(Topic ID: 51272)

AC/DC Auto-Plunger is starting to get weak - FIXED!


By RacerRik

6 years ago



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  • 47 posts
  • 16 Pinsiders participating
  • Latest reply 6 years ago by bub2010
  • Topic is favorited by 23 Pinsiders

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ACDC_Autoplunger_Bushing_9542.jpg
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#1 6 years ago

So my AC/DC is a couple months old now and it seems like the auto-plunger is getting weak - it fails to make it to the saucer fairly often. When brand new, it never missed. Then after a month or so it would miss once in a great while. Now it is getting to where maybe only 50% of the ball launches make it to the saucer.

Anybody else seen this problem and if so, what did you do to fix it?

#2 6 years ago

Do the normal checks first. Coil sleeve okay ? Plunger end not worn or broken ? Plunger hitting ball squarely ?

LTG : )

#3 6 years ago

Thanks Lloyd, but I have not tried to troubleshoot this yet as it is alien to me! The auto-plunger uses a fork type mechanism to launch the ball. This game has a traditional pull back plunger along with an auto-plunger.

So, since I have no experience with this type of mechanism, 1st I searched and found nothing and then I posted asking if anyone else has expereince with it.

#4 6 years ago

Mine is the same way figured it was supposed to be this way.

#5 6 years ago
Quoted from RacerRik:

So, since I have no experience with this type of mechanism, 1st I searched and found nothing and then I posted asking if anyone else has expereince with it.

Search harder. ( it's been covered with every game using it )

Same basics I listed, with the additional look at the plunger/kicker with the ball resting waiting to be kicked to see if both sides ( forks ) are touching or hitting the ball.

And look at the kicker part, it is two pieces peened together, be sure it is still tigh and not coming loose.

LTG : )

#6 6 years ago
Quoted from RacerRik:

So my AC/DC is a couple months old now and it seems like the auto-plunger is getting weak - it fails to make it to the saucer fairly often. When brand new, it never missed. Then after a month or so it would miss once in a great while. Now it is getting to where maybe only 50% of the ball launches make it to the saucer.
Anybody else seen this problem and if so, what did you do to fix it?

Yes, having the same problem and my game has less than 200 plays and is barely 60 days old. It is getting progressively worse.

#7 6 years ago
Quoted from vdojaq:

Yes, having the same problem and my game has less than 200 plays and is barely 60 days old. It is getting progressively worse.

Age doesn't matter. Crap happens.

Look into it. Might need fixing or simple adjusting. And then you'll be enjoying your game again.

LTG : )

#8 6 years ago

I thought it was my imagination as I noticed it the other day. But the next day seemed ok. Seems sporadic, will have to keep an eye on it.

#9 6 years ago

Thanks Lloyd - I will check the fork to make sure it is peened together tight. It does look like something is out of whack because the manual plunger is not centered between the forks. I t looks like both mechanisms are off. The forks are too far to the left and the manual plunger is too far to the right. I will have to mess around with it some more to figure out if there is slop to allow adjustment or if something needs to be bent on the fork mechanism.

I guess I did not know what term/s to search for cause my search came up empty.

#10 6 years ago
Quoted from RacerRik:

The forks are too far to the left and the manual plunger is too far to the right. I will have to mess around with it some more to figure out if there is slop to allow adjustment or if something needs to be bent on the fork mechanism.

See if they are hitting the plunger, perhaps it needs adjusting to center it.

LTG : )

#11 6 years ago
Quoted from Eskaybee:

I thought it was my imagination as I noticed it the other day. But the next day seemed ok. Seems sporadic, will have to keep an eye on it.

Yep - that is how mine is. It may work OK for an entire game - then it misses 6 in a row! Really annoying when you are trying to make the jukebox shot and you drain the ball and then think that's OK, cause the autoplunger is going to make it for me.... Then it misses. And to make the worst, I have intentionally let it drain to give it another shot at the Jukebox and it misses again, wasting all my precious ball save time in the process.

Then again, it is AC/DC so you know it is as mean as hell!!

#12 6 years ago

My auto plunger has been great. But I am about to go through my second Change Song Jukebox switch.
My last two games it missed changing the song 3 times in a row.
And on top of that the first T in TNT does not always register as a hit.
Tried cleaning the opto and reseating the connectors, but no dice. Still does not register a hit most of the time.

#13 6 years ago

The stern auto plunger mech has always been crap. The metal plate that screws to the PF is made to break, and with any small amount of wear, it throws the aim and precision (loosely speaking) out the window.

