Differential Swap...if it isn't broken, should I fix it?

[AW139Driver]

Recently got my 1500 Hemi back with a new lift on it. 6 inch BDS with a 3 inch body lift. That done, it fits my 40 inch Toyos nicely I think. I had all the work done at a shop and they recommended that I swap out the stock 3.55 gears for 3.92s (Nothing taller will fit). They didn't have the time to do them when I had the lift done and I'm due to take it back next week. Thing is, I've been driving the truck for almost 4 weeks now and it drives just fine in my eyes. A little slower of the line, but really not much. If I stomp on it, it goes just fine. I don't tow anything with the truck, and the most I haul in it might be the occasional piece of furniture. I've yet to go four wheeling in it, probably won't. Cruises nice on the highway. Gets up the steep hills by my house easy enough. I really have it for the snow and simply because I like it. Question is this, am I hurting anything leaving the stock gears in it? A mechanic I trust said he wouldn't touch it if I'm satisfied with the performance. He wasn't aware of any harm that leaving it stock would cause (I just wonder about stresses on the drivetrain). Always looking for a second opinion, does anyone have any thoughts on it? Thanks in advance for not beating me up too bad.

 

[satxwy]

In theory, it will stress your trans more and make your engine work harder than it would otherwise. In real life, if you can't notice any issues with it, I think it would be fine to leave it. 3.55 to 3.92 isn't a huge leap numerically anyway.

Now, as for your truck, that thing looks nice! Love the lift and tire set up.


Sent from my iPhone using Tapatalk

 

[kg93]

thats a beast! where in jersey are you? id honestly like a ride in your truck if your not too far. im installing a 6" kit right now and already have the body lift and bils.

I was thinking just go 37s, but it 40s work fine i would do it in a heart beat.

oh and also you have a 2010 you can easily do 4.55 gears

 

[AW139Driver]

Thanks

 

[smoothee]

If you're happy with it as is then that's the main thing. And if you were to do a swap then it isn't worth the hassle or money to go to 3.92's, IMO. Especially since Moe's has recently released a straight swap 4.56 option for us.

And yes, very nice truck!

 

[AW139Driver]

thats a beast! where in jersey are you? id honestly like a ride in your truck if your not too far. im installing a 6" kit right now and already have the body lift and bils.

I was thinking just go 37s, but it 40s work fine i would do it in a heart beat.

oh and also you have a 2010 you can easily do 4.55 gears

Thanks.
Its a 2011, I think the case is 9.5 in but the 4.55s need the 10.5 in case to fit (2500). Just a consideration, the first 40s I looked at were with a 20 inch rim. Those were 15.5 wide and that was causing them to rub on the upper knuckle. The 17 rims called for a 13.5 in wide tire which fit no problem, and I like all the sidewall actually. Plus 40 x 17s were about $150 cheaper each than 40 x 20s They did say they cut out just a little corner of the wheel well liner at the bottom, closest to the front of the stepbar for some clearance, but I couldn't really see it.

 

[AW139Driver]

thats a beast! where in jersey are you? id honestly like a ride in your truck if your not too far. im installing a 6" kit right now and already have the body lift and bils.

I was thinking just go 37s, but it 40s work fine i would do it in a heart beat.

oh and also you have a 2010 you can easily do 4.55 gears

Thanks.
Its a 2011, I think the case is 9.5 in but the 4.55s need the 10.5 in case to fit (2500). Just a consideration, the first 40s I looked at were with a 20 inch rim. Those were 15.5 wide and that was causing them to rub on the upper knuckle. The 17 rims called for a 13.5 in wide tire which fit no problem, and I like all the sidewall actually. Plus 40 x 17s were about $150 cheaper each than 40 x 20s They did say they cut out just a little corner of the wheel well liner at the bottom, closest to the front of the stepbar for some clearance, but I couldn't really see it.

 

[AW139Driver]

Here are a couple more pictures

 

[AW139Driver]

If you're happy with it as is then that's the main thing. And if you were to do a swap then it isn't worth the hassle or money to go to 3.92's, IMO. Especially since Moe's has recently released a straight swap 4.56 option for us.

And yes, very nice truck!

