Diesel bodies mounted to frame via screws?

When I am installing screws, I try to be very careful to catch the threads that were already cut into the plastic, and not over-tighten them. Because of this, it is very rare that I create any new damage.

I am not certain what sort of screws they are currently using. It seems to be common for older trains to have originally been assembled with self-threading screws (different than self-tapping sheet metal screws). It is rather easy to miss picking up the threads that were already cut into the plastic. I think it helps to use a screwdriver with a small handle so you can feel the resistance. Also, I never use power drivers on trains, or anything else that requires care in catching threads.

I think it also helps to use replacement screws with matching threads. Most Lionel parts dealers seem to carry them.

All that written, it certainly would be great if threaded inserts were placed in the ends of those plastic posts.

RULE NO. 1

You always lift an engine by supporting the frame and not by the shell.

How can you expect 4 or 6 screws threaded into plastic to lift 6 to 7 pounds?

Good points C W.

I wonder if brass inserts would be an improvement? Excluding cracking the plastic in the receiving hole by over tightening the screw wouldn't it be easier to modify a stripped plastic receiving hole than a stripped or floating brass insert?

I'm kind of leaning towards the thought;  the pros and cons being equal maybe the cost of adding brass is the deciding factor.

I have always found the weakest link in an otherwise high end diesel is the fact that the frame screws usually screw right into the plastic of the bodies.

How true that is. I have had some early MTH and Weavers that I have had to either tap new holes or that the screw mount completely broke.  The idea of using brass inserts or at least metal is a good one. Williams as I discovered has used brass inserts on its GP 30s. I imagine the biggest reason that MTH/Lionel have not used them would be cost.

Doug 

Sorry guys, I had to chuckle at this.

Years ago I bought a Datsun (not even Nissan yet) pickup from my Dad. Little did I know he had fiddled with just about everything from one end of it to the other. So, one freezing cold night I was going out to meet some friends - and as I made the hard turn on a clover leaf exchange - the entire carburetor fell off the engine. Had it towed home - and next morning discovered Dad had stripped the screw mounts - and had inserted match sticks in the holes to hold it all in place.

And then there was the time I tried to set the emergency brake. Pulling the lever had no effect. Closer examination revealed a bungee cord instead of a cable for the "link".

I still get tickled thinking about it.

When you go to put the screws back in, here's a trick I've discovered.  Insert the screw, and then turn it backwards until you feel the detent, normally that will line up the old threads and it'll drop right in and not try to make new threads.

When replacing screws i always turn the screw counter clockwise about i turn until you hear and feel it click into the existing threads....do this and you can't go wrong...don't apply pressure to it just turn until you get it...you may have to do this 1 or 2 times,but it works...joe

The brass eyelet is a good idea and would be nice to have. Tooling revisions, extra manufacturing steps and material costs may be preventing it? I still think it's a good idea though. Maybe something for the manufacturers to think about for any future new tooling.

Many new Lionel Legacy shells have brass inserts for the shell screws.  Of course, they went to the tiny screws that are a PITA to work with, but they do have those brass threads...

That is a good trick, and one worth using.  I've never had a problem with diesel plastic bodies and screws, but then I'm always careful because it is plastic.

I don't normally have an issue, but some time back I noticed that they went in a lot easier when I did this.  I realized that they frequently don't find their old threads if you don't "hunt" for them.  Doing this also minimizes the strain on the posts and results in fewer broken or split posts.  However, I've gotten pretty good at fixing the posts with brass tubing and JB-Weld.

To me fixing mounting holes is the easiest fix I perform in model train repair. If a mounting post seems like it is close to stripped....on reinstall I place a plastic strip in the hole and bond it with a few drops of solvent glue. Allow to dry and put it together. Screw now has new plastic to grip. Splitting and broken mounting posts are easy too.

Buy some .030 x .030 plastic strip....use 2 per hole if needed. It will tighten right up.

The first time I remove a body screw and reinstall I always wipe the threads of the screw on a bar of ivory soap. And what others have said don't cross thread or over tighten.

Clem

When Lionel-Flyer issued the first run of U30Cs a few years back, I had to remove the body shell as it was mounted "cock-eyed". The reason, as I soon found out, was a cross-threaded body mount screw into a brass insert in the shell posts. I wish they would take away power screwdrivers on the assembly line, or at least make them hand-start screws into brass inserts before tightening.

Along this same line with power screwdrivers, I still haven't been able to loosen a electro-coupler mountain screw on a Flyonel SD70ACe..

I just fill the hole with JB-Weld and re-drill the hole for the mounting screw.

Filling holes etc may work...but to me that is no different than using touch up paint on a factory correct item.  That would bother me.

OK.......a repair of a mounting post inside the shell once successfully completed and not seen again has ZERO affect on the loco to me......paint defect maybe so......an 'invisible' internal fix could never lessen my application of anything.

