3k Yank Performance Converter 4t60e

[geldartb]

Dex-VI is a semi-synthetic blend so it should be fine.

Supposedly, the Dex-6 is backward compatible with Dex 3; meaning that you can add/mix the 6 with 3 but it's not recommended to add 3 to a transmission that has 6 in it

its designed to be backward compatible with DEX III

DEXRON-VI is generally Gp III although the spec does not preclude the use of PAO/Ester base combinations. The confusion arises because in the USA group III stocks can be labelled as synthetic.
Yes DEXRON-VI was designed to be backward compatable so it can be used in all Hydramatic transmisions that called for DEXRON-III or earlier DEXRON specifications. Try not to mix DEXRON-III with DEXRON-VI, only because if you do that you are in fact diluting the DEXRON-VI fluid with a less stable product and therefore throwing away much of the advantage. All you need to remember is that DEXRON-VI is far superior to DEXRON-III and also that DEXRON-III no longer 'exists' in terms of licensing so there's no control over the formulations (if you go out and buy a 'DEXRON-III' fluid in reality you have no idea what you're paying for!). In contrast, GM controls the formulations for DEXRON-VI licensed products ... so you know exactly what you're buying.

[torq455]

yep. though GM Dex VI is only $9 per quart. i bought Valvoline Dex VI synthetic to use in my 4T65E.

[3400-95-Modified]

I have the same Valvoline Dex 6 in my 60e.

And yeah you bastard I had to buy a new 3.29 diff after that since I realized later that the 3.69 ratio was more effective over the 3.42.

[torq455]

ROFL!!! that's too funny! so how's the valvoline working? can you tell any differnces from the Dex III?

[gectek]

i went from a 3.69 in the 06 bu to a 3.42 and it seems to be doing better with acceleration and will prob run a better et...still waiting for the track to finish with const.

[3400-95-Modified]

Now why going from 3.69 to a 3.42 would improve acceleration? I went from 3.42 to 3.69 and my ET got much better, But I can't say that was ALL the gear change that helped. I may try 3.42 again next year if I can come up with some extra LSD parts somewhere.

The Valvoline is working fine, no issues with it, but I havent run this with Dext III so I have no comparison.

[IsaacHayes]

Bah you guys suck with your high FDR ratios. I'm 2.97

[gectek]

because it has a 3.9 in it, built in low end tq. it was ok with the 3.69 but not enough usable gear, esp for the crappy stock cam. you should see the tq curve on it...in the higher rpms it doesnt go up, the HP either.

[torq455]

yeah, you can have too low of a FDR. Dave went higher and went faster. these engines with even a radical cam still seem to keep a rather flat torque curve--and a healthy one at that. so, with the higher FDR, you take advantage of the torque, and spend more time there, especially during launch.

--got my car to the track finally. it ran ET .16 slower, and MPH .4 slower with my tranny swap. Now, compared to the old tranny: added ~100 lbs, wider tires (205 to 225), spare tire, and had a FULL tank of gas. i kinda think if i changed the FDR, which would end up being 3.20:1, it would go faster. i still have some shift timing to sort out--when to lock TCC and what RPM to shift at, and a little ECM tuning.