Discussion in 'The Garage' started by southernspeed, Jan 10, 2005.
What box is this? They say it's from a '95??
hard to tell, but kinda looks like a 4L80E
It is a 4L80E .
I concur also.
Thanks. Am I right in thinking they're not so good for putting behind a 350"? Don't they have a tall first gear?
This was behind a 6.5? deisal on a prototype Hummer apparently!!
They have a 2.48 to 1 first gear ( same as a TH400 ) . It will work fine behind a SBC if the truck is geared as it should be . The tranny is a heavy unit and has a lot of internal friction so you will feel a power loss if compared to a manual tranny . A 4L80E is very stout and a good choice if you need a good auto tranny with an O.D.
bottom line is power robber but is strong slushy box
I'm converting my '78 tp TBI. Would the stock ECM support this trans or does it need something different to operate it?
Also, coming from a diesel, is it the same as a one from a gas truck?
Actually, I guess the stock ECM for a TBI truck should control it, since the 4L80E were used '90-91(both years?) in the one tons?
Was going to say no, but that is not true! In any case, if you don't have the ECM (PROM really) from a 4L80E equipped truck, it probably won't work "as is".
I would also check to make sure that the control (how the ECM handles it, or the electrical innards/wiring) of the tranny didn't change from it's inception (IE the year you would use a PROM from) to the one you have.
some computers dont have the circuitry to control a tranny. you'd need a computer from a vehicle that originally came with TBI and a 4L80E, shouldn't be too hard to find.
1)I would make sure whatever ECM you choose that is from a 4l80E equipped vehicle.
2) I am not positive what controls the shift points on those transmissions but on the older 700R4's and th400's that are behind the 6.2's have a governor that is different between a gas and diesel version transmission.
EVERY shift is controlled electroniclly, there is no governer on the E (electric) trannies. the only difference is the converter (low stall on diesels).
i just noticed the cooler line locations in the pic, its a pre 96 tranny.
I couldn't find any info that cleared this up. It doesn't look like a "standard" '87-91 TBI ECM (1227747) will run the 4L80E.
With the RPO code for the 4L80E it's first year, (just in case it ever changed) you should be able to find info by searching that RPO with 4L80E someplace like google.
Big change '95-96 with the computer systems, so I'd want to make doubly sure what year the transmission was before I started hunting down a whole bunch of other info that may end up being impertinent. (and it looks like tranny year has been at least ID'd as being '95 or older)
Thats what I figured. Good point about the converter, I forgot about that.
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