My ACDC does this randomly as well, and I've looked at everything and adjusted this thing every which way. I don't care, I use the shooter rod all the time.

#14 6 years ago
Quoted from Atomicboy:

The stern auto plunger mech has always been crap. The metal plate that screws to the PF is made to break, and with any small amount of wear, it throws the aim and precision (loosely speaking) out the window.

ya, make sure to re-tighten those screws that support the ball trough ejector down to the pf as well, they get loose over time, and will spit the ball into the plunger lane poorly, or even crack the welds on top of the ejector itelf.

concerning the auto plunger, just inspect it, maybe take it apart, clean the sleeve and inside coil, re-assemble and tighten everything up. good luck, LTG pretty much covered it.

#15 6 years ago

I fixed the problem tonight so I thought I would report back in case it might help others who have the same problem.

So I did a bunch of checking into this problem. Nothing was loose, the plunger fork was riveted tight, the coil and sleeve were all fine. There really is no adjustment to align the fork so it can't be out of alignment.

The problem turned out to be that the left "tine" of the fork was bent away from the other tine. That was causing the right side of the fork to hit the ball first and making the plunge unbalanced. I carefully bent the tine back into alignment and now the autoplunger shoots smoothly and strong.

This does leave some unanswered questions: What caused the fork to bend? Does that just happen over time? Will I have to bend this back again after more use? Will the fork break off if I keep bending it? Is it a defective part?

Has anyone else seen this fork bending problem?

#16 6 years ago
Quoted from RacerRik:

Has anyone else seen this fork bending problem?

No. But I have seen some impressive spoon bending.

#17 6 years ago

Ha! There is no slight of hand with this fork bending...

2 months later
#18 6 years ago

Ok, so the mech on these is fastened with e-clips...and not tightly. Can these eclipse be tightened? It doesn't look that way, as the appear to click into a groove. There is a lot of side to side play of the fork due to the mech being loose. How do I adjust this sothe fork cannot move from side to side in the shooter lane?

#19 6 years ago
Quoted from TheFamilyArcade:

Ok, so the mech on these is fastened with e-clips...and not tightly. Can these eclipse be tightened? It doesn't look that way, as the appear to click into a groove. There is a lot of side to side play of the fork due to the mech being loose. How do I adjust this sothe fork cannot move from side to side in the shooter lane?

Before bending the forks remove the eclip and bend the U shaped mount to take out the side to side play.
This adjustment has to be done first or you are wasting your time adjusting the forks.
Look at the forks first to determine which way to bend the tabs to shift the forks.
You have to do this on every Stern the side to side slop changes the launch on every ball.

#20 6 years ago

Thanks so much! I've always wondered if this was fixable. I knew I was missing something in my analysis. I am ok at diagnoses, just not at finding a cure.

#21 6 years ago

Mine started acting poorly again. It got so bad, it was only making the launch to the jukebox about 1 in 4 times. And sometimes it was so bad the ball did not make it all the way up the launch ramp so it had to try again..

I fixed it right this time! Tracelifter was right on target with the slop on the fork pivot. Mine had at least 1/8" of play at the fork tips. I decided the plastic bushings are the problem. I made a new single piece bushing out of brass and now my fork has almost zero play and the shooter is making the shot to the jukebox every time.

#22 6 years ago

Here are some pictures of the bushing in case anyone else wants to build one. I used 3/8" brass rod stock. I turned the narrow section down to 0.318" and 7/16" length. I left 1/16" shoulder and reamed the center bore to 0.249". It is a snug fit into the U bracket.

ACDC_Autoplunger_Bushing_9539.jpg ACDC_Autoplunger_Bushing_9541.jpg ACDC_Autoplunger_Bushing_9542.jpg

#23 6 years ago
Quoted from RacerRik:

Here are some pictures of the bushing in case anyone else wants to build one. I used 3/8" brass rod stock. I turned the narrow section down to 0.318" and 7/16" length. I left 1/16" shoulder and reamed the center bore to 0.249". It is a snug fit into the U bracket.

That is awesome.
Please make and sell these. I know I would want one. I'm sure my bushings are getting worn by now.
If nothing else, is anyone near a parts manual with the part number for the plastic bushings?

#24 6 years ago

The part number for the plastic bushings is 545-5423-00 (at least on NASCAR).

Here is the link at marco:

http://www.marcospecialties.com/pinball-parts/20-8790

Having said that though, I would buy a turned brass bushing if they were available.

#25 6 years ago

I would not mind making some of these for sale, but it takes me a long time to machine them - my lathe is old school - not CNC....

