6 Speed Auto's

[Intrepidman]

Worthwhile or not, I still feel like my car could use more gears and I am not willing to go manual.

So far I see two options
Option 1) The TCI 6X Six Speed - geared as follows
1st 2.97
2nd 2.23
3rd 1.57
4th 1.18
5th 1.0
6th 0.75

To me this seems pretty useless unless someone is looking for six Really Close ratios (4th and 5th are practically identical) and the gap from 1st to 6th is actually smaller than the 1st-4th gap on the stock 4L60E.

Option 2) The 6L80E - geared as follows
1st 4.03
2nd 2.36
3rd 1.53
4th 1.15
5th 0.85
6th 0.67

Has anyone heard anything positive about this tranny?
I really haven't heard much, but what I have heard is that it is hard and very time consuming to tune, and isn't reliable in high power applications (500rwhp+)
1st gear also seems pretty steep. I don't know anything about building transmissions, but could a performance shop change the first gear ratio?
And are any shops currently turning out beefed up performance versions of this tranny?

[robcas47]

All I know is I'de like a A6 with a paddle shifter if ever given the chance. Maybe a C6 owner with one might chime in with their opinion.

[JaycenK]

The problem with them is the shifts. The way they are set up from the factory to run is with a form of torque management and with that the pcm has to pull timing to try and preserve the trans every time it shifts. The modern engines are now also running variable valve timing that can aid in making the timing issue almost none exsistant. If your pulling timing your losing time as they say. A proper stall for your engine build on a th350/th400 or even a 4l60e/4l80e will beat a 6 speed auto racing in a straight line. Having owned a tundra with a 5speed auto I liked the close ratio box when towing. It kept me in the power band and allowed me to tow around town and on the interstate more effectively than with previous 4 speed autos with similar power. That said I drove a tundra with the same engine as the one in my truck but with a 4 speed auto behind it and the 4 speed NOT towing was quicker out of the hole and through second gear than the 5 speed due to the pcm pulling timing as the engine got to the read line faster due to gearing than a 4 speed that can hold the timing longer, but the 5 speed had the advantage of gearing from mid 2nd to 4th flat out wide open in a straight line due to the fact that it took advantage of the varible valve timing. With that big as truck cruising at 55 to 60 and then going WOT with it it was fast due to the gearing from 2 through 4th. I could run with most production cars from 55 to 90 but at 80 to 90 the aero really killed it. So close ratio is not a bad thing but like you said finding someone to tune them correctly is the key. On the other hand if you want to run a set of 4.11's the 6 speed set up properly can be a great thing to achieve a great track car and daily driver. I would like to see some real world results of the 6speed auto V's the 4l60e or 4l80e.

[Marc 85Z28]

Option 3: Put a quality performance torque converter in front of your 4L60E and forget about the 6 speed auto swap.