Just bought an 03 4L80E for my 5.3turbo 79 Malibu project, should be between 5-600 rwhp. The guy told me it was slipping in reverse but all forward gears were good. I'm not sure if its something mechanical or electrical wrong with it? (any suggestions??)

Looking for suggestions as to what do do with it

 

Sounds like the forward clutches are burnt. It will need a rebuild and some hydraulic mods.

 

What do you suggest??

 

You should consider a rebuilt saves you from big problems

 

I was planning on doing a rebuild, I guess I was referring to mods.

 

Anyone??

 

Your gonna need a rubuilt anyhow

 

The forward clutch pack is not on in reverse, it's the direct clutch pack that is gone. Get a good overhaul kit from a local transmission parts supplier. Transtar, WIT, or Precision International are good vendors and supply everything you will need. I recommend high energy frictions or Raybestos Stage1 for your application. A new 34 element intermediate sprag to replace the old. Rollerize the back of the case with a th350 pump bearing. Dual feed the direct clutch pack. If you are not familiar with hydraulic modifications look into shift kits like Trango, Superior, ect...

 

Here are some building tips.

Case: Use a Sonnax no walk out case bushing and install it from the tailhousing side of the case. This will give the output shaft more support and also center the th350 bearing in the case. Always check output shaft and intermediate shaft clearances. Then check band lugs in the case makeing sure they are not loose or punched in.

Intermediate clutch: Keep the wavey that is already there and use a Torqueflite 8 forward drum snap ring .106". I machine my case and use a spiral lock ring but .106" snap ring is a good upgrade from stock.

Direct drum: Check sprag race and sealing ring area for wear. Drill a .055" hole on the inner corner of the edge where the outer lip seal rides. Use six high energy frictions using the .077" steels and set your clearance to .060"-.075". Replace the old sprag with a new one.

Forward drum: I do alot machine work on this drum for support but, you can start with cheking for ring and bushing wear. Add five high energy frictions and set your clearance.

 

4th clutch housing: Check for cracks in the bolt support area. I machine mine down and add an extra clutch since I do alot of 4l80e's for Enterprise moving trucks.

Overdrive planet: It is rebuildable so, you can tear it down and change the washers to reset clearances.

These are just a few tips to help you out on your build. More performance oriented modifications like dual feeding, strategic bearing placement, and billet parts can also be used.

 

Thats great advise, thank you very much!

 

One of our Stage 2 rebuilds will fill the bill perfectly.

 

Braiden1

 

I'm glad I could help. Like I said before, I'm not here to sell or steel potential clients, just trying to help the DIY enthusiest. Here are a few more tips.

Overdrive roller clutch: There are two types the .310" O.D (witch is the stronger of the two) and the .195" O.D (the weaker one). The later models have the weaker version. You can get a complete overdrive drum and an overdrive planet from an early unit to upgrade to the stronger roller. I use a sprag from a european type transmission and machine the race and case harden it for my upgrade but, that is a bit too much work for the DIY.

The pump: Always use a new boost valve. I prefer the sonnax or superior type because of quality. I,ve seen the transgo valve go out in as little as 20k miles. You also want to make sure the end plugs in the valves are not leaking. Use a Ford C6 pump bushing on the late pump for better support and an added oiling groove.

Remember the key for it to live a long life is to keep everything running on center so, check all your bushings for wear and replace if worn.

 

MINT! Cold beers in my fridge anytime your in my area. Thanks man

What about stalls? I love Coan and Art Carr but its been a while since ive run an auto and theres lots of newbs in the game now

 

Thanks, the core I have is an 03', is that a good year to have?

 

@ TDMKR496, Yes, Any 4L80E is good. @ cam, I use Edge performance converters here in Cali. but have also used Protorque with good results.

 

Braiden1, thanks for the mod info. About using the th350 pump bearing, how do you account for the different thickness in the thrust washer and the bearing. Do you subtract the difference when checking output shaft clearance? or do you have to machine to make up the difference?

Another one, what is a rule of thumb for bushing to shaft clearance?

Thanks,
Stevebbc

 

call jakes and get his rebuilt kit. He's pretty much the 4l80e king. great prices too. Will answer your questions, get you the right parts and bring it back, better, faster, and stronger than it was before no doubt. good luck with your build.

 

@stevebbc the th350 pump bearing measures approximately .140" and the two rear steel washers that it replaces measure around .140"-.150" so, no machining required it is a direct replacement. You can also use the th350 pump shims (.005" ea.) to set your clearance. Bushing to output shaft clearance should be around .002"-.004" when you use the sonnax bronze bushing part# 34006-SP.