Hornby class 31 mazac chassis disintegrating

[cheesysmith]

I have over the years got 5 of the Hornby class 31s that have self disintegrated when they have been cheap for repowering some Lima models. It works out cheaper than buying the bits as spares. My question is I know of the expanding chassis, and the weak point in the design caused by this of the chassis ends breaking where they are thin at the ends under the cabs. But has anybody have any evidence of the centre section t fault? I was asking because I have the option of just using the motors and bogies/driveshafts on a lima chassis, or using the entire Hornby centre section in a Lima body. The latter would simplify things as well as maintaining a large ballast weight for haul edge power.

 

I know the reaction in the mazac would eventually cause it all to revert to powder, but I have one of the first Hornby blue 31s, and apart from the ends, there is no sign of anything wrong with the centre section.

 

 

Ps-it may by worth while checking your other Hornby diesel models with the same chassis design. Not just for mazac rot, but I got a new Hornby class 56 chassis to repower a old mainline model, and upon checking fould it was suffering from drooping buffer beam at one end. I think this may have been caused by the design having thin sections at the ends where the cabs are. As a post script, the drooping ends allowed me to cut off the thin sections and just use the centre section and bogies, which fitted perfectly into the old mainline body.

[34theletterbetweenB&D]

I have been doing the very same thing, 'stuffing' my old Airfix Brush 2 (class 30) bodies with s/h 'ends rotted off' Hornby drives to good effect. The most recent Hornby 30 mech I have acquired is the worst I have yet seen, with paint crazing visible in the middle of the cast block where the rubber cushions that hold the motor apply pressure: however it shows no signs of falling apart, runs beautifully.

 

Worst case scenario of the mazak block completely failing is no disaster. I'd assemble the drive line on a slab of 1/8" steel or brass with appropriate holes and cutouts for the pivots and gear towers, gluing the motor on with silicone. The 'self aligning' nature of the drive design means that this doesn't have to be a precision job so even my fumbling fingers and wonky eyesight are up to it.

[Dungrange]

Having recently discovered that one of my Class 31 models from circa 2007 (Dutch 31110) has the dreaded Mazac rot, I'm wondering what best to do with it.  It still runs okay, and as has been said above, the chassis block seems fine.  I've removed the plastic body and the cracks seem repairable (with a little weathering to disguise).  The only part that has noticeably rotted / expanded is the thin part of the chassis under the cab.  At one end, it's probably only expanded less than a millimetre, but at the other end, I'd say its expanded by maybe two millimetres.  Would it be possible to just cut these ends off and glue into the body leaving a small gap between the central part of the chassis and the rotted parts, or would that simply be a waste of time?

[34theletterbetweenB&D]

12 hours ago, AlexHolt said:

... They most likely will keep expanding and falling apart though.

They will, the contaminant causing the failure is distributed throughout the casting. But the rate of failure is slow, so provided that enough clearance has been provided by slightly shortening the end pieces that drop off, there's years in them yet! (My worst specimen is now about a millimetre too long over bogie pivot centres. So provided there was a millimetre clearance each end between the main casting ends and the broken off cab floors when reassembled, that should be good for about twenty years. You should feel you have had your money's worth by then?)

[newbryford]

2 minutes ago, 34theletterbetweenB&D said:

 that should be good for about twenty years. You should feel you have had your money's worth by then?)

 

Hell no - I want it replaced under warranty............................

 

[newbryford]

5 hours ago, AlexHolt said:

 

The worst specimen I ever had was a schools class where one end of the chassis was pointing 45 degrees away from the other end. 20 years is probably fine, by then you would hope it would be retooled or another manufacturer would have made one. This kind of thing wouldn't have happened if Hornby had used higher quality metal. 

 

Mazak rot and model railways isn't confined to Hornby.

There are many recorded instances of other manufacturers suffering the same fate.

[newbryford]

1 hour ago, AlexHolt said:

 

I know but the worst and most documented cases are with Hornby models.

