Hornby Class 31 Potential new problem

[Dan Griffin]

After the problems faced with certain Class 31's that been well documented, I fear I may have stumbled upon another problem that may have  potential to damage more locos.

 

I have two 31's in my fleet which seem to be effected at the moment. the Rail express 31130 coal sector loco and the 31/4 FM rail version.(both the same body shell version with headlight) these were not effected by the chassis issues. I also have a 31111 but have yet to check this.

 

the problem I have found is that the plastic used inside the body shell has become very brittle. I removed the body's to service these locos and fit sound chips and have discovered the plastic  that holds the screw thread in place has literally crumbled away. its virtually turned to dust leaving the brass nut to fall loose.

 

the body securing screws have not been over tightened and the locos have been stored indoors in ambient normal  household temperatures.

 

I now have to try and work out how to secure the body's to the chassis now.

 

check your 31's if you have these versions.

[cravensdmufan]

Checked my 31 130 and it's OK.    268, 439 and 110 OK as well.

 

Will keep an eye on them though, so thanks for the information.

[The Johnster]

This could result from using mineral based lubrication if it's got on the plastic; it won't do nylon gears any good either.  If this is the case, I would remove the bodyshell and clean the chassis with 'electronic/switch/PCB' type aerosol spray; cheap stuff from a market stall or pound shop will be fine*.  The force of the spray will drive the old lube out, and all you need to do then is leave the chassis until the cleaner has all evaporated off, which you can tell by sniffing the chassis, but do this on your own or you may have some odd questions to answer.   Then lubricate afresh at the points specified in the owner's manual sheet (download from H as pdf if you haven't got one), put the top back on, and be amazed at how quiet and smooth your loco now is (hopefully!). Use an organic lubricant; your model shop, even online, can recommend one and it is worth buying hypodermic syringe to apply it.  Use the least amount you can get away with.  

 

My apologies if this is about grannies and eggs.  Brittle plastic will not become less brittle over time, but this procedure will prevent matters becoming worse.  Use the spray cleaner to wipe the inside of the bodyshell down with absorbent tissue if there is any sign of old lube on it anywhere; the loco will need particularly careful handling in future, but the running should not be affected.

 

Don't use WD40!

 

 

*while you're in there, pick up a tube of cheapo superglue.  This is great for fixing parts together that you might want to dismantle at some time in the future, such as loco bodies which have lost the chassis fixing screws.  We have all sacrificed loads of these to the Carpet Monster.  The glue will hold the body on, then when you need to take it off again a twist with a screwdriver blade will break the bond without damaging anything.  You will need to scrape the residue off body and chassis and start again, but it's much less frustrating than trying to find a tiny screw, and in any case yours don't have threads to screw into.

Edited August 21, 2020 by The Johnster

[34theletterbetweenB&D]

11 hours ago, Dan Griffin said:

... I removed the bodies to service these locos and fit sound chips and have discovered the plastic  that holds the screw thread in place has literally crumbled away. its virtually turned to dust leaving the brass nut to fall loose...

There are several potential causes here.

You seem aware of the thermal cycling problem, the differential expansion rates of the metal and polymer can see the 'captive insert' nut break up the moulding.

I have (unproven) suspicions of machining residues on the 'captive insert' degrading the polymer; much the same effect as the mineral oil mentioned by @The Johnster. Now, if it is such residues on the brass then the effect will be highly localised to the moulding around the brass, the rest of the body shell should be good. If it is 'another contaminant' such as mineral oil, then I would expect more than just the specific mouldings around the nuts to be affected, but a pattern of embrittled plastic in the body shell, dependent on where the mech has distributed the stuff.

 

For comparison with your 31111, ( R2571?) I picked up one of these last year, and it is perfect in all respects.

 

11 hours ago, Dan Griffin said:

...I now have to try and work out how to secure the bodies to the chassis now...

Really simple 'cheap and dirty' method: I would use a really thin smear of blu or black tack just  2 or 3 mm deep on the bottom edge of the chassis block side on the centre line. The body is a very snug fit, and that will 'hold' in normal handling, easily separated with a scalpel blade.

[The Johnster]

Pound shop glue is more secure.  
 

 

 

Marginally... 

[stewartingram]

Bathroom sealant used sparely is good at holding things on, and makes them easily removable.

[adb968008]

Ive seen a couple like this on ebay recently.

 

i’d suggest using double sided tape between the chassis block and body shell, using the right amount holds it strong enough to lift, and you can still take it off if needed.

[boxbrownie]

If there is just enough stump left of the plastic column you could try fitting a interference fit brass tube over the stump and filling the tube with plastic filler and reinserting the brass screw “thread nuts”.

[The Johnster]

No, that sounds far too much like proper engineering for a bodger like me.  Some good loco body fixing ideas though.

[boxbrownie]

21 minutes ago, The Johnster said:

No, that sounds far too much like proper engineering for a bodger like me.  Some good loco body fixing ideas though.

  Fair enough but it’s the kind of solution I love to apply.....great sense of accomplishment when your “bodge” turns out to be a better solution than the original 

[The Johnster]

You are right.  I am sometimes amazed at what can be done with whatever is to hand. a bodgerigar, and a bit of lateral thinking, but I am just as often disappointed.

Edited August 22, 2020 by The Johnster

[railroadbill]

Having read  this, I took the body off my 31 111. No problem with mazak  or crumbling plastic.  However one of the 4 body securing posts had sheared off. There's a little external moulded spline that stopped it turning so the screw came out ok, fortunately.  I've just glued it back on.

 

 

 

 

[rob D2]

It’s not a new thing,

had one years back that had three shattered nut holder column things.

 

Hornby seriously deserve someone to come along and do a 31. As much as I like the running of mine , it was apparent with 31102, that they have made zero effort to upgrade the original over 15 years 

[Gilbert]

2 minutes ago, rob D2 said:

It’s not a new thing,

had one years back that had three shattered nut holder column things.

 

Hornby seriously deserve someone to come along and do a 31. As much as I like the running of mine , it was apparent with 31102, that they have made zero effort to upgrade the original over 15 years 

Decent wheels would be nice as well.....

[34theletterbetweenB&D]

4 hours ago, rob D2 said:

...Hornby seriously deserve someone to come along and do a 31. As much as I like the running of mine , it was apparent with 31102, that they have made zero effort to upgrade the original over 15 years 

Given the current round of competing 'upgrade' models of BR diesels underway, pretty sure you will get your wish. After all it is a long lived class with multiple liveries. Should it happen, I hope the new version will correct the major flaw of the Hornby model, the incorrect cab side window position; which makes this model unacceptable in my opinion (no matter how superb the workmanship of a nine-pound note, it's always, only and ever a wrongun...).