Let's talk about rear gear ratio on these 1500's, mostly street driving, limited towing

[redfishsc]

Hey guys-n-gals,

Just wanted to chat and see what opinions are (especially experienced opinions) about rear gear ratios on these 1500's. Obviously this applies to the 4WD trucks but that requires swapping the gears in both diffs.

When the bearings went bad in my truck (1999 C1500 Suburban), I pulled the factory 3.42 and put in a Motive 4.10 and Eaton Truetrac Posi (which is awesome, by the way).

I almost wish that I had put in a 4.56.

So far, I've not found any discernible loss in mileage. Neither have I bothered to calculate it, but I still use the same 5 gallons of gas per week making my short commute to work. We also make a repeated "long haul" about 4 times a year to see family, and I still use around 35 gallons of gas.

I monitor my trans temp using a bluetooth OBD2 dongle paired with a smartphone, and I can even read my torque converter slip RPM. So far, whether towing or not, I am generally able to tow in 4th gear, verify that the TCC isn't slipping, and see my trans fluid temp is staying under 190 (usually 160 or less if not towing).

I run 31X10.5 tires on this truck, and honestly they look WAY better than the short little tires that came stock on it. These are the 5-bolt 15" stock wheels.


The only thing we tow is our camper, which weighs around 2,000lbs fully loaded with gear (1600 empty). It does tow a little better with the 4.10's, especially low speed and around town. Honestly the change when towing wasn't as much as I thought it would be.


Anyone here running 4.56's on a daily driver?

 

[Project400]

Man I've thought about it. I'm going to 285's soon and already have 4.10's to go in but might just go 4.56 instead

 

[slowburb]

My daily driven suburban is geared 4.56 on about 33 inches of tire. That works out to a little warmer than 4.10 and stock tire height.

 

[redfishsc]

Man I've thought about it. I'm going to 285's soon and already have 4.10's to go in but might just go 4.56 instead

I doubt very seriously that you will detect much of a difference. If you are lucky enough to find a full GM rear end with factory 4.56 already in it, maybe that would be a reasonable swap, but personally I wouldn't go through the hassle of swapping up from 4.10 to 4.56 unless I did a HUGE amount of driving/towing.

Now if the rear end needs servicing anyhow (new carrier/pinion bearings or new posi or whatever) then sure, lol, it's a GREAT time to upgrade.

My daily driven suburban is geared 4.56 on about 33 inches of tire. That works out to a little warmer than 4.10 and stock tire height.

Thanks, how do you like that setup?

I had a pile of people warn me not to go 4.10 on my truck, but honestly it was a great decision except I wish I had gone 4.56 like I said above. But. I'm not about to swap it just because of that lol.

 

[slowburb]

Thanks, how do you like that setup?

I had a pile of people warn me not to go 4.10 on my truck, but honestly it was a great decision except I wish I had gone 4.56 like I said above. But. I'm not about to swap it just because of that lol.

It's just about perfect. My rig is nowhere near stock. 6" lift and 33" AT's, warmed over L31 (cam/tune/exhaust/etc.) with an S10 converter, built 4L60E and a 14 bolt semi-floater w/ TruTrac. The 4.56's allow for reasonable get up and go in city setting, and I cruise 75-80 on the highway in between 2200 and 2500 RPM. I tow my boat with no problem. Regearing allows this 5500# rig to get out of its own way, with spirit, at will.

 

[redfishsc]

Nice. The Truetrac is a gem on these heavy Subs. I put one in mine when I put in the 4.10's mostly because I didn't trust the 200K mile Gov-bomb that was in it.

I seriously considered swapping to a 14 bolt. I was just going to buy one used, gut it, and put 4.10s and a Truetrack in it, but the reality is that it would have been obscene overkill for me. I don't tow much heavy with this truck, and I would have also had to either get custom 5-bolt axle shafts made, or redo the front hubs to 6 or 8 bolts.... then go buy new wheels and tires.. .which would have doubled/tripled the cost.

But dang I wanted to do it lol.

 

[Supercharged111]

I'd hardly call it overkill. More like how it should have been stock.

 

[redfishsc]

I'd hardly call it overkill. More like how it should have been stock.

Ok, true enough, lol, I'm not a fan of these 10 bolt rears. I just couldn't justify the expense, it got out of hand very quickly for something that I only use for towing 4-6 times per year on a 2400lb camper.

 

[Supercharged111]

I'm lucky to have a pull and pay nearby. $125ish drum to drum. I found a 4.10 G80 truck, snagged both diffs, replaced the output seals, and slapped it in my truck. Under $300 for the swap. I got super lucky because the rear was still nice and tight.

 

[redfishsc]

Lol I did it the hard way. I gutted the 10-bolt and rebuilt it. Fortunately it was just a rear wheel drive.

I'd love to get a K2500 with the big block. Gas mileage might suck but my commute to work is only 4.5 miles, so who cares, lol. K2500's are not easy to find in my area.