A friend from work is planning to install a 700R4 behind a built 396 BBC in his '68 truck. He's figured-out he needs the tail housing from a 4x4 700R4, a shortened driveshaft and a custom crossmember, to make things fit where there used to be a TH400. I told him that a 4L80E is basically a TH400 with a locking converter, an overdrive gear and is electronically controlled for shift-points and firmness. Hopefully I didn't overlook anything.

But my questions are: is this a straight across swap(for location and fit) and what does he need to get the lock-up and shift points to work in a non-computerized application?

 

Sorry, it won't work. A 4L80 is a computer controlled tranny. Line pressure and shift points are all electronic, you have to have a computer to use one.

 

The 4L80 is also a lot bigger and heavier than the TH400. You can get the computer to run the tranny from JET. There's no other way to use the tranny. It's not cheap but neither is the tranny.

If the swap was that easy, there would be a lot more 4L80 trannies put into cars.

At least my truck came from the factory with one installed


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Thanx for the help

From what I've read on the 4L80E, it is dimensionally identical to a TH400(which would make sense as the first three gears in both boxes are identical. I've also read that, despite the addition of a fourth gear, the length is the same, as are the mounting locations.

Could someone who ACTUALLY has experience with a 4L80E correct if I am wrong on these points. I am well aware that the 4L80E is computer-controlled. However, I remember reading awhile back("Street Rodder" mag if I recall) about a company(other than JET) who makes an outboard computer for this tranny. In this particular app - a 4500 lb truck, a very torquey big-block, 4.10:1 gears and 30" tires - the 700R4 does not seem like the best choice.

[This message has been edited by 88IROCs (edited October 09, 2001).]

 

The 4L80E is much bigger and heavier than a 400. Also, they are prone to breaking parts. Almost everyone I do comes in with something broken. I have seen Cases, Drums, Pistons, Valve bodies, Servo's, Input Shafts, etc break on these. I am not sure why so many people want to put them into their cars.

 

I doesn't sound good for the 4L80, if you plan on using the 700 the tailhousing off a 4x4 won't work, in fact all 4x4's with 700's that I have seen don't have tailhousings, they have a 3" tailshaft and the transfer case bolts right up to the trans.



[This message has been edited by Jay 727 (edited October 10, 2001).]

 

[This message has been edited by Jay 727 (edited October 10, 2001).]

 

How much horsepower are you planning on putting out? What rear end gear ratio are you using? The 2004R when setup right might work out very well for this application. (1) The gear ratios for the 2004R are 2.74 1.63 1.00 0.67, compared to the TH400 2.48 1.48 1.00. You lose apx. 1/3 the rpm in overdrive. (2) You will not need to cut the driveshaft. (3) Replace the TH400 yoke with the TH350 type. (4) The trans is almost the same length (within 1/8"-1/4"). (5) It will use the same crossmember location as the TH400. There are a lot of plus' here. I have replaced the TH400 a few times with the 2004R in truck applications and have seen 20-30% increase in gas mileage on the open road. Around town it stays pretty much the same. The torque converter I have used in all these applications is the Continental 11.5" low stall, high torque multiplier, non-lockup. These torque converters were designed for this type of application. Kris the owner of Continental came up with this one. There have no problem with heat in these setups either. If I can be of help, let me know?

 

Pro-Built,

Thanx for the info on 200R4's. With what you've pointed-out, this tranny would make the most sense for my friends' truck. If you don't mind, I've got some more questions:

- My friend is pretty sure the 396 is putting out at least 475 lbs/ft at peak. Which parts would need to be upgraded to allow the 200R4 to live behind this motor?
- The truck's owner would like to do the rebuild himself. Where can he get books or videos to help him?
- Which models years and/or vehicle models should he look at when he is looking for a core? Which ones should he avoid?
- My understanding was(is?) that the 200R4 was only used behind B.O.P. motors, if this is true, is an adapter plate necessary for a Chevy app?
- Can the 200R4 use a lock-up converter? I've heard that a converter from a 700R4/4L60 will mate, is this true? Who makes low-stall(1500 - 1800 rpm) converters for the 200R4, as the main use for this truck is as a,....well,... truck(towing and hauling).

Thanx again for your help!

[This message has been edited by 88IROCs (edited October 11, 2001).]