Advice on fixing a poor running Hornby Class 121

[Menelaus]

I have a Hornby Class 121 Bubble Car which ran beautifully straight from the box so I expected my usual running in protocol to be a doddle...

 

...but after about 10 minutes at half speed its performance deteriorated dramatically. If it was a car you'd say it was on kangaroo petrol. Hesitant, jerky movement then acceleration more suited to a scalextrix track before slowing dramatically to a crawl and then repeating the performance.

 

Track was clean and other locos ran faultlessly. Taken it apart and no obvious faults visisble tho' as the motor itself seems to be sealed couldn't check that thoroughly but the gear train and pick ups looked fine. Can't return it because between running it from the box and the running in session, I superdetailed the body and underframe...

 

Anyone had similar problems and found a solution?

[Sc59401]

I have a few examples of its Lima ancestors and this problem is usually caused by wheels needing cleaned. Not sure whether or not the Hornby version suffers as much but it's worth a try.

[Brinkly]

Are the pick ups set properly as that might also contribute to poor running? As John said the old Lima models had the ability to pick up dirt on the wheels like nobody's business!

 

Regards,

 

Nick

[Oldddudders]

I have always found that poor running of the type you describe needs to be tested when pickups are not an issue. Thus I have some wander-leads, with a small croc-clip on each end, and invert the recalcitrant loco in a Peco foam cradle, attaching the leads to whatever pickups are on offer, and the track. Then using the ordinary throttle, you can check the behaviour of the motor and drive train. If they are smooth and controllable - it's pick-ups. I echo those who say Lima wheels need cleaning much more often than those of other manufacturers.

[Guest 40-something]

Hi Folks

 

I follow the route that OldDudders takes, a set of wander leads is invaluable. The other night I stripped down a lima 117 that I bought on ebay a while back as a non-runner for under a tenner and found that whilst it didnt run on the rails, clipping the wander lead to the brush keepers on the motor bogie saw the motor run good.

 

A strip down of the wheelsets on the dummy and power bogies uncovered the problem, filthy pick-ups. A quick clean-up of the pick-ups and wheels with meths saw the chassis running great. I stripped the motor down afterwards and cleaned it all up as well.

 

So, i would say first port of call is the pick-ups!

 

 

[steveb860]

The op clearly states this is the Hornby version which comes with a new motor and better wheels, and not the old Lima version.

I too have one of these new Hornby bubble cars, and it too runs like a dog, even more so under DCC.I also had a 101 DMU with the same motor and that was awful.And yet I hav a 153 which I believe has the same motor, and it runs beautifully. Havn't had time to take an in depth look at it yet, but have considered buying an old Lima 121 chassis, and re-motoring with a model torque replacement motor.

[delticman]

You don`t mention if the poor running occured after fitting a decoder. My Hornby Class 121 ran beautifully straight out of the box but after fitting a Bachmann 3-function decoder I was dismayed to find it ran like a dog!

I had the same trouble with the Hornby (also re-motored ex Lima) Class 59.

Cured both of them by fiddling about with CV`s and finally settled on adjusting the values thus :- CV53 = value50; CV54 = value20; CV55 = value55.

Both are now smooth and responsive. I have never had to adjust CV`s apart from address on any other locos.

I hope this may help.

[Simon_R]

Have you contacted Hornby? I've always found their service departmemnt very helpful. The fact you've chosen to detail it should have no effect on the warranty status if your after a repair rather than a replacement. If the motor or circuit board has a fault (a faulty capacitor could cause strange running) they should replace it under warranty

[LocustBeetle]

Hi, sorry I cannot offer much useful advice - just sympathise.

I too have a kangeroo fueled Hornby 121. The lima one I have is a much better/smoother runner - The Hornby version(non decoder)is that jerky it seems to lift one set of wheels on the powered bogie if running powered end first. I tried cleaning then testing for a loose /poor connection off the track and found nothing amiss, the only thing I noticed was a lot of "slack" on the power bogie pivot.

I added some weight above the non powered bogie and things did improve, its awaiting further investigation........

[steveb860]

You don`t mention if the poor running occured after fitting a decoder. My Hornby Class 121 ran beautifully straight out of the box but after fitting a Bachmann 3-function decoder I was dismayed to find it ran like a dog!

I had the same trouble with the Hornby (also re-motored ex Lima) Class 59.

Cured both of them by fiddling about with CV`s and finally settled on adjusting the values thus :- CV53 = value50; CV54 = value20; CV55 = value55.

Both are now smooth and responsive. I have never had to adjust CV`s apart from address on any other locos.

I hope this may help.

 

Hi Delticman and Menelaus, and welcome to the forum.

I mentioned running was "even more so after fitting a Decoder"(of which i have tried Lenz silvers, TCS and a Zimo,none of which helped. However I shall try your suggestions for CV setings when i find time.So thanks for those.

It would seem these Hornby motors are rather hit and miss as to their quality.Hopefully someone out there has a difinative fix for them.

[Menelaus]

Gentlemen - thank you all for your helpful comments. I checked the pickups at the time and they were fine, similarly the wheels, but I think I have a solution.

 

The problem occurred whilst running under analogue control, but it was always the intention to chip it, so today I did. Now I know received wisdom is "if it doesn't run properly on analogue, adding a chip won't improve things" and they were dead right, it didn't!! I had 2 chips available, one Lenz and one Bachman. As the Lenz would need hard-wiring, I chose the Bachman. No improvement, in fact I think it was worse. So I read the data sheet. And there it was "Back EMF", and I seem to remember reading something about how it affected these Hornby motors.

