4L80 in a '71

[909]

I have a 350 in my 2WD '71 but recently a 4L80 came up for sale at a good price and I would like O/D. If it is in fact the old mechanical type that he claims it to be would this be a difficult conversion to make? I'm expecting to just move the engine mounts forward.. seems like everyone agrees that's the easiest way to go? But what I have no idea about is if there's kickdown linkage or anything else would have to be changed aswell?

[boynton]

I'm fairly certain these have a tcm that you have to install.

[Bigdav160]

All 4L80's came from the factory as electric shift. Not mechanical

[hugger6933]

You will have to have a TCM or a PCM to control the shifting. I have two of these laying around from 3/4 tons I have parted recently and was looking into them as a possibility. For a little less than $1200 depending on whose kit you chose some are as low as $ 700 it can be installed. They are said to be as tough as nails and I would think could take about anything the average 350 could throw at it. The speedo is another concern but it can be addressed fairly easily for another$ 300 or so. Also a TPS needs to be hooked into the carb on your motor so the throttle position can be watched. Jim

[909]

TE=Bigdav160;6330564]All 4L80's came from the factory as electric shift. Not mechanical[/QUOTE]

Okay I was under the impression that it was mechanical until it became the 4l80 e in '91 for trucks and '95 in the vans and usually the e is left off because there wasnt many non e versions.

[boynton]

Originally Posted by 909

TE=Bigdav160;6330564]All 4L80's came from the factory as electric shift. Not mechanical

Okay I was under the impression that it was mechanical until it became the 4l80 e in '91 for trucks and '95 in the vans and usually the e is left off because there wasnt many non e versions.[/QUOTE]

There is a mechanical version of the 700r4 almost every trans since 91or 92 has some sort of electronic controller.

[Bigdav160]

Okay I was under the impression that it was mechanical until it became the 4l80 e in '91 for trucks and '95 in the vans and usually the e is left off because there wasnt many non e versions.

There was. It was called the 3L80. Otherwise known as the TH400

[special-K]

The 700r4 was called 4L60 from 90-92,but there was never a non-electronic 4L80e.

[luvbowties]

Originally Posted by 909

I have a 350 in my 2WD '71 but recently a 4L80 came up for sale at a good price and I would like O/D. If it is in fact the old mechanical type that he claims it to be would this be a difficult conversion to make? I'm expecting to just move the engine mounts forward.. seems like everyone agrees that's the easiest way to go? But what I have no idea about is if there's kickdown linkage or anything else would have to be changed aswell?

If it's a 4L80, then it's a 4L80E like BigDave said. Re-iterating on and expanding on 'Hugger's' reply, you will need an electronic controller--includes the "brain-box", wiring, & TPS. Also, you'll probably come out cheapest on the speedo to run an electronic speedo, like SW, AutoMeter, VDO, and other well-known gauge-mfg.'s make: these should wire directly into the 4l's elec. speedo output terminals.

Here, below, is a site where you can order at least all exc. the speedo-portion(maybe that too, by now), directly from the mfg.--a company about 10 miles from where I live here in SC. I've communicated with them about a year ago via email, and they seem to really "know their stuff". Their units are sold under other names by online retailers, I am sure.

We've heard around the "tracks" that these trannies are essentially a TH400 with od added. GM must think they are strong, as they use them a lot in their heavier and/or more powerful trucks.

Sam >> http://www.usshift.com/contact.shtml <<

[trucks72]

I have used usshift twice before. I love it. They will help you in any way possible.

[boynton]

Also if you are looking for better gas mileage then I would go with a 4L60e still a great transmission, not as expensive and shaves a few pounds as well as the gear ratios being better for fuel economy. I gpod rebuilt 4L60e should last a good 200k mi and are good for about 550 whp. These are the transmissions you will find in any 1500 for the last 20 years or so (obviously with differences in the last 20 years ie mounts/electronics) but a great alternative and could save you some $ cores around here are $2-300 and good used are $6-800. Just a side note for you

[hugger6933]

