[65Rat]

I’m wanting better highway manners on my Malibu to keep it comfortable and everything cool. The two shops I’ve discussed with recommended a 4L80E swap. Other enthusiasts (thank you Lew) are recommending Gear Vendors OD. Both seem to be great options, just curious what others experience have been and what would be the difference in cost. I believe my existing TH400 is pretty well built so no concern with it in general other than highway RPMs. Adding a ton more power is not in the cards at the moment as I like what it produces today but I definitely want a setup that is as bulletproof as possible. Being able to handle more down the road would be nice (if I blow up the motor and need to replace) but not a top priority.
I’d also like to avoid cutting the floor pan if possible.

1965 Malibu
Blueprint 496
FiTech EFI
575 FWHP and around 430 RWHP
TH400
3.55 rear end with Detroit Locker

 

[shovelrick]

GV and you'll also have 6 speeds if you want to use all gear combos

 

[71350SS]

The only thing I can add is the Gearvender won't weaken your drivetrain while I don't know if the 4L80E will be as strong as your T400..

 

[cage2592]

I'm in the GV camp as well. I mentioned this before but I think the newer GV are smaller in DIA. than the older GENs. You'll of course need a new driveshaft for either so thats a wash. You will still be below the cost of the 4l80 though as you will need a new converter and standalone trans controller.

Mike

 

[lucifershammer]

My thoughts are also that since you already have a well built TH400, go with the GV.

 

[weidhopper]

My vote is for the Gear Vendors bullet proof

 

[kolo]

with the 400 already built, the GV will help revs. Get the GV control unit that is built by MSD, too much interference with other box. (obvious statement) You won't have the TC lock up.
I have a built 4L80 w a GV and 3.50 gears w a detroit trutrac in a Currie 9 inch. Tuning the 4L80 is all in the computer, very nice and easy to change. 2180 rpm at 80 mph is a good talking point, but in reality, probably didn't get me much- BUT- I am very happy with it tho. Didn't cut the tunnel open, had to do some massaging and did remove part of the brace in the tunnel.

 

[yanniziomas]

Gear Vendors makes sense, I had one on my ‘68.

I installed a 4l60e last winter on my ‘66 with 383 abc and 3.7 rear gears. Never, ever going back to non-electronic transmission 👍

 

[PileDriver]

The GV can have vibration problems and I've seen it more than once. My uncle fought and fought vibration at highway speeds with his TH350/GV and changed everything from yokes, driveshaft length, and material (steel/alum). Finally caved and went 4L80E. Smooth as butter.

I vote 4L80E. They're excellent transmissions and quite frankly I'm surprised they're not more popular with gearheads everywhere.

 

[Bronze68]

I had the exact same decision to make a couple or so years ago with my 71. I ran a TH400 that I LOVED; reverse manual shifting, and somewhat built. I definitely wanted OD, and I read/researched the topic for a long time. I had myself sold on both the GV and the 4L80 multiple times each way. I spoke directly to GV, as well as Jakes's Performance about their take on both. Both had good arguments.

Disadvantages I considered:
GV: Would have to hammer the floor pan - didn't really want to do that on this particular build but would live with it, had to find a home for the small brain box, had to worry about out how/where to mount the switch - which was not ideal with a horseshoe shifter
4L80: added weight and took away more power at the rear wheels

Advantages
GV: 2/3's the price of a well-built 4L80, could still use the same TH400 I loved so much
4L80: didn't have to hammer the floor pan at all (just a close fit in a couple of spots)

Ultimately, I decided that the power loss from the 4L80 was not a concern, as I was starting with almost 600 hp & tq, and I just wasn't going to run this thing at the track more than maybe once/twice a year - if that. I also like the cleaner install of not hammering the floor pan, and not having to worry about the electronic aspect since I would be using a manually shifted valve body. Looking back, I remember well the mental turmoil I put myself through, but would definitely pick the 4L80 if I had to do it again.

4L80 and TH400 share many of the same parts in stock configuration. I would argue that the 4L80 is today's best/strongest transmission option when comparing stock to stock, and easily the strongest when built-up (although that's a relative concept depending upon what/how your comparing).

This is not to say I dislike GV or think they are inferior. I think the concept is great. Just not what best fit the bill for my desires.

 

[540 Olds]

I went with GV OD, BUT...I do have vibration I can't seem to track down; same with a buddies '65 GTO. He went GV OD and has same problem. I believe this is more of a problem than GV admits; not sure, but I read about many people having vibration issue after install. They usually claim driveshaft length not correct with their trans yoke.

Mine is in the 75-85mph range...smooth as silk at 100. Nothing serious, just a nuisance.

 

[Badd64]

I can tell you this about a 4l80e in a 64-65 chassis... It requires a lot of work for correct pinion angle. Easiest thing to do would be to slice off trans tunnel at floor from firewall all the way back to where the tunnel comes back up for the pinion. Slice off the dip section where tail shaft would sit and move tunnel back to that point. and then raise the tunnel off the floor approximently 1.5-2 inches. Put ttans in and pray it fits. You might still have to make a hump for the for the rear solenoid on driver side and the hump near top rear on pass side.... I was able to get to 1 deg down angle this way... However, I am a big tire big block car that is being set up for as little parasitic loss as possible.

In other words, it will fit but be prepared for a LOT of cursing and fab work. Had I known before I started this project I would've stuck with a turbo 400 and just stayed off the freeway.

Btw Mine is a 29 inch tall tire with 3:90 gears

 

[gnicholson]

400 and a 308 or 273 is always an option

 

[cage2592]

400 and a 308 or 273 is always an option

Brings up a good point and the route I went. Plenty of HP/TQ with a TH350 and 3.00 gear in a 9" with 28" rear tire. I drive HWY constantly.

65Rat, you'd be surprised at how nice it drives If you feel you have the HP/TQ you want.

Mike

 

[weidhopper]

Maybe I'm lucky but I have no vibration with my GV would definitely do It again