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Old 10-27-2019, 08:29 PM   #1
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Default NAG1 Selector Valve Clip Broken during Reinstall - Fix

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Background (fix is below):
I wanted to try and clean N2 and N3 leads on the conductor plate and do a general inspection, so I removed the transmission valve body to inspect and clean. Now, after talking to a local Sprinter tech, I know I should have just replaced the whole conductor board. Ihave transmission shudder while accelerating and he said a new board is the only way to cure the shudder. (Is that true? My driveshaft is good and I have not done DARF because shudder on deceleration is very minimal.) Now, this is all assumptions but the plastic clip at the end of the selector valve rod broke somehow and this is my best guess as to how it happened. When I went to reinstall the valve body by raising it back into position, the selector valve, which moves much more freely than I would have guessed, slid out of the original position from when the valve body was removed from the trans. It wasn't far out of alignment during the install, but it must have been enough for the plastic end piece to miss slipping over the shift detent plate pin. Then, after I buttoned up the transmission, the detent plate pin was on the outside of the channel it should be resting in and must have smashed a hole through the plastic clip wall when I shifted through the gears.

When I dropped the trans pan again to investigate why the van wouldn't move I was disheartened to see the tiny yellow plastic piece with a hole punched through it. The shift-detent-plate-pin had no where to go but to hulk-smash it's way into the channel of the plastic piece where it belonged.

I started looking online. I found absolutely nothing until, finally, I found a $163 selector rod that had a new plastic clip at the end.
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I wasn't sure on how to install that, so my mind imagined the worst: Having to split the valve body halves and deal with a mess of unknown proportions. That could have potentially landed me in the zone of a $900 new valve body and doing that install in sub-freezing weather up to a week later. So I dropped that option. I mean, after all, this is a 10 plastic piece! There had to be a better option. So, I called around to local sprinter garages. I was told to go to a Mercedes dealer and have them get me one. NOPE. It wasn't even a part number they could order. Not even the "Valve body selector rod" that I found online could be found in their parts system. So, I decided to see if I could remove the broken plastic clip and fix it myself. Here is how it went...

FIX - with pics!!

Removing the valve body is documented elsewhere and is likely the reason you're in this mess to begin with. So, I'll start with step #1) Remove valve body 'again'.

I used a $2 tin foil turkey roasting pan to keep the mess contained and so I could bring it inside where I could work in a warmer environment (starting to get pretty cold here in MN). I also covered the table well so I wouldn't accidentally get ATF on the table and I would have more room to work safely.
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Here are my supplies:
-"JB Weld Plastic Bonder" - I wasn't sure which epoxy to buy, but this was a 'plastic bonder' so I felt like I had a good chance of it holding together inside the trans.
-Acetone (stole the lady's professional 100% acetone nail polish remover to save myself a trip to the garage for the big can)
-Cotton swabs (be careful not to leave fibers behind)
-Couple of small screw drivers
-Scalple (disposable ones are cheap online) or an exacto knife. This is not needed, but I did use it to cut away some extra epoxy that dripped and dried over the channel where the pin rides.
-Safety wire and safety wire pliers.
-Drill and small drill bit (not pictured) I used a 1/16" bit, but I could have used smaller if I had a smaller bit.

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CONT'd in next post...

Last edited by POE; 10-27-2019 at 09:11 PM.
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Old 10-27-2019, 08:47 PM   #2
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Default Re: Selector Valve Clip Broken on Reinstall - Fix

1) Use some small screwdrivers to lift the retaining clip off of the selector valve rod and pry it off. The plastic piece is pretty gripy on the rod but be gentle and work the plastic piece off slowly once the clip is pried up. You can see the triangular retaining clip in the middle of the plastic piece here:
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Back side, you can see how the rod is shaped to retain the clip:
3.1.jpg

2) Clean the plastic piece with some sort of solvent. Not sure what's best. I used acetone. I used cotton swabs to get into the small crevices.

3) Drill a couple holes to anchor the safety wire. Since the wires cannot block the channel entrance they need to be anchored here and wrapped over the back side of the plastic body. I also used the scalpel to cut notches in the plastic where the wire would be wrapped around corners. I did this to help hold the wire in place during this process and, who know, maybe it adds strength after it all cures, too?
05.jpg


CONT'd on next post...

