used cars jump track

[GRASHLEY]

I am relatively new to N scale. I have purchased several cars, both new and used.  Some are Rapido, others are knuckle couplers of various brands.  Some are great runners.  Others, not so much.  I have replaced some trucks and couplers with MTL, which sometimes works.  I have added weight up to NMRA recommendations, which sometimes works. 

Any suggestions??

I also have a couple new cars which like to "lose" their wheels (one set, out of warrenty).  Is the only fix to replace the trucks???

I have some cars that roll smoothly, but have excessive drag.  What do you suggest?

Thank you in advance.  The folks on this site are truly experts and very helpful.

Gordon

[RGW]

It is possible the some wheel set are out of gauge. old atlas metal wheels can be slide back and forth on the Axle if the are out it will cause binding. some times mixing different brands of trucks and axles does not work well ether.

I have hold the car upside down and  try spinning the wheels,if they do not spin for a few seconds I remove the wheel and check for problems , maybe crud on the inside truck where the axle point goes.

MT trucks normally  roll very well,so maybe different brand of wheels in the MT truck or the axle is popped out on one side

[gatrhumpy]

You need to get an N scale gauge and check the distance between the flanges. It will also allow you to check your track.

[skipgear]

More info needed....

What type of cars? .... how long are they?
What radius track?
Do you have reverse curves?
Do some of the cars have body mount couplers?
Is there a certain place they derail or is it random?

MT trucks are a safe answer for replacement but you must make sure they are shimmed correctly and the coupler box does not interfere with anything on the bottom of the car. 

[James in FL]

Hi GRASHLEY,

Different manufacturer's trucks require different axle length.
If a truck is losing its wheels it maybe because of the wrong axle length or maybe because the side frames are out of whack (bent outwards).
Excessive drag, same as above, but side frames too narrow, or possibly electrical contact wipers on the wheels or axles.
My preference is metal wheels over plastic ones.
Just my preference, other modelers prefer plastic, we all choose what we like.
There is no wrong or right.

A couple of thoughts here,
The trucks should swivel easy, almost to the point of being sloppy (left to right), this is controlled by the friction of the bolster pin (king pin) where it holds the truck to the frame.
The truck should also be able to move slightly (rock) up and down vertically in the straight position.
Usually .010 is more than enough to compensate for bows and dips in sectional track and joints along connecting sections.
Another thing to look at is to see if the wheel sets are rubbing the bottom frame of the cars, or the coupler pockets, at any point throughout their swing.
Wheel sets come in different diameters, most commonly in 33 and 36 scale inches.
Be sure yours are the correct diameters for the rolling stock you are installing them on.
All of this easily adjusted/corrected with shims.

As to rolling stock weight;
I have been in N scale since the very early 80"s.
I don't weigh cars, I don't have a scale.
The few pieces of rolling stock I felt I needed to add weight to, have been old Con-Cor/ Rivarossi passenger cars and a few cabooses from various manufactures.
I live along the coast so fishing tackle is readily available in all grocery stores, drug stores, convenience stores, etc.
In the passenger cars I use 1/4 oz. lead over each truck, hammered until it fits inside the width of the body.
Cabooses, 1/8 oz. over each truck, again hammered.
Elmers white glue or double sided foam tape is my preferred way to secure the weight in place.
Unless a car comes from the factory, equipped with body mounted couplers, I generally don't convert over.
The few exceptions are locos converted to MT and some tenders and a few cabooses.

If you want to use the MT trucks on Bachmann stock, you will need to ream the bolster hole on the trucks to 9/64ths IIRC.

Are the cars that are de-railing directly behind the loco?

Post back

Good luck

[Len]

One other thing to check on the used cars. Instead of spreading the truck slightly when removing wheels, some people pry them straight out. Often using a small screw driver as a lever. This often leaves a 'V' shaped notch in the bottom of the truck, leading to wheels that either fall out or get jammed at an angle creating drag. The only fix for this is to replace the truck.

Len

[James in FL]

Good point Len,
I have seen the V shape scarring in the bottom of the truck frames, never to the point as to where it was so deep to drop the axle but yes, it is certainly plausible to cause a mis-alignment of the axle.

As an afterthought for the OP;
Clean the axle journals in the side frames where the axle point fits.
Crud in there (fuzz, lint, fibers, cat hair, etc.) severely effects the rolling resistance.

