have a higher top speed.

 

Actually, I have been told that an Auto AE71 diff is a 4.3, so it gives acceleration, whereas a manual AE71 / manual Ke70 diff give top speed.

don't quote me on it, it's what i've found.

[LittleRedSpirit]

Thanks for the info. I reckon i'd valule acceleration over top speed, also, the engine has no overheating problems.

I have a 4.3 diff already (got it from an Auto AE71).

Thanks again.

 

 

Auto AE71 diffs have 4.1 ratio.

 

The ratio is how many turns the tailshaft makes, compared to one rotation of the wheels. So if it currently rotates 3.9 times to one turn of the wheels, and the other 4.3, you will notice a few differences.

 

Gear it down, eg swap 3.9 for 4.3 - lower top speed, better acceleration, closes gear ratios in the box seemingly. Revs higher at any given speed compared to the higher ratio diff.

 

Go the other way from 4.3 to 3.9 and you increase top speed, decrease acceleraton, probably increase fuel economy due to cruising at lower rpms at any given speed.

Edited April 20, 2009 by LittleRedSpirit

[Sam_Q]

like I said earlier the diff ratio wont be the limiting factor in the top speed if the revs arnt being maxed out. Remember that in some cars top speed is achieved in fourth gear not fifth,