4T80E/Turbo-S/C... TIME FOR A NEW THREAD? - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 02-07-2006, 05:08 PM   #1
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Default 4T80E/Turbo-*/C... TIME FOR A NEW THREAD?

AFTER TWO YEARS, NEARLY 400 POSTS, AND ALMOST 30,000 VIEWS MAYBE IT'* TIME FOR A NEW THREAD... FOR THE LATEST, SEE THE "NAME PONTIACJEFF'* TWIN-CHARGED BONNEVILLE PROJECT"

It'* going in a '96 SSEi in conjunction with the Twin-Charged 3800 SII.

The first thing that jumps out is the enormous side cover and general girth of the -80. In stock form it is rated at a conservative 305lbs.ft. torque capacity. There are a few Caddys pushing WAY more than that thru. I'm sure in stock form it will handle 450hp and 450lbs.ft. I estimate the hard parts to be good for 550-600lbs.ft. before hard part breakage occurs (using GMs 2:1 margin of safety factor). I will be rebuilding it using old transmission tricks of the trade for shift improvement and clutch life. The 98-up SSEi pcm and program with Caddy shift tables in place of the -65 tables will be used to control it. All inputs and outputs are identical b/t the two transmissions. A custom trans harness will be needed to add the necessary wires and run them to the pcm.

Of course, custom mounts will be needed, as will BOTH axles. Both -80 axles have a female inner joint (the differential uses an output shaft as well). I will be installing my EP Limited Slip Differential in the transmission before final assembly.

As for fitment, a new tailshaft support bracket will be fabricated, as will front and rear trans mounts. I might use a W-body-style rear mount and add upper dogbones if it looks like it will be easier.

The rear knock sensor WILL need to be eliminated and a little grinding necessary for the rear lower bellhousing bolt. The block hits the trans (barely) and the bolt holes do not line up. I already have a strap/bracket in mind for this issue.

Both the block and trans bolt holes will get a helicoil insert, enabling me to bolt the strap/bracket and tie the two holes together. (The block was drilled and tapped for a 10mmx1.5 bolt to line up with the -80 bellhousing)
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Old 02-07-2006, 05:12 PM   #2
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Default Re: 4T80E swap has begun...

Quote:
Originally Posted by pontiacjeff
How do I post pics here? I have a bunch to show so far.
www.photobucket.com

Like this: [ img]http://www.mfxpop.com/~aarons/95ssei/95sig.gifi[/img]
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Old 02-07-2006, 05:14 PM   #3
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Code:
[img]url_of_image_here[/img]
Can't wait to see. Why are you doing this?
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Old 02-07-2006, 05:18 PM   #4
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Quote:
Originally Posted by J Wikoff
Code:
[img]url_of_image_here[/img]
Can't wait to see. Why are you doing this?
hopefully I'll get the pics up before I leave today...

b/c I am planning 450+hp at the wheels and don't want to waste 1000'* on exotic parts for a -65 to make it last.
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Old 02-07-2006, 05:32 PM   #5
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wow...this is interesting....i wanna see the pics of this progress, along with the Twin charging
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Old 02-07-2006, 05:40 PM   #6
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4T80E-note the enourmous girth!



And the side cover!



new t.*. bracket required



rear ks might need to be deleted, can't tell til it'* bolted up all the way



the rear lower bolt holes don't line up... the -80 is so big, GM had to move the bolt hole in and up. A little grinding on both the trans and block will be required for clearance.



The fix will be something like this, but in reverse: (courtesy Will, Fiero)


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Old 02-07-2006, 05:48 PM   #7
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Holy crap.
Is that d/* cover even going to fit in the engine bay? Or are you going to have to shift the engine over to the p/* side?
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Old 02-07-2006, 05:52 PM   #8
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Quote:
Originally Posted by 95naSTA
Holy crap.
Is that d/* cover even going to fit in the engine bay? Or are you going to have to shift the engine over to the p/* side?
The rear of the side cover is the exact distance that the W-body trans mount is from the bellhousing face. I might make a frame stand off and use a side mount like the w-body or just keep the front/rear mounting config like the H-body uses. I'd almost rather use the W- with it'* upper dogbone config.

One other thing... the -80 centerline is ~.375" wider than the -60/-65 (9.500" vs. 9.125") so the axles will have a slight rearward slant... not nearly enough to even give a second thought about.
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Old 02-07-2006, 05:57 PM   #9
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Quote:
Originally Posted by 95naSTA
Holy crap.
Is that d/* cover even going to fit in the engine bay? Or are you going to have to shift the engine over to the p/* side?
jeeeze that makes the l67 look so small...


curious to know how much better the 4t80'* hold up vs a modded 4t65e w/LSD
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Old 02-07-2006, 06:00 PM   #10
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Jeff....consider that the H body core support WILL NOT handle a dogbone mount or mounts....
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