TH400 / 4L80e Caution. W/pics

[Foot Performance]

Re: TH400 / 4L80e Caution. W/pics

I havent ever heard of this either. I have heard of the 4l80e have a line pressure problem where line pressure ramps up and breaks the case but I dodnt think that it is this drastic.

I will be doing some digging on this. It kinda reminds me on the powerglides that would flip the sprag and cuase them to sling parts threw the trans case. I wonder if something like that is happening?

 

[thunderace31]

Re: TH400 / 4L80e Caution. W/pics

You're absolutely right. I had figured that out too, I just didn't edit my post. There wasn't a lot of interest in this thread, so I left it alone.

I didn't know the drums broke in stock applications. But then, I'm not a trans guy by profession. I don't work on them every week. My 400 problems (both of them in 35 years of owning the car) were int sprag 'flipped' (no second), and a worn-out fwd clutch. I just have not had problems with 400s, so I don't know much about them.

I also didn't know that Spectra could be laminated. Or that it was used in those types of applications. I used to do a lot of off-shore racing sailboat stuff. I know a length of Spectra line's weight to strength ratio is pretty amazing.

Cool stuff. I learned some things. Thanks for participating.:tup:
Dave.

The stock drum is not a hardened part and they brake if you put to much power to them. I had a Chevelle with a 540 Scott Shifferoff engine in it that made over 750HP and it broke a built Th400 in 500 mile and a few pass's the drum broke like this one. You can get a nice billet drum for them and also do things to reduce the drag in the trans that helps the Drum live. It all cost a lot of $$$ and most trany guys dont do it unless you tell them you want them. TCI for example dosnt use a built drum in any of there transmitions at all. And they have a lot of Drum failures. This example Id say was hardened and exploded do to heat and Friction. There had to be a very high Line pressure for it to explode like this. Not a common failure or one I have never seen before. I dont think it had a very good sheild if it couldnt contain it. I had a 2 TH400's do this and neither came thru the floor like this the Shield held it in. Or many be was a half Shield that didnt cover the hole top of the trans I have seen a few sold by company's that are do not.
Spend your money on good parts and get a shield that covers the whole top of the trans you will have nothing to worry about. Also never reuse a shield after it has seen damage such as this as it may not hold a 2nd hard hit and also could be the issue with this one if it was a full shield. Also dont buy them used

 

[hatrik8]

Re: TH400 / 4L80e Caution. W/pics

Damn that's some crazy stuff. Time for steel toe/foot driving shoes??

 

[thunderace31]

Re: TH400 / 4L80e Caution. W/pics

Damn that's some crazy stuff. Time for steel toe/foot driving shoes??

lol Better make that full steel Boosts that go to the knee! Look up Big Daddy Don Garlettis NHRA drag racing accidents on Google He lost his foot from the Ankle down and it had to be put back on from a trans explosion! That was when he invented the rear engine dragsters we see today
:tup:

 

[alwayscode390]

Re: TH400 / 4L80e Caution. W/pics

So, its best to let it coast IN GEAR for autos and manuals after a run? ---

 

[midnightbluS10]

So ,who makes a shield for a 4l80 or 85E


Carbon fiber/kevlar construction in the previous pics?:tup:

I think the only option is a universal blanket from Summit/Jegs.

 

[TYTILIDIE]

Re: TH400 / 4L80e Caution. W/pics

The OP in the link Dave provided was using a shield. It went through the shield. What do you do when that happens?

Limp?:lol:

 

[RMcCourt]

Re: TH400 / 4L80e Caution. W/pics

..

I was cruising around some of the other car forums I go to tonight, and stumbled onto the issue of TH400 forward clutch drum failures. I know the 4L80 uses the same architecture, but I'm not sure if the forward drum is a cast piece like the stock 400 drum.

I don't think many of us make the kind of power these guys do, but the damage is impressive, and SCARY. Especially the first pic. It happened on a dyno, and the operator was injured. Go figure. Anyway, just something to be aware of with the 400 and maybe the 4L80. I was totally unaware of these issues with the 400 until this evening.

Here's the thread these pics came from, if interested.

 

[BMFB]

Re: TH400 / 4L80e Caution. W/pics

4l80s are different, and a cheap upgrade for a th400. I have one in mine.