Th400

[impala454]

Just bought a Th400. Took it apart. Broken torrington bearing so both front and rear planetary are trash.
Do you see anything else that looks bad? It had two snaprings for the center support one regular and one thinn I didnt noticed untill case was empty?

 

[impala454]

More pictures

 

[impala454]

Pump looks ok? Its only 6 bolts. Case has 7 threaded holes shall I drill the pump for one more?

 

[impala454]

Some rust on the pumpshaft but guess thats no problem?

 

[impala454]

Could ithave been working with that broken parts? Was told it was working. What cause a failure like that?
Going behind a BBC 454 600-700 hp. Plan on new rebuild kit from amazon see picture. Complete direct drum from a 4l80e. Freakshow 3500 rpm torque converter. Turn the outputshaft so a slip on yoke fits and obviously new(usd good) planetary gears.
Sounds like a good Idea on the parts to use?

 

[Exhaustgases]

The sun gears and ring gears may not look bad but they ate the same stuff the planets did, so if your using new planet carriers etc. I would not run them on the possible messed up sun and ring gears. 7 holes and pump only uses 6? Thats goofy, are they all like that? Makes no sense to have a threaded hole in the case not being used, that is a huge spread area not being bolted down. How about the gasket does it have the hole? Maybe that pump was some aftermarket goof up?

 

[wwillson]

@clinebarger do you have experience with the TH400?

 

[marc1]

Re: two center support snap rings. GM Hydramatic fixed earlier issues with the center support lugs embedding into the soft aluminum case. The upgraded center support was machined a little thinner and a snap ring was placed in first against the aluminum case, then the center support, then the final snap ring to hold everything in place. It was common to upgrade older THM400's to this newer design. I did it on my 1968 GS400 to save the case which had been badly embedded. So make sure you replace the one that goes against the case when you reassemble. The symptom with the impacted center support was a flaring 1-2 shift.

 

[GMBoy]

Cline is the best hopefully he will chime in

 

[impala454]

Found a guy local that had good used parts planetarys, gears and even a good used 400 34 element direct drum.
So for same money as a rebuilt loaded 4l80e drum I got the stuff above so in the end it turned out ok.
So back on track. had the output shaft machined at work to fit a slip yoke.

 

[impala454]

Output shaft machined to fit slip yoke

 

[clinebarger]

Could ithave been working with that broken parts? Was told it was working. What cause a failure like that?
Going behind a BBC 454 600-700 hp. Plan on new rebuild kit from amazon see picture. Complete direct drum from a 4l80e. Freakshow 3500 rpm torque converter. Turn the outputshaft so a slip on yoke fits and obviously new(usd good) planetary gears.
Sounds like a good Idea on the parts to use?

Likely alot of endplay that beat up the torrington over time.

Rollerize the Output.
4L80E Forward Hub.
Dual Feed the Direct Clutch.
High rate direct return springs.
Install NEW pump gears
Sonnax LB1 Boost Valve & Spring.....Shim if needed to achieve @190 PSI with the Modulator unhooked at 2500 RPM.
Borg Warner High Energy Frictions in the Forward, Direct, & Intermediate (Stock 4L80E).

Those stamped steel pistons are trash.....Ether find some Aluminum TH400 Pistons....
Or Run a 4L80E Molded Steel Direct Piston in both the Forward & Direct Drum & a 4L80E Aluminum Intermediate Piston & Wave in the Center Support.

A billet Input Shaft is a good idea when making over 600 foot pounds & shocking it with a loose converter.

 

[impala454]

Likely alot of endplay that beat up the torrington over time.

Rollerize the Output.
4L80E Forward Hub.
Dual Feed the Direct Clutch.
High rate direct return springs.
Install NEW pump gears
Sonnax LB1 Boost Valve & Spring.....Shim if needed to achieve @190 PSI with the Modulator unhooked at 2500 RPM.
Borg Warner High Energy Frictions in the Forward, Direct, & Intermediate (Stock 4L80E).

Those stamped steel pistons are trash.....Ether find some Aluminum TH400 Pistons....
Or Run a 4L80E Molded Steel Direct Piston in both the Forward & Direct Drum & a 4L80E Aluminum Intermediate Piston & Wave in the Center Support.

A billet Input Shaft is a good idea when making over 600 foot pounds & shocking it with a loose converter.

Plan to rollerize the output.
Will look up the 4l80e hub.
Plan to dual feed either with a transgo kit or leaving seals out and plug holes.
Is it a rule to always use new pump gears even if within spec?
Have some new parts from a partial transgo kit springs etc and a B&M seperator plate.
Ordered the amazon kit. Hope its ok.

Will look pistons up.

Probably under 600 ft/lbs.
Not sure 3500 is rated as high stall?

 

[impala454]

Can get these pistons in sweden for ok price. Are they what I want?

 

[clinebarger]

The Intermediate Piston will work fine, There are SEVERAL different Aluminum Direct & Forward Pistons manufactured from '64-'73!

First Rule.....You need a Bleed Capsule in either the Drum or the Piston, But NOT both!!!
If your Direct Drum has a Bleed Capsule, Use a piston without a Bleed Capsule.

The Forward/Direct Piston in the photo appears to have a Bleed Capsule.

In the interest of simplifying things, I would.....
**Run a NEW 4L80E Molded Direct Piston in the Forward Drum/Clutch. You will need either the return spring assembly or at least the bottom spring retainer. If you're buying a complete 4L80E Direct Drum....It will have the return spring assembly you need for the Forward Drum!

**4L80E Direct Drums usually have a Bleed Capsule, So you need a piston without it.....GM 8625514 is a good piston to use & there is one on E-bay HERE

 

[clinebarger]

I see that your Forward Drum has a bleed capsule, So you can run a Molded 4L80E Direct Piston.

I say 4L80E Direct Piston because 4L80E Forward & Direct Piston are different inside diameters where the TH400 uses the same inside diameter in BOTH Drums.

 

[impala454]

I have bought a th400 smooth direct drum and alu pistons from th 400 hopefully Iget some good parts I can post pictures when I have them in my hand.

 

[impala454]

I see that your Forward Drum has a bleed capsule, So you can run a Molded 4L80E Direct Piston.

I say 4L80E Direct Piston because 4L80E Forward & Direct Piston are different inside diameters where the TH400 uses the same inside diameter in BOTH Drums.

sonnax 34322-01 good? Or not better than oem 4l80e?
Is sonnax 34322-02K what I want?
-02 is not that much more and comrs with bearing.

 

[clinebarger]

Sonnax parts are top shelf!! I view things from a different perspective....TH400/4L80E parts aren't exactly hard to come by here.

Use the rollerized Hub!

 

[impala454]

Sonnax parts are top shelf!! I view things from a different perspective....TH400/4L80E parts aren't exactly hard to come by here.

Use the rollerized Hub!

No but a used 4l80e forward hub on ebay eith shipping and import charges to me is 50$ than the sonnax+I can get the no walk sonnax kit from same place and save more of that 50$ difference.