Thanks. Just out of curiosity, would that straight swap fit on a 1500? I was told those gears wouldn't fit in the case.

 

[smoothee]

Thanks. Just out of curiosity, would that straight swap fit on a 1500? I was told those gears wouldn't fit in the case.

Yup. I'm looking at doing the swap myself in the new year.

 

[AW139Driver]

Yup. I'm looking at doing the swap myself in the new year.

What are you running currently? You swapping out because you're having issues with the current setup or are you trying to get more performance out of it?

 

[smoothee]

I'm running the 3.55's like you right now. Yeah, doing it more for performance. My truck is decently quick now, but I'm not running 40's, lol. I don't race my truck or anything, but it's always nice surprising people.

 

[AW139Driver]

I'm running the 3.55's like you right now. Yeah, doing it more for performance. My truck is decently quick now, but I'm not running 40's, lol. I don't race my truck or anything, but it's always nice surprising people.

True. You have the info on where to get those 4.56s? I'm curious to take a look at them. I just tried searching Moe's and got nothing.

 

[smoothee]

True. You have the info on where to get those 4.56s? I'm curious to take a look at them. I just tried searching Moe's and got nothing.

Gears

Here ya go. They are vendor on here, and Matt is a great guy to deal with.

 

[AW139Driver]

Gears

Here ya go. They are vendor on here, and Matt is a great guy to deal with.

Thanks, I appreciate it.

 

[Thatdude596]

if u can switch to 410 or 456 I'd highly recommend it for numerous and obvious reasons in short lol.

 

[Jimmy68]

40's on a 1500? With 3:55's?
Used to break **** with 35's on a 1500 and needed 4:10's to move them.
40's were 4:88 and Dana 60 territory.

How is it that these half tons today survive the abuse big tires deliver?
Or do you guys actually not leave the pavement? (or improved road)

 

[14RAM4X4]

40's on a 1500? With 3:55's?
Used to break **** with 35's on a 1500 and needed 4:10's to move them.
40's were 4:88 and Dana 60 territory.

How is it that these half tons today survive the abuse big tires deliver?
Or do you guys actually not leave the pavement? (or improved road)

That's the same thing people say about TJs with the D30 fronts on 35s let alone 37s. BUT, you see them on the trail like that. Depends on how you drive it. I've see TJs & LJs on 35s & 37s crawl up the same trails as other jeeps with D44s or 1 tons. Better wheel placement, less tire spin, etc.

Now if you flog it, boom goes the stub shaft - if you're lucky. If you're not lucky, it's the R&P.

I don't plan on flogging my truck like I did my Jeep. I will use it like a truck and tow/haul stuff. Maybe the occasional mud hole. Some washed out dirt roads, trails, etc. No more waterfalls, boulder strewn creek beds, etc for me... at least not until I get my XJ and build it in a few years.

Now for the OP, if you're happy with the performance, then I wouldn't go through the expense (the **** me, gear swaps on these trucks is expensive) to swap gears. If you feel like it's a dog and it really bugs you, then I would go with the gear swap.

 

[AW139Driver]

Thanks for the thoughts. To Jimmy68's post, no I'm not planning on taking it off road. Its just for me to enjoy and be able to get to work when it snows and the humps at DOT take 3 days to plow the roads. And I'm thinking 1500s are handling bigger tires now because the performance is better than it use to be...not sure about the quality though. Fingers crossd.

I get that there is more weight to get moving, stock tires were about 40-45 lbs and the Toyos are about 100 lbs. So about 100 to 110 extra pounds for each axle to turn, but given the stock payload capability of about 1800 lbs. or towing about 4000 lbs., the extra 200 lbs. on the drive-train doesn't seem like too much, but maybe I'm missing something? Because while getting it moving might be a little harder, once its moving, that extra inertia from the extra weight is going to keep it moving easier. As it is, cruising around town, it kicks into ECO mode all the time. Which by the way, can you disable that? Because the truck gets a little vibe to it when it kicks in and I just can't imagine freewheeling 4 cylinders, then re-engaging them all the time is good for anything, but again, I'm probably wrong.

 

[kg93]

You can disable mds with a tuner