4L80E "Necessary" fixes?

[adam728]

I keep reading posts, websites, and of course, shift kit manufacturer literature that makes it sound as though a shift kit is necessary to make a 4L80E reliable. Most talk about high pressure spikes causing valve body fractures or clutch/band failures.

How true is this?
and
Is this only in regards to performance applications?

I'm just wondering if it's something worth bothering with for my 92 C2500 350 tbi (wooo-hooo power, err, wait, no). Not interested in performance, truck probably has never seen the high side of 3000 rpm. Just want reliability. I'm figuring I'll be more likely to f something up putting a kit in and be stranded than I would be if I just left it alone.

Anyone actually kill a 4L80E here? How?

[2500ak]

I believe there is a pressure relief built into the fluid circuit, but it has a tendency to either clog, fail or not evacuate quick enough. So Yes drilling in a bleed valve is a good idea.

Stiffer accumulator springs lower clutch slip during shifts, and because the pistons move less accumulator bore wear.

The larger boost valve and the separator plate are the big ones though, they triple the pressure to the third clutch, from 60 to 180. When the 80e's wear out over time that's usually the clutch to go.

There isn't much that you can do to beef up the reverse band, that's the other thing that fails in them. Mainly because its a band and not a flat clutch.

Gearcommand is just plain fun, puts a plug at the end of the manual valve and lets you hold any gear to fuel cut off, but will still downshift.



For what it's worth the 80e is an amazingly strong transmission, but it has some bad, lazy, soggy shifts. Tuning can help with this, but cranking up the pressure can cause that pesky high pressure parts breakage.

The install wasn't that hard, my trans had 117,000mi on it when I installed mine last summer. I'm 100% sure it didn't shift anywhere near as good when it was brand new. Has around 122,000 now.

Once you drive your truck with a SK you won't know how you managed to drive without it.

Here's my install article it never got stickied sadly.

http://www.fullsizechevy.com/forums/...hd2-4l80e.html

When it comes down to it, is it really nessessary? No it isn't, but its good insurance.

[adam728]

I've read that when you first posted it, plus probably another 5 times since. Glad to hear you had a higher mileage truck too when you did it, I've got 127K on mine and wondered if that would have any negative effects when adding the kit.

I'll probably eventually put the kit in, money is just UBBER tight right now.

[2500ak]

Yeah, its always nervewracking to tear into a trans, If you keep an eye out you can find the kits pretty cheaply on places like e-bay. You just have to be careful that you don't get the old style kit, its an ok design but they don't have the Transgo separator plate, you have to modify your old one with plugs.

The 4L80e isn't like the 60e, in that the 60e has bands which will eventually wear out and break. The 80e's only bands are used for reverse, and when you put the shifter in low or 2nd they'll kick on for engine breaking and distributing very heavy loads across the drum better.

Everything else is operated with flat clutches, and you can squeeze the plates on either side of them so hard you practically don't need clutches between them given enough line pressure to get them to lock up.

And the hard parts are nearly unbreakable.

Only thing the kit really doesn't correct is the TCC lockup valve, mine was okay when I had the VB out but I really should have upgraded that too. There's a kit by either superior or sonnax I can't remember that's just a reamer and a valve and some springs. You use the reamer to ream out the bore put in the larger improved valve so you never get lower or inconsistent TCC pressure.

When I change my fluid this summer I'll probably install one of those.

[para driver]

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[adam728]

Yea, I've researched and definitely want to make sure I get a newer kit when I go for it. An extra $20-30 is nothing if it saves haveing to do more precision drilling. Wish I still had access to a Bridgeport, much more confident with that than a hand drill at home!

I just want to make this trans last as long as possible. I know my grandfather had an issue with the truck not shifting at one time. Said he took it in and everything was fine after that. I have no idea what, if anything was done. I've had no problems, only thing I notice is that it shifts hard from 1st to 2nd when cold.

Luckily it's still a stone stock 210 hp TBI 350 (probably a lot less by now), and the most I tow with it currently is ~1200 lb trailer. At most I might flat-tow my Jeep back down from Michigan, but even that loaded with spare parts and tools will most likely be under 3700 lbs (was right at 3600 with a full tank a few years back).

[2500ak]

A power drill works fine for the drilling.

All you need is to drill two holes in the VB itself, one is just connecting a fluid passage to an empty square shaped passage. The key to that is just wrapping the bit in electrical tape so that it doesn't mess up the VB's seal to the transcase.

The other, which a d-press might have been useful for is drilling a hole from the underside of the VB to that unused passage for the bleed valve. Mine is a bit off center but it still works fine.

Drilling the plate itself is really easy. You've got three hole, one for each shift so take a marker and circle them, then double check to see if you've got the right holes.

They're easy to find they're right next to the holes where the check-balls seal. Just take power drill and enlarge them to suit your taste, in terms of how you want it to shift.

[Smith97_454]

Definitely install a Transgo HD2. Have one in my truck and its great. I also have my **** tables zerod and when i get on the truck it really can snap your neck even on 38's

[2500ak]

Definitely install a Transgo HD2. Have one in my truck and its great. I also have my **** tables zerod and when i get on the truck it really can snap your neck even on 38's

I still need to have that done, I was looking at the stock 3/4 ton shift tables they're terrible, .4 seconds for a 1-2 shift, really?

I'm thinking of having my pressure upped in normal mode to where they are in T/H, then take the difference between T/H and regular and add it to the actual T/H settings.

This seems like a better way than drilling for firm, I've heard firm is too much for trucks.

You're truck looks awesome by the way.

[para driver]

Anyone done the the full rebuild job here? I got a great deal on a 4l80e, but I think it's wise to do the rebuild before I install it. Any good links or references? I need more information than the ATSG manual.