4L60 on my '74
Thread Starter
Instructor
Joined: May 2013
Posts: 177
Likes: 17
From: Turin Italy
4L60 on my '74
Hi all, I am looking to swap out my thm400 for an overdrive transmission.
I was thinking to use a 700R4 but the 4L60 (not 4L60-E) should be a better transmission. What do you think about this idea? There are a lot of parts around the transmission that should be changed? Any opinions would be appreciated!
I was thinking to use a 700R4 but the 4L60 (not 4L60-E) should be a better transmission. What do you think about this idea? There are a lot of parts around the transmission that should be changed? Any opinions would be appreciated!
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Same transmission....just made in different years.
The 700-R4 was retitled as the 4L60 when GM standardized their transmission model codes. When that trans became 'electronic', it was dubbed the 4L60E.
The 700-R4 was retitled as the 4L60 when GM standardized their transmission model codes. When that trans became 'electronic', it was dubbed the 4L60E.
Pro
Joined: Sep 2017
Posts: 516
Likes: 72
From: Modesto California
I'm using a 15 psi Hobbs pressure switch screwed into my 4th servo pressure tap to control my lockup automatically. At one time I used two pressure switches; one in the 4th servo pressure tap and the other in the 3rd gear pressure tap but the lockup in 3rd gear got really annoying because it'll stay in 3rd gear clear down to only 19 mph in city traffic. There is also a 2nd gear pressure tap at the rear of the case so it would be possible to get a 2nd gear lockup but I can't imagine anyone ever doing it.
Last edited by 71VetteLover; Sep 26, 2017 at 04:36 PM.
Pro
Joined: Sep 2017
Posts: 516
Likes: 72
From: Modesto California
The '82 ECM's locked the converter clutch in 3rd and 4th gears and owners quickly became VERY annoyed with the 3rd gear lockup. It was that 3rd gear lockup that made many owners switch to aftermarket PROMS that only allowed a 4th gear lockup at 43 to 45 mph minimum.
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Safety Car
Joined: Dec 2007
Posts: 4,229
Likes: 39
From: Beautiful East Texas
As I recall...Used the same x-member but a small metal plate was installed to relocate the mount slightly forward of the standard position used in the TH400 application...
I'd need to check to be 100% sure but I think this is the case.
btw... the 700R4 conversion really makes the car much more friendly to drive as these days we're all accustomed to rolling down the road at 70 mph at 1800 or so rpm with
better mileage, less noise, reduced wear and tear not to mention the better acceleration t due to the lower gear ratio...
My only regret about the whole experience was the shop I chose was not really Corvette 'friendly"... they hacked up some of the install and I've had to go behind and correct a few items that I was unhappy with.
I created a thread on the conversion several months back... I'll see if I can link to it:
https://www.corvetteforum.com/forums...onversion.html
mardyn
I'd need to check to be 100% sure but I think this is the case.
btw... the 700R4 conversion really makes the car much more friendly to drive as these days we're all accustomed to rolling down the road at 70 mph at 1800 or so rpm with
better mileage, less noise, reduced wear and tear not to mention the better acceleration t due to the lower gear ratio...
My only regret about the whole experience was the shop I chose was not really Corvette 'friendly"... they hacked up some of the install and I've had to go behind and correct a few items that I was unhappy with.
I created a thread on the conversion several months back... I'll see if I can link to it:
https://www.corvetteforum.com/forums...onversion.html
mardyn
Last edited by mardyn; Sep 27, 2017 at 09:20 AM.