4L80E too much transmission?
12-19-2015, 07:46 PM
#12
TECH Enthusiast
I stall tested it today with my HP Tuners attached. Phoenix's 2,600 (Built for a 6.0L) stalls 2,750 behind my 5.7.
12-21-2015, 03:29 AM
#14
All the points mentioned already are all valid. Tahoes and Suburbans, in my opinion, are harder on transmissions than pickups in everyday use anyway because their extra weight over the rear end increases traction and loads up the drivetrain more in spirited driving where a pickup would just break traction.
I actually love the close ratios of the 4L80-E vs. the 700R4 and all its electronic variants. Wide open throttle shifts in the 80-E have minimal RPM drop even with a stock converter, and every upshift is smooth, linear, and consistent because each is a single clutchpack-apply event. I'm sure you're aware of how sloppy the 2-3 upshift is in every 60/65/70E - that's because there's a moment of fourth gear in there because it has to engage the 3-4 clutch pack before letting the 2-4 band go. It's a dual-event shift and the reason that it feels so nasty. The 1-2 shift in a 60/65/70 is a band engagement. Bands suck for shifting because it's nearly impossible to get them to apply linearly. The bands (2) in the 80 are only used for reverse and manual downshifts for engine braking. Every normal upshift in an 80 is a multi-disc clutch pack engagement - made possible by the 80's THREE planetary gear sets instead of the 60's two. Every shift feels great and they respond very well to tuning changes for apply rate.
I can tell you with absolute guarantee that with a 4L80-E in it you can FULLY remove all torque management entirely. Do not try that with any 60/65/70. You can also enjoy worry-free engine braking with an 80.
I would have to recommend not trying to mod the OEM driveshaft. They are incredibly thin and not performance oriented. Custom-built aluminum shaft would be much better and you can get a 3R to 1350 joint at the pinion end for the 8.6" and then just swap the joint if you ever change the rear to a 9.5". When choosing a 4L80-E there are two types of output shafts used in 2WD units - fixed yoke and slip yoke. You cannot put a slipyoke onto the output shaft of a fixed-yoke unit, but if you do end up with a fixed (bolted) yoke version you can always build a driveshaft for it that has a slip-splined section built in, but it will be steel and not aluminum.
The downsides have already been mentioned
- expenses to swap
- weight
- reduced fuel economy
- overall final drive ratio range
I actually love the close ratios of the 4L80-E vs. the 700R4 and all its electronic variants. Wide open throttle shifts in the 80-E have minimal RPM drop even with a stock converter, and every upshift is smooth, linear, and consistent because each is a single clutchpack-apply event. I'm sure you're aware of how sloppy the 2-3 upshift is in every 60/65/70E - that's because there's a moment of fourth gear in there because it has to engage the 3-4 clutch pack before letting the 2-4 band go. It's a dual-event shift and the reason that it feels so nasty. The 1-2 shift in a 60/65/70 is a band engagement. Bands suck for shifting because it's nearly impossible to get them to apply linearly. The bands (2) in the 80 are only used for reverse and manual downshifts for engine braking. Every normal upshift in an 80 is a multi-disc clutch pack engagement - made possible by the 80's THREE planetary gear sets instead of the 60's two. Every shift feels great and they respond very well to tuning changes for apply rate.
I can tell you with absolute guarantee that with a 4L80-E in it you can FULLY remove all torque management entirely. Do not try that with any 60/65/70. You can also enjoy worry-free engine braking with an 80.
I would have to recommend not trying to mod the OEM driveshaft. They are incredibly thin and not performance oriented. Custom-built aluminum shaft would be much better and you can get a 3R to 1350 joint at the pinion end for the 8.6" and then just swap the joint if you ever change the rear to a 9.5". When choosing a 4L80-E there are two types of output shafts used in 2WD units - fixed yoke and slip yoke. You cannot put a slipyoke onto the output shaft of a fixed-yoke unit, but if you do end up with a fixed (bolted) yoke version you can always build a driveshaft for it that has a slip-splined section built in, but it will be steel and not aluminum.
The downsides have already been mentioned
- expenses to swap
- weight
- reduced fuel economy
- overall final drive ratio range
12-21-2015, 08:01 PM
#15
All the points mentioned already are all valid. Tahoes and Suburbans, in my opinion, are harder on transmissions than pickups in everyday use anyway because their extra weight over the rear end increases traction and loads up the drivetrain more in spirited driving where a pickup would just break traction.
I actually love the close ratios of the 4L80-E vs. the 700R4 and all its electronic variants. Wide open throttle shifts in the 80-E have minimal RPM drop even with a stock converter, and every upshift is smooth, linear, and consistent because each is a single clutchpack-apply event. I'm sure you're aware of how sloppy the 2-3 upshift is in every 60/65/70E - that's because there's a moment of fourth gear in there because it has to engage the 3-4 clutch pack before letting the 2-4 band go. It's a dual-event shift and the reason that it feels so nasty. The 1-2 shift in a 60/65/70 is a band engagement. Bands suck for shifting because it's nearly impossible to get them to apply linearly. The bands (2) in the 80 are only used for reverse and manual downshifts for engine braking. Every normal upshift in an 80 is a multi-disc clutch pack engagement - made possible by the 80's THREE planetary gear sets instead of the 60's two. Every shift feels great and they respond very well to tuning changes for apply rate.
