I knew this trans was dead... TH350 Rebuild

[da_raabi]

That bent retainer sure could have contributed to it, wonder how the hell that happened? All things being equal i would guess the PO did it during install. Whatever method he was using to compress it wasn't applying even pressure. Leaving out the intermediate servo spring is a common mod to make the 2-3 shift much harder but i think there's more to it than just leaving out the spring.

Do you think the retainer can be fixed? Or should I just replace it?

So these are the mods it would appear the PO did to this trans:

1. Removed all but 1 check ball
2. Removed intermediate servo spring

I'll bet the guy probably didn't use the wave plates either, but I've still got to check that.

This sure is interesting! I'll be working on some of the component rebuilds this week. I'll be curious to see what the other clutch packs and the pump look like inside.

 

[crazy4offroad]

The retainer, I would just replace it. I might have one in my spare parts if you can't find one.

 

[crazy4offroad]

Leaving out the intermediate servo spring is a common mod to make the 2-3 shift much harder but i think there's more to it than just leaving out the spring.

I was wrong here, the intermediate servo applies the intermediate band for smoother 1-2 shift as well as trans-assisted engine braking in 2nd gear, it has nothing to do with the 2-3 shift. People remove the spring and install a spacer to block its function, making 1-2 shifts faster but at the cost of losing the trans-assisted engine braking in 2nd. Commonly used for manual VBs and various brand shift kits. Expect to chirp the tires when shifting into 2nd often.

 

[HotRodPC]

Bought it off some guy north of Orlando. What pisses me off is he said it was a good transmission. Oh well, it was $150, so that's not too bad.

I'm looking at about $475 or so for a rebuild, unless I find more issues. That includes a torque converter, rebuild kit, torrington bearing kit, HD 700R4 center support with the wider low sprag, new intermediate sprag with a hardened carrier and a shift kit. Already got a new governor 2 weeks ago that I'll just clean and re-use.

That sounds like it's going to be a good strong build though. That's the nice thing about Th350 and Th400 builds. Dirt ass cheap if you do them yourself.

 

[da_raabi]

Just took the pump apart. Is it normal for this "chewing up" of the oil passages one one of the pump halves? It's very inconsistent, not all passages are like this. Notice the bluing of the shaft too.

Time for a whole new pump?

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[crazy4offroad]

Just looks like a rough casting. That blue mark, i think a torrington bearing rides there so it shouldn't be anything to worry about

 

[da_raabi]

Ok cool. I'm glad the pump halves are ok. I think the $150 it would take to replace them would have made this build unfeasible.

On the subject of the pump gears, when should they be tossed? I took a real close look at them, and they look pretty good. No scoring or gouging, just a slight wear (kinda-shiny spots as supposed to the dark grey on the rest of the gear) on a few of the teeth (on the faces where they contact the outer gear). Very hard to take a picture of, you can only see it in a certain light. Also, when placed into the pump case half, there is a slight "wiggle" in the center gear between it and the half-moon guide and the outer gear. Not a lot, but I don't remember that on my 400 build.

Should the gears be replaced or do they sound ok? I'm being extra thorough on this rebuild due to the excessive trouble I had with the trans as I have no idea what was the original failure point.

 

[da_raabi]

Well I got the pump put back together. I decided to go ahead and get a new pump gear set as I'm pretty sure mine was toast. Figured I'd heir on the side of caution. Bought it for $18 from Phoenix Transmission Parts on eBay. It was at my door in 24 hours, shipped free. Can't beat that!

I also scraped and split a low/reverse friction and stuck it behind the apply piston. Apparently that makes shifts a bit more crisp. Made for a nice and easy/free little upgrade.

Still haven't decided whether to dual feed internally or with a shift kit. I'm torn on that one.

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[HotRodPC]

If it's a non lock up model, I'd do the dual feed via transfer plate or shift kit if you have it already. This way, you can always take it if you decided later on you don't want that harsh of a shift without having the pull the transmission.

 

[crazy4offroad]

Sorry I'm late. I dont think dual feed makes the shifts harsher, but makes them stronger. You're essentially doubling the potential apply pressure to the clutch pack. Dropping check balls will make the shifts harsher/more instant. I have a video somewhere that shows how to check the pump gears for wear. Work has been an evil heartless bitch this week.

 

[da_raabi]

Quick update:

Measured the clutch pack clearance in the directs. Using a dry (no seals either) piston and 4 new clutches and steels, I measured a clearance of .062". Since I'll be buying a pre-machined replacement piston off of eBay, I measured to see if any would work. Turns out one available is machined to .680. Including the extra clutch and steel, this would result in a clearance of .050". This all sounds about right, right?

Also, I noticed something odd about the low/reverse planet. It looks like extra holes were drilled in it. One was not even de-burred! Is this a modification on TH350s? Would the fact that the planet got scorched by the burned up clutches cause any issues? It's just got a bunch of black on the outside is all.

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[crazy4offroad]

0.050-0.080 is spec, if your measurement is exactly 0.050 you may want a little more. I've never seen that mod on the lo/reverse planet. If I had to guess those are slinger holes to shed excess residual oil, kinda like a crank wiper. It looks like a butcher job, it can't be very balanced with just holes here and there. That is something I would probably want to swap out even though it may be unhurt from the burnt clutches.

 

[da_raabi]

0.050-0.080 is spec, if your measurement is exactly 0.050 you may want a little more. I've never seen that mod on the lo/reverse planet. If I had to guess those are slinger holes to shed excess residual oil, kinda like a crank wiper. It looks like a butcher job, it can't be very balanced with just holes here and there. That is something I would probably want to swap out even though it may be unhurt from the burnt clutches.

Is it .05-.08 because of the fifth clutch? The Ron Sessions book said .04 to .06 max.

And I'm pissed about the low planet. There's only one f/s on eBay and it's $45. Plus it looks like it's got holes in it too. Some people just shouldn't be allowed to work on transmissions... I wonder if that's part of why the low clutches scorched so bad?

This trans is gonna nickle and dime me to death I swear...

 

[crazy4offroad]

Is it .05-.08 because of the fifth clutch? The Ron Sessions book said .04 to .06 max.

Hmm I'm not sure, 0.050-0.080 is stock spec, if the book is covering the additional clutch and calls for that spec I say go with that instead.

 

[da_raabi]

Hmm I'm not sure, 0.050-0.080 is stock spec, if the book is covering the additional clutch and calls for that spec I say go with that instead.

.040-.060 was what the Sessions book called for for a stock 4-clutch pack. Looking online, the widely available tech article put together by Jakeshoe (of Jake's Performance) calls for .010 per clutch and ultimately between .050 and .070.

So it looks like you were right.

Airing (sp?) on the side of caution, I should probably see about getting a piston machined to .680. This would plop my clearance down to .060, which is right in the middle of the intended range. I'd hate to get a piston that ends up getting me a clearance that is too low.

Also, would measuring clearance be any different if the clutches were wet vs dry? I talked it over with the wife (she's also a mechanic, she just works on stuff with wings) and we both thought it would not make much difference.