 

So I set about reprogramming the relevant CVs 53, 54 & 55. After some experimentation the best combination was CV53 set to 10, 54 to 16 and 55 to 60. With the throttle set to 126 speed steps, the running is much improved and will now crawl along on 1/126. It's not as smooth as my benchmark (a Heljan Hymek) so i'm going to try some more combinations including the one suggested by Delticman.

 

I'll let you know how I get on. Meantime, thank you all for taking the time to reply to a first timer.

[Brinkly]

Meantime, thank you all for taking the time to reply to a first timer.

 

That's alright, we all started with 1 post at some point!

 

Regards,

 

Nick.

[Gwiwer]

A swift count suggests I own eight of the Hornby 121 bubblecars plus a class 101 triple with the same wheels, pickup and motor unit I believe. Almost all at some time have adopted the "kangaroo" method of propulsion. Some have also slowed to a very modest branch line speed after only a few hours (or less) of run time.

 

The wheels and pick-ups were tested and found to be in good order. The motor runs evenly to full speed when the units are in the test cradle. The track is clean.

 

However these units all suffer from having all the weight at one end on a motor bogie which is rather freely suspended and has been observed to do its own little dance at times when the units are in motion. That is sufficient to cause interruptions to even power pickup.

 

The wheels are not Lima brass ones but are Hornby bright metal versions of the same with Lima back-to-back dimensions which does power pick-up no favours.

 

I suggest two solutions. One is to try to ease the wheels out a little to get the back-to-backs closer to modern standards. The other is to add some ballast weight where ever you can over the trailing bogie to balance the cars and reduce their tendency to bounce. This latter alone has improved performance of my units so fitted; a little lead is stuck beneath the floor as close to the bogie as possible since there is nowhere inside to place it without it being visible.

[Pete Bevan]

 

So I set about reprogramming the relevant CVs 53, 54 & 55. After some experimentation the best combination was CV53 set to 10, 54 to 16 and 55 to 60. With the throttle set to 126 speed steps, the running is much improved and will now crawl along on 1/126. It's not as smooth as my benchmark (a Heljan Hymek) so i'm going to try some more combinations including the one suggested by Delticman.

 

 

I have been experiencing the same problems as above and tried both the Back EMF settings by Delticman and Menelaus and found the former (quoted above) to sort out my issues the best.

 

Thank you both of you, I'm still just getting into DCC, so I am on catchup when it comes to the finer details of programming!

[JZ]

Haven't looked at the Hornby motored 121. But my Lima one has had the trailing axle pick-up removed and replaced with PB wipers both sides and some extra weight over it. As has been mentioned Lima wheel can attract dirt just by being Lima wheels. At some point I will replace with Ultrascales.

[mark.lovely]

I've got 3 Hornby class 121's and a Lima class 117 that I've re motored with the new Hornby motor and they are all terrible at slow running. After trying out several decoders I've found that it's not the motor. It's the back emf function on the decoders that's causing the problem.

Finally this week I've sorted it. Fit them with DCC decoders that enable you to switch off the back EMF function and you'll see the jerking and poor slow running has gone.

I can recomend the Gaugemaster Opti 25 decoder.

After intalling the chip, set CV 61 to 0. This switches off the back EMF, then push the throttle to around 4 and you'll see a major improvement.

 

If your not happy with this you can always reset the decoder by setting CV 8 to 8.

 

I'm now running all mine problem free on the layout rid of back EMF!

[Stevelewis]

I have only just read this thread, but one thing that occurs to me is I believe that there is no mention of removing any capacitors when fitting decoders, I learned that when I started to fit decoders back in the last century ( well 1998) that some items responded poorly to control settings and did not perform as required, the simple act of locating and snipping off the capacitors eliminated around 95% of the problems.

 

Having fitted decoders to many locos over the years ( I stopped counting at around 400) the first thing I do is remove any capacitiors.

[andythebud]

Gentlemen - thank you all for your helpful comments. I checked the pickups at the time and they were fine, similarly the wheels, but I think I have a solution.

 

The problem occurred whilst running under analogue control, but it was always the intention to chip it, so today I did. Now I know received wisdom is "if it doesn't run properly on analogue, adding a chip won't improve things" and they were dead right, it didn't!! I had 2 chips available, one Lenz and one Bachman. As the Lenz would need hard-wiring, I chose the Bachman. No improvement, in fact I think it was worse. So I read the data sheet. And there it was "Back EMF", and I seem to remember reading something about how it affected these Hornby motors.

 

So I set about reprogramming the relevant CVs 53, 54 & 55. After some experimentation the best combination was CV53 set to 10, 54 to 16 and 55 to 60. With the throttle set to 126 speed steps, the running is much improved and will now crawl along on 1/126. It's not as smooth as my benchmark (a Heljan Hymek) so i'm going to try some more combinations including the one suggested by Delticman.

 

I'll let you know how I get on. Meantime, thank you all for taking the time to reply to a first timer.

 

It's been 7 years since this post and it is still helping me. The other day I ran my class 121 that I had chipped at the time when I bought it and forgot that it stuttered in one direction and would suddenly just shoot off beyond the speed setting. Last night I adjusted the 3 CVs above and it runs smoothly. So thankful to those who contribute their knowledge to this forum.