Hey. Everyone.. I figure Id revisit my thread again to make it obvious again. I still havent changed the gearing yet. Havent had the money. Trying to plan to move out of this state soon. But just wanted to see if anybody out there has any kind of better answer to my question. I thank everyone that has had input on this so far but it hasnt answered what I need to know.. So to make it clearer. If anybody has an older dodge truck with a 6bt lifted on 40s or so, what gears are you running??? Im not changing anything with my drivetrain BUT the gearing and the GEARS ONLY!! I obvioulsy have the 727 auto trans. Im starting to agree with Montepig72 in that with what he wrote down looks like it makes sense to bring it towards what a stock dodge RPMs would be at highway speed. Just looking for another opinion from someone that has been in this position. Thanks in advance

 

dont know about diesels. but my 79 k20 with 4.10 sm465 and 38" tires. at 65 im going about 2400 rpms. now the sm465 is a 1:1 transmission. with 40s i think i was only a hundred under that. i wouldn't mind 3.73, but then you will lose some spin in the mud but with a granny gear i still should have other options.

 

Think of it in terms of percentages: 4.11's are about 10% faster than 4.56's at the top end, and will still leave you about 90% of your present low-end grunt. If you're pretty thrilled with your present low-end, you'll probably not miss that 10%, and the transition will probably be pretty seamless.

3.73's yield about 82% of the reduction of your present 4.56's.... means they'll be 18% faster at high end, and that you'll lose 18% of your low-end gruntiness. Will you miss it? Probably not. Will your torque converter notice? Probably. Might need an upgraded TC and some additional cooling to give it longevity.

 

I run 35s with 373s but have a gear vendor... love it!!

 

I dont have the granny gear not being a stick..But I still have 4 wheel low If I needed the extra low range....As for low end power,I think I have too much. I dont think I will miss it going with the 3.73s. I do have my IP turned up along with a fuel pin and 4000 rpm spring. IMO maybe Im right or wrong,but I dont "think" I should have a problem moving the truck with with everything turned up like it is... Also whats the deal with having to get another torque convertor? What will happen to this one? Any recommendations? I have the trans running to the factory cooler on the side of the engine,then through my radiator,and then throung a hugh aftermarket cooler in front of my radiator then back to the trans. So far I dont notice any issues..A trans temp gauge is next on my list....

 

Howdy, again! When you swap in the faster gearsets, just like the 10% or 18% faster wheel-roll, you should expect about that same amount of additional slippage before you get a good "hookup" in the TC. The aftermarket guys make replacements that have different turbine/stator geometries to recapture that not-slipping-much OEM feel. When you have more power at the crank AND more resistance at the tranny's output shaft, the fluid-couple pays the price, in terms of heat. The more-efficient TC will actually run a little warmer in "slip" before achieving stall. Sounds like you have enough cooling already, so that might not be an issue. Expect to change brake pads/shoes more often, though.

 

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