 

Only because of the internet....................

 

They just happen to be the latest afflicted.

 

Try and find a Trix EM1 without mazak rot...................................

[sandwich station]

8 hours ago, AlexHolt said:

 

I know but the worst and most documented cases are with Hornby models.

 

The only Hornby locos I have had trouble with are ones that have been produced since production was moved to China. I have a lot that were made before this time and none have mazak rot.

[37114]

On 19/08/2016 at 11:50, cheesysmith said:

I have over the years got 5 of the Hornby class 31s that have self disintegrated when they have been cheap for repowering some Lima models. It works out cheaper than buying the bits as spares. My question is I know of the expanding chassis, and the weak point in the design caused by this of the chassis ends breaking where they are thin at the ends under the cabs. But has anybody have any evidence of the centre section t fault? I was asking because I have the option of just using the motors and bogies/driveshafts on a lima chassis, or using the entire Hornby centre section in a Lima body. The latter would simplify things as well as maintaining a large ballast weight for haul edge power.

 

I know the reaction in the mazac would eventually cause it all to revert to powder, but I have one of the first Hornby blue 31s, and apart from the ends, there is no sign of anything wrong with the centre section.

 

 

Ps-it may by worth while checking your other Hornby diesel models with the same chassis design. Not just for mazac rot, but I got a new Hornby class 56 chassis to repower a old mainline model, and upon checking fould it was suffering from drooping buffer beam at one end. I think this may have been caused by the design having thin sections at the ends where the cabs are. As a post script, the drooping ends allowed me to cut off the thin sections and just use the centre section and bogies, which fitted perfectly into the old mainline body.

I have 2 Lima/Hornby hybrids,  both were created in the different ways you describe, both ways have their pros and cons but I would always bin  the block:

 

1 loco uses the centre section of the Hornby chassis but the cab ends of the Lima model, the hardest part with this is securing the shell to the chassis,  I ended up creating mounting points in the body and used the original Hornby screws. However the block is disintegrating near the screw holes...

 

The other loco uses the whole Lima chassis frame but the internals of the Hornby model. This is a bit more work and getting enough weight in is difficult but this is the way I would go in the future, one of the main reasons being when I removed the motor from the Hornby block, the whole mazac block shattered into pieces. This is enough to convince me removal of the mazac block completely is essential to any Lima repower.

[pheaton]

23 hours ago, AlexHolt said:

 

I know but the worst and most documented cases are with Hornby models.

I would say the Heljan 47 was just as widely known as the hornbyy 31s

[Ray M]

Agreed, surely the first Heljan 47s  where the king of rot.

[cheesysmith]

As a post script I like say I have since taken the route of using the Hornby bits in Lima chassis. But a question still stands. Is all the failures of these chassis due to mazac rot or a poor design with the thin chassis sections at the cab ends breaking under shock loadings (being dropped etc?).     

 

All mine are packed away due to house move, but has anybody got some of the first chassis with the broken ends who can check if the centre section has disintegrated further? My class 56 chassis with the broken buffer/cab sections have shown no sign of any rot.

 

Just wondering how much is the rot and how much a design week point? And has anybody else had any other Hornby models with a similar chassis design with any problems?

[37114]

7 hours ago, cheesysmith said:

As a post script I like say I have since taken the route of using the Hornby bits in Lima chassis. But a question still stands. Is all the failures of these chassis due to mazac rot or a poor design with the thin chassis sections at the cab ends breaking under shock loadings (being dropped etc?).     

 

All mine are packed away due to house move, but has anybody got some of the first chassis with the broken ends who can check if the centre section has disintegrated further? My class 56 chassis with the broken buffer/cab sections have shown no sign of any rot.

 

Just wondering how much is the rot and how much a design week point? And has anybody else had any other Hornby models with a similar chassis design with any problems?

IMO It is not design, it is 100% contaminated Mazac, the conversion I did still continues to degrade around the screw holes. If it was bad design other later models would be affected and that doesn't seem to be the case. 

