08 conrod falls apart again!

[w124bob]

Both of my 08's have had connecting rods fall apart, either the plastic crank works loose off the axle end or the very small rivet fails . Neither loco has really had more than an hours running since purchased, typically the tiny rivets disappear meaning a complete new set of conrods needs to be fitted. So my blue example has been de motored to be hauled dead in transit to Doncaster(it's numbered 08307 withdrawn in '77). It's a pity I've had these issues but 3 fails on both loco's means my next 08 will be a Bachmann one.

[The Johnster]

What are you doing to them, Bob?  The only thing I can think of that might cause such a problem is running them around curves tighter than Hornby's recommendation, especially if binding on such curves results in you applying more power to force the loco around.  Is it the end crank or centre that is giving trouble; it has to be because the rods are being forced sideways beyond the design limit.  Some sideplay is essential of course, but there should be no more at the coupling rod crankpins (pins, not rivets, rivets are a different thing and don't have to move) than is allowed at the wheels.  A loco like this should be able to manage a no.1 curve, but you may have flexi track laid to tighter radius.

 

Hopefully they were all under warranty!

[Steamport Southport]

17 minutes ago, The Johnster said:

What are you doing to them, Bob?  The only thing I can think of that might cause such a problem is running them around curves tighter than Hornby's recommendation, especially if binding on such curves results in you applying more power to force the loco around.  Is it the end crank or centre that is giving trouble; it has to be because the rods are being forced sideways beyond the design limit.  Some sideplay is essential of course, but there should be no more at the coupling rod crankpins (pins, not rivets, rivets are a different thing and don't have to move) than is allowed at the wheels.  A loco like this should be able to manage a no.1 curve, but you may have flexi track laid to tighter radius.

 

Hopefully they were all under warranty!

 

I think the 08s are recommended for Radius Two or possibly even Three.

 

These aren't the Railroad version but the new "super detailed" version. Even the Sentinels are for Radius Two and above, and their wheelbase is tiny.

 

 

Jason

[atom3624]

I ended up gluing the crank onto the axle of mine - holds fine and is now OK.

 

Pushing on, it would come off ...

 

Now all is OK.

The superfine detail and skinny coupling rods are a bit of a worry.

 

 

Al.

[truffy]

2 hours ago, The Johnster said:

rivets are a different thing and don't have to move

They only have to be counted. All present and correct?

[vulcan product fan]

3 hours ago, w124bob said:

Both of my 08's have had connecting rods fall apart, either the plastic crank works loose off the axle end or the very small rivet fails . Neither loco has really had more than an hours running since purchased, typically the tiny rivets disappear meaning a complete new set of conrods needs to be fitted. So my blue example has been de motored to be hauled dead in transit to Doncaster(it's numbered 08307 withdrawn in '77). It's a pity I've had these issues but 3 fails on both loco's means my next 08 will be a Bachmann one.

sent mine back to Hornby last year the crank shifted and it threw the rod off  . They put it back together for me .

[w124bob]

Both are of the current super detailed 08 neither have been on anything like sharp curves, only my club layout(Dewsbury Midland) or straight test track both have had cranks part company from the axle end, the crank pins have very little metal on the back . I note that the chassis seems to be designed with quite alot of both vertical and side play, far more than the J15/J36 . The are both over 3 years old and renumbered heavily weathered, my green one threw a crank and has been repaired using tiny amount of super glue on the shifted crank. The blue one had a complete new set of cranks and side rods from of Peterspares fitted one side, it's now the other side that has failed and those crank pins just disappear. 

[atom3624]

Superglue didn't work for me - after 30 minutes' 'shunting' - going round and round a 4th radius circlular 'test track' it came off - I probably didn't leave it to set fully.

 

Ended up with 2-pack Araldite, left over 2 days.

It's been right ever since, but I keep an eye on it.

Just looks 'right' at a scale 15 mph  shunting carriages about!

 

 

Al.

[PMP]

5 hours ago, w124bob said:

Both of my 08's have had connecting rods fall apart, either the plastic crank works loose off the axle end or the very small rivet fails . Neither loco has really had more than an hours running since purchased, typically the tiny rivets disappear meaning a complete new set of conrods needs to be fitted. 

A potential fix for this is replacing the rods with the etched Brassmasters 08 rods. The Hornby rivet as you mentioned may not have much purchase on it due to the coupling rod material.The Brassmasters rivet works superbly and you won’t have any trouble with it. If you’ve not done it already check the original rods that they are true both horizontally and laterally, that can have a large effect on the seating of the rods on the axle end.
The Bachmann 08/09’s appearance can be massively improved with the same conversion.

[Porcy Mane]

I've had a good few Hornby 08's through my hands with broken/ bent coupling rods or sheared pivot pins. The problem has always been poor crank quartering. This can normally be seen with the coupling rods not remaining parallel with the railhead when running. Atoms3642 video above is a good example of this. If the quartering is out the coupling rods will fail prematurely

 

Although I've substituted the rods and cranks  on this loco,  (and they're still not perfect) zip this video forward to 2min 50s as it shows how they should run.

 

 

 

P

[atom3624]

Interesting indeed.

 

I looked more closely at the quartering, and there is a VERY SLIGHT variation with the centre pair cf the outer sets, but I think it is also compounded by the vertical movement permitted in the centre drivers as well.

 

Thanks for sharing.

 

Al.