Tamiya JS-2 Recoil
 

I have a Tamiya JS-2 whose recoil has stopped working.
I have checked all the usual things, everything else works as it should.
No obvious loose wires, jams, interference's etc.
When I fire the the gun the tracks recoil but there is no movement in the gearing assembly for the barrel.
I have checked the wires and plugs.

NO !! THERE IS NO SNOW AND ICE IN THE BREACH OR TRAVEL MECHANISM.

Any help would be appreciated.


Wayne

Test the motor. Tamiya uses Mariuchi 130s in everything, they are good motors, but couldn't hurt to direct wire it so you can rule out the MFU.

I had a failure with mine also. It wasn't the motor or the MFU. Must have been in the cable. Tried the one from my KT and all worked well. Ordered a new one and it has been good now for about 4 months.

ausf and tanker 10 thanks for the reply.

ausf:
I had a similar recoil device but smaller and tried it with various size batteries and it worked so I tried a battery direct to the recoil motor, a very small spark and small puff of smoke. OOPPSS !! ( Maybe motor or a capacitor type attachment at the motor wiring attachment location.
Now the barrel still does not recoil and the track recoil does not work but everything else does.

Tanker 10:
Where did you buy the replacement recoil device and how did you get it in the restricted space.
I see a nightmare coming when I try to make the switch inside the turret ) I had previously broken the plastic sleeve tab that attaches to the recoil device with a bolt and it is now glued to that same tab on the existing recoil.

I may be leaving it as is.


Thank You

Wayne

Yes Wayne, they are not easy to change on the JS-2 but it can be done. If I remember correctly, I unscrewed the recoil unit from the bracket first then removed the mounting bracket. I used magnetic tipped screw drivers and tweezers. As far as you gluing the black plastic piece that mounts to the barrel and recoil, maybe you can get a sharp blade and saw it off. At any rate, I would re-order that part too.

I purchased my recoil unit from Jason's store on eBay You could also try the AAF tank Museum. I use them also. Karen and Natasha provide great customer service.

Tanker 10
Thanks I have bought a lot of items from Natasha, I sourced all the parts for the Leopard above and inside the tracks to convert a display model to RC.

Thanks

Wayne

Tanker 10:
I looked on Jason's store and could not find parts at all for the JS-2.
There were various bearings for several tanks.
how did you locate parts for the JS-2

Wayne

4205031 Tamiya 1/16 King Tiger Jagdpanther Russian JS-2 Recoil Unit

Tamiya 1/16 King Tiger Production Turret Recoil Unit. Parts 14205031Also for the Jagdpanther and JS-2

I used the search box to find it again. I got this same one from Jason's store. This is his listing on his site.

There are more JS-2 parts on the site as well. Unfortunately, there aren't photo's for all of his items, you just have to look. As I said, try his search box. There is a photo for the recoil unit.

Joe

I couldn't get a link to work, sorry.

Joe:
Thank You I finally got the site to accept the number and I have ordered it.

Thanks Again
Wayne

GREAT, good luck Wayne.

I have received the Barrel travel mechanism from Jason's store and I am now looking for the 2 piece plastic sleeve attachment listed as F1 & F2.
Any one out there have them or know where to get them without buying the whole F Bag from Tamiya sup-pliers for about $40.
http://www.rcuniverse.com/forum/atta...mentid=2161999
Thanks

Wayne

Wayne I've looked in my" spares" box and I do NOT have one. I would try making one from styrene or brass if I needed one.

Joe;
I have been attempting to remove the recoil device from the turret but I can not see how to get at the screws on the back side.
I removed the motor and cover from the under side thinking i would try the new motor but there seems to be something restricting the sliding mechanism so I will need to replace the whole assembly.
I put grease on the slide bars but something is stopping it 1/3 from the front.( I will continue to play with the slide checking for bends, glue drops etc.)
My best guess is the plate that slides along the bars is twisted.

Any other ideas.

Wayne

Hi Wayne, take a look at the screw (the brass one with the large head) that is in the center of the recoil gear. Is it sticking up, stopping the mechanism from recoiling or going forward?

If I remember right, I took the two small black screws out of the recoil unit first. They are the ones holding the recoil unit to the bracket.

Also, before you install the new recoil unit, remove that big brass screw and put some loc- tite on the threads. That large screw backed out on mine and was causing some of my problems.

I'm going to go and look at mine again and see if it triggers a thought.

Never mind paragraph two, I see now you can't get to the two small screws. You're just going to have to find a way to get that bracket off. I used a 90 degree phillips screw driver to break them loose and then a long thin phillips.

It's been a while since I looked at a Tamiya recoil unit so I don't recall if they use limt micro switches? If they do I'd check these.
Somehow I think these could be prone to failure with more frequency than the motor.

Just a thought..

Jerry

Wayne,

I recommend you isolate the problem as either electrical or mechanical (if you haven't already)

If electrical, the unit won't do anything. If mechanical, the recoil motor will try to work (you can check this by touching the recoil motor during a recoil event. If it is trying to work, you'll feel it. If that's the case, pop the motor out of its cradle, and then hand cycle the recoil unit back and forth. You can easily bend the metal shuttle with a pair of long nose pliers. Once it works freely, reassemble.