[Foden]

Just to throw this in there, I have one of the affected batch (31110) that has had the body removed and replaced onto a later chassis. This was done in advance of any signs of rot as a rescue mission to re-use the loco, rather than a cure after the rot had set in as it were.

 

The chassis was binned after it was relieved of everything useful, but it never showed any signs of rot. This was in 2017.

 

The model in question was dry stored in its box from new, having come out only a few times for a few minutes, I’m wondering if these storage conditions played a part in its condition.

[34theletterbetweenB&D]

The favourable storage condition is 'kept warm', as in comfortable room temperature. In cold conditions the change to the crystalline structure of the alloy which the contaminant promotes is energetically favoured. All very imprecise, but I will leave it to the enthusiast wanting better information to plunge into a literature search!

[tomparryharry]

One remedy you might like to try, is to make up a putty window mixture which should be oil-heavy. The linseed might well neutralise the oxygen propagation properties of the alloy. Mazak should have a high alloy content of copper, but I know the scrap metal business, it's most likely old motor-car batteries.....

 

I do wonder if there is a market for having 'new' chassis eights cast off in something like a tungsten alloy. It can be done, and there are quite a few small- batch foundries still going strong.  I'd guess that the big producers will not take kindly to this, having better parts made....

 

Cheers,

Ian.

[Dungrange]

On 24/12/2019 at 11:23, newbryford said:

Hell no - I want it replaced under warranty............................

 

Mick - so do I.  The only problem is that the warranty on my toy train ran out about 12 years ago.

 

On 23/12/2019 at 22:25, AlexHolt said:

Its been a while since these were widely talked about as being problematic. If I remember correctly people were filing them back so they didn't push against the bodies and create cracks on the body. Then covering any broken off or cracked parts in super glue. They most likely will keep expanding and falling apart though.

 

Alex - yes, I had thought I'd been lucky and got a model from a 'good' or uncontaminated batch.  Ten years on from purchase and the model showed no signs of any expansion or cracks on the body.  Obviously mine just took longer to fail than those who were reporting issues a decade ago. 

 

On 24/12/2019 at 11:20, 34theletterbetweenB&D said:

They will, the contaminant causing the failure is distributed throughout the casting. But the rate of failure is slow, so provided that enough clearance has been provided by slightly shortening the end pieces that drop off, there's years in them yet! (My worst specimen is now about a millimetre too long over bogie pivot centres. So provided there was a millimetre clearance each end between the main casting ends and the broken off cab floors when reassembled, that should be good for about twenty years. You should feel you have had your money's worth by then?)

 

That's the sort of approach that I suspect I'll take, but I'm not in any rush.  The chassis block itself shows no issues and looks nothing like the Heljan example up thread.  I have to admit that I was unaware of similar issues with the Heljan Class 47, but then I don't own any, so clearly didn't pay any attention to similar reports. 

 

2 hours ago, Foden said:

Just to throw this in there, I have one of the affected batch (31110) that has had the body removed and replaced onto a later chassis. This was done in advance of any signs of rot as a rescue mission to re-use the loco, rather than a cure after the rot had set in as it were.

 

The chassis was binned after it was relieved of everything useful, but it never showed any signs of rot. This was in 2017.

 

The model in question was dry stored in its box from new, having come out only a few times for a few minutes, I’m wondering if these storage conditions played a part in its condition.

 

This is the same model that I have (31110) and interestingly, when I last looked at it (probably in 2017 or maybe even 2018) there were no issues with mine either.  Perhaps our models were from the same batch, but you removed the chassis from your model in time - I didn't.  Like you, mine has spent most of its life stored in its box and only sees occasional use when I take it to the club for a run, so storage conditions may play a part in the life of the model.  Of course I'm also assuming that those batches with a higher proportion of contaminant in the alloy will degrade faster than those which may have been less contaminated.

