'72 K2500 with 454/t350/NP205...swap in a 4L80e?

[superchevy]

My first 67-72 4x4...new to the 4x4 world...going to use this truck for towing, and would like to swap in a 4L80e behind the 454 in place of the t350. Would like to hear from you guys...since the 4L80 is an electric t400, will it bolt right to the NP205? need an adapter? I know there will be a length difference, so driveshafts will have to be shortened/lengthened?
Thanks for any help, SC.

[milled]

th350 is worlds better than the 4l80e. If it were me I'd stick a gearvendor on you're th350. More reliable peroid.

[superchevy]

Thanks, but I'll stick with the 4L80e...I've never had a problem with one in any of the late model 3/4 tons I've had. SC

[FormerMember]

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[Musclerodz]

Originally Posted by milled

th350 is worlds better than the 4l80e. If it were me I'd stick a gearvendor on you're th350. More reliable peroid.

I will disagree here. The TH350 would fall apart behind a BBC with any power or pulling a trailer.

Just did this in my Blazer. You will have to change the input gear on the 205 to 32 spline which will require machining the case for the larger bearing. There is a factory adapter but goo luck finding one. bite the bullet and by a T-case adapter from Advance Adapters, or buy their whole kit. The conversion money wise is not for the faint heart. Figure $3k minimum to buy the parts and get everything installed and modified. Even with me doing all the work myself, including the 205 machine work and overhauling the 4L80E, I have $600 in the 205 conversion parts, $300 for tranny parts, $200 converter, $600 in the stand along tranny controller, $500 for new driveshafts. Cost does not include 205 which came out of the truck or the tranny which the core I got for free from a friend. If you have to pay for the tranny overhaul and 205 rework add another $1200-$1500 on top.

[special-K]

How about finding a NP241 from the last Blazers and Suburbans.On a`91 K3500 CrewCab with a 4L80E,did they use the NP205?

[FormerMember]

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[special-K]

Thanks,I know I hadn`t seen any 205s that late.

[1969 GMC]

Originally Posted by special-K

Thanks,I know I hadn`t seen any 205s that late.

There were 4l80e/205 combos available in 1991 only. Pretty rare. But, they do exist. EDIT: I think another reason why they are so rare in this year was that they were optional...but this is just my personal guess. I have seen '91s with the TH400, also, which is why I say this.

However, I agree Tim...using a pass. drop NP241 would probably be the way to go in this case. If you ever end up offroading this truck, then just put a good skidplate under the 241. This will be easier to find, and cheaper.

[FormerMember]

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[milled]

Originally Posted by Musclerodz

I will disagree here. The TH350 would fall apart behind a BBC with any power or pulling a trailer.

Just did this in my Blazer. You will have to change the input gear on the 205 to 32 spline which will require machining the case for the larger bearing. There is a factory adapter but goo luck finding one. bite the bullet and by a T-case adapter from Advance Adapters, or buy their whole kit. The conversion money wise is not for the faint heart. Figure $3k minimum to buy the parts and get everything installed and modified. Even with me doing all the work myself, including the 205 machine work and overhauling the 4L80E, I have $600 in the 205 conversion parts, $300 for tranny parts, $200 converter, $600 in the stand along tranny controller, $500 for new driveshafts. Cost does not include 205 which came out of the truck or the tranny which the core I got for free from a friend. If you have to pay for the tranny overhaul and 205 rework add another $1200-$1500 on top.

Not from what i've seen and done. I made that statement form years of snowplowing and racing. A turbo 350 is reliable to 600hp and the heavier th400 is a 1000 hp trans. I havn't found a OD automatic trans liked yet. I'll bet that the 350 w/g-vendor is about the same length and weight as the 4l80e. Also no shift solenids and MILLIONS of parts. To each his own.

[FormerMember]

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[milled]

Originally Posted by grendel

None of STOCK Th350's I've run would ever hold to 600hp. Just isn't going to happen.

It will with a rebuild and quality clutch packs. Go to any track on any given sunday you'll see th350's pulling 10sec (500-600hp). The gm od trannies are problematic to say the least. If you're shooting for the best in class nothing beats the TH400 and $2500 real overdirve. Not only that but you can split the gears. For towing their's nothing better.

[FormerMember]

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[milled]

Originally Posted by grendel

I really have to disagree.

