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The purpose of an Automatic Transmission is similar to that of a manual transmission, the auto tranny's primary duty is to allow the engine to operate in its narrow range of speeds while providing a wide range of output speeds.
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Which Transgo shift kit do I need? And which extras?

June 27th 2020, 4:04pm

Hey y'all.....

I'm planning to put in a shift kit when I change the tranny fluid, as I'd like some improvements.... Mostly I want to to feel better and last longer.... Gonna be towing a trailer (about 2000 lbs or so) and already have a cooler installed.....

Transgo makes two kits - the SK-4L60e and the 4L60e-HD2...... As far as I can tell the main difference is that the HD2 kit is described as giving "muscle car shifts" and also includes "gear command" which lets you shift up and down using the lever and holds the gear you choose to any rpm....

I've read this thread several times :https://www.astrosafari.com/viewtopic.php?f=70&t=14895

and it seems to give a good description of the ins and outs of installation of the HD2 kit, plus some add-ons, but then his description of how the transmission behaves afterwards sounds like maybe that's more than I really need to do to get what I want.... I don't need it to whack me on the backside every time it changes gears, but I do like the idea of it shifting cleanly without the waffling it does now....

Some questions I'd love to have clarity on:

Is the SK-4L60e kit combined with a corvette 2nd gear servo enough to get the tranny shifting crisply?

If I need the HD2 kit, do I still need a corvette servo, or do the spacers and springs that come with the kit take care of that job sufficiently?

If I'm understanding right, adding the Sonnax super hold 4th gear servo will let the tranny stay in 4th longer before downshifting, is that correct? If so, can I use that with either of the transgo kits?

What exactly does the "gear command" feature of the HD2 kit give me? It seems to me that I can already choose gears using the lever (though it will shift if RPMs get too high).... Would this feature allow me to hold 3rd gear up hills without downshifting to second by keeping the lever in 3rd?

Any insight would be so appreciated.....

Also, any thoughts on whether 'tis better to install a drain plug kit into my OEM pan, or buy a replacement pan with a drain plug built in....

Re: Which Transgo shift kit do I need? And which extras?

June 27th 2020, 4:58pm

I can't answer on the shift kits but as for the pan, I bought the plug kit from summit and no matter what I did it leaked so I ended up buying a pan with the drain already in it and never had a problem again.

Re: Which Transgo shift kit do I need? And which extras?

June 27th 2020, 5:10pm

We've installed 3 drain plug kits and are about to install the fourth. Not a single leak, not once. I bought a deep pan with the drain plug installed for the 727 on our RV - and no leaks there, either - because it was actually more expensive to buy a deep pan without the plug. It only had a shallow pan and the deep pan added 2 (3?) quarts to the capacity, plus put the bottom of the pan down into the breeze better.

As for the shift kit, I'd recommend the SK-4L60E. We put a TF-2 kit, listed as a reprogramming kit like the 4L60E HD2 kit, into the RV when we rebuilt the 727 (same time as installing the deep pan) and we should have gone with the lesser of the two kits. It bangs really hard into gear now. There's absolutely no slippage and the trans temp stays much lower, plus the fluid looks as perfect as it did the day we poured it in, but shifts are more than a bit harsh.

The only feature of the TF-2 is listed as: Instant full-race shifts

Then there's:
2-3 bind-up
Converter slip-shudder
Leaks out vent or lever seal
Pump bushing and seal burn up
Drain-back complaint

Re: Which Transgo shift kit do I need? And which extras?

June 28th 2020, 12:12am

Thank you for the input....

I am currently leaning towards the SK kit, as I don't really need it to bang into gear.....I'm open to further input....

Main thing that could change my mind would be if that gear command feature would make it so I could keep it in 3rd when going up hills as it currently downshifts into 2nd at a pretty awkward speed (I know that's not the intended purpose of that feature, but still if it would work that way, it might be something to think about)
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