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Discussion Starter · #1 ·
When I put 3.73's in my automatic 96 LT1 firebird, I noticed a big difference. I also noticed that highway speeds now suck. So I switched to some 3.42's. I would like to put my 3.73's back in, cause they just felt right in the car. It seemed faster, and probably was.

So of course what any engineer would say, is that the obvious answer to the problem is that you need another gear. The 6l80e has two more gears. I want to be able to run about 85 mph at 1,800 RPM's. With two more gears, that should be more than doable. What all do I need to do to make that transmission fit my 96 LT1 car?
 

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I think that you will never recoup the money spent on getting a 6L80E installed to justify the cost from gained MPG.

Is it doable? Sure, won't be easy or cheap.

Better off getting a gear vendors unit for a double OD if its that important to you.



 

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Nope, it will bolt up to the tailshaft of your 60e and give you an additional gear. Kinda hard to see but its like an extension of your trans, so you need a shorter DS.


Whether you have a LT1/LS1/BBC etc the 6L80E is just a large trans and will require some serious clearance work to make fit. It also would require a standalone shift controller AFAIK.



 

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There it's a 4l80e 6speed available. Not sure on price, but again you will probably have floor plan clearance issues.

Just drop in a T56.

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There it's a 4l80e 6speed available. Not sure on price, but again you will probably have floor plan clearance issues.

Just drop in a T56.

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Doesn't help him, as the final gear is still a .75 OD, same as a stock 80e.

Just adds a few grand to a already very expensive swap.

T56 is the best bet really :lol:



 

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When I put 3.73's in my automatic 96 LT1 firebird, I noticed a big difference. I also noticed that highway speeds now suck. So I switched to some 3.42's. I would like to put my 3.73's back in, cause they just felt right in the car. It seemed faster, and probably was.

So of course what any engineer would say, is that the obvious answer to the problem is that you need another gear. The 6l80e has two more gears. I want to be able to run about 85 mph at 1,800 RPM's. With two more gears, that should be more than doable. What all do I need to do to make that transmission fit my 96 LT1 car?
A T56 with .5 od and 3.73's will spin at 2100 rpms at 85. My T56 with 3.42's spins at 1950rpms at 85.

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Discussion Starter · #9 ·
There is a 4l80e 6speed available. Not sure on price, but again you will probably have floor plan clearance issues.
Which 4l60e are you referring to, that is a 6 speed? Never heard of it. I thought it was called the 6l80e lol.

Want to stick with an automatic. Had my fun with standards already, and I like to be able to drive my car in traffic if need be. Its not really a daily, but when I do want to go somewhere its usually Fort worth or Dallas and its high traffic. Standards ain't no fun in high traffic.
 

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Which 4l60e are you referring to, that is a 6 speed? Never heard of it. I thought it was called the 6l80e lol.

Want to stick with an automatic. Had my fun with standards already, and I like to be able to drive my car in traffic if need be. Its not really a daily, but when I do want to go somewhere its usually Fort worth or Dallas and its high traffic. Standards ain't no fun in high traffic.
He means a 4L80E not the 4L60E, and its a not a stock trans.

TCI makes a new planetary set that gives you gears in between the stock gears. So again, end gear is the same as stock.



 

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Which 4l60e are you referring to, that is a 6 speed? Never heard of it. I thought it was called the 6l80e lol.

Want to stick with an automatic. Had my fun with standards already, and I like to be able to drive my car in traffic if need be. Its not really a daily, but when I do want to go somewhere its usually Fort worth or Dallas and its high traffic. Standards ain't no fun in high traffic.
Its a 4L80e six speed. Google it. But the OD does you no good in our cause its taller (.75 vs .69 in yours) than the 4L60e OD. And that transmission has now girth than the 60 too.

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Discussion Starter · #12 ·
Ok different idea. What about mating a 6l80e up to an LS motor? Say one day I get tired of my LT1, or its just time for a motor swap cause its wore out. I could get that caddy v8 or whatever other V8 LS engine comes with the 6l80e in the escalade. Probably a 6.0 liter.

That way, there wouldn't be any costs trying to get them to fit together. Not like there would be, if you made a 6l80e fit an LT1 engine. Perhaps under those circumstances, it could become worth it? Buying and engine and tranny combo still stuck together from the junkyard, comes to mind.
 

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I was told by a competent trans guy ,that the new six speed trans
has quite a bit more internal friction than our stock LT1 automatic
transmissions. Its possible that you may really feel the difference
in the amount of drag with the six speed auto.
 

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Ok different idea. What about mating a 6l80e up to an LS motor? Say one day I get tired of my LT1, or its just time for a motor swap cause its wore out. I could get that caddy v8 or whatever other V8 LS engine comes with the 6l80e in the escalade. Probably a 6.0 liter.

That way, there wouldn't be any costs trying to get them to fit together. Not like there would be, if you made a 6l80e fit an LT1 engine. Perhaps under those circumstances, it could become worth it? Buying and engine and tranny combo still stuck together from the junkyard, comes to mind.
Its a much bigger trans, so, trans tunnel, yea say good bye to that.




Thats a 60e vs 6L80E

Not trying to be a downer, but its not an easy swap. Lots of custom work.



 

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Discussion Starter · #15 ·
Holy carp. I was thinking it was just longer. Gearvendors it is, I guess. How exactly does that thing work? Does it just engage the 5th gear whenever you set it to? Might be hard to figure out where to set it to engage, seeing as how the 4rth gear is already an overdrive gear. And as such, isn't really built for "speed".
 

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SNM; Is that big trans going into your Camaro or something else?
No, thats a huge beast. :lol:

I have a 4L80E in mine, one OD is enough for me, 3.08 rear gears ftw :p



 

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Discussion Starter · #18 ·
He means a 4L80E not the 4L60E, and its a not a stock trans.

TCI makes a new planetary set that gives you gears in between the stock gears. So again, end gear is the same as stock.
Hmm. So is the 4L80e smaller than the 6L80e? Perhaps size wouldn't be an issue with the 4L80e six speed? Or are you saying that the 4L"80"e, is made by this TCI company, so it's not really going to help?
 

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Hmm. So is the 4L80e smaller than the 6L80e? Perhaps size wouldn't be an issue with the 4L80e six speed? Or are you saying that the 4L"80"e, is made by this TCI company, so it's not really going to help?
The 80e is much smaller, it fit into my trans tunnel fine.

You would gain NOTHING from the extra money to have a TCI 6 speed 4L80E, as said before its final gear is the same, so your cruising RPM will not be different between the 4 and 6 speed 80e's.

TCI does not make the 4L80E, its a GM unit.



 
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