I had a 650hp, 9 second Chevelle that would eat stock and well rebuilt transmissions all day long. Th400 or Th350's. I had to go to a TCI Competition trans with billet input shafts, custom machined planetaries, etc.

I blew a TCI Comp TH350 that they replaced under warranty with one of their TH400's.

Also, you know that a 4L80E shares allot of the same components and architecture as the venerable Th400?

Seems you're making a broad statement with the "The gm od trannies are problematic to say the least. " Yes, the early 700R4's had problems, but almost any GM OD trans made after 93 is as solid as the ones they replaced.

The solution you propose is quite strong and quite expensive...

I'll try to find the website where a 4l80e wizzard who builds diesel and hp performance trans. He wrote about a page of falts with the 4l80e. Whatever, any trans including the e40d aot 4l60e jarco power glide a wind sail will get these trucks down the road. Anything to do with a transmission is $$$ or anything else for that matter these days. I'll post the link later. It will cost about the same to do a th400/gv vs a real 4l80e or close. But what I will give you outa all the domestic od market the 80e is the best option out there. They just need to be built right.$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

[milled]

This is the place for the 4l80e guys- nice kit!
#K80. Fits all Chevy 4L80E transmissions. This is the level 3 Quadzilla kit with a converter upgrade. You get all 3 Alto Red Eagle Power Packs for 1st, 2nd and 3rd, Blue Plats Special clutches and steels for overdrive and the overrun clutches plus a Transgo stage 3 Quadzilla Shift Kit. In addition you get a filter, 34 element sprag, gasket and seal kit, oversize black Kevlar band and the #6XX torque converter rated at 1200 horse power. All of this for $1722.00. YOU SAVE $149.00 HERE !, 8% OFF (Deduct $921.00 without the torque converter.)
Acouple of problems he listed should be addressed
#2V. Common problems in vehicles with a 4L80-E transmission include uncontrollable line rise (upwards of 500 psi), high line pressure in reverse, broken direct clutch drums and/or broken cases. These problems can be caused by excessive EPC torque signal pressure. The Sonnax self-regulating reverse boost valve eliminates these problems by limiting EPC pressure. The boost valve has an encapsulated relief valve that will allow EPC pressure to exhaust if it exceeds 95-105 psi. A closely toleranced sleeve is included with the kit. This restores the hydraulic integrity between the valve and sleeve, which can also cause the problems mentioned previously. O-rings have been added to the sleeve to compensate for pump bore wear and prevent pump scrappage. Cost $51.00

4L80E Actuator Feed Limit Valve Kit

• Kit includes wear-resistant sleeve and anodized valve with annular grooves to prevent side loading.

• Valve operates in full-contact sleeve, providing 54% more support.

• Boosts oil pressure to the shift solenoids.

• Eliminates AFL oil loss, corrects low line pressure
LINK http://www.transmissioncenter.net

[FormerMember]

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[jahoneycutt]

So it is possible to put a 4l60 in place of my 1970 th30, but the package is longer.

So what if i com by moving the motor forward with 1/4" or thicker plates to off set the motor mounts?

[72chevyk10]

Originally Posted by milled

Not from what i've seen and done. I made that statement form years of snowplowing and racing. A turbo 350 is reliable to 600hp and the heavier th400 is a 1000 hp trans. I havn't found a OD automatic trans liked yet. I'll bet that the 350 w/g-vendor is about the same length and weight as the 4l80e. Also no shift solenids and MILLIONS of parts. To each his own.

i agree i have a stock th350 behind a mild 454.(and a fairly heavy right foot) and its doin just fine.

[Dieselwrencher]

It is all in what you want and how you are going to use it. I will say one thing. I am more into the diesel side, and the TH400, TH350, will not stand the torque of a diesel. Unless you spend gobbs of money on them and replace everything 2-3 times besides the case. With that being said, there are guys that have 4L80E's behind 600hp 1150+ ft lbs of torque 5.9 cummins diesels and the transmission's biggest upgrades are: torque convertor, top quality clutches, valve body up grade. And they actually live behind the diesel and you aren't removing the trans every other month like you would be with a TH400 or Th350. The TH trannys can take a lot either way in a gasser, but the biggest down fall to them is when you have to spend $2500 or more to get a secondary OD unit on top of your transmission build. So if this guy knows he is going to tow a lot and wants an OD and is limited on wheel base, I think he has the right idea. Sorry for hijacking your thread. LOL