Hornby M7 0-4-4 Conversion

[Dave HarrisParticipant]

Hi.

I have an M7 to convert and I goto manual sheet 3.2.3.(7) for list of parts and goto store and find wheel set + washers x2 but not “coupling rods 7’6″ centers” part no 4752.

PS: Search function seems to not work well!

Can anyone help please?

Best regards

Dave

[Paul TomlinsonParticipant]

Dave, Hello. M7 coupling rods are available from Alan Gibson, part no. 4M84 – I cannot find any in the EMGS Store. You might like to contact John in EMGS Stores directly, in case he can help? Cheers.

[Trade OfficerKeymaster]

Dave

I don’t stock the complete set of AG coupling rods as there are too many and they don’t sell particularly well. The ones I have I inherited when I took over 5 years ago.

The Tech Sheet is obviously out of date as if I had it in stock it would be 4M84. i don’t know when it was changed from 4752 – at least 5+ years ago

I am in the process of starting to go through the manual sheets as there probably parts that are no longer available / I don’t yet stock etc 4M84 is now on that list!

Sorry I can’t be of help on this occasion

 

John

[Dave HarrisParticipant]

The sheet is dated 2007!

[Dave HarrisParticipant]

Many thanks everyone for your help.  I’m placing order as is.

Dave

[John CutlerParticipant]

Hi Dave

The M7 was one of my early RTR conversions and is fairly straightforward; I have done 2. Both suffer from wobbly driving wheels and are due to return to Works to correct! This might also partly explain why they are not particularly good runners compared to others. The possible pitfalls are the pick-ups; wobbly wheels do not help! On mine I think I did not bend them out enough to be in constant contact with the drivers; at least one M7 seems to rely predominantly on pick-up from the bogie! In hindsight I am not sure I agree with the recommendation in the Manual Sheet to allow a  lot of sideplay. That undoubtedly exacerbates the pick-up issue. However, I found that the M7 does not like A4 turnouts at all and complains at A5s. Maybe the answer is to allow slack in the sideplay but fit new pick-ups?

I hope this helps.

Good Luck!

 

 

[Geoff StennerParticipant]

May be worth having a scout around the S4 Forum and find Philip Hall’s writings on this. He seems to have had success with M7 conversions, but I don’t know whose wheels were being used.

4-coupled are always a problem ( to me) unless the bogie carries some weight. There is also a side-play problem if curves are tight as the decision has to be made re allowing bogie play or driving axle play (rear on 0-4-4t and front on 4-4-0). A compromise might be keeping the bogie with a fixed centre pivot but allowing some wheel side play, and also allowing some driving axle side play too, so that the side play is spread along the wheelbase. I have done this in S7 on the equivalent of 1:6 crossings.

[John CutlerParticipant]

One of the M7s has been in Works. I discovered that the bogie did not easily slide across laterally as designed by Hornby. This was partly due to some slight moulding flash on the top of the bogie; this has been reported by others elsewhere. The other cause was the Hornby retaining tube for the bogie. This needs to be positioned high to allow the bogie to hang loose from the body. If the bogie is held tight, it may be free enough to move to allow some vertical movement of the axles but not enough to allow smooth lateral movement of the bogie, as I found.

Correcting this has resulted in a marked improvement in track-holding through (bumpy) turnouts. It still does not like A switches though!

 

 

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