Hi all,

I used to have a 2004 Durango with the Hemi engine, and it felt quicker than my Aspen. The only real difference is that the D was a 4x2, and the Aspen is full-time 4wd. Does the additional drivetrain loss due to pushing 4 wheels rather than 2 result in a real loss in acceleration for these vehicles? It makes sense that it would, but I don't have any proof.

It still moves nicely, but it doesn't move with the same urgency that my Durango did, and I even have the higher gearing that comes with the tow package (the D did not have this).

Thanks!

EDIT: The D had smaller wheels as well (17" v. 20" on the Aspen), which I'm guessing also contributes due to rotational mass and wheel weight.

 

there should be no difference at all, infact i would expect it to help acceleration by improving traction by using all tires' traction against the road surface. the actual difference would be in traction, weight, gearing, or engine power

 

This is what's blowing my mind. The 2004 Durango I had was a 2wd Hemi. The option differences between the vehicles are that the 2008 Aspen has:

- 4wd
- 20" wheels (v. 17" on the Durango)
- sunroof
- DVD system
- 2nd row buckets and heated seats
- Higher gearing (3.92) and tow package

Everything else is the same, so the weight difference shouldn't be enough to notice such a difference. As I said, the Aspen even has higher gearing for towing, so I expected it to have more pep. Both vehicles have the same Hemi engine.

Maybe the added options and the additional wheel size is enough to cause this. I wish we had a Chrysler engineer wandering around here to throw their $0.02 in.

 

Are the transmissions different? Different shift points? I know our Aspen doesn't set you in the seat unless you are in first, or you put your toe into the accelerator. It kinda does the S M O O T H acceleration when driven nicely. But when you want to go it's there, deep down.

 

Gear ratios for the 2007 (I assume the same as the 08) Aspen:

1st 3.00
2nd 1.67—upshift; 1.50—kick-down
3rd 1.00
4th 0.75
5th 0.67
Overall Top Gear 2.38 with 3.55 axle or 2.63 with 3.92 axle

I confirmed that these are the same for the 2004 Durango, so that's not likely the culprit. I took a look at overall wheel size comparisons as well, as the 2004 Durango had 265/65 R 17, and the Aspen has 265/50 R 20 tires.

As it turns out, Chrysler did their homework, and there's little difference in these sizes. Comparing the Durango to the Aspen's wheels:

10.43" v. 10.43" width
6.78" v. 5.22" sidewall height
30.56" v. 30.43" overall height
96.02" v. 95.61" circumference difference.

So the increased wheel size has been adjusted for sidewall height, and there's no real difference between them. This puts me back to the drawing board. At this point, I have to assume that the additional parasitic drivetrain losses to the wheels due to full-time 4WD are the cause.

 

15951a, Try putting your "toe" into the pedal thru the floor from 0 mph. Ours will sometimes spin all 4 tires from a complete stop and a good toe to the floor.

Have you tried T/Haul? Is there a fix for the computer for the tranny? Just guessing here! lol