4:56…. Or … 4:88? That’s the Question

[NickTransmissions]

@NickTransmissions- 1 other question I had, was about re-gearing the front diff. I read somewhere that if your re-gear to 4:56 then you can’t utilize the 4wd option until you re-gear the front. Does that sound right?

Yep, you got it!

When i did my Blazer's gears, I disconnected and removed the front drive shaft so that I can re-gear the rear dif and use it as a 2WD to determine if 4.56 was going to work or not. I ended up going to 4.88 then did the 4.88 gears in the front diff to get 4WD back.

 

[swathdiver]

@NickTransmissions- 1 other question I had, was about re-gearing the front diff. I read somewhere that if your re-gear to 4:56 then you can’t utilize the 4wd option until you re-gear the front. Does that sound right?

ABSOLUTELY! You must do them at the same time. Otherwise the computer systems will go haywire.

 

[S33k3r]

The computer going haywire is the least of your problems! You'll end up with a bucking bronco, and you'll kill your transfer case. Front and rear *MUST* match on a 4WD/AWD vehicle. **MUST**!

A rebuilt transfer case for a 2003 Sierra Denali is expensive... And a royal PITA when the repair shop doesn't properly seal it 3 times... Or you get a defective unit from GM that requires you to try to reseal it 3 times before GM replaces it.

 

[Dantheman-2003]

Yep, you got it!

When i did my Blazer's gears, I disconnected and removed the front drive shaft so that I can re-gear the rear dif and use it as a 2WD to determine if 4.56 was going to work or not. I ended up going to 4.88 then did the 4.88 gears in the front diff to get 4WD bac

Yep, you got it!

When i did my Blazer's gears, I disconnected and removed the front drive shaft so that I can re-gear the rear dif and use it as a 2WD to determine if 4.56 was going to work or not. I ended up going to 4.88 then did the 4.88 gears in the front diff to get 4WD back.

@Nick- That’s not a bad idea they’re doing the rear 1st. I gotta gear & axle shop here locally that quoted me about $3k to re-gear the front and rear diffs, new bearings, seals etc. That’s quite the expense. Guess the other considerations is, run it lightly as is with the 3.73’s for awhile until I save up a few bucks for the gears. Like I said, it don’t run terribly slow now with the 3.73’s. Probably won’t win any drag races, but I can probably live with putting it around for awhile.

 

[NickTransmissions]

@Nick- That’s not a bad idea they’re doing the rear 1st. I gotta gear & axle shop here locally that quoted me about $3k to re-gear the front and rear diffs, new bearings, seals etc. That’s quite the expense. Guess the other considerations is, run it lightly as is with the 3.73’s for awhile until I save up a few bucks for the gears. Like I said, it don’t run terribly slow now with the 3.73’s. Probably won’t win any drag races, but I can probably live with putting it around for awhile.

The main concern transmission-wise, for when big tires are added, is the direct and overdrive clutch packs and how long the transmission remains in those gears when vehicle is accelerating as well as the internal gear ratio spacing in the transmission relative to the factory final drive. It's in this particular aspect that the 6L transmissions have an advantage over the 4-speeds. The 6L80 has two overdrive gears and uses multiple clutch packs for each gear and can down shift much more readily to access additional clutch packs upon acceleration so it's a lot more resilient to big tires where the diff's gears are still stock. In other words, many hands make light work

The 6L80 has more hands to bring to the table.The 4L60E, by contrast, uses only one clutch pack for both third and 4th gear (it uses the band to achieve 4th) and has a bigger gear ratio gap between third and forth so actually requires a little longer to downshift once the ECM senses the need and commands the down shift.

It's on heavier acceleration where stress and potential damage occurs when a vehicle has much larger tires than factory and is in high gear at the time.

That said, take it easy and without any super hard accelerations in 3rd or 4th gear so as not to bog the engine and stress that 3-4 pack while you save for the gears...If at all possible, get your rear diff updated w/new gears and disconnect the front drive shaft, keeping the vehicle in '2H' until you can have the front diff done as well. Confirm this won't mess anything up computer-wise or cause odd DTCs to set. I say this because my only experience doing one diff at a time and disconnecting the front drive shaft was on a 76 vehicle that had absolutely no computerization at all.

 

[Dantheman-2003]

The main concern transmission-wise, for when big tires are added, is the direct and overdrive clutch packs and how long the transmission remains in those gears when vehicle is accelerating as well as the internal gear ratio spacing in the transmission relative to the factory final drive. It's in this particular aspect that the 6L transmissions have an advantage over the 4-speeds. The 6L80 has two overdrive gears and uses multiple clutch packs for each gear and can down shift much more readily to access additional clutch packs upon acceleration so it's a lot more resilient to big tires where the diff's gears are still stock. In other words, many hands make light work

The 6L80 has more hands to bring to the table.The 4L60E, by contrast, uses only one clutch pack for both third and 4th gear (it uses the band to achieve 4th) and has a bigger gear ratio gap between third and forth so actually requires a little longer to downshift once the ECM senses the need and commands the down shift.

It's on heavier acceleration where stress and potential damage occurs when a vehicle has much larger tires than factory and is in high gear at the time.

