4.10 gears versus 3.54 gears
 

Ok guys, here's my dilema. Right now, I am running 285 75R 16 tires, I have 4.10 gears on my rig, and the best mpg I am getting is 16. I plan on getting guages, getting the valves and timing adjusted, and soon getting the 3k gsk and a #10 plate. Probably will be getting the afc springs as well. I have a bumper pull trailer that weighs about 5k, but the most I would probably ever pull would be around 10k. My truck has 105k miles on it. I have replaced the overflow valve with a new one from marty, have replaced the fuel lines, have a 3" straight exhaust with a resonator from a later model ctd (to eliminate drone), and have a scotty II ordered. As a side note, I am aware of the kdp and have a kit to prevent it, just have not made time to take care of it. I am really wanting 20 mpg or more, but in all my searches and reading, have not confirmed in my mind that it will give me the mpg that I am after. I do have plans to bomb my truck beyond the 3k gsk and #10 plate, and that is something else to take into consideration.......with the 4.10's, am I going to get better performance keeping the 4.10's, or is it going to require shifting too much and I will lose speed, or will the modifications make the 3.54 gears ideal. Right now, my max speed is 87. It gets to 80 fairly quickly for a stock truck, but climbs slowly to 87 and will not reach 87 on any uphill run. You can see my other truck specs in my sig. Thanks for any and all advice. BTW, I did the wheel cylinder upgrade and raised the lower linkage end of the proportioning valve to sit on top of the axle and now I can easily lock the rears up momentarily until the abs releases them. I am very pleased with the brake upgrade, especially considering the price invested.

Waylan

4.10's are a waste. I swapped to 3.54's picked up 3-4 consistant MPG and i was pulling 20-30k lbs constantly. liked the change to 3.54's gave me the mileage and RPMs to play with on the highway, on hills or grades i could drop a gear or two and have plenty or RPMS and speed to play with before witht he 4.10's i was always tached out and way below the speedlimit when i had to downshift


Do it you won't regret it

I think the 4.10 are the problem as well. as they say, cant have your cake and eat it. 3.54s would be better for mpgs, and your not towing that much anyhow.

yea but isn't having the larger 4.10 rear easier on that tranny?:rolleyes:

They say that on automatics but my 6spd had 337k miles on it and 200k on the clutch and was still going strong. Id say all but 20k miles were with 3.54 gears and probably 2/3 of the trucks life it was hooked to some pretty large loads.

Actually i kinda wonder about that arguement even more sometimes because isnt 4th ...5th on a 6spd direct and isnt better that witht he 3.54's one is able to use direct more up to 55 mph cruising easily at 2200 or so rpms on alot of various rds vs 4.10's where the truck is almost limited to always being OD above 50 mph because its tached out? [eyecrazy]

I do agree though the higher speed gears do increase strain but i wonder if the effect is really that much.

go with the 354. My dad has the same truck i have (in my sig) but just an intake and exhaust. When my truck was stock his was alot faster with 33" tires. Also when we pulled my chevy II on a trailer 5k-6klbs total neither truck had any trouble at all. The best millage I get is about 14-16city 19highway. he is consistnatly around 21. His best is 23. Hes got about 240k miles. orginal clutch. always 33" tires.

Thanks guys so much for the responses. I am checking on prices for gear sets right now and have a local guy in town that will do it fairly reasonable as far as labor. Do you know if the carrier has to be changed out as well to go with the 3.54 gears? Thanks again.

Waylan

I went from the 354 gears to a 373 ProLock rear and love it, the 410 rear is just to looow. Towing light like you are the 354's are good. I tow 12,000+ and I like the 372 rear.
Bruce

Let me know what it cost to switch the gears. Im in same boat with 4:10's. Thought of putting in a USGear 2 speed but $2400. plus labor is alot. Most of my miles are light/ empty but i do pull a forklift quite a bit and about 4 times a year pull a gooseneck loaded to 25,000+lbs. I juzt know im tacked out on interstate and getting 15-16mpg when diesel is 2.00 gal. By the time I downshift Im doing 45 mph!

The difference between the two gear ratios is 100 rpm 3.54's to 3.73's. And i recall the difference being roughly 350 rpm from 3.54's to 4.10's.

:D

Like i said before the change from 4.10's to 3.54's made a world of difference and i used to pull 25-30k lbs regularly

Personally the 4.10's are awful on a stock truck. Even with the 4kgsk it is god awful running 4.10's. The 3.55's are the way to go on anything that's not strictly a heavy tow rig.

Instead of swapping in 3.55's I decided to change my gear ratios effectivly by putting 38.5 tires on the truck. Truck drives 100x's better. The 4.10's are grusome.

That's the only reason I suffered through the 4.10's is because I knew I would be lifting the truck for bigger tires one day.

3.55's and 38.5's would be too much highway gearing. You'd hardly ever use OD.

So what all is involved in doing the swap and is a set og gears expensive. Is there other things to buy besides the gears or what? I too want the 3:55 gears but dont have much money. If anyone wants to trade even my 4:10 for your 3:55 I would gladly do that. I am in Ky. I might even have a place to do the swap if you have the know how. Thanks for any responses.

Regards
Smoke Show
Mitch Ratliff

Mitch
if you find two people who want to trade let me know...im in ky too and hate the 4:10 gears....still thinking of that 2 speed but alot of money! I'm just wondering what it will save me on fuel....ive got to make five trips to Fl loaded heavy one way (20,000-28,000#) wonder how much it would save me on diesel cost. Anyone have any idea/experience?

I have stock 3:55's in a 97 4x4 long bed with 97,000 miles. I'm running 315's right now and it feels like the truck needs more gear (ie 4:10's). From what I understand, the carrier break on the front 60 and rear 70 is 4:10 and lower so the gear swap wouldn't require carriers. Question: Do you guys think I would run out of power on the top end with the 315's, 4:10's, and a 3K GSK? If not, I might be willing to work out a trade with someone with factory 4:10's. The only problem would be that both trucks would have to sit for however long it would take to disasemble both axles and ship the parts. Thoughts?

MIke

wouldn't the swap price of getting rid of the 4.10 rear to a fuel saving 3.55 outweigh the price of fuel?