85 c4 questions
Thread Starter
2nd Gear
Joined: Apr 2017
Posts: 2
Likes: 0
85 c4 questions
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
Melting Slicks
Joined: Nov 2013
Posts: 3,451
Likes: 336
From: Greater Cincinnati Area.
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.
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.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
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.
Last edited by John A. Marker; Aug 21, 2017 at 10:21 PM.
Melting Slicks
Joined: Nov 2013
Posts: 3,451
Likes: 336
From: Greater Cincinnati Area.
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.
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.
Last edited by confab; Aug 22, 2017 at 12:57 AM.
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
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.
Team Owner
Joined: Sep 2001
Posts: 62,180
Likes: 1,740
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
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.
Melting Slicks
Joined: Nov 2013
Posts: 3,451
Likes: 336
From: Greater Cincinnati Area.
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.
Last edited by confab; Aug 22, 2017 at 02:19 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
5 Best & 5 Worst Corvette Daily Drivers
Joe Kucinski
The Headlights of Every Corvette Generation Explained
Joe Kucinski
5 Best & 5 Most Overrated Corvette Track Packages of All Time!
Joe Kucinski
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
Melting Slicks
Joined: Feb 2003
Posts: 2,688
Likes: 815
From: Saskatoon Sask.
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.
Team Owner
Joined: Sep 2001
Posts: 62,180
Likes: 1,740
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
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.
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.