35 inch tire with 3.73 gear

[4WDKC]

Timely discussion as I'm trying to determine which gears to use in my K5.
It now has a 6.0/4L65e/NP241 with the original 3.08 gears.
I'm running 33's and don't plan on changing the tire size.
I was thinking 3.73 but should I go with 4.11's instead?
Assume I will need to change the front as well to match?

I was told 33s and 410s are perfect combo for towing/performance, after having the 35s and 410s I belive it to be a much better option than 373. Yes you will need to change both.. its not cheap to do a gear swap so what I did was buy axles with the gears i wanted and swap them in.

$200 gears
$100 install kit
$ 10 crush sleave
$20 gear oil
$ ??? installation cost if you dont know how

X2 = $1000?

or buy someone elses axles and swap them in..I went with 14bff as I was planning on towing at the time.

 

[RoryH19]

Thanks.
I was thinking axle swap too if I can find some. I need to replace my rear springs anyway since the 4" lift it currently has is spring front, block rear. Either way I will do the work myself but the swap will probably be faster and as you point out cost effective.

 

[roundhouse]

Thanks.
I was thinking axle swap too if I can find some. I need to replace my rear springs anyway since the 4" lift it currently has is spring front, block rear. Either way I will do the work myself but the swap will probably be faster and as you point out cost effective.

I used the shackle flip kit from ORD I think to eliminate the rear blocks

The Alcan springs are outstanding and don’t cost much more than crappy super stiff springs

The Alcans are soft enough that we had to re install the front sway bar


When you replace springs
Get all new bolts and bushings
And a box of sawzall blades

Just cut the old bolts and use the new ones
It’s a lot faster than messing with removing the old ones

 

[RoryH19]

My rear springs are shot. They are original and the left side sits lower than the right by ~ 1/2" give or take.
Never heard of Alcans, I'll look them up.
Good point on the u-bolts, would be much easier to just cut.

 

[RoryH19]

@4WDKC
Been researching 14 bolt diffs to swap for my ten bolt.
Looks like the 88-99 4x4 1500 and light duty 2500 have 6 lug with 3.73 and 4.10 options (GT4 and GT5 respectively).
Also read that the 4x4 option should be the same width as my K5 and that if a 1310 - 1350 u-joint is used I will be able to reuse my driveshaft.

Did you use one of these for your swap?
Did you also swap the front axle?

Anything else I need to know?

Thanks.

 

[bucket]

@4WDKC
Been researching 14 bolt diffs to swap for my ten bolt.
Looks like the 88-99 4x4 1500 and light duty 2500 have 6 lug with 3.73 and 4.10 options (GT4 and GT5 respectively).
Also read that the 4x4 option should be the same width as my K5 and that if a 1310 - 1350 u-joint is used I will be able to reuse my driveshaft.

Did you use one of these for your swap?
Did you also swap the front axle?

Anything else I need to know?

Thanks.

Overall width is wider than the stock rear axle, it's more in line with the front axle. The spring perches will need cut off and welded back on in the correct location.

 

[Camar068]

didn't I read recently multiply tire size by 12 and that gives you a close guestimate? 33x12 = 396, 35x12 = 420, etc. May have seen it on facebook. Then again, if you have a weak trans you may want to go a bit higher I'm sure.

Good discussion. Reminding me of @HotRodPC advise to me. Hopefully I don't regret 3.73 lol.

 

[4WDKC]

@4WDKC
Been researching 14 bolt diffs to swap for my ten bolt.
Looks like the 88-99 4x4 1500 and light duty 2500 have 6 lug with 3.73 and 4.10 options (GT4 and GT5 respectively).
Also read that the 4x4 option should be the same width as my K5 and that if a 1310 - 1350 u-joint is used I will be able to reuse my driveshaft.

Did you use one of these for your swap?
Did you also swap the front axle?

Anything else I need to know?

Thanks.

No I found one from a square body and swapped it in, get the spring perches from the donor its alot easier than tryn to squeeze the ubolts in enough to re use the half ton perches. Also you will need a conversion u joint, some people report having to shorten their driveshaft, I didnt as my truck was lifted. I also picked up a matching front axle to swap in but never got around to it.

 

[crpntr78]

Hello, not meaning to hijack a thread but 4WDKC, you sold your truck before you moved right? Illinois if I remember right. I'm curious what you got for it if you don't mind my asking? I'm from central Missouri and am looking in to selling my 86 K10 sometime this year and seeing as we are both from the midwest figured pricing would be comparable. Thanks

 

[RoryH19]

Overall width is wider than the stock rear axle, it's more in line with the front axle. The spring perches will need cut off and welded back on in the correct location.

Wider would be better if it's closer to the front width.
Ah yes, not surprised if I'll have to move the perches.

 

[RoryH19]

didn't I read recently multiply tire size by 12 and that gives you a close guestimate? 33x12 = 396, 35x12 = 420, etc. May have seen it on facebook. Then again, if you have a weak trans you may want to go a bit higher I'm sure.

Good discussion. Reminding me of @HotRodPC advise to me. Hopefully I don't regret 3.73 lol.

Good to know on the determining factor for ratio.
I've been going back and forth between the 2.
Maybe I should go 4.10 unless I can't find a donor.

Trans is from the same 04 Escalade I removed the engine from, 6.0 HO with 4L65e. Trans has the additional planetary than the 4L60e/700R4. I think my axles will blow up first.

What diffs are you using with 3.73's?

 

[RoryH19]

No I found one from a square body and swapped it in, get the spring perches from the donor its alot easier than tryn to squeeze the ubolts in enough to re use the half ton perches. Also you will need a conversion u joint, some people report having to shorten their driveshaft, I didnt as my truck was lifted. I also picked up a matching front axle to swap in but never got around to it.

Right I've read Napa has the conversion u-joint available.
Have a 4 inch lift so my driveshaft should be ok, I hope.

So you went with 3/4 ton axles with 8 lug?
Was the front a dana 60?

 

[Camar068]

Good to know on the determining factor for ratio.
I've been going back and forth between the 2.
Maybe I should go 4.10 unless I can't find a donor.

Trans is from the same 04 Escalade I removed the engine from, 6.0 HO with 4L65e. Trans has the additional planetary than the 4L60e/700R4. I think my axles will blow up first.

What diffs are you using with 3.73's?

I've currently have the stock GM corporate 10 bolt with 3.08's. I've got the gears, gotta wait until tax time to get someone to change them for me.

 

[RoryH19]

I've currently got the stock GM corporate 10 bolt with 3.08's. I've got the gears, gotta wait until tax time to get someone to change them for me.

Same here, 3.08s front and back from the factory with 33s.
I'll start looking for a 14 bolt rear and probably just keep my front 10 bolt. Will just match the gears once I have the rear diff.

 

[roundhouse]

I think a lot of avalanches had a strong axle that was a six bolt

We’ve been runnng 35s with a 14 bolt and 3.73 gears for a while

We broke two 10 bolts with normal street driving
The ten bolt might be ok in a four cylinder S-10 but it has no business in a full size V-8 pickup