That said, take it easy and without any super hard accelerations in 3rd or 4th gear so as not to bog the engine and stress that 3-4 pack while you save for the gears...If at all possible, get your rear diff updated w/new gears and disconnect the front drive shaft, keeping the vehicle in '2H' until you can have the front diff done as well. Confirm this won't mess anything up computer-wise or cause odd DTCs to set. I say this because my only experience doing one diff at a time and disconnecting the front drive shaft was on a 76 vehicle that had absolutely no computerization at all.

@Nick- such a great perspective and I appreciate all the detail you've included in the write up. I'm going to think on it. Since I'm in project mode, I'm leaning towards just doing the gears now and finding the money somewhere. Get the gears done so I can move on to the tuning. But if I don't do it now, I might just cruise it for a minute.

In the big picture of this Tahoe project, I well intend to upgrade the transmission. I looked into a beefed up 4L60 Monster Transmission replacement with some upgrades. They want around $2,200 shipped with torque converter and oil. Since you are a transmission guy, what are your thoughts on a transmission upgrade from Monster? Or what transmission upgrade would you recommend for my project?

 

[NickTransmissions]

@Nick- such a great perspective and I appreciate all the detail you've included in the write up. I'm going to think on it. Since I'm in project mode, I'm leaning towards just doing the gears now and finding the money somewhere. Get the gears done so I can move on to the tuning. But if I don't do it now, I might just cruise it for a minute.

In the big picture of this Tahoe project, I well intend to upgrade the transmission. I looked into a beefed up 4L60 Monster Transmission replacement with some upgrades. They want around $2,200 shipped with torque converter and oil. Since you are a transmission guy, what are your thoughts on a transmission upgrade from Monster? Or what transmission upgrade would you recommend for my project?

Thanks, Dan...

I'd recommend NOT monster. You can likely have built a better transmission then they can for less than 2k if you have a competent local shop do your build.

To get ideas, check out my 4L60E high performance video series. I go balls to the walls with this build but you don't need to do everything shown to have a stout transmission for your vehicle. The main areas to focus your trans are:
1. Hydraulic improvements (Sonnax LB4L60e Boost Valve kit, AFL drop in valve, block off 3-2 downshift valve, convert TCC PWM regulator valve to 'on-off', take 3-2 downshift spring and stick it inside of the AFL spring to increase AFL pressure for all of your shift solenoids and EPC
2. 3-4 clutch - I'd go with a Borg Warner high energy max pack that uses 8 or 9 frictions and specially machined apply and backing plates
3. Sonnax super hold servo for 2nd and 4th gear coupled with a Kevlar lined wide 2-4 band - this will dramatically increase the apply surface area for each piston which translates to much stronger 2nd and 4th gear apply force on the band to keep it clamped tight on the reverse drum (you need to buy a new drum as well)
4. Block off 4th accumulator (i show how to do this in that video series)
5. Sonnax Smart Shell and 4L70E induction hardened reaction shaft
6. 5 pinion front and rear planetary carrier sets (optional unless you plan on doing major off-roading, mud-bogging or very heavy towing/hauling)

Thats just a quick list off the top of my head - if you're wanting to rebuild it yourself, let me know and I'll help you as much as I can from here...

4L60E HP Build Up (PT 1)

 

[Dantheman-2003]

Thanks, Dan...

I'd recommend NOT monster. You can likely have built a better transmission then they can for less than 2k if you have a competent local shop do your build.

To get ideas, check out my 4L60E high performance video series. I go balls to the walls with this build but you don't need to do everything shown to have a stout transmission for your vehicle. The main areas to focus your trans are:
1. Hydraulic improvements (Sonnax LB4L60e Boost Valve kit, AFL drop in valve, block off 3-2 downshift valve, convert TCC PWM regulator valve to 'on-off', take 3-2 downshift spring and stick it inside of the AFL spring to increase AFL pressure for all of your shift solenoids and EPC
2. 3-4 clutch - I'd go with a Borg Warner high energy max pack that uses 8 or 9 frictions and specially machined apply and backing plates
3. Sonnax super hold servo for 2nd and 4th gear coupled with a Kevlar lined wide 2-4 band - this will dramatically increase the apply surface area for each piston which translates to much stronger 2nd and 4th gear apply force on the band to keep it clamped tight on the reverse drum (you need to buy a new drum as well)
4. Block off 4th accumulator (i show how to do this in that video series)
5. Sonnax Smart Shell and 4L70E induction hardened reaction shaft
6. 5 pinion front and rear planetary carrier sets (optional unless you plan on doing major off-roading, mud-bogging or very heavy towing/hauling)

Thats just a quick list off the top of my head - if you're wanting to rebuild it yourself, let me know and I'll help you as much as I can from here...

4L60E HP Build Up (PT 1)

So good! I'll check out the video for sure. I've heard others say stay away from Monster and that I can rebuild the 4L60 myself with better upgrades. Ima save these notes for when I get to that juncture. For now, gotta figure out what I'm going to do regarding the gears and a few other items for the build. At least for now, the transmission runs pretty smooth but eventually I plan to upgrade.

 

[NickTransmissions]

So good! I'll check out the video for sure. I've heard others say stay away from Monster and that I can rebuild the 4L60 myself with better upgrades. Ima save these notes for when I get to that juncture. For now, gotta figure out what I'm going to do regarding the gears and a few other items for the build. At least for now, the transmission runs pretty smooth but eventually I plan to upgrade.

Ive rebuilt several Monster units and they're nothing special. Lots of marketing dollars spent though, lol.