TH400 Direct Drum/Sprag Question

[NickTransmissions]

Thanks for the tip on quoting your posts. I had edited my last post to include a question about the friction discs if you don't mind taking a look.

Never ever reuse frictions if going back through a transmission, that's flate rate tactics....Flat rate shops fix only what has already failed, leaving everything else in, regardless of wear, so that the other comsumables fail shortly after their 30-90 day warranty expires. This puts the customer back to square one, money down the drain.

 

[tenthirtytwo]

Thanks for the info!

For the bearing conversion of the rear thrust washer, is GM P/N 9436851 what I'm looking for? (for the bearing). What PN are the shims for the new bearing?

I concur with everything that Nick has already stated. Here's another option for rollerizing the output shaft in the TH400, all in one kit. Sonnax offers their 34006-SPB TH400 HD Case Bushing Kit. I use this kit regularly on anything used in HD, 4x4 & definitely on snow plow truck applications. You should be able to find it on Amazon or Summit

 

[Matt69olds]

Make sure you take some detailed notes on how far down in the bore each bushing sets.

Before I had the fancy bushing driver tools, I used a cam bearing installation tool for a lot of bushings. Once again, unless your planning to build a lot of engines and transmission’s, it’s probably best to just pay a transmission shop to drive the bushing in for you.

Know anyone with a lathe? You could probably machine a driver pretty easily.

 

[Kilian]

Make sure you take some detailed notes on how far down in the bore each bushing sets.

Is it just good practice to replace the bushings when in the transmission?

 

[NickTransmissions]

Is it just good practice to replace the bushings when in the transmission?

Yes, always - unless bushing kits are not available for a given unit (ie FMX, last time I checked). You wont have that particular issue with the GM long. 3 speeds like the TH400. They are hard on bushings, always replace the existing ones. Drive the rear case bushing in from the rear so it's flush or slightly below - check with your output shaft, th350 pump bearing and shim installed (put the black side of the bearing face down in the case).

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[Kilian]

Yes, always - unless bushing kits are not available for a given unit

What about the Torrington thrust bearings, should those also be replaced?

Also, I haven't had time to go through all of your videos yet, but do you have a picture of the plug used when doing the dual feed setup? Thanks!

 

[NickTransmissions]

What about the Torrington thrust bearings, should those also be replaced?

Also, I haven't had time to go through all of your videos yet, but do you have a picture of the plug used when doing the dual feed setup? Thanks!

Use a 3/8" cup plug, red loctite around the OD. These should be available online. That portion of the dual feed process where i install the cup plug should be in PT3 of the "4L80E high performance" video series (yellow transmission).

If the bearings are in good shape it's fine to reuse unless the trans either overheated or sufferered a gear train failure - Id replace if so.

 

[Kilian]

If the bearings are in good shape it's fine to reuse unless the trans either overheated or sufferered a gear train failure - Id replace if so.

Good to know, thanks.

As far as the modulator, any recommendations for what to use? I figure that should be replaced as well to make sure that I'm starting with something good.

 

[NickTransmissions]

Good to know, thanks.

As far as the modulator, any recommendations for what to use? I figure that should be replaced as well to make sure that I'm starting with something good.

Order a standard vacuum modulator for a TH400 from any transmission parts supply shop or buy from a local trans parts supplier.