Old 3.54's vs. new 3.73's?

[Scooby]

My question: For those who had 3. 54's with a 6 speed and have traded to 3. 73's with a 6 speed, how do you like them - any difference? I don't tow a great deal but have a heavy slide in. The 3. 73's would seem right, but I'm wondering if the same thing is happening where the 4. 10's were getting better mileage than the 3. 54's were due to the engine's higher RPM sweet spot.



I currently have an '01 2500 auto with 3. 54's and am considering an '03 Dually. I have only driven an '03 with 4. 10's - it's really hard to find one with 3. 73s here.



Thanks!

 

[wanderson]

3.73s Likem alot!

I have had two CTD 6 speeds with 3. 54s. One was a 99 and the other an 01. I now have an 03 6 speed with 3. 73s and I think this is a great setup. For the daily driving I do and the occasional pulling, this gearing and power combination is a pleasure to drive. Mileage with winter fuel at 70 mph empty is 19+. This so far is about 1 mpg better than my 99 or 01 in the winter. My experience has been I will get about 1. 5 mpg more with strait No. 2 in the summer months. Currently at about 5500 miles and engine is getting stronger.



Wayne.

 

[wanderson]

3.73s Likem alot!

I have had two CTD 6 speeds with 3. 54s. One was a 99 and the other an 01. I now have an 03 6 speed with 3. 73s and I think this is a great setup. For the daily driving I do and the occasional pulling, this gearing and power combination is a pleasure to drive. Mileage with winter fuel at 70 mph empty is 19+. This so far is about 1 mpg better than my 99 or 01 in the winter. My experience has been I will get about 1. 5 mpg more with strait No. 2 in the summer months. Currently at about 5500 miles and engine is getting stronger.



Wayne.

 

[Fireman]

I'm ging to go out on a limb here, and say that the 3:73 should be pretty close to the 3:55 because of the increase in tire size. I havn't done the math, but they seem to be very similar. I imagine that it has made the 4:10s a little taller too, like maybe 3:92s.

Just some loose thinking,
Firema

 

[Scooby]

Thanks Fireman and Wayne,



I've been under a rock for the last several months, so I wasn't aware of the tire size difference.



Fireman, do you have 4. 10's on your rig? Get tired of shifting?



Wayne, do you use first gear?

 

[Mathew Clausen]

Although the wheels are now 17", the new tires are 265/70-17 vs 265/75-16 on the old (lower profile). Actual diameter and revs/mile come out almost identical (according to Michelin website anyway). So you end up with essentially the ratio difference - 5% more rpm for the same speed vs 3. 55's.



Personally - I don't tow anything and preferred the lower rev's on the highway of my 01 w/3. 55. The new one is so much quieter though that you don't really notice other than looking at the tach. When I wear out the stock tires I will probably look for something a little taller to help out.

 

[Fireman]

Scooby,

I have 3:73, and I tow 12,000# max.

I love shifting.

Fireman

 

[wanderson]

I only use first gear when starting on a hill or starting out with a load or a trailer. I would think with the power these new HO's have, you would need 4. 10s only if you towed heavy for most of your driving and if you tow in the mountains alot. IMHO. Good luck with your decision.



Wayne.

 

[DPKetchum]

Back when i worked in a D. C. dealer the rep several years ago said 3. 73 were coming and after lots of testing etc said this gearing would work much better then 3. 55 etc. said wished it would come sooner. I had 3. 55 in mine and it had no grunt with 9600lbs behind it. Felt like it was gonna break something starting off and on inclines lost lots of speed. 4. 10 are ok and solved that problem but really wanted 3. 73 or 3. 91. They werent available even aftermarket and the aftermarket guys(Gears and Rears)comminted these were a better gear ratio in there minds for these size trucks.

 

[lawdog]

I am planning on ordering a 2004 3500 SRW S/B QC HO Auto. I also plan on putting on the 315 BFG's I tow about 7000 lbs in the winter. Do you guys recommend 3. 73 or 4. 10 I was planning on 4. 10 so my final is closer to the 3. 5 or so I have now on my 2000 with 265's

 

[Jeremiah]

Taller wheels 'n' tires

Originally posted by lawdog

I am planning on ordering a 2004 3500 SRW S/B QC HO Auto. I also plan on putting on the 315 BFG's I tow about 7000 lbs in the winter. Do you guys recommend 3. 73 or 4. 10 I was planning on 4. 10 so my final is closer to the 3. 5 or so I have now on my 2000 with 265's

If you guys are running 265 R70 17's and switch to 265 R70 19. 5, your final ratio will drop from the factory 3. 73 to 3. 44.

 

[DHess]

At 75 mph, my '03 is turning about 300 rpms less than my '99 did - both had 4. 10. '99 was 5 speed and '03 is 6.



Dave

 

[Scooby]

Dave,



What kind of mileage are you seeing? I know this is a loaded question - so many variables - but on average city/highway?



What rpms are you turning at 70 or 75?



Thanks!

 

[lawdog]

Do not want 19. 5's, I want the big truck look of 315's with the 2" leveling kit...