4l80e

[Bernie Steffen]

Question for Chris. Sometime in the past, I read an article, that said it could be possible to recalibrate the valve body on the 4l80e trans so it would be possible to hit overdrive in all gears. In essence Six speed auto. I can't remember where I read it but is it possible? Thanks for all the info you impart. Bernie Steffen

 

[jakeshoe]

Bernie,
It may be possible with some fancy VB work.

The 4L80 is essentially a TH400 with an OD unit added to the front of the main drive.
If you could turn the OD on in each gear, and then back off at the gear change, it would function as a 6 speed.
However getting the shift timing right, so that it didn't hurt parts by having a bind-up, or hurt clutches because of a flair might be tricky.

Very few applications should need such a unit, very close gear spacing. Only a high strung very narrow power range engine would need it.
It might be neat to turn the OD on at the top of 1st, then shift to 2nd, then 3rd.
Or even to have the option of launching with OD on, but go through 1-3 normally, however on the 3rd shift, you would actually be in OD.
Would be good for testing purposes anyway.

I'm sure it could be done, but it would also be harsh on the OD clutches to make 3 gear changes and releases in a short time. That's alot of heat buildup in a short time.

 

[Nemesis]

There was a corvette in the late 80's or early 90's that let you switch into overdrive in every gear with a button in the center console. I drove the thing so I now it exist.

 

[mikestertwo]

86' Corvette

 

[Eticket]

I have one in my GN and can't think of a need for this at all.

 

[chris718]

ive never heard of that.i recently purchased 15 4l80e cores and am interested in finding someone who would like to try one in a gn.i can lighten all internal parts on the vertical mill and cnc turner as well

 

[Bernie Steffen]

the reason for this modification was for towing purposes. I was just reading all the threads about overdrives and I was just remembering. any way thanks for the info. Bernie Steffen

 

[sdteb]

chris check your email

 

[PaCemkr86]

this sounds good.. im intrested.. are there any provisons for a transbrake?

 

[mybuick]

it was called the 4+3 trans it was a 4 speed stick shift trans and in 2,3,4 gear you can press a button and it will have a atomatic overdrive. the bad part of the trans is if you beat on it it will break. my friend has it in a 88 vette and the car is sitting in the garage with a blown up trans...