Best approach to improve strength of front diff and axles on lifted 2007 Tahoe LTZ

[BigRedB]

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

This is pretty useful to find out differences in speed and rpm for different rear gears. You just have to know your final transmission ratio, and tire height.

thanks a million, I will definitely check this out

 

[AJMBLAZER]

Question- what do you want to do with this truck?

In your first post you mentioned hole shots. Any offroading? If so, what?

Frankly, don’t add a LS or locker to the front axle. The 8.25” isn’t the strongest axle out there. Regearing will help with reducing stress on it but unless you’re doing some serious wheeling you have no use for a traction adder up front. Even if you were aiming for Moab the 8.25” would be on borrowed time with just the open diff.

I’ve used a PowerTrax NoSlip before. Good locker and easy to live with for a full locker. Clunked sometimes and torque steered if you got into it but overall it was well mannered. Offroad it was awesome. Point the truck and go, as long as I had traction on one of the rear tores I was moving forward.
That said, if you’re regearing anyway, go with a full carrier replacement locker like the OG Detroit Locker. Had one of those as well and you can’t beat them for being bomb proof. Handles similar to a NoSlip.
Your vehicle has the advantage of being long, heavy, and an automatic. The same type of locker in a lightweight Jeep can be very quirky on the road.
Again though...a locker is kind of overkill unless you’re going offroading. A factory G80 locker or a helical gear limited slip (Detroit TruTrac comes to mind) would be perfectly good on the pavement.

Lastly, go 4.56’s. Your 4L65E has no reduction in the top gear. Your 3rd is 1:1. Those heavy, tall Nitto’s are going to suck some power so a bit of extra gearing won’t hurt. The rpm difference between 4.10’s and 4.56’s isn’t much. Couple hundred rpm at best and nothing to a fast revving LS motor.
Better to go a touch lower than to find yourself, after all that expense, wishing you still had a bit lower gears.

 

[BigRedB]

Question- what do you want to do with this truck?

In your first post you mentioned hole shots. Any offroading? If so, what?

Frankly, don’t add a LS or locker to the front axle. The 8.25” isn’t the strongest axle out there. Regearing will help with reducing stress on it but unless you’re doing some serious wheeling you have no use for a traction adder up front. Even if you were aiming for Moab the 8.25” would be on borrowed time with just the open diff.

I’ve used a PowerTrax NoSlip before. Good locker and easy to live with for a full locker. Clunked sometimes and torque steered if you got into it but overall it was well mannered. Offroad it was awesome. Point the truck and go, as long as I had traction on one of the rear tores I was moving forward.
That said, if you’re regearing anyway, go with a full carrier replacement locker like the OG Detroit Locker. Had one of those as well and you can’t beat them for being bomb proof. Handles similar to a NoSlip.
Your vehicle has the advantage of being long, heavy, and an automatic. The same type of locker in a lightweight Jeep can be very quirky on the road.
Again though...a locker is kind of overkill unless you’re going offroading. A factory G80 locker or a helical gear limited slip (Detroit TruTrac comes to mind) would be perfectly good on the pavement.

Lastly, go 4.56’s. Your 4L65E has no reduction in the top gear. Your 3rd is 1:1. Those heavy, tall Nitto’s are going to suck some power so a bit of extra gearing won’t hurt. The rpm difference between 4.10’s and 4.56’s isn’t much. Couple hundred rpm at best and nothing to a fast revving LS motor.
Better to go a touch lower than to find yourself, after all that expense, wishing you still had a bit lower gears.

Thank you tremendously for the guidance!!! I love this forum

OK definitely not even a LS on the front end. I will regear it only and be done.

The truck will see very light off road use, I have a 99 Tacoma for my off road adventures. I will use it to tow the Tacoma to the trail head, so it will see mud some sand, sugar sand, slippery boat ramps, Occasionally water and mud during heavy rains I have been known to hit a mud puddle or 2 as I see them in areas along the road. It feels good to get down in it, not too deep only 3/4's of the tire, throwing roost with those mud grapplers.

I like the idea of a locker on the rear end if I only even need it once. I will take a look at the OG Detroit for sure.

Thanks for pointing at the 4.56 ratio, my gut is telling me I wouldn't be happy with the 4.10. I read some where that the perfect ratio for the Tahoe with 35's is 4.28 when calculated but it doesn't exist off the shelf, so intuitively it feels right to gear down to 4.56 rather than gear up to 4.10

Im seeing the dollar signs but Big Red is worth it, no rust only 130k, everything works. Over the life of the truck as things broke I replaced them.

Whew... these parts are adding up, now that Im looking at akk of it. I think the universe has aligned in this moment for me to get all of this done the right way.

The engine rebuild is covered. To get the rest of the stack for Big Red I am sacrificing an 88 Wrangler, I got the wrangler for a sweet price. The owner gave it away due to the jeep death wobble, but that's just a front end rebuild. I was surprised after I got it that the axles were full of mud too, but ironically when I got the Tacoma it came with 2 jeep axles its previous owner was going to do a SAS to the Tacoma but didn't. Soooo, im going to use the axles on the jeep, rebuild the front end, put on new brakes too, tighten up the backlash in the steering gearbox, and put it up for sale. It will provide more than I need for the parts to build the Tahoe, I may even have a little left over to do a few things to the Tacoma. To sacrifice a mopar to build a Chevy somehow seems very appropriate

 

[AJMBLAZER]

If you’re towing then 4.56 is definitely the way to go.

Glad to help. Just trying to help avoid mistakes I made myself in the past.

 

[BigRedB]

I still cant shake the desire to improve the front diff. My heart wants the Chevy 2500 HD front diff it has a 9-3/4" ring gear. I dont see why I cant install one on the front of the Tahoe.

Please correct any errors in my logic...

I would need a shaft out from the stock T-Case to the front diff, 30 spline on one end - 33 spline on the other
I may need to fabricate/modify mounting points on the truck with a bracket etc to install the diff
The axles would need an 8 bolt pattern for the diff connection with a 30 tooth spline on the other end to assemble to the stock bearing hub assembly.

I am sure I can order the RCV front axles in this configuration, at this point to adapt to the 2500 HD front diff with the stock bearing hub assembly, the high cost of the axles is money well spent

I would need to make the shaft between the diff and T Case with a custom spline on one end - this is very possible, not that difficult or expensive

The mounting is a question, I have not physically compared the mounting differences between the 8.5" and 9.75" front differentials, It is possible, straight forward for a CNC mill... I have access to one, I also can model in 3D specify material etc, a bracket or mounting point mod on the truck shouldnt be too bad unless there are unexpected parts in the way (this the portion of the of my plan that needs work)...

Is there any reason this wouldnt work?
Would this impact the std 4wd set up in the LTZ, 4x4 hi, low, AWD, 2wd...
Even if it is unnecessary, I still want to do it, I can do the work, this is one very special truck,

Any advice is greatly appreciated...

This is the last detail... for now