[RGW]

On MT trucks. I have had problems with the trip pin being to low and catching on frogs. easy fix  i cut them off.

[GRASHLEY]

Thank you for all of your good responses.  It is appreciated.

Random thoughts and responses:

One car losing its' wheels is a brand new Atlas.

I have several "Old Tyme" Passenger cars.  Most of them run okay.  One gave problems and I replaced the problem truck with an MTL passenger truck.  Conversion car.  Still have problems.

The rest of my cars are 40 - 50 foot, mostly box cars.   The layout is a simple oval.  Inner loop is 9 ¾ radius.  Outer loop is 11 ½ radius. 

There are a couple places more prone to derail, but "good" cars have no problem in these areas.  "Poor" cars can derail anywhere.   "Poor" cars will derail anywhere in the consist.  "Good" cars seldom derail, regardless of location.  Long consists  derail a little more, farther back in the consist.  I suspect correct weight would fix this???

Except for a couple cabooses, all cars are truck mount couplers.

How do you shim a car?? Why do you shim a car??   The trucks set the space to the track.  This also fixes the coupler height.  How can these be adjusted?  Why is the height of the car above the truck, which can be shimmed, important?

I do have an NMRA gauge.  I will check flange spacing.

I have had cars with too low trip pins.  I carefully bent it up a little.

How do you clean truck axle ends?  Toothpick??  dental pick??  Other??  Can or should the axle ends be lubricated??

[Len]

If your cars have different weights, you want the heavier ones up front on long trains. Otherwise you may have what's called "string lining", where lighter cars in the middle of the train pop off the rails.

A tooth pick will work for cleaning out the truck journals. Trucks made with a plastic called "Delrin" don't normally have to be lubricated. But it doesn't hurt to give them a shot of powdered graphite before you reinstall the wheels after cleaning. Do not use oil, it attracts dust and dirt that will build up, creating the problem all over again.

Does the problem 'Old Tyme' car have a problem on both radius curves your using, or just the 9-3/4R? I had a double test loop of Kato track in my old repair shop with both size curves. I found some cars, even with a published minimum radius of 9-3/4, just didn't like the tight curves. But they'd run fine all day long on 11R.

Without seeing it, it's hard to say what's going on with the Atlas car, it might be a damaged truck or axle. You could contact Atlas directly.

James - I saw the 'V' notch problem way too many times, on both N and HO cars, when my repair shop was still open.

Len

[James in FL]

Gordon,

Good cars vs Bad cars;
If all your "bad" cars weigh less than your "good" cars, yeah try to add a little weight to them.
Like I said before I don't weigh cars, I have no idea what the weight is, but enough weight to me is when they don't string line or de-rail easily.
Yes, heaviest cars in front, progressing to lightest cars toward the back of the consist will help string lining.

Shimming;
The only reasons to shim (between the trucks and the bolster) are if your wheel flanges or wheel treads are interfering with the bottoms of the cars.
I have whittled off protrusions from the car floors as well to stop interference with the swing of the truck.
Shims can also help to remove excessive slop in the truck, where the truck is just too sloppy on the bolster and the pin cannot be pressed further in to minimize this.

Good with the NMRA gauge but don't stop just checking and adjusting the wheel sets where appropriate, also check the track gauge in the problem spots.
Double check for rail height difference at your joints.

Trip pins can be a hassle at times bending is OK, but too much bending will have negative effects on auto-uncoupling.
Also, I have broken a few couplers doing this where I was not careful.
If possible, rather than bending, push the pins up into the couplers.

Cleaning axle journals;
Dip a Q-Tip in some iso alcohol and press it into the journal while rotating it, roll it between your fingers.

On your used cars;
Check for, and remove, any built up wheel crud, or replace the wheel sets,
And as Len posted, look for any excessive V notching on the bottoms of the trucks,
Be sure the axle points are seated properly.

[Ken G Price]

On plastic wheel set, you should check for bent axles. On some of my cars that had your problems I finally noticed that the axle was bent and the wheels were at an angle to the track. Caused all kinds of problems. Replaced the wheels and now runs fine.

[GRASHLEY]

Thanks again.  I never considered track radius, but it is a BIG issue for some cars.  They may simply be upper track (11 radius) only cars.  You have given excellent suggestions.  Now I have some work to do!

Gordon