If you need to take out the recoil unit, the recoil stay will need to come loose from the back side of the mantlet. You'll also need to disconnect the black ABS part that connects the barrel to the recoil unit (on the F sprue). Once you do all that, it should come out. Tight, but not impossible.

As to the F1 and F2 parts, I usually can repair them 80% of the time by melting them together using Tenax (which is MEK based). Just give it plenty of time to harden up after you do the repair.

Jeff:
Thank You for your suggestions. ( I was away for the last 5 days, we went North to our cottage and cut grass Friday and shoveled snow Sunday) (Just got back this afternoon. )

I have done all the above.
I took the motor out ( It was not working)
The recoil ass'y only slides 2/3 of its travel and roughly
Then F1 & F2 attachment tab was previously broken into 3 parts, I super glued the remainder to the metal bracket and screw. I would say the ass'y is pretty much trashed by the time I get it all apart. ( I might salvage the screw )
I will try tomorrow to separate the pieces.


I have a new recoil ass'y

Wayne

You could always buy a debonder for the glue. http://www.basspro.com/Zap-Debonder/...ductextensions or http://http://www.hobbylinc.com/htm/hlc/hlc161.htm

My experience with debonders is that they don't work after the parts have been bonded for a couple of weeks. Maybe the stuff you posted the link to actually works?

Jeff:
Reading your explanation below I can not see how the device can be removed once the barrel has been disconnected from F1 & F2.
There still 2 screws attaching the backside of the device to the bracket attached to elevation ass'y behind the mantlet.
Also there is the ball joint connection and spring attached to the same bracket and recoil device.

the recoil stay will need to come loose from the back side of the mantlet. You'll also need to disconnect the black ABS part that connects the barrel to the recoil unit (on the F sprue). Once you do all that, it should come out. Tight, but not impossible.

I feel as this is an impossible mission but I must find the way.

Any thoughts.

Thank You
Wayne

Wayne,

I checked on my JS, and I was mistaken that I had disassembled a JS. I had disassembled my KV-122, which is similar. After examining a disassembled JS (I'm working a project) and comparing that with my instructions, there's just a few ways to get the recoil unit out in my opinion.

Simplest is to remove it just like it went in. You will, of course need to break the glue joint that forms the nose of the turret (part D2 needs to be removed from the turret). It would be a reverse of step 33 in the instructions, sans splitting the top/bottom half of the turret. Once you pull off the nose, everything comes out with it. Destructive...but you would just have a plastic repair and touch up paint to get it back together. I'd also suggest scratchbuildiing some sort of bracket to utilize screws to secure the nose when you replace it. That way, you've never got to do this again. Time consuming, yes...but possible.

Second idea is possible, but I'm not sure how feasible it would be. The idea is to drill access holes through the roof of the turret to get to the two mount screws on the top side of the recoil unit. You'd have to drill two blind holes in the correct spot. Very difficult, but might be possible. Afterwards, you could plug the holes with some tape, or just putty them over and repaint. Just don't do too good of a job patching the holes, as you'll need to find them again.

Sorry to give 2 bad options, but they seem to be the only ones from my viewpoint.

Jeff:
Unfortunately I see two problems that seem to prevent both methods from working.(Both are visible in step 33)

1/ --The ball and cap connection for the elevation motor.
2/-- The spring for the elevation ass'y.

Both of the above are not really accessible to reattach from the underside of the turret once you have the assembly back in the turret
I also wonder if after cutting the nose off if the recoil ass'y will actually pass through.
Yes I am pretty negative but I have been looking at it for a month and I suspect I will fail in the reattachment process .
I continue to look at the slider ass'y and why it move smoothly for 2/3 of its travel and stops. I can not see any obvious twists or bends. Since I now have a new motor and wiring it would great if I could make the existing ass'y work. ( Wishfull thinking EH ! )
I am still investing time in attempting the seemingly easier method. I am sliding the travel ass'y back and forth attempting to make it do 100% of the travel distance.
I have increased the distance to about 90 % ( At this point I am having some success so I will continue to try this for a time )
Thank You for your tme and effort, if you think of anything else I would be glad to hear.

Thank You
Wayne

Jeff and All:

I won, I have it back together and it works.
Unfortunately I could have fixed it without buying recoil system. (Oh well EH !!)
Quite often over the years I have fixed many things by taking them apart and reassembling them with good success.
That is exactly what happened this time. If I had done this in the beginning I may not have fried the motor and/or wiring for the recoil.( Since I bought a new recoil I just replaced the motor and wiring and left the old recoil assembly in place.)

The problem was fairly simple but not obvious to me. The turret nose includes 3 major parts which all fit together with the barrel sliding through all three.( Assy #'s 28, 29 and 30 in the manual if you have one D1 & D2)
Inside the turret there is the elevation ass'y then the Turret nose D2 and the exterior mantlet.
All three fit tightly together with the barrel sliding through with little clearance.
The exterior mantlet D1 came loose and bound against the barrel and stopped it from returning to after fire position.
I glued the offending pieces together and now everything works.

Thanks for all the help

Wayne

Glad you got it sorted, I ran out of suggestions.