I believe I hurt the trans last year during AutoX at LSFest and developed a bad vibration doing the drag race which I thought was a bent driveshaft. New driveshaft fixed 80% of the vibes but still occasionally had a vibration on acceleration. The trans also developed a leak I could never pinpoint. Trans seemed to operate normally until a few months ago when it started holding first a little longer with a harder shift to second. I attributed that to fluid level due to the leak. During LS Fest this year it got progressively worse and would not make a 2-3 shift wot. Truck has been parked since September with intentions to pull the trans and go thru it. I knew I was going to try to get on it today so I took it for a spin around town last night to check out the big car event in town this weekend. Trans seemed to operate fine in D3 but shifting to M2, trans would not hold any power. Shift back to D3 and it would hold a little in second but felt like it was slip/grab/slip/grab... Pulled the trans today to go thru it expecting to find a rolled intermediate sprag or burnt intermediate clutches or band.

Well... Looks much worse... Cracked Case!

Cracked 4L80 Case

4L80, lots of clutch material but no metal chunks

Lots of metal sludge on magnet

As can be seen from the pics, there were was lots of material in the pan and fluid but no metal chunks suggesting hard parts failure. I am trying to decide if I want to open it up to see the condition or just go ahead and scrap it. The case is cracked behind the pump so a SFI bellhousing swap is not an option. If the case has already cracked for what ever reason, I presume a weld repair would also crack or the case would crack in another spot.

Any ideas on what would cause the case to crack here? I did a quick Google search an didn't find another one cracked in this location.

 

Well,

It’s trash. What happened last year? It’s possible you cracked it then and then in the coarse of self diagnosing, you ended up with a full crack.

I broke a brand new trans 11 years ago on the dyno when the DS broke.

I broke that trans in 3pcs.

 

ive done that in my old crewcab dually, and t400. the bbc had a bit too much torque for the type of drifting i was doing with the ole girl.. lol

 

The driveshaft didn't completely fail, My driveshaft guy said it was slightly bent after checking it. Front and rear ujoints were dry and tapered but rotated freely.

I am seeing other reports of this happening with a failed or bound drive shaft. I have a new 4" aluminum ds now but once I figure out a replacement, I will be going thru my entire drive line making sure everything specs out right.

 

The vibrations is what did this. If the shaft was bent, it was out of round and would have vibrated like crazy.

I’m betting if you’d had a GoPro watching the DS you would have seen how bad it was.

In one of my 60e issues, I chewed up the ring/pinion in the G80 and that killed my sprag.

It sucks, trust me, I know.

 

If it was slightly bent and the U joints were dry and tapered...that sounds like the driveshaft has failed to me

What do you consider completely failed? broken in 2 pieces?

Vibration is hell. I'd bet that was the sole cause of your issues

 

Get a new case, dont bother trying to repair it. A new case is like $150 from WITTrans, but keep in mind there are some minor specific year differences.

 

You got me excited for nothing. Used cases are running in the $2-300 range. I just checked WITTrans and a new late model case is $554. I will just keep looking for a rebuildable used trans unless I decide to do a Magnum swap.

I do have the trans on the stand draining for disassembly. I am really curious to see what the internals look like.

 

I was alluding to a broken or bound driveshaft as "completely failed". I would agree that anything but a perfectly straight and balanced driveshaft has failed to an extent.

 

Oh, well my year was a lot cheaper or they've just gotten a lot more expensive in the last few years 😕