Not sure I could pay for my time and still sell them at a cost that would be bearable.

-1
#26 6 years ago

Nice work OP! That's a great idea. Seems to be a common early-wear area, those plastic bushings. Thanks

Mike

#27 6 years ago

Those plastic bushings are junk! I am certainly not a Stern basher since I love my AC/DC, but I could not help thinking that Bally/Williams would have used a brass bushing there and I would not be making this thing myself....

#28 6 years ago
Quoted from RacerRik:

Not sure I could pay for my time and still sell them at a cost that would be bearable.

I'd pay $10 plus shipping for one, dunno if that's where it would need to be or not to cover your cost + profit.

#29 6 years ago
Quoted from RacerRik:

Those plastic bushings are junk! I am certainly not a Stern basher since I love my AC/DC, but I could not help thinking that Bally/Williams would have used a brass bushing there and I would not be making this thing myself....

If you call any mech or part on a Stern junk you will be called a Stern basher.
Don't say anything negative about Stern even if it is true.
Woz is even worse one question and you start a category 5 sh!tnado and the thread is locked.

Stern rocks! Each game better than the one before and it ain't the booze talkin' I really mean it.

#30 6 years ago
Quoted from Wolfmarsh:

I'd pay $10 plus shipping for one, dunno if that's where it would need to be or not to cover your cost + profit.

Agreed. I'm not wanting to pay the Home Depot .35 cent price.
I think we all realize this would take a lot of time and effort.
So as crazy as a $10 bushing may sound I'm sure we would have no trouble paying that or more.
But from what you posted above, it does sound like a lot of work and trouble on your part.
Thanks for posting the photo and the specs.

#31 6 years ago

Oh, I would gladly pay $15.00 plus shipping for this item. I used to own an Avengers Pro that had Major issues in this area. I would have easily paid $30.00.

#32 6 years ago
Quoted from RacerRik:

Those plastic bushings are junk! I am certainly not a Stern basher since I love my AC/DC, but I could not help thinking that Bally/Williams would have used a brass bushing there and I would not be making this thing myself....

Williams used brass on the tube for the long flipper shaft on No Fear and it wears poorly. I stuck nylon ones in my game it it lasted forever.

LTG : )

#33 6 years ago

I just played a couple games and not a single auto plunger shot missed - which is awesome!! I might go ahead and build some of these since it seems like there is a lot of interest in them. It would probably be prudent to wait a little while to make sure the brass stock I used is going to hold up. I used C360 alloy brass rod.

If I am going to make a batch of these, I could get some thick walled brass tube stock and it would make the machining job easier since it saves me the center boring step - just have to run the 0.249" reamer through to accurately size the bore. I found a source for 0.375" OD / 0.245" ID tube which would be perfect.

One concern I have is how accurate are the brackets from Stern. I only have a sample of one - which is no sample at all really. If I machine the bushings exactly the same size as mine - are they going to fit everybody else's brackets?

#34 6 years ago
Quoted from LTG:

Williams used brass on the tube for the long flipper shaft on No Fear and it wears poorly. I stuck nylon ones in my game it it lasted forever.
LTG : )

That is a valid concern. There are many different alloys of brass each with different wear properties. I have a No Fear game myself with many thousands of games on it and the long flipper bushing has been holding up well. I did lubricate it with white lithium grease though. Nylon is self lubricating - brass is not. I did lube this auto plunger bushing with a small dab of white lithium grease also. I will have to see how it holds up.

The main problem with the original bushings on AC/DC is that they are split and do not fit to a close tolerance even when brand new. My auto plunge fork has had lots of wiggle since day one. If the brass does not hold up - I could machine a tight tolerance nylon bushing that would be much better than the two split bushings.

#35 6 years ago
Quoted from RacerRik:

I could machine a tight tolerance nylon bushing that would be much better than the two split bushings.

To me that would be better than brass.

#36 6 years ago

I'm cool with a better nylon bushing as well. Does not have to be brass.

#37 6 years ago

The problem with using nylon for this application is the wall thickness of the bushing ends up being too thin. When you try to machine thin nylon, it flexes and you end up with inaccurate cuts.

Now if you want to spend a fortune and set up a mold to make these, you can make the wall as thin as you want.

To use a proper sized nylon bushing (meaning one that can be machined accurately), you would need to drill out the holes in the U bracket to allow a larger OD on the bushing. 0.375" would probably do it, but that does not leave much metal in the bracket. And it certainly eliminates the plug and play feature of the brass bushing.

I still think the brass bushing is the way to go. I really don't expect to see much wear here since it is only rotating a few degrees.

