Rear End swap help years compatability

[swathdiver]

The 2012 has a 1355 u-joint. Yours has a 1344 or Saginaw 44 u-joint. You can get a conversion joint so that you won't have to swap yokes.

Thought the track width was an inch different between generations, did you measure that?

I THINK a Spicer 5-3205X will work. Triple check.

 

[Marky Dissod]

Too big of a deal is being made about the rear end ratio - 3.08 came as a factory option ...

Have you missed an important detail? ...

I need help to figure out if I can make this diff I picked up work with my 2003. Dude said it was off a 2012 Suburban ...

Was 3.08 EVER an option for GMT800s with 4L60Es?

bonester, you'll need to tune the 4L60E to avoid 4th entirely if you can't do better than 3.08.
The weakest GMT800 axle was 3.231, for 2WD Tahoes.
Pity the fools who try to Tow / Haul anything heavier than farts with 3.231, nevermind 3.08.

 

[rockola1971]

Have you missed an important detail? ...Was 3.08 EVER an option for GMT800s with 4L60Es?

bonester, you'll need to tune the 4L60E to avoid 4th entirely if you can't do better than 3.08.
The weakest GMT800 axle was 3.231, for 2WD Tahoes.
Pity the fools who try to Tow / Haul anything heavier than farts with 3.231, nevermind 3.08.

Exactly. A 3.08 will get horrible gas mileage and be way to tall for 4th gear. We are talking near BBC mileage here.

 

[bonester624]

Hey thanks for all the info everybody. Got it installed few weeks go and have been driving it without any issues. Simply bought a spicer conversion u joint only 30$ (Spicer 5-3205x) and everything bolted right in. Only had to plug abs sensor holes and swap backing plates. Rear is quiet as can be. Taking off from a stop is pretty sucky with the 22 inch wheels I had on there but swapped to a set of 16 inch wheels and my takeoff is a little better. And like "Marky Dissod" mentioned I need to tune my 4l60e to avoid 4th until maybe 80 mph as it likes to downshift a lot while hwy driving if i need to speed up. Besides that the gov lock diff is in great condition when I opened it up. What do you guys think? On occasion I will be towing small cars, will it really be that sucky? Dude I got it from swapped it due to that same reason they were towing a 30ft trailer with it. I built my 4l60e with a transgo HD-2 kit, 9 clutch 3-4 setup, corvette servo, new separator plate, new bushings etc, I went through it all so it can take some abuse. Made a silly youtube video showing the swap hit that like and subscribe man thanks.

 

[Alex_M]

Have you missed an important detail? ...Was 3.08 EVER an option for GMT800s with 4L60Es?

bonester, you'll need to tune the 4L60E to avoid 4th entirely if you can't do better than 3.08.
The weakest GMT800 axle was 3.231, for 2WD Tahoes.
Pity the fools who try to Tow / Haul anything heavier than farts with 3.231, nevermind 3.08.

I looked back at some old dealer catalogs I had - you're right. 3.23 was the tallest ratio available in the gmt800 Tahoe's. Not the "weakest" - the taller the gear generally the stronger the gear set actually is, but certainly the tallest set. Just a clarification, not trying to be a d-bag.

Still, I think with a conservative throttle foot while towing, there's no reason for immediate concern. It will be sluggish, but it will get OP around just fine and it will sip on fuel on the highway. Hell, my Tahoe gets better fuel mileage on 35s than it got on 33s. There's thousands of full size GMs running around with 3.08 gears behind their 4l60e's, 700r4s, and TH350s. Not optimal, but perfectly serviceable if you're not abusing your vehicle.

 

[Mudsport96]

Just put it in 3rd manually and use tow/haul mode until you can get a tune. But personally, I would only leave it in there until you can find another 3.42 or 3 73 to replace the 3.08. Once you speedo is recalibrate, ill bet you see a drop in mpg.

 

[Marky Dissod]

Still, I think with a conservative throttle foot while towing, there's no reason for immediate concern.

Staunchly disagree. 3.73 or more gear would be better for his vehicle, especially for his 4L60E, which is basically a 1/2ton transmission.

It will be sluggish, but it will get OP around just fine and it will sip on fuel on the highway.

So long as he's NOT towing / hauling. Once he's towing / hauling, he better stay out of 4th altogether.

Hell, my Tahoe gets better fuel mileage on 35s than it got on 33s.

What axle gears do YOU have on your Tahoe that gets better MpGs on 35" tires?

There's thousands of full size GMs running around with 3.08 behind their 4L60Es / 700R4s, & TH350s.

Just because CAFE MpG tests forced GM into thinking that they could get away with such ridiculously tall gearing does NOT mean that they actually should have - even if they did.
The Caprices RoadMasters & Fleetwoods that had their 4L60Es rebuilt most often were the ones with 2.56.

