# 6 speed auto



## KarLvr (Oct 28, 2010)

Has anyone had experience or knowledge of installing a 6L80 trans in a 65 GTO. Thanks


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## Rukee (Feb 8, 2007)

With the stock 389?


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## KarLvr (Oct 28, 2010)

With a LS series


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## BearGFR (Aug 25, 2008)

KarLvr said:


> With a LS series


Is it too late to talk you out of the LS? :confused

Just sayin...

I see you're in Sherman --- I'm just down the road from you in Garland. I've got a 69 GTO project underway and recently finished building my "400".

Bear


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## KarLvr (Oct 28, 2010)

I have total respect for the 400 series engines and mods to them. My plans at the present are to use an LS 3 480 hp crate or pull out. I was curious if anyone had tried a 6L80 and if the trans tunnel is large enough.


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## BearGFR (Aug 25, 2008)

KarLvr said:


> I have total respect for the 400 series engines and mods to them. My plans at the present are to use an LS 3 480 hp crate or pull out. I was curious if anyone had tried a 6L80 and if the trans tunnel is large enough.


For your perusal, here's the dyno sheet from my "400". In the interest of full disclosure, it's now a 461 due to a +.035" bore and 4.250" stroke. 

You're spending the bucks though, so you get to make the decisions. Anything that keeps a classic Pontiac alive is a good thing.

I don't know if that tranny will fit your tunnel, but if not I'm sure it's nothing that a little hammer and dolly work wouldn't fix.

Bear


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## KarLvr (Oct 28, 2010)

Yes, I'm sure we could resize the tunnel, I wanted a bolt together set up, without body changes to my car. The engine is bascially that and a 4L65E can be used which requires no major changes. I just wanted to used the 6 sp trans. Thanks for the response.


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## Eric Animal (Oct 28, 2007)

Check with TCI transmission, they have a package set up for the 6L80e and should be able to supply dimensions and such!:seeya:


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## Eric Animal (Oct 28, 2007)

What rear gears will you be running? The 6l80e has a 4.02 1st gear!!!! and a 0.67 OD.......


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## KarLvr (Oct 28, 2010)

I had some problems with a 12 bolt rear end so went with a 9 inch along with disc brakes frnt and rear. I used strange gears ( 3.25 s ) where that the car will be easy to take on Rod runs. More interested in lower RPM s at 70 to 75 MPH. I emailed TCI asking about the size of the 6L80. I have a friend with a transmission rebuild business and yesterday took a close look at the 6L. They are longer, but don't seem a great deal larger in diameter. They are definately heavier built.


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## Eric Animal (Oct 28, 2007)

Strange makes a good, strong product. A 3.25 rear will give you a final drive ratio of 2.18:1 ! Coming outa the hole in 1st will be like a TH400 with a 5.27:1 rear gear !


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## KarLvr (Oct 28, 2010)

I like that final ratio idea, just have to determine if the trans will fit the position.


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## Eric Animal (Oct 28, 2007)

Try www.v8tv.comthere is a blog and video of guys putting an LS motor with a 6L80e tranny into a 66 GTO.....


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## crustysack (Oct 5, 2008)

you will have to modify the trans tunnel to fit the 6 speed, that tranny is MUCH larger than what was there originally. I put a LS! and a 6 speed manual in my 65 and had to cut the tunnel out and make larger


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## Eric Animal (Oct 28, 2007)

I'm gonna have to do that to my hood!!!arty:


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## KarLvr (Oct 28, 2010)

Thanks for the help.....I think a 4L65E is the direction. I don't want to cut the tunnel.


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