Binds on curves

I have three sets of MTH Premier Madison passenger cars.  All have six wheel, identical (I believe) trucks.  Two of the sets run fine around my O42 curves (minimum for these cars) but one does not.  The wheels on all five cars bind on the curves.  Three of them roll through the curves without too much resistance, but the other two bind a lot.

When I roll a car by hand, I can feel the friction when it enters the curve.  If I push a car and release it, it stops on the curve.

All axles have been oiled and roll freely.  All the couplers swing to the limit of their travel and the trucks swivel freely.   The only thing that is different is the "bad" cars are about ten years older than the others.

Has anyone else encountered this problem? 

John

Original Post

Set a car on it's roof spin the wheels and rotate the trucks when you reach the point where the spinning stops fast look and see what is rubbing.  MTH specifies O-42 or larger for it's 18" cars so they should be able to negotiate your curves without problem. Also, If the axles don't have enough end play within the side frames they will bind in curves.  j

Just a thought, so don’t panic yet: Inspect the diecast trucks to make sure zinc rot isn’t the issue. If you see any swelling, warpage or what look like stress cracks, it’s symptomatic of zinc rot, a manufacturing flaw caused by an impure batch of molten zinc. Relatively uncommon, but it has found its way in Madison passenger truck castings for K-Line and Williams in the past.

I only am suggesting this because you mentioned the cars are 10 years older than the ones that are working flawlessly in your O-42 curves.

If the trucks look fine, then the problem lies elsewhere.

Jim R. 

Thanks, everyone, for your advice.  I examined the cars closely this morning and found something I didn't expect.

The trucks on the old and new cars are not the same!  I assumed they were similar because the side frames look alike, but the design is different and the trucks are not the same length.  The space between the first and third axles on the old trucks is 2.5 "; it's 2.75" on the new.  That discovery leads to another question - shouldn't the shorter trucks be better on tight curves?  My experience is the opposite.

The wheels appear gauged properly, 1.25" to the outside of the wheel set.  I set the cars on the roof, the wheels spun freely and the trucks rotated smoothly.  The end play on the axles varied.  Some seemed pretty tight to me.  I rolled a car into a curve by hand in two directions.  I felt more resistance from the the end with a tight axle.  I'm starting to think insufficient free play might be my problem.

I didn't see any evidence of zinc rot, but a friend with the same cars had the problem.  Two trucks from a five car set were defective.

Now the question is can I adjust free play without damaging the truck?  I suspect the side frames are rather brittle.  I wouldn't want to put much pressure on them.

The ultimate solution would be to build the newer, larger layout I've been thinking about for years.  O54 curves would surely cure the problem.

John

I have a similar set and found that the wiring to the trucks is very short and prevents the truck from properly rotating.  I only run them on a modular layout with really wide curves.  Not worth my time to add one inch of wire to both trucks.  The engine i use to pull requires 72 inch curves.

Liagent 

I guess I was not clear I was not inferring the trucks did not rotate freely but rather when they rotate beyond a point are the wheels rubbing on something? If the wheels don't rub on anything I would look to not enough end play in the axles.  Something I would look at, is the distance between the wheels on their axles on the trucks that don't bind up vs the distance between the wheels  on the trucks that do bind up. Last I would remove the side frame on one side of a truck that rolls free in the curves and on one of the trucks that binds up. Measure the length of the axles that bind vs those that run free. Would be best to have a caliper to do this measurement as a few thousanths can make a difference.   Harbor Freight has a cheap digital caliper that I understand is serviceable .   With a car upside down set a section of track on a truck and roll it it back and forth compare good trucks with those binding.             J

Regarding curve track, I have decided to go with a minimum of O72 track; that way, since I have gone with a Lionel Vision Line Big Boy and AC-9, I have no worries about derailments.  When I got into the hobby in 2014 and knew nothing about curve track, I initially bought a bunch of O36 not knowing what that meant - Homer Simpson DOH!  but can use that for smaller engines.

RickM46

And now it starts.

RoyBoy posted:

I had an early set of MTH premier heavyweight cars that would derail on O-54 curves. Removing the center axle on each truck solved that problem.

Like it!!   I did that on a pair of HO Athearn ALCO PA-s that derailed every time while coming in from the diverging side of a turnout installed at the top of a grade as part of a reversing loop. The front flanges would clear the rails.

Steam Crazy posted:

I have three sets of MTH Premier Madison passenger cars.  All have six wheel, identical (I believe) trucks.  Two of the sets run fine around my O42 curves (minimum for these cars) but one does not.  The wheels on all five cars bind on the curves.  Three of them roll through the curves without too much resistance, but the other two bind a lot.

When I roll a car by hand, I can feel the friction when it enters the curve.  If I push a car and release it, it stops on the curve.

All axles have been oiled and roll freely.  All the couplers swing to the limit of their travel and the trucks swivel freely.   The only thing that is different is the "bad" cars are about ten years older than the others.

Has anyone else encountered this problem? 

John

How about side by side pictures of the offending and good trucks from the bottom?

BOBBYD, here’s the photo you requested.  The offending truck is on the left.   JOHNACTON,  the wheels don’t rub on anything.  I’ll try measuring with a ruler before I buy calipers.

I checked free play again; a couple of wheel sets have virtually none.  I’m leaning toward free play as the culprit.  Does anyone know how to increase free play without damaging the truck?

John

 

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I have had similar problems with 2 tenders new out of the box; for each side frame holding the axles, I was able to loosen the 2 phillips screws holding a side frame and there was enough slop under the screws to allow more end play.

RickM46

And now it starts.

Steam Crazy posted:

I have three sets of MTH Premier Madison passenger cars.  All have six wheel, identical (I believe) trucks...

It may be irrelevant at this point if you have identified the problem as axle end-play. However, the trucks don't look identical to me, so it's not surprising that they are behaving differently.

MELGAR

romiller49 posted:

Looks like not enough testing with the new trucks to advertise as running on 042.

I think he is having difficulty with the older trucks Rod.

Steam Crazy posted:

 The only thing that is different is the "bad" cars are about ten years older than the others.

 

The older trucks were giving me the problem, but no more.  I'm pleased to say I solved it following advice from Bobby and Rick!  I loosened the side frames and tightened them while holding them outward.  All the cars now track smoothly around my O42 curves.

I also re-learned an old lesson - don't jump to conclusions.  I should not have assumed the trucks on all three sets were the same without more investigation.  Thanks y'all!

John

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Ted S


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