47RH No OD

Drothgeb

Drothgeb

Almost Fast-N-Loud
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Sep 18, 2010
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OD is not engaging. PCM is bypassed. Power is supplied to the OD and Lockup solenoids through a switch, and then there are separate switches to ground out OD and Lockup. Lockup works fine, OD does not. Checking ohms through both coils are about the same in the mid 30s. So both coils are fine, and have complete circuits. It doesn't work with the PCM connected either. It was working fine, then it wasn't.

With PCM bypassed, does the temp sensor still play a factor in OD?

What else plays a factor in lockup?
 
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put a pressure gauge on the OD port. Could be a simple OD housing seal blown out.
 
It goes from 0 to about 25psi when it should be engaging in OD.
 
Shouldn't it be full line pressure when od engages? That sounds really low. I'd think either your solenoid isn't engaging all the way, or you have a blown seal.
 
You should see full line pressure at the overdrive test port when overdrive is engaging, more like 150psi + on a high performance transmission. Sounds like there is a blown overdrive piston seal.
 
Tore it apart today. Lip seals on the piston look good, so did the OD clutches.

Any more ideas while it's apart?

I put in new seals, clutches, steels and a new solenoid. I'm putting it back in tomorrow morning, we'll see???
 
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Did you check out the small check ball on the overdrive piston retainer/backing plate? If everything looks tight, no where for fluid to leak, and you've dropped the pan and the valvebody is tight to the main case, you're finally common check point is to replace the overdrive solenoid.
 
Big Blue24 said:
Did you check out the small check ball on the overdrive piston retainer/backing plate? If everything looks tight, no where for fluid to leak, and you've dropped the pan and the valvebody is tight to the main case, you're finally common check point is to replace the overdrive solenoid.
Click to expand...

It was the check ball!

I was in a hurry and didn't notice last night in the dark. This morning when I went down, the ball was laying right there on the floor.

Thanks for your help Big Blue!
 
The OD piston retainer needs to be replaced. Can I just unbolt it, and install the new one or, will the thrust washer inside the trans slip out of place, and require removing the trans to replace?
 
That sucks. The low/reverse drum slides over the retainer and is held on with a snap ring. Sounds like the trans will have to come out.
 
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The collar that holds the ball in place is what failed. Is it possible to make a new collar or, maybe a cover plate with hole in it to hold the ball in place?
 
I call it my Killer Check Ball Tab. :hehe:

P1010841_zps1ebd074a.jpg
 
So I'm ready to assemble this morning, but then I thought it was a good idea to check clearances. Turns out that the OD thrust washer was too thin and, and the new clutches are thicker than the old ones. It all ends up only leaving me .050" clutch pack to piston clearance. I've read that should be .100-.150". But, if I leave out the wavy spring, I'm at about .110".

Is it acceptable to leave out the wavy spring?

I've only got a few more weekends at the track, then I'm tearing the engine and tranny down to freshen them up, so it would only be a short time fix.
 
What OD brake setup are you running? 5 or 6 frictions? Does it have the stock reaction plate or stepped? Check out this thread.
47re Clutch Pack Upgrades - Competition Diesel.Com - Bringing The BEST Together

When upgrading to the 6 clutch setup and stepped reaction plate you leave out the wavy spring. My old 5 friction setup with the stock reaction plate used both the flat and wavy, but if you need more clearance I don't see why you couldn't leave out the wavy?

Hopefully BigBlue will chime in.
 
The wavy spring in od helps soften engagement, remove it, mine isout as well
 
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