4 weeks later
#38 6 years ago

Just within the past 2 days I started a topic about the same problem and it was linked over here. You gonna start make these? I might buy a couple. I have an Avatar I've put prolly 500 plays on it since I've had it (near 1,000 total) and so far it is rock solid, but you never know. Ultimately for skill shots and lighting up all of the lanes the plunger is likely what most high level players use. Been thinking of turning auto launch off anyway for this reason, but would still like it to function normally if I want it to.

So...is there no standard tubing with an acceptable inner/outer diameter stock? Meaning tighter or as tight as the plastic ones that are stock?

If you aren't making them anyone have any plastic ones they can put in an envelope and mail to me? (or maybe someone local to Columbus, OH) Marco's 5.99 for shipping something that small sucks when a single stamp would cover "shipping" for probably 8-10 of them.

#39 6 years ago

I have not decided to make any of these for sale yet. Since there was a concern about wear on the brass, I have just been playing my AC/DC to see how well it holds up. I have a couple hundred games on it since putting in the brass bushing and so far it is holding up great! Out of all those games, the auto-plunger has only missed the juke box maybe a dozen times, so the success rate is fantastic!

As far as stock sized tubing, you need something with a flange on one side, so tubing is not going to be the answer. You can try new OEM plastic ones, but I think they are sloppy from the beginning, so they may improve your shot success, but still leave plenty of misses which I found very annoying on my AC/DC.

And turning off the auto-plunger sounds terrible - it would pretty much ruin multiball if you had to manually keep plunging balls while still playing the ones on the field...

#40 6 years ago

oops.. wasn't thinking about the multi ball aspect, but wasn't sure if multiball over-rode the "auto plunge" feature or not. Gonna have to try that and see what happens. That would be an interesting loophole though if multiball would start and you could keep launching single balls until all 2,3,or 4 drain... seems to me though that it would cause a shooter lane jam up if this were true though.

3 months later
#41 6 years ago

I found an easy fix last night and posted it on this attached thread. I also determined the problem to be the worn plastic bushings and the slop they allow, but this was an easier "work around" the problem and my ACDC is now working perfectly:

http://pinside.com/pinball/forum/topic/tech-help-please-acdc-autofire-plunger-getting-weaker-and-weaker#post-1336664

#42 6 years ago

I don't get what you're saying, I must be missing something. But putting in a thin "stopper" for the link essentially, this is fixing it?

#43 6 years ago

Until someone can come up with an easier solution...yes! At least it is now working properly with a minimum of effort to make it work. When the velcro gets worn thin I will use two sided tape on a metal shim to preload that sloppy linkage. We obviously are not getting any valid repair suggestions from Stern on the problem.

#44 6 years ago

I would bet that there is a standard sized oilite brass/bronze bushing that would work exactly like RacerRik's custom made part. When I worked in special machine design we had catalogs from every manufacturer with their standard sizes. Maybe we have someone out here in the pinball world who has access to that information? RacerRik listed the nomimal sizes that would be needed. Worst case scenario is that we might have to file 1/16 off the overall length of a standard piece to make it work.

#45 6 years ago

I've been looking online for the past hour and all the manufacturers for flanged oilite bushings seem to be in the UK! I will go to a well stocked machine parts supply place I know of in Detroit after the holidays and see what they have. I'm pretty sure those crummy plastic split sleeves need to be replaced with a sintered bronze bushing in standard dimensions.

#46 6 years ago

I don't have any experience with stock size bushings but I doubt you will find one that is the right size. The dimensions are critical if you are going to get the play out of the auto-plunger. 1/4" inside should not be a problem but 0.318" outside does not equate to a standard fractional size. 5/16" would be 0.3125" which would be sloppy in the hole on the plunger bracket. You could step up to 3/8" (0.375") and then drill out the hole in the bracket, but I did not want to modify the stock part and potentially weaken it since a 3/8" hole would not leave a lot of material behind. The 1/16" flange width and 7/16" turned length are also very critical or you won't be able to get the circlip back on. There is no adjustment for that other than go slightly undersize and use very thin washers.

I think your best bet is to find a machinist that does small jobs and have him build a bushing ( or bushings) to the specs I posted.

#47 6 years ago

Anyone having this problem check out this thread where it has been getting discussed more. I seem to have observed a couple of things and found another way that you may be able to fix yours pending what the "weak link" is in your shooter fork linkage.

http://pinside.com/pinball/forum/topic/tech-help-please-acdc-autofire-plunger-getting-weaker-and-weaker

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