 

I'll probably just leave the body off for now and leave this as one of these 'to do' tasks, that at my current rate of progress may be several years away. The alternative is of course to make a small micro layout / diorama of a scrap yard and dedicate this locomotive to the items awaiting the cutters torch, although I don't think 31110 was still in Dutch livery when it met that fate.

[kevinlms]

3 hours ago, Foden said:

Just to throw this in there, I have one of the affected batch (31110) that has had the body removed and replaced onto a later chassis. This was done in advance of any signs of rot as a rescue mission to re-use the loco, rather than a cure after the rot had set in as it were.

 

The chassis was binned after it was relieved of everything useful, but it never showed any signs of rot. This was in 2017.

 

The model in question was dry stored in its box from new, having come out only a few times for a few minutes, I’m wondering if these storage conditions played a part in its condition.

I'm no chemist, but it seems to me that there was a problem with the recipe. It is bound to affect the thinnest parts of the casting first.

I can't see it improving with age, as it isn't like a quality wine.

By all means experiment, but long time, the problem is going to get worse, not stop. it's a chemical reaction. 

[34theletterbetweenB&D]

1 hour ago, tomparryharry said:

...I do wonder if there is a market for having 'new' chassis blocks cast off in something like a tungsten alloy. It can be done, and there are quite a few small- batch foundries still going strong.  I'd guess that the big producers will not take kindly to this, having better parts made...

Then again, no objections heard to Peter's Spares supplying cast brass replacements for the T9's physically weak motor clamp/worm cover, or moulded parts with which to reassemble failed split axle wheelsets. It probably needs a dealer with a good estimate of the demand to get a decent price for a batch run of such a supply of replacement parts.

 

My suspicion would be that the demand falls off rapidly with the complexity of using the replacement part. A relatively simple 'remove old, screw on new' or 'remove wheelset, replace broken part, replace wheelset' falls into general 'I can do that' territory. Completely stripping the failed chassis block casting and restoring all the parts for full functionality might well limit demand? But it would be a neat solution if it could be brought off.

 

The other fly in the ointment I would anticipate is another manufacturer bringing out a superior Brush 2 (30/31). There's enough wrong with the current Hornby model's appearance for a competitor to improve on, and the limited number of subjects in BR diesel traction means that a fifty years plus in service multiple livery options unit is going to be picked up sooner or later. That too might well put a crimp on potential spares demand, as superseded Hornby models become more readily available s/h.

[tomparryharry]

11 minutes ago, 34theletterbetweenB&D said:

Then again, no objections heard to Peter's Spares supplying cast brass replacements for the T9's physically weak motor clamp/worm cover, or moulded parts with which to reassemble failed split axle wheelsets. It probably needs a dealer with a good estimate of the demand to get a decent price for a batch run of such a supply of replacement parts.

 

My suspicion would be that the demand falls off rapidly with the complexity of using the replacement part. A relatively simple 'remove old, screw on new' or 'remove wheelset, replace broken part, replace wheelset' falls into general 'I can do that' territory. Completely stripping the failed chassis block casting and restoring all the parts for full functionality might well limit demand? But it would be a neat solution if it could be brought off.

 

The other fly in the ointment I would anticipate is another manufacturer bringing out a superior Brush 2 (30/31). There's enough wrong with the current Hornby model's appearance for a competitor to improve on, and the limited number of subjects in BR diesel traction means that a fifty years plus in service multiple livery options unit is going to be picked up sooner or later. That too might well put a crimp on potential spares demand, as superseded Hornby models become more readily available s/h.

Quite right. The discussion does pivot about demand. From a personal viewpoint, I don't have a demand, not being a D/E modeller. The technical problems do interest me, and I do sympathise with those modellers afflicted with this problem. What I don't like is the philosophy of "pile 'em high, sell 'em even higher". 

 

I'm rather releived it's not me.

 

Ian.

