Hornby Class 08 poor running

[michaelp]

Hi all, 

I have run in a brand new Hornby Class 08 loco on DC which runs fine, however, since hard wiring a Zimo 645 decoder the loco speed was a bit erratic during acceleration and deceleration, I have adjusted CV56 from the default of 55 to 11 and had partial success, the acceleration and deceleration seem fine now but the starting and stopping in the low speed steps is a bit juddery.

Is there anything else I can try to get the loco running smoothly at all speeds?

Thanks in advance to anyone who can help

Michael

[RobjUK]

I don't use the Zimo decoder, but looking at the manual, the two digits in CV56 have different functions, the proportional and integral parts of the speed feedback.

 

Try adjusting each separately up and down a step or two at a time? The info on page 19 of the manual suggests trying such as 73 for jerky response & one of the items in the motor table uses 91..

 

Also try adjusting the digit values of CV9 separately as again they have different functions.

 

The manual I was using, in case the page numbering is different to yours:

http://www.zimo.at/web2010/documents/MX-KleineDecoder_E.pdf

 

[Marcoblanco]

Hard wire..?? No plug...?? 

[michaelp]

Yes, no plug

[newbryford]

Check the pickups. Not just for cleanliness, but also contact with the wheel.

Both Hornby and Bachmann 08s share a similar design and it's not unusual to find a loco where only 4 out of 6 pickups actually contact the wheels across the excessive  lateral movement of all axles.

 

cheers,

Mick

[michaelp]

Thanks Mick,

I will check the pick ups.

 

Michael

[terryj]

i have one dcc fitted and it will  not even go around curves never mind over points it seems to rock on the 2 driving wheels opened the bottom up and there are brass bushes set into the chassis and the axles run through them so no way of adjusting anything unless i attack the chassis with a dremmel 

[34theletterbetweenB&D]

On ‎31‎/‎05‎/‎2019 at 18:23, terryj said:

...it seems to rock on the 2 driving wheels opened the bottom up and there are brass bushes set into the chassis and the axles run through them so no way of adjusting anything unless i attack the chassis with a dremmel 

Sounds to me like the brass bushes in which the axles run are probably not properly seated and/or free moving in the chassis block casting. (It is quite easy to have this happen if the keeper plate is removed.)

 

If the model is a new purchase and has never had anything done to it, return to retailer for replacement. If this isn't the case, then try some gentle and patient 'fiddly work' to see if the seating of the bushes may be improved.

[terryj]

bushes are rock solid as in can not remove but it runs so bad may just use brute force and ignorance to get them out 

ebay bagain ? so cant return