Last edited by POE; 10-27-2019 at 08:53 PM.
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Old 10-27-2019, 08:48 PM   #3
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Default Re: Selector Valve Clip Broken on Reinstall - Fix

4) I kept the two lengths of wire parallel as they crossed over the broken hole. I did this to create as much wire surface area over the hole as possible. If the epoxy brakes loose I hope the wires create enough surface area to let me shift the transmission in a pinch without the detent plate pin slipping out through the hole (in theory the wires would still catch and retain the pin). Then after the wires rounded the first corner I put a couple twists in them to keep them tight and from slipping off either side of the plastic piece. I cut a couple more grooves in the last corner to help retain the wires position and then finally anchored the wires around the valve rod connector opening.
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5) I used tinfoil to create a backstop/form for the epoxy to rest against. If the epoxy stuck to the foil, which it did, I wouldn't mind leaving a bit of foil behind stuck to this piece. I first used a smooth piece of foil to cover from the back of the channel wall, across the bottom of the channel grove and up over the broken front wall of the channel (big "U" shape). Then I make another slimmer and longer "U" shape to stretch the length of the channel wall, tip to tip, to help reinforce the first piece and also help protect epoxy from getting on any other internal surfaces of the channel. I then stuffed the rest of the open room inside the channel with loosely crumbled tin foil so it could all maintain it's shape. After stuffing it full, I used a flat head screwdriver to flatten the foil form under the wires so I had the perfect shape for filling and recreating the broken wall.
10.jpg


CONT'd on next post...

Last edited by POE; 10-27-2019 at 08:53 PM.
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Old 10-27-2019, 08:49 PM   #4
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Default Re: Selector Valve Clip Broken on Reinstall - Fix

6) Apply goop of choice. I applied it liberally in hopes of added strength. There is a retaining piece of the guide channel rod (on the valve body) that the plastic clip glides along to keep it's alignment. It has a stopper at the end, but it does not contact the plastic clip during normal shifting and leaves room for this epoxy to be built up a little bit. I shaved some epoxy height off of mine in preparation of hitting that stopper, but once it was installed, it didn't come close enough to require the trimming that I did. In the last pic you can see how I shaved some off by that stopper.
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Finally, reinstall the plastic piece to the selector valve rod and you're ready to put the transmission back together!

This has only been tested for a few miles so far. But if anything happens I will certainly come back and update my post. There is not much pressure on this plastic piece so I cannot foresee heavy forces tearing it apart anytime soon. I just hope the ATF doesn't dissolve my epoxy somehow.

Last edited by POE; 10-27-2019 at 09:08 PM.
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Old 10-28-2019, 04:20 PM   #5
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Default Re: NAG1 Selector Valve Clip Broken during Reinstall - Fix

Nice fix. I believe all NAG1 use the same valve piston. So you can probably get one from a junkuard for cheap, minus have to lay under the vehicle for 30 minutes to pull the valve body. Many chrysler/jeep vehicles used the NAG1.
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Old 10-28-2019, 04:40 PM   #6
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Default Re: NAG1 Selector Valve Clip Broken during Reinstall - Fix

Quote:
Originally Posted by Midwestdrifter View Post
Nice fix. I believe all NAG1 use the same valve piston. So you can probably get one from a junkuard for cheap, minus have to lay under the vehicle for 30 minutes to pull the valve body. Many chrysler/jeep vehicles used the NAG1.
How would you replace the selector valve rod? Is it as easy as sliding the old one straight out and putting the replacement straight in? If that's the case, it would be fairly easy to find one in a junk yard, as you say, or order a $163 new one online. I guess it's a matter of choosing the path of least resistance. But, yes, if the rod easily slides out for quick replacement, that opens up more possibilities. I would still do the repair as I did above being that winter is setting in here in MN and I would not want to go to a junk yard unless they already had the transmission out of a junk van for easy pillaging.
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Old 10-28-2019, 04:55 PM   #7
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Default Re: NAG1 Selector Valve Clip Broken during Reinstall - Fix

The piston will slide straight out of the valve body. They can sometimes hang up a bit if there is a wear lip in the bore, but you can rotate them around to make it easier.
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Old 10-28-2019, 04:58 PM   #8
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Default Re: NAG1 Selector Valve Clip Broken during Reinstall - Fix

Quote:
Originally Posted by Midwestdrifter View Post
The piston will slide straight out of the valve body. They can sometimes hang up a bit if there is a wear lip in the bore, but you can rotate them around to make it easier.
Very cool. Thank you for confirming! Makes for a lot more options in fixing a broken clip.
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Old 11-05-2019, 04:32 AM   #9
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Default Re: NAG1 Selector Valve Clip Broken during Reinstall - Fix

Perfect candidate for a 3D printer.
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