700R4/NP241 vs 4L80E/NP241 Length

[cobra20]

Can anyone tell me the difference in length from bellhousing to the center of the u joint on the slip yoke between the 700R4/NP241 combo and the 4L80E/NP241 combo?

 

[89Suburban]

Any ideas @HotRodPC?

 

[cobra20]

Yeah I got the 4L80E yesterday from Pick N Pull and I'm trying to get everything figured out so I can just pull my 700R4 and replace it with the 4L80E without my suburban being down for a couple of days replacing trannies.

 

[marks86]

your going to have to drill new holes for the trans cross member. no big deal you can do it with the cross member installed just support by a jack

 

[HotRodPC]

NO, I wouldn't have a clue on those differences. Sorry

 

[cobra20]

yeah I've got to find a drive shaft that will fit with my rear axle and the 4L80E/NP241 combo. My rear drive shaft is 9 inches longer than the one that was in the 3/4 ton suburban

 

[HotRodPC]

To have a driveshaft lengthened is pricey since they have to start with a new tube. To shorten one isn't really all that bad since they just cut it down, then reweld the end U joint cap back on. Done right, if it was balanced and didn't vibrate before, for a shorten, unless they're cutting the weight off, usually doesn't need rebalanced either if cash is tight.

 

[cobra20]

Well cash will be definitely tight because my 700R4 pan is leaking and I'm having a hard time trying to get it to stop leaking

 

[HotRodPC]

Is it a victim of overtightening? This does 2 things. #1 is squishes out the pan gasket, especially if it's cork/rubber combo. #2 it also dimples the pan bolt holes to where the flange doesn't seal since the dimples end up working like spacers and keep the flange from getting to the mating surface of the trans. Same principle as overtightened valve cover bolts. To fix the dimples, just like a valve cover, use the round end of a ball peen hammer, then smack the back of the hammer with another hammer to reverse the dimples. Then use a new pan gasket and torque the pan bolts ONLY to about 15 foot lbs or 175-200 inch lbs.

 

[350runner]

This^^^ also I've never had any luck with the rubber gaskets. Cork based trans pan gaskets with snug bolts have made life drip free

Sent from the dust in front of you!

 

[MadOgre]

What makes a gasket leak is whether there are any deformities in the pan or mating surface or over torqueing the pan bolts. 10-12 ft lbs

Also both pan and transmission mating surfaces need to be clean and dry

I have put rubber gaskets on twice this summer and not even a hint of a leak from either.

The 4L80 is an excellent upgrade that most of us are considering even with out experiencing current transmission difficulties.

You do need an electronic controller for the 4L80. Do you have one? You will also need a TPS splitter for the controller


The 4L80 is 1 1/2" longer then the TH400 if that helps. Like Mark says just install everything with the cross member installed to the tranny and use a floor jack to push the cross member up tight to your frame and then drill your new holes and install.

I think you will have to shorten your driveshaft at a shop

 

[MadOgre]

The 4L80E is 2 3/8" longer then the 700r4