4.10's or no?

mass-hole · **Posted:** Thu Apr 26, 2018 12:07 pm

I just ordered myself a set of Detroit Truetracs for the front and rear. The questions is, do I swap in 4.10's while i am in there? At the moment I am running 265/70R16 Duratracs(30.7" i think) but I just recieved a set of LT265/75R16 Duratracs(31.7") for a great price. They only weigh a lb or two more than the 265/70's which I have very little issue turning at the moment. I can pretty much climb anything in 5th gear around here, and there is some pretty steep stuff.

4.10's almost perfectly returns the overall gear ratio back to stock with the 32" duratracs but my engine is not stock and is making ~400 ft-lbs, so its not like it struggles to spin the 31's.

lfhoward · **Posted:** Thu Apr 26, 2018 6:21 pm

I don’t have a CRD so i don’t have the torque you do, but I’d say yes, go for the 4.10’s while you’re in there. I am running 31’s and they are right on the edge of being too big/heavy for the stock gear ratio (3.73, 3.7L gasser). 32’s, even if they are a similar weight, have a radius that is 1” longer, which is extra effort to turn a longer lever. It’s more fun and more economical to drive if you’re closer to the stock ratios.

WWDiesel · **Posted:** Thu Apr 26, 2018 9:55 pm

mass-hole wrote:

I just ordered myself a set of Detroit Truetracs for the front and rear. The questions is, do I swap in 4.10's while i am in there? At the moment I am running 265/70R16 Duratracs(30.7" i think) but I just recieved a set of LT265/75R16 Duratracs(31.7") for a great price. They only weigh a lb or two more than the 265/70's which I have very little issue turning at the moment. I can pretty much climb anything in 5th gear around here, and there is some pretty steep stuff.

4.10's almost perfectly returns the overall gear ratio back to stock with the 32" duratracs but my engine is not stock and is making ~400 ft-lbs, so its not like it struggles to spin the 31's.

How much lift do you have that allows you to run 265/75's and do you have any scraping or rubbing issues with them?
I am running 245/75's with a 2.5 lift with no rubbing issues currently. I have a full set of 265/75 ProComp's AT's that I could put on the Jeep, but I am concerned there could be some rubbing issues.
I too like you have plenty of power, so that is not a problem, but clearances could be.... :roll:

mass-hole · **Posted:** Thu Apr 26, 2018 10:04 pm

I haven't mounted the 265/75 yet.

I've got the ome hd springs with a jba top plate. I do have a clevis spacer in the garage that I had removed because my ucas were hitting the spring over bumps. I am also running Moab wheels which are a different back spacing. I also flattened the pinch welds and have the ARB so no issues with the clearance in the front.

It's close with the 265/70's but I should be ok with the extra 1/2".

WWDiesel · **Posted:** Thu Apr 26, 2018 10:13 pm

mass-hole wrote:

I haven't mounted the 265/75 yet.
I've got the ome hd springs with a jba top plate. I do have a clevis spacer in the garage that I had removed because my ucas were hitting the spring over bumps. I am also running Moab wheels which are a different back spacing. I also flattened the pinch welds and have the ARB so no issues with the clearance in the front.
It's close with the 265/70's but I should be ok with the extra 1/2".

Let us know how the fitment is once you get them all mounted. :wink:

tjkj2002 · **Posted:** Fri Apr 27, 2018 3:48 pm

WWDiesel wrote:

mass-hole wrote:

I just ordered myself a set of Detroit Truetracs for the front and rear. The questions is, do I swap in 4.10's while i am in there? At the moment I am running 265/70R16 Duratracs(30.7" i think) but I just recieved a set of LT265/75R16 Duratracs(31.7") for a great price. They only weigh a lb or two more than the 265/70's which I have very little issue turning at the moment. I can pretty much climb anything in 5th gear around here, and there is some pretty steep stuff.

4.10's almost perfectly returns the overall gear ratio back to stock with the 32" duratracs but my engine is not stock and is making ~400 ft-lbs, so its not like it struggles to spin the 31's.

How much lift do you have that allows you to run 265/75's and do you have any scraping or rubbing issues with them?
I am running 245/75's with a 2.5 lift with no rubbing issues currently. I have a full set of 265/75 ProComp's AT's that I could put on the Jeep, but I am concerned there could be some rubbing issues.
I too like you have plenty of power, so that is not a problem, but clearances could be.... :roll:

A long lost CRD'er thought he didn't need 4.10's running 235/85R16's(32" tires),had the GDE tune also.