[kevinlms]

7 minutes ago, tomparryharry said:

Quite right. The discussion does pivot about demand. From a personal viewpoint, I don't have a demand, not being a D/E modeller. The technical problems do interest me, and I do sympathise with those modellers afflicted with this problem. What I don't like is the philosophy of "pile 'em high, sell 'em even higher". 

 

I'm rather releived it's not me.

 

Ian.

The 'pile 'em high, sell them even higher', is NOT the real issue with these particular models. Otherwise ALL models from the same factory would have the mazac rot, perhaps on a random basis. But they don't, so it is a question of quality control - in this case of the castings. From all accounts, there was a large batch of models with the same fault.

 

It doesn't affect me either, since I don't have any of the faulty models. A friend of mine does and it isn't a question of storage, as someone else raised earlier. My friend has other models from Hornby of the same age and they are stored side by side with the Class 31 in the original packaging, with none of the others showing any sign of the rot.

[Georgeconna]

chassis here: https://www.ebay.co.uk/itm/153607542327

 

Replaced my affected Loco and it is back in action. Still Annoyed having to do this however at my expense.

[tomparryharry]

3 minutes ago, kevinlms said:

The 'pile 'em high, sell them even higher', is NOT the real issue with these particular models. Otherwise ALL models from the same factory would have the mazac rot, perhaps on a random basis. But they don't, so it is a question of quality control - in this case of the castings. From all accounts, there was a large batch of models with the same fault.

 

It doesn't affect me either, since I don't have any of the faulty models. A friend of mine does and it isn't a question of storage, as someone else raised earlier. My friend has other models from Hornby of the same age and they are stored side by side with the Class 31 in the original packaging, with none of the others showing any sign of the rot.

Hi Kevin, I'm sorry to hear about your friends predicament. Happily for me, I do indeed know how to make Mazak; material composition, quality control, that sort of thing. My point is that your friend has probably paid top dollar for the model, and his/her disappointment is probably palpable.  From my perspective, I'd like to know how to resolve the problem. As I've said, I'm not a D/E modeller. but if it happened to me, how would I resolve it?

 

Cheers,

Ian.

 

PS. I should also say the phrase "pile 'em High, sell'em higher is a sad situation that arises when profit overtakes quality.

[kevinlms]

1 minute ago, tomparryharry said:

Hi Kevin, I'm sorry to hear about your friends predicament. Happily for me, I do indeed know how to make Mazak; material composition, quality control, that sort of thing. My point is that your friend has probably paid top dollar for the model, and his/her disappointment is probably palpable.  From my perspective, I'd like to know how to resolve the problem. As I've said, I'm not a D/E modeller. but if it happened to me, how would I resolve it?

 

Cheers,

Ian.

 

PS. I should also say the phrase "pile 'em High, sell'em higher is a sad situation that arises when profit overtakes quality.

I'm not so sure the problem can be fixed.

 

After all, if the floor plan of a car rots out, can it be economically repaired? You might be prepared to have a go - providing you have the tools & materials to attempt a repair (MOT issues ignored for discussion purposes). But if you have to pay someone to come up with a solution and spend a fair bit of time on the problem, unless the car is something special, is it worth it?

 

Actually, he didn't pay top price for it, as it was from a prominent discount house. But if it had come from somewhere that sold without discount (or the notorious Australian markup!), then he would have had exactly the same issue!

[tomparryharry]

3 minutes ago, kevinlms said:

I'm not so sure the problem can be fixed.

 

After all, if the floor plan of a car rots out, can it be economically repaired? You might be prepared to have a go - providing you have the tools & materials to attempt a repair (MOT issues ignored for discussion purposes). But if you have to pay someone to come up with a solution and spend a fair bit of time on the problem, unless the car is something special, is it worth it?

 

Actually, he didn't pay top price for it, as it was from a prominent discount house. But if it had come from somewhere that sold without discount (or the notorious Australian markup!), then he would have had exactly the same issue!

There you go Kevin; my point exactly.