Anyone with locos with bad posts feel free to send them to me for 'storage'.

Excellent advice John!

I always add some synthetic grease to the screws before I put them back in. It makes it easier to find the threads. They seem to just slide into proper position.

Roger

I'm at a loss as to how you'd fix one of these.  What's different about doing that over other repair options?

Just a tip on the nose screws on the F3A.  They are #4s with a countersink head, with a slot for the screwdriver, or a cross indent for one of 3 types of screwdriver.  The thing is, screw threads per inch were changed to what was called the "Unified" [with Britain] standard, with the #4s being one of the sizes affected.  This occurred about 1954; as a general rule Lionel updated to new standards without much delay.

There are some exceptions where Lionel did not change, such as the brass tophat nut that holds the "O" switches together.  But it looks to me like the F3 nose screws did change. 

The then new unified standard for sheet metal screws became 4-20, and it derived from the 4-40 machine screw by -20 being half the -40, covered by the unified rule making the sheet metal thread count half that of the machine screw [the coarse series, IIRC].  These screws had been either 4-22 or 4-24.  Either way, the difference is enough to tear out the threads in the plastic post, if the wrong screw goes back in.

There is more to worry about here.  If you have an original engine, you have either one or the other.  If you lose a screw, it's a help to lose only one from an AA pair.  Then you only have to find a matching one.

Believe it or not, it is still easy to find the old STZ screws.  This is both good and bad.  Typically, I've found, your local big box home store imports these, and even after 60 years, our Pacific rim friends are still making these to the old pre-unified standard.  So much so, that it's hard to find a current screw in such stores.

So, if you have a second-hand MPC F3, it may have one of the older screws as an incorrect replacement if this screw was ever lost.

But you could have an even more modern F3 repro [Postwar Celebration?], with the #3 [!!!] posidrive screws.  I notice that no one thought to change the plastic shell mold... .

I assume the #3s, being smaller, were cheaper...     --Frank

That's how I get the lid back on a pickle jar.

I also use JB Weld to repair stripped holes in plastic. A process akin to glass bedding a rifle barrel/action is followed.

I understand the concept of "self-threading" screws, but I follow a different process than drilling a hole and then forcing a self-threading screw into a new hole that may not be adequately supported by a surrounding thin plastic wall.

My first step is to clean out the damaged material including all remnants of the old thread. It is important that there be solid undamaged plastic remaining. The screw should be a "drop" fit into the cleaned hole. If chunks of the previous surrounding plastic are damaged they should also be removed.

I then apply thin coat of paste wax to the entire screw and let it dry. I also wax any surfaces of the mating part (frame etc.) that may come in contact with the JB Weld that may be squeezed out of the hole. If you don't wax completely and carefully you may not need the screw!!

With a toothpick I work a minimum amount of JB Weld into the hole, being sure to coat the sides of the hole. I do not fill the hole - there must be some room for the screw without squeezing the epoxy out. The JB Weld is also used to re-create any missing "chunks" using masking tape to construct a dam. The screw may also be thinly coated with the JB Weld - but don't rub it on, you may damage its wax coating.

The frame (or whatever) is placed in its proper relationship with the plastic shell, clamped if necessary, the screw fully inserted without it being turned, and the JB Weld allowed to set.

Once set, the screw is removed. New threads have been molded to receive the screw being used.

This technique has been successfully used on a number of F3 shells and tender bodies.

To me there a 100% improvement over the post war where you screwed thru the ends of the engine and almost always cracked the screw hole.( and a lot of times the screw hole was a little low so it raised the shell a tiny bit) Again take your time and don't put them in tight,tight just snug to hold the shell 

Some of the small switchers are a real PITA to remote the shell.  Of course, changing the location of the screws probably wouldn't fix that.

I'm at a loss as to why they can't engineer the posts to be a bit more robust, I suppose that's another topic...

EASY!!! After working in the plastic injection kit biz........it would cost more.  There are limits on mold design that makes a bigger more rugged mounting post cost a lot more.

Mold drift and plastic thickness can cause other issues and slow molding time. So basically.........cost.

I guess if cost was not an issue, they would make the shells attach with the screw/lever system that Lionel used on their Postwar switchers and Alcos. GREAT system!

-Roger

Yes, this is a case of can't ='s won't based on cost. 

Why can't the manufacturers use tabs like they used on Lionel F3 shells in postwar units. 

Just a 1/4 turn of a screw in three or four locations and the shell is off. These screws could be better fastened to the shells too and never wear out.

I use soap to lube my screws before every in or out from a shell as per Jim Barrett suggestion years ago.

Including the big, ol' rivets through the body holding the latch brackets on...

Rusty

I brought some brass inserts from Grainger last year because the screw holes in my post war shell were a little big and the screw barely catching.  I think 50 of them was about $14.  And I got a box of 100 brass screws, 4:40, to attach the shell with.  

Marty