89 Silverado 700r4 to 4l80e swap

[Supercharged111]

Is MAP input not considered for downshift behavior (and possibly TCC lockup?) Curious, have no experience here, just wondering if that's why tayto mentioned it.

Richard

It's not on the Vortec. MAP is used to calculate load, but I'm not sure if the TBI trucks bothered with that. It's clear it wasn't needed for the 6.5 if the TCM didn't get a MAP signal.

 

[Nad_Yvalhosert]

That's possible because there's only about a half inch difference in length and between a TH400 and a 700R4.
A 4L80 is 3 inches longer.

And O.P. has a donor truck. Therefore he has the spare parts to choose from.

 

[tayto]

You should only need TPS and RPM to control the trans.

ya I wasn't debating that, i thought map was referenced in the shift logic but I might be wrong. either way, the standalone gm controller was for the early 4L80Es w/ the bosch force motor. I suppose you could downgrade a 94+ unit but this seems silly to me. I still stand by using the 94/95 TBI pcm as a standalone "low buck" controller. more complete hac & definition file and works with the 94+ units (91-93 can be converted with out much effort).

 

[Supercharged111]

ya I wasn't debating that, i thought map was referenced in the shift logic but I might be wrong. either way, the standalone gm controller was for the early 4L80Es w/ the bosch force motor. I suppose you could downgrade a 94+ unit but this seems silly to me. I still stand by using the 94/95 TBI pcm as a standalone "low buck" controller. more complete hac & definition file and works with the 94+ units (91-93 can be converted with out much effort).

Well it's just a newer gen PCM all around from what I recall so in that regard alone it would be superior.

 

[Erik the Awful]

That's possible because there's only about a half inch difference in length and between a TH400 and a 700R4.
A 4L80 is 3 inches longer.

Interesting. My 4L80 is about half an inch longer than my 700R4. The transmission mount pad is about 3" further back.

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[618 Syndicate]

Interesting. My 4L80 is about half an inch longer than my 700R4. The transmission mount pad is about 3" further back.

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Interesting. Not what I found, Advance Adapters (which I consider a reputable source) shows a 700 as 23.3 and a 4L80 as 26...

 

[95burban]

Www.Usshift.com has some pretty awesome controllers

 

[Supercharged111]

Interesting. My 4L80 is about half an inch longer than my 700R4. The transmission mount pad is about 3" further back.

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I didn't ghetto grind 3" of splines off the front driveshaft, and could swear I took less than an inch of of the rear when I did my 4L80 swap.

 

[Schurkey]

the 89 is the light 7200 lbs 3/4 ton with 6 lug wheels and 94 is a 3/4 ton with 8 lug wheels. Both are 4x4

What is the condition of the "donor" truck?

Are you swapping parts the "wrong direction"? In other words...should you be fixing-up the "donor" truck instead of the '89?

 

[wittensville]

What is the condition of the "donor" truck?

Are you swapping parts the "wrong direction"? In other words...should you be fixing-up the "donor" truck instead of the '89?

My 89 is the nicer truck especially the interior, the 94 has no title.