Chris Mauch

Ok so i am looking to drop a 383 with about 400 hp into my vette and am wondering if my auto is able to handle it also if the torque converter will work or what would be the best route to take im just not happy with the power that the stock engine has with that said anyone have any tips or any thing you would recommend for this build

confab

IMVHO, that's too hot for the trans. You'll be rebuilding it soon.

The 85 4L60 was weak in stock form. Fortunately, many of the later "E" parts will retro right back into it and mixed with some aftermarket stuff, you'll be good.

But as it is, I would budget for a rebuild.

Ideally the converter would be matched to your cam and power curve. Mine is warmed over stock, and a 2K (roughly) stock high stall converter works well and is an inexpensive solution. If you need more, there are aftermarket stalls that run the gambit.

Hope this helps.

John A. Marker

The 85 came with the 700R4 transmission not the 4L60 as indicated above. You should have the trans rebuilt to handle the HP. As noted above, try to match the torque converter to the cams torque curve.

confab

OP, don't be confused.. 700R/4L60 are the same transmission, but GM made some improvements on the 700 and called it the 4L60.

Mainly sprags. Both were not suitable for your combination. (Especially now, after so much time) But a good rebuild and update will put you in the ballpark. Because all the good stuff from the 4L60 and the 4L60E will retro into your transmission, and they are cheap upgrades.

Get a good shop to do it and it'll be fine. Just budget for it. Because you will need it.

383vett

The 383 will add more torque off the line and should increase the effective stall of your stock converter. It should be fine as well as the 700R4. It's not like you will be adding 100 horses under the hood. If the tranny eventually goes, it can be upgraded unless you have the extra $$$ to do it when the motor is being swapped.

vader86

Your 85 has a 2000rpm stall TC, and the 700 should hold up for awhile. Eventually the torque output of the engine will kill it and you'll want to do some upgrades then when you have it rebuilt, but I would just drive it as it is for now.

John A. Marker

Yes, the next generation of the 700R4 was the 4L60. But your still stuck with the 700R4 and like Vader86 said......it will hold up for awhile, bu tit will go South and need to be rebuilt.

confab

You can retro all the 4l60 & 4L60E stuff right back into it. Including the big forward sprag. You can even add the rollerized sun shell if you want.

I own a transmission shop and we do it all the time for the older units in performance cars. They're cheap upgrades. It all works together just fine.

arbee

The renaming of this transmission has nothing to do with "generations" or upgrades per se. In 1989 this transmission was called a 700R4. In 1990 it is called a 4l60. In this year, GM standardized its nomenclature for its transmissions. "4" is 4 speed, "L" is longitudinal, "60" is the strength rating GM devised.(not sure of the ft/lb rating). Likewise, the 4T65 front wheel drive transmission stands for "4" speed, "T" transverse and "65" as the torque rating. Place a 1989 700R4 next to a 1990 4L60 and you won't tell the difference.

dclafleur

So is it a race between the 700R4 and the Dana 36 for which goes first?

vader86

D36 can hold up to the torque if applied smoothly, its the instantaneous torque applied to the diff that will snap things. Instantaneous torque will get multiplied more by sticky drag radials and slick tires, so never put those on the car and it will probably live a long time. Street tires have enough slip in them that they should spin and that will lessen the instant shock.

But, it will go when it wants to go. It could last 50K without a hiccup or it could go within 5K if you hook up hard.

The 700 will start to show something in the 1-2 shift first I bet, and it will probably wear out long before the diff.