Looking for technical data on 3.43 vs 3.73 Gen 4 AISIN vs Gen 4.5 HO AISIN.

[phatboy64]

I know there are a lot of opinions out there regarding 37’ and various topics. This isn’t that, it is a question to folks who have real data.

2014 3500 AISIN 3.43 with 35” tires vs 2023 3500 HO AISIN 3.73 with 37”

With no data and just my thoughts I am thinking they would “preform” very similar. I am basing this off my real time experience of having owned both and my memory of my 4th Gen 3500 which is fading fast.
So my question is looking at the 14’ AISIN gear ratio with the 3.43‘ and 35“ and the 23 AISIN with 3.73 and 37“ how do they compare, for example, at 75 mph, what would the rpm be, how do the shift points compare….

What I am looking for is technical data the would backup or shoot down my thoughts about them performing the same….

 

[AH64ID]

There are some variances among manufactures and sizes so your tires may be a little different. The following data is using Toyo M/T specs in 35x12.50R18 (593 rev/mile) and 37x13.50R18 (560 rev/mile).

At 75 the 37/3.73 combo is going to be turning ~2610/2010/1650 (4th/5th/6th).

At 75 the 35/3.42 combo is going to be turning ~2535/1950/1600 (4th/5th/6th).

So they are very similar, the 37’s will probably feel a little more sluggish due to the increased rotational mass.

For reference with stock tires these are the rpms.

3.73’s ~2920/2250/1840 (4th/5th/6th)
3.42’s ~2675/2060/1690 (4th/5th/6th)

If you were to regear the ‘23 with 4.10’s you would be geared just a bit lower than stock tires with 3.73’s, so performance would probably be similar to stock.

37/4.10 combo ~2875/2210/1810 (4th/5th/6th)

 

[phatboy64]

Thanks.

That is interesting data, I was thinking the rpm would have gone down with the larger diameter tire, also the gap between the 4.10’ and the 3.73 seems marginal, 55/40/30. I am not sure it would be worth the $$ re-gearing but I am sure I am missing something.

 

[AH64ID]

Thanks.

That is interesting data, I was thinking the rpm would have gone down with the larger diameter tire, also the gap between the 4.10’ and the 3.73 seems marginal, 55/40/30. I am not sure it would be worth the $$ re-gearing but I am sure I am missing something.

Those differences are from stock, not from where you are now.

3.73 vs 4.10 with 37’s will be a 265/200/160 difference.

If you tow moderate weight that’s huge but if you’re mostly empty it’s probably not worth the cost.

 

[jsalbre]

For comparison sake, 37s on 4.10s put you at nearly the same RPMs as 33s (stock) on 3.73s.

 

[phatboy64]

Those differences are from stock, not from where you are now.

3.73 vs 4.10 with 37’s will be a 265/200/160 difference.

If you tow moderate weight that huge but if you’re mostly empty it’s probably not worth the cost.

Right. My mistake I was looking at the wrong numbers. Now it makes sense.