Not optimal, but perfectly serviceable if you're not abusing your vehicle.

If he'd asked before doing, NONE would recommend 3.08 over a more appropriate axle gear.
I recommend 4.10 MINIMUM. What was the towing weight rating for 3.23, by the way?

No one said you were trying to be a d-bag.
What does it make me, if after tuning IronBlock LT1s for 11 years, I think that GM should NEVER have offered 2.56 2.73 2.93 or 3.08 in ANY LT1 cars?

Just put it in 3rd manually and use tow / haul mode until you can get a tune.
But personally, I would only leave it in there until you can find another 3.42 or 3.73 to replace the 3.08.
Once you speedo is recalibrate, I'll bet you see a drop in MpG.

What Mudsport said, except:
while towing, put it in 3rd AND use Tow / Haul mode SIMULTANEOUSLY until you get tuned - and don't waste any time getting tuned.
Even when not towing / hauling, 4th gear may not save you any MpGs unless you happen to be going downhill.
and
'3.73 or 4.10 to replace the 3.08'.

OP, I sincerely hope your 4L60E doesn't wind up needing a rebuild. On a related note, where's your ATF temp gauge?

 

[bonester624]

Staunchly disagree. 3.73 or more gear would be better for his vehicle, especially for his 4L60E, which is basically a 1/2ton transmission.
So long as he's NOT towing / hauling. Once he's towing / hauling, he better stay out of 4th altogether.What axle gears do YOU have on your Tahoe that gets better MpGs on 35" tires?Just because CAFE MpG tests forced GM into thinking that they could get away with such ridiculously tall gearing does NOT mean that they actually should have - even if they did.
The Caprices RoadMasters & Fleetwoods that had their 4L60Es rebuilt most often were the ones with 2.56.
If he'd asked before doing, NONE would recommend 3.08 over a more appropriate axle gear.
I recommend 4.10 MINIMUM. What was the towing weight rating for 3.23, by the way?

No one said you were trying to be a d-bag.
What does it make me, if after tuning IronBlock LT1s for 11 years, I think that GM should NEVER have offered 2.56 2.73 2.93 or 3.08 in ANY LT1 cars?What Mudsport said, except:
while towing, put it in 3rd AND use Tow / Haul mode SIMULTANEOUSLY until you get tuned - and don't waste any time getting tuned.
Even when not towing / hauling, 4th gear may not save you any MpGs unless you happen to be going downhill.
and
'3.73 or 4.10 to replace the 3.08'.

OP, I sincerely hope your 4L60E doesn't wind up needing a rebuild. On a related note, where's your ATF temp gauge?

I laugh at 4l60e's. They are so easy to rebuild. I can rebuild a 4l60/700r4 fairly quick. I have gotten really good at rebuilding them, theyre pretty simple transmissions. Can have one torn down and diagnosed in maybe 20 mins. Wouldn't call myself an expert but am fairly confident in my capabilities. My last 4l60 was behind my 92 camaro and ended up selling it to a lowrider dude for 1100 dollars when I converted to a 6 speed(t-56)manual. Rebuilt that one too, way more simple. The 4l60 in my tahoe has less than 3k miles and doesn't skip a beat. Have rebuilt 5 4l60s and have never had the slightest issue. I really like to beat on the 4l60 in my tahoe to see how long it will last, see how good of a job I did. But yeah knock on wood dont feel like rebuilding it anytime soon but I welcome it. I have never rebuilt a rear end but that's my next project. I will post a picture of my 3.73 ring and pinion to see what you guys think about it, if I could possibly reuse them. I could have waited and found a better gearset but I'm a sucker for good deals and said f it let me give these 3.08s a try. They suck, now I know haha. I did do some research before buying it but like I said sucker for good deals, not to mention It came with an eaton gov lock which is a pretty good unit from what I have read and for 100 bucks couldn't pass it up. Also its fairly newer than any 2000-2006 rear ends I could have went for and less wear if we go by age alone. I don't have a temp guage atm but I will purchase an obd2 HUD to display my trans temp soon. And dont mind the check engine light, was for a p0430 cat code but a gallon of laquer thinner fixed that and was able to pass smog. Well see how long it keeps the p0430 away haha.

 

[Mudsport96]

I wouldn't be beating on it for the sake of beating on it. I twisted the output shaft off of one. WITH A 4.3 in a blazer.Transgo kits do save a weak design, the only think saving a 4l60e from a 5.3 is the torque management.

 

[Marky Dissod]

... could have waited and found a better gearset, but I'm a sucker for good deals, and said
f it let me give these 3.08s a try.
They suck, now I know ...

So, not a good deal, then?

My Z71 already came with 3.73. My soul wilts every time I step on it.

3.90 4.10 or 4.30 will always be better deals than lesser gears.