3.54's - pros and cons

["Mad Max"]

Folks,



I am seriously thinking about running 3. 54's in the rig, D60 front and D80 rear. The rig will be primarily a tow rig, around 18k gross. I very much like the 3. 54's - very 'happy' highway gear. Have had 3. 54's in both my CTD's so far, and I really like the highway manners.



With a NV4500 there'll be plenty of 1st and 2nd gear to get going, and with gentle manners I think the rig will have great 'legs' with a nice highway gear. Once the clutch is engaged it's all about power anyway, and there'll be plenty of that.



I don't want to be the quickest (acceleration) truck around, but I do like 'lower' rpm's than higher. No sled pulling, no drag racing, just street driving and towing. I decided I don't need the Gear Vendor, and I want to make up the difference with at least a 3. 73, but my preferance is 3. 54 gear.



With 3. 54's and a 35" tire, 75 mph = 1900 rpm - sweet . 85 mph = 2150 rpm - sweeter Oo. .



I haven't bough gears, hence all the research and feasibility studies.



Thoughts?



- M2

 

[IRoss]

How much lift is needed to run 35" tires anyway? I run 33's and that seems pretty much the limit as far as rubbing on the trim goes... .

 

["Mad Max"]

Short story, around 8" of lift. But I'm putting the rig on air bags just like I did my Ramcharger; 4-links front and rear, plus a 3" body lift, so there'll be plenty of lift per se. But also, the tires are 285-70/19. 5's - medium-duty truck wheels and tires, so they're not overly wide, more taller, and it'll be a dually. The truck will be pretty high, probably around 8" of lift.

- M2

 

[rumblefish]

I've got 235/85's on my dually. Way back when it was srw, I could pull 23mpg running 75-80 on the highway. When I swapped to the drw axle, it had 4. 10's. I was lucky to get 16mpg. I put 3. 54's back in it and have been very happy ever since. No way I'd go to 4. 10's again. I think you are on the right track. If you run into a situation that the gears are a bit steep, you can pull it back to 4th and still be alright. I say go for it. For me, its a no-brainer even with 35's.

 

[Niki]

I guess it all depends on what you plan on towing. Anything within the weight ratings should easily be handled by a 3. 54 truck. I owned a 95 w/ 4. 10s, and I hated them, and got bad mileage.

 

[jcshaney]

My truck with 4. 10s even with my 25 foot gooseneck loaded 12-15,000 I still rarely use first gear. Also the milage not good 18-20 on a good day emty. more power than i'll ever need.

just my 2 cents

 

[DValentine]

Sam, with the stock truck I was a little disappointed with the towing, at the time I had a 24 foot airstream. With my mods, I now tow a 27 fiver, and weigh in over 15 K combined. I at times wish I had a gear splitter for a double overdrive. With what you are doing to your engine, I think you will be happy with 3. 54's even with the 35's.

 

[dpuckett]

I have only had 2 trucks with 4. 10s, and neither one NEEDED them. I think they are a waste of money and MPGs. I have towed in the mid 20s GCVW with 3. 54s and some pump tweaking, and done just fine. Can you go for a 3. 31 D60? I know they are available for the D80.



Daniel

 

["Mad Max"]

That's great info fellas, thanks so much. I'm definitely convinced to go/stay with 3. 54's. Called Randy's R&P - $1500 for everything - 2 sets of gears, 2 sets of kits, and one $580 Tru Trac posi for the rear which will also serve as the correct carrier for the 3. 54's (54's won't bolt up to a 4. 10 carrier. )

I'll do the work, and R-R&P has great tech info online. A couple new tools and I can do diffs. Sweet.



- M2

 

[boatpuller]

Just curious why don't you want the Gearvendor anymore? What changed your mind?

 

["Mad Max"]

Honestly, less moving parts. Plus I'll only have to have one button on the handle for the e-brake now.

I very much like the idea of achieving the correct balance with the ring gears verses a double overdrive. I always thought I had to go with 3. 73's because of the '02 D80 rear axle, and after I discovered I can stuff 3. 54's in the D80, well that clinched it.



The GV is for sale, and anyone with a 205 could use it. There's nothing at all wrong with it at all or my faith in its performance. It's a sweet unit - not too big and very stout - planetary gearset, and it couldn't be any simpler. But with the 3. 54's I simple don't need it. Crazy selling something so nice and completely new, but that's the way it is.



- M2

 

[MMiller]

I run 3. 55's with 305's(true 33" tires) and the only time I wish I had lower gears is when I hooked to a big load of hay, trying to get it started going up a hill from a stop light. It does take a little clutch assault to get it going, but thats upwards of 29,000# gross. I'll be going back to a 33x12. 5 or another comparable 32" tire. Anyother time I love the 3. 55's and would even still like another OD. I wish I could afford your GV and I'd try it.



With a 4x4 I always have the option (and use it alot) to use low side of the t-case, and the hubs unlocked.



Michael