Topic: Dual Cases With Automatic Tranny (4L60E)

[7Jake]

I'm currently performing my 4.3L / Auto conversion and I'm going to run dual cases behind the 4L60E.  The 4L60E has a 3.06 first gear and I was told by somebody not to do 4.7's in the rear case as it'll be too hard to hold back.(torque converter issues).  My question is, it seams to me that the torque converter transfers power to the transmission based on engine rpm, not transfercase gear ratio, right?  How does this effect the ability to stop the vehicle?  I'm going to put 23 spline inputs in both cases, so I figured why not do a 4.7 gearset in the rear which comes with a new input shaft. I know some of you, including somebody at Marlin, have automatics with dual cases, What gears are you running and how is it to drive, on and off the trail.  If it matters, I'm running 5.29 R&P with 40" tires

[alwayzbroken]

It affects the stopping by providing so much power at idle that the brakes are overpowered and can't hold the vehicle still. I am sure you know that a vehicle with an automatic tranny always wants to move forward, that constant drive force with duals and 4.7s will overpower the brakes. The concept is extremely basic if you have driven a vehicle with an auto and have an understanding of gearing. It is not as important to fully understand why, as to just know what will happen.

[7Jake [OP]]

So it sounds like the torque converter never fully disengages the transmission.  Thanks for the input, I guess I'll probably stay with 2.28's in both cases.

[alwayzbroken]

Thats right, that is why an auto will creep forward when you let your foot off the brake. You could run a 4.7 if you are willing to put it in neutral every time you want to come to a complete stop with the gearset engaged. You would have stupidly low gearing which would be cool.

[insane04]

or get crazy and goto a high stall torque converter

im putting doubles behind a 700r4 right now so i will keep you posted

[7Jake [OP]]

OK, if there's no other input, I guess I'll be stupid and put in clocked 4.7's.  I'll just have to kick it into neutral once in a while, if I even use both cases.  Why try to be normal? I drive a Toyota with a turtle on it.

Gear options with duals with stock gears; 36:1,  84:1
Gear options with duals with 4.7 in rear  36:1,  76:1,  173:1

[alwayzbroken]

OK, if there's no other input, I guess I'll be stupid and put in clocked 4.7's.  I'll just have to kick it into neutral once in a while, if I even use both cases.  Why try to be normal? I drive a Toyota with a turtle on it.

Gear options with duals with stock gears; 36:1,  84:1
Gear options with duals with 4.7 in rear  36:1,  76:1,  173:1

Remember that the gear reduction is in effect doubled by the torque converter.

[insane04]

ill make you a deal on a new in box marlin 10 degree clocked adapter. pm me if you are interested