what is the limit of 6L80E ?
03-10-2010, 01:11 PM
#1
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what is the limit of 6L80E ? my friend has a prochaged A6 C6 which is has the 6L80E tranny
he want to forged the buttom and to rise the boost but he is affraid that the tranny will not handle 700 whp
any help will be appreciated
he want to forged the buttom and to rise the boost but he is affraid that the tranny will not handle 700 whp
any help will be appreciated
03-11-2010, 01:35 AM
#4
I think the biggest issue we're going to see with the 6L80/6L90E platforms over time is the fact that they are synchronous shift.
One set of clutches must release and another set must apply and the timing MUST be spot on or you get a bind-up or a flare.
The builders who deal with the 700-R4, 4L60E's, and 200-4Rs (727s, Powerglides, C4's and a bunch of others as well) know this and have seen how critical the shift timing is on this type of trans.
In the past we have generally been dealing with a band releasing and a clutch coming on for the upshift under power.
It's not too difficult to calibrate a trans for this. It's trial and error and it's also one reason why many of the good builders are hush-hush about their feed hole sizes and release hole sizes. It's a hard earned calibration that can differ when using different clutch clearances, clutch materials, clutch count, release/return springs, etc.
However,
a band releases very well. It's like a drum brake. It will hold the drum until the last moment and then release, once it does so, it typically has very little drag. It's a "clean" releasing friction element.
A clutch pack does not release as well typically. It's more similar to a disc brake. It always has some drag.
An example of the above being a factor is on the 700/4L60E units.
Most builders had the upshift timing figured out pretty quick. However many STILL don't have it correct on the downshift. A 3-2 kickdown downshift, the 3-4 clutches must release and the 2-4 band must apply.
The band will APPLY, even with a stock servo, but the clutches have a hard time releasing fast enough.
GM started using special 3-4 release springs at the outer edge of the steels to solve it. The aftermarket has heavier return springs for the apply piston, larger exhaust holes, various methods to slow band apply/speed 3-4 release.
Almost every shift on the 6L units is a clutch off/clutch on shift. It is going to be very difficult to calibrate that for big power and good shift feel.
One set of clutches must release and another set must apply and the timing MUST be spot on or you get a bind-up or a flare.
The builders who deal with the 700-R4, 4L60E's, and 200-4Rs (727s, Powerglides, C4's and a bunch of others as well) know this and have seen how critical the shift timing is on this type of trans.
In the past we have generally been dealing with a band releasing and a clutch coming on for the upshift under power.
It's not too difficult to calibrate a trans for this. It's trial and error and it's also one reason why many of the good builders are hush-hush about their feed hole sizes and release hole sizes. It's a hard earned calibration that can differ when using different clutch clearances, clutch materials, clutch count, release/return springs, etc.
However,
a band releases very well. It's like a drum brake. It will hold the drum until the last moment and then release, once it does so, it typically has very little drag. It's a "clean" releasing friction element.
A clutch pack does not release as well typically. It's more similar to a disc brake. It always has some drag.
An example of the above being a factor is on the 700/4L60E units.
Most builders had the upshift timing figured out pretty quick. However many STILL don't have it correct on the downshift. A 3-2 kickdown downshift, the 3-4 clutches must release and the 2-4 band must apply.
The band will APPLY, even with a stock servo, but the clutches have a hard time releasing fast enough.
GM started using special 3-4 release springs at the outer edge of the steels to solve it. The aftermarket has heavier return springs for the apply piston, larger exhaust holes, various methods to slow band apply/speed 3-4 release.
Almost every shift on the 6L units is a clutch off/clutch on shift. It is going to be very difficult to calibrate that for big power and good shift feel.
03-11-2010, 02:58 AM
#6
TECH Resident