The 4L60E was brought into the truck market by gm for the 93 model year. I built those trucks,well rebuilt them and kept up with every little change they made as I had tons of parts to know what would change into what model. The3/4 ton and 1 ton Diesel version of the C/K trucks had the 4L80E in the early 90's with a stand alone computer. If one of those could be found and rechipped or reflashed [I don't know what kind it was so I don't know what term fits] to fit your application. These trans are as tough as they come, they are similar to the turbo 400 with decades of updated knowledge put into it as well. It is heavy and the gear splits are a little different for your regular street truck without a ton of motor.If you were to get a 4L80 E get one with the cooler lines spread apart from each other with them both in line. the other is one on top of the other like the older trans we are all use to. The "spread "cooler lines trans is a newer design and has all of the later factory upgrades. and the 700R4 The newer core you can get here the better off you will be as well, the model year 89 and up had a newer pump and valve body making it better. It[the 700 really got better each year ]. The 4L60E is a good one as well the removable bellhousing started in model year 96 and it has a newer design valve body from what I have been told but you must be careful there as the trad v8[350smallblock]and LS motor have similar bolt patterns the LS has a center bolt that some may ignore . The torque is different lengths on the old vs. new V8's ,and old converter on a newer engine will pour oil EVERYWHERE!! [don't ask how I know] wasn't me but it did happen in my shop. Also if you put a newer converter on a older engine it will go but the holes may be off and spacers for the hub will be needed to keep it seated in the trans oil pump. Jim

[909]

Originally Posted by hugger6933

The 4L60E was brought into the truck market by gm for the 93 model year. I built those trucks,well rebuilt them and kept up with every little change they made as I had tons of parts to know what would change into what model. The3/4 ton and 1 ton Diesel version of the C/K trucks had the 4L80E in the early 90's with a stand alone computer. If one of those could be found and rechipped or reflashed [I don't know what kind it was so I don't know what term fits] to fit your application. These trans are as tough as they come, they are similar to the turbo 400 with decades of updated knowledge put into it as well. It is heavy and the gear splits are a little different for your regular street truck without a ton of motor.If you were to get a 4L80 E get one with the cooler lines spread apart from each other with them both in line. the other is one on top of the other like the older trans we are all use to. The "spread "cooler lines trans is a newer design and has all of the later factory upgrades. and the 700R4 The newer core you can get here the better off you will be as well, the model year 89 and up had a newer pump and valve body making it better. It[the 700 really got better each year ]. The 4L60E is a good one as well the removable bellhousing started in model year 96 and it has a newer design valve body from what I have been told but you must be careful there as the trad v8[350smallblock]and LS motor have similar bolt patterns the LS has a center bolt that some may ignore . The torque is different lengths on the old vs. new V8's ,and old converter on a newer engine will pour oil EVERYWHERE!! [don't ask how I know] wasn't me but it did happen in my shop. Also if you put a newer converter on a older engine it will go but the holes may be off and spacers for the hub will be needed to keep it seated in the trans oil pump. Jim

Thanks for the insight.
I forgot to add that this is from a '93 GMC one ton van.
Its a really good price and I'm sure it'll be able to handle all the power/money I can throw at it that's why its appealing. What I'm not sure of is if its worth the swap. I'm counting on putting a one piece rear main engine and mounting it forward. Is there anything I'm overlooking?

[boynton]

This is great info...you have probably forgotten more than i know!

Originally Posted by hugger6933

The 4L60E was brought into the truck market by gm for the 93 model year. I built those trucks,well rebuilt them and kept up with every little change they made as I had tons of parts to know what would change into what model. The3/4 ton and 1 ton Diesel version of the C/K trucks had the 4L80E in the early 90's with a stand alone computer. If one of those could be found and rechipped or reflashed [I don't know what kind it was so I don't know what term fits] to fit your application. These trans are as tough as they come, they are similar to the turbo 400 with decades of updated knowledge put into it as well. It is heavy and the gear splits are a little different for your regular street truck without a ton of motor.If you were to get a 4L80 E get one with the cooler lines spread apart from each other with them both in line. the other is one on top of the other like the older trans we are all use to. The "spread "cooler lines trans is a newer design and has all of the later factory upgrades. and the 700R4 The newer core you can get here the better off you will be as well, the model year 89 and up had a newer pump and valve body making it better. It[the 700 really got better each year ]. The 4L60E is a good one as well the removable bellhousing started in model year 96 and it has a newer design valve body from what I have been told but you must be careful there as the trad v8[350smallblock]and LS motor have similar bolt patterns the LS has a center bolt that some may ignore . The torque is different lengths on the old vs. new V8's ,and old converter on a newer engine will pour oil EVERYWHERE!! [don't ask how I know] wasn't me but it did happen in my shop. Also if you put a newer converter on a older engine it will go but the holes may be off and spacers for the hub will be needed to keep it seated in the trans oil pump. Jim

[Bigdav160]

Is there anything I'm overlooking?

I don't remember seeing a 4L80e in a G van. It might be C/K truck only.

Even the diesel (6.2/6.5L) offered in the G van had a 4L60.

[909]

Sorry Jim I misunderstood your first post, you're a great source of info! From what I gather it's more money/effort than it's worth to put it in the '71 with o/d being the only gain since i'm sure the 350 will hold up fine. For $200 I think the 4l80 might have to go in the '95 though.