I can tell you with absolute guarantee that with a 4L80-E in it you can FULLY remove all torque management entirely. Do not try that with any 60/65/70. You can also enjoy worry-free engine braking with an 80.
I would have to recommend not trying to mod the OEM driveshaft. They are incredibly thin and not performance oriented. Custom-built aluminum shaft would be much better and you can get a 3R to 1350 joint at the pinion end for the 8.6" and then just swap the joint if you ever change the rear to a 9.5". When choosing a 4L80-E there are two types of output shafts used in 2WD units - fixed yoke and slip yoke. You cannot put a slipyoke onto the output shaft of a fixed-yoke unit, but if you do end up with a fixed (bolted) yoke version you can always build a driveshaft for it that has a slip-splined section built in, but it will be steel and not aluminum.
The downsides have already been mentioned
- expenses to swap
- weight
- reduced fuel economy
- overall final drive ratio range
I actually love the close ratios of the 4L80-E vs. the 700R4 and all its electronic variants. Wide open throttle shifts in the 80-E have minimal RPM drop even with a stock converter, and every upshift is smooth, linear, and consistent because each is a single clutchpack-apply event. I'm sure you're aware of how sloppy the 2-3 upshift is in every 60/65/70E - that's because there's a moment of fourth gear in there because it has to engage the 3-4 clutch pack before letting the 2-4 band go. It's a dual-event shift and the reason that it feels so nasty. The 1-2 shift in a 60/65/70 is a band engagement. Bands suck for shifting because it's nearly impossible to get them to apply linearly. The bands (2) in the 80 are only used for reverse and manual downshifts for engine braking. Every normal upshift in an 80 is a multi-disc clutch pack engagement - made possible by the 80's THREE planetary gear sets instead of the 60's two. Every shift feels great and they respond very well to tuning changes for apply rate.
I can tell you with absolute guarantee that with a 4L80-E in it you can FULLY remove all torque management entirely. Do not try that with any 60/65/70. You can also enjoy worry-free engine braking with an 80.
I would have to recommend not trying to mod the OEM driveshaft. They are incredibly thin and not performance oriented. Custom-built aluminum shaft would be much better and you can get a 3R to 1350 joint at the pinion end for the 8.6" and then just swap the joint if you ever change the rear to a 9.5". When choosing a 4L80-E there are two types of output shafts used in 2WD units - fixed yoke and slip yoke. You cannot put a slipyoke onto the output shaft of a fixed-yoke unit, but if you do end up with a fixed (bolted) yoke version you can always build a driveshaft for it that has a slip-splined section built in, but it will be steel and not aluminum.
The downsides have already been mentioned
- expenses to swap
- weight
- reduced fuel economy
- overall final drive ratio range
12-22-2015, 07:29 PM
#16
James,
Thank you for your time and the awesome explanation.
That is all I needed to hear.
My Tahoe already has an aluminum driveshaft, it being a retired trooper Tahoe.
Do you think it has a heavier wall driveshaft? Otherwise, what company would you recommend for a new driveshaft?
Thanks again
Thank you for your time and the awesome explanation.
That is all I needed to hear.
My Tahoe already has an aluminum driveshaft, it being a retired trooper Tahoe.
Do you think it has a heavier wall driveshaft? Otherwise, what company would you recommend for a new driveshaft?
Thanks again
12-22-2015, 07:59 PM
#17
Thanks, glad to be of help.
I'm not familiar enough with the OEM specifications of GMT800 propeller shafts to say whether or not it would be feasible to modify the stock shaft. There are two criteria - in order to install a 1350 yoke at the transmission end of it the existing 3R yoke has to be cut off, so there needs to be enough length remaining of what's left. The other factor is material thickness and whether or not your fab shop is going to comfortable welding the OEM material and rebalancing it. I'm only familiar with local shops around me (Riverside, CA) and always use Inland Empire Driveline in Corona. Almost any driveline shop can make what you need though, they're nothing special.
As to the differences I was talking about between the fixed-yoke and slip-yoke versions of 480-E, here and example that shows the different types of shafts compatible with each. Note the slipyoke on the aluminim shaft pictured is for a Gear Vendors overdrive and is short, 4L80-E slipyokes are a lot longer.
I'm not familiar enough with the OEM specifications of GMT800 propeller shafts to say whether or not it would be feasible to modify the stock shaft. There are two criteria - in order to install a 1350 yoke at the transmission end of it the existing 3R yoke has to be cut off, so there needs to be enough length remaining of what's left. The other factor is material thickness and whether or not your fab shop is going to comfortable welding the OEM material and rebalancing it. I'm only familiar with local shops around me (Riverside, CA) and always use Inland Empire Driveline in Corona. Almost any driveline shop can make what you need though, they're nothing special.
As to the differences I was talking about between the fixed-yoke and slip-yoke versions of 480-E, here and example that shows the different types of shafts compatible with each. Note the slipyoke on the aluminim shaft pictured is for a Gear Vendors overdrive and is short, 4L80-E slipyokes are a lot longer.
12-22-2015, 08:23 PM
#18
James, can you comment on conversion U joints. I keep reading that they are never recommended in performance applications.
I just recently swapped my entire driveline over to 1350s and upon install I noticed that the 1350 isn't that much bigger than the 3R. So why is the conversion joint so much weaker than the straight 1350?
I just recently swapped my entire driveline over to 1350s and upon install I noticed that the 1350 isn't that much bigger than the 3R. So why is the conversion joint so much weaker than the straight 1350?