He bought my front D30A when I went SFA which had 4.10's so he re-geared the rear and the 1st trail run he was amazed and wondering why he didn't do the gear change sooner.

mass-hole · **Posted:** Fri Apr 27, 2018 9:18 pm

tjkj2002 wrote:

WWDiesel wrote:

mass-hole wrote:

I just ordered myself a set of Detroit Truetracs for the front and rear. The questions is, do I swap in 4.10's while i am in there? At the moment I am running 265/70R16 Duratracs(30.7" i think) but I just recieved a set of LT265/75R16 Duratracs(31.7") for a great price. They only weigh a lb or two more than the 265/70's which I have very little issue turning at the moment. I can pretty much climb anything in 5th gear around here, and there is some pretty steep stuff.

4.10's almost perfectly returns the overall gear ratio back to stock with the 32" duratracs but my engine is not stock and is making ~400 ft-lbs, so its not like it struggles to spin the 31's.

How much lift do you have that allows you to run 265/75's and do you have any scraping or rubbing issues with them?
I am running 245/75's with a 2.5 lift with no rubbing issues currently. I have a full set of 265/75 ProComp's AT's that I could put on the Jeep, but I am concerned there could be some rubbing issues.
I too like you have plenty of power, so that is not a problem, but clearances could be.... :roll:

A long lost CRD'er thought he didn't need 4.10's running 235/85R16's(32" tires),had the GDE tune also.

He bought my front D30A when I went SFA which had 4.10's so he re-geared the rear and the 1st trail run he was amazed and wondering why he didn't do the gear change sooner.

What brand gears do you recommend. It looks like maybe there is Nitro and Oem?

tjkj2002 · **Posted:** Sat Apr 28, 2018 9:38 pm

mass-hole wrote:

What brand gears do you recommend. It looks like maybe there is Nitro and Oem?

Front go with OEM(dana/spicer) and the rear Yukon or OEM is best but Nitro gears are okay also.

WWDiesel · **Posted:** Sat Apr 28, 2018 10:18 pm

This is a good vendor for sourcing replacement R&P gear sets:
Randy's Ring & Pinion
https://www.ringpinion.com/

tjkj2002 · **Posted:** Sun Apr 29, 2018 2:10 am

WWDiesel wrote:

This is a good vendor for sourcing replacement R&P gear sets:
Randy's Ring & Pinion
https://www.ringpinion.com/

Be aware very few places sell the correct D30A gear sets and that place is not one of them.

Rears yes but fronts no.

bugnout · **Posted:** Mon Apr 30, 2018 9:25 pm

I highly recommend them. I have Dana gears front and Yukon in the rear

rayman · **Joined:** Mon Aug 06, 2018 1:11 am **Posts:** 1

It's been a while since original post, but I wonder if anyone can share info on diff kits (ring gear & pinion) for 4.10.
I'm new to Jeep KJ, and struggling to understand what specs I should look for?
Also info on lockers would be appreciated.

mass-hole · **Posted:** Tue Aug 28, 2018 2:19 am

rayman wrote:

It's been a while since original post, but I wonder if anyone can share info on diff kits (ring gear & pinion) for 4.10.
I'm new to Jeep KJ, and struggling to understand what specs I should look for?
Also info on lockers would be appreciated.

I ended up purchasing mine through JBA. You know they are selling the right parts for the kJ and I don’t feel like the prices were out of line.

That said, for a tuned CRD, I don’t know if they are completely necessary Unless you are:

-in the mountains
-at high altitude
-running 31 or 32” tires

If you are in mostly flat terrain I don’t think they will buy you much.

GordnadoCRD · **Posted:** Tue Aug 28, 2018 3:31 am

I have pretty much stock diameter tires and stock gearing.

My engine and trans setup is somewhat different from Mass's, as well as completely different theatre of operation, being on Oregon Coast.

In my circumstance, the only reason to NOT run higher ratio is financial. This is with a KJ that sees less than an hour a month offroad, on the average.

If I had the money I'd have 4.10s and DTTs going in right now. When 3rd can get you past 90mph, there's just too much wasted gear ratio in the trans.

Heck if 4.56 would fit in front I'd plan on that eventually.

4.10's or no?

Who is online