lionel 21" passenger kadee conversion - mounting hole not tapped

@swise posted:

Hello all,  I've searched as best I can to find this subject in the forum, but didn't find it.  Hopefully someone has some advice on my problem:

I'm converting my newly purchased lionel 21" SF passenger cars to kadee 747 couplers (don't like the kinematics - but lets not go there).  I removed one of the lionel couplers and prepared to mount the shim that lionel provides for attaching the 747.  However the hole in the passenger car metal floor appears to be not tapped!  So the machine screw provided with the shim won't thread in.  Has anyone else dealt with this?  What is the size/thread count for these screws?  Can I use self-tapping sheet metal screws instead as an easy fix?  Or do I need to tap the holes (I don't have a tap kit though)...

Thanks in advance!

Steve

Sounds like that would be the easiest route...

Mark in Oregon

If you plan to do a lot of kadee installs most people use 2-56 screws but 2mm will work as well. 2-56 screws can be had at most hardware stores. 2mm you have to look harder. I would suggest getting a 2-56 tap for future use.

Pete

I did a similar conversion a while back and found one hole also not tapped.  I have a tap set so did it, I believe a #4.  I did it to reduce the gap between cars when moving, but found out that when done, it was actually greater than with the kinematic couplers!  So I removed all the Kaydee's and replaced the original couplers and live with the gap when moving.

Thanks all.

Turns out I have access to a 2-56 tap.  So I'm going that route.  Is it true that the screw mounting the lionel shim to the bottom of the passenger car chassis is 2-56?  Anybody know for sure?   It's bigger than the ones used to mount the kadee coupler box to the shim.  Those are v-e-r-y tiny.  

For the record, only one car of the 6 I purchased failed to have the holes tapped.  It was the baggage car of the 4-pack.  All the others were tapped, and I just finished installing the kadee 747 couplers.  Not too painful, and I only lost 1 kadee spring!

@swise posted:

Thanks all.

Turns out I have access to a 2-56 tap.  So I'm going that route.  Is it true that the screw mounting the lionel shim to the bottom of the passenger car chassis is 2-56?  Anybody know for sure?   It's bigger than the ones used to mount the kadee coupler box to the shim.  Those are v-e-r-y tiny.  

For the record, only one car of the 6 I purchased failed to have the holes tapped.  It was the baggage car of the 4-pack.  All the others were tapped, and I just finished installing the kadee 747 couplers.  Not too painful, and I only lost 1 kadee spring!

 

Somewhere, some place there is a room...filled to the ceiling with "lost Kadee springs"... 

Mark in Oregon

@PeterA posted:

I did a similar conversion a while back and found one hole also not tapped.  I have a tap set so did it, I believe a #4.  I did it to reduce the gap between cars when moving, but found out that when done, it was actually greater than with the kinematic couplers!  So I removed all the Kaydee's and replaced the original couplers and live with the gap when moving.

Hey PeterA, you say you used a #4 tap.  Did you use the screw included with the lionel conversion shim?  IE is that screw #4?  I realized that screw is bigger than 2-56 so I need to know if its #3 or #4.

Thanks,

Steve, upon reflection, it was not as big as a #4.  I have a tap set and think it may have been a #2-56 tap size.  And the included screw worked.

Hey Steve!

Hope all is well with you and the family. I miss our operating sessions on your layout!

Ricky

The thing to do is remove one correct screw and compare it to the tap. Held side by size, all grooves match if pitch matches. If pitch doesn't match on EVERY thread, if one pops up, it's not a match (english sizes are pretty easy to distinguish from metric, but some sizes along with deviation from standards in manufacturing can hook you. I.e. the fastening happens, but the fail points are lower.)

This doesn't mean the dia. is correct though, just a "first step", test dia via tapping some scrap material and trying the new hole... then tap the work.

Hi Stevo (and Ricky) .  The 2-56 tap and screws is good advice.  I've done a ton of kaydee's using them.  The only exception is on engines.

Hey Ricky/Bill!

PeterA, 2-56 is too small.  The tap goes right through the hole it is supposed to be threading! .  So its #3 perhaps.   The lionel replacement part number doesn't describe the screw sizes so I'm left to figure it out (or call them ).  I'm trying to avoid buying a set of taps, but perhaps i should.  Or I could go buy this from Lowes for under 2$!  

https://www.lowes.com/pd/Hillm...Thread-Gauge/3183019

This screw isn't the kadee mounting screws.  This is the mounting screw for the lionel kit shim that screws into the bottom of the passenger car and provides the proper mount for the kadee 747. 

Steve, the machine screws that come in the mounting kit are M3 x .5 pitch. If you want to use those screws thats the tap you will need.

Pete

Thanks Pete! 

@Strummer posted:

Somewhere, some place there is a room...filled to the ceiling with "lost Kadee springs"... 

Must be a siphon from there to my shop; got a box full of the things,