So how did you get the wheels on the Pacer?

I tried and failed with an Ultrascale pack in OO . I've been driven into a Branchlines chassis instead . However I do have a second Pacer to sort out, so I still have an interest in fitting the Ultrascales somehow

Which ones? Front or back?

The front ones you need to assemble in the motor - so they need to be split, hence why I bought the DIY kit anyway. The rear one is going to need the pin point bearing holes opening up a fraction - I'll probably try and get a reamer for this purpose. I can see why it is tight, it's the fact that the axle is longer.

Which ones? Front or back?

The front ones you need to assemble in the motor - so they need to be split, hence why I bought the DIY kit anyway. The rear one is going to need the pin point bearing holes opening up a fraction - I'll probably try and get a reamer for this purpose. I can see why it is tight, it's the fact that the axle is longer.

I started with the back ones . I didn't get much further..... . It was trying to open up the holes and get the things in somehow that went wrong. There seems to be a boss on the back of the wheels which fouls the moulding supporting the axle . I tried cutting down the moulding instead of thinning it , and wrecked the thing. At that point I gave up. Mind you this was in OO. It may be Ultrascale have designed the wheels in question for EM and simply supplied them for OO with different axles, ignoring the fact that the Back to Back is narrower - result the axle unit moulding is too wide to fit between the bosses on the back of the wheels in OO

Gouing the Branchline replacement chassis route generates a replacement axle unit moulding as a discarded spare , so I can have another go

Well I've trial fitted the rear ones... I've not got a back to back gauge so I've roughly measured the back to back. It is then a case of filing down the centre supports in the rear truck to clear the bosses on the wheelset. I can understand why this is an issue on the OO wheelset - it was tight and I've had to take off about .5mm to get the wheels to spin freely, but spin they do!! And the outer frames don't need adjusting at all!

The Pacer is now balancing precariously on OO track - time to sort that Exactoscale order I think!!!

Had a conversation with Dave at Ultrascale this morning - seems I've got my back to back a little tight, as actually I should need to file a little from the outside faces - I'll wait until I get the back to back before I do any more with the wheelsets.

We also discussed the OO and EM wheelsets. The wheels are different on each kit, and designed so that the boss on the wheels fits around the boss on the truck perfectly - so in OO and EM they should just drop in (well placed in and then the side plates gently prising apart at the same time so the wheel still sits around the centre boss - fiddly but do-able).

A bit late now but if you needed to drill out pinpoints a little then the freebie from Ultrascale - 26mm Pinpoint axle Bearing drill http://www.ultrascale.co.uk/mis0001.php# is rather good.

While waiting for Ultrascale you can you your digital calipers to set the B2B, the cheap ones from Aldi etc will at least get you to 17.7mm and they do show 2 digit and mine were pretty much spot on to the exactoscale jig. Which B2B are you going to use? 17.67mm or 17.75mm? Exactoscale sell both as well as something like 17.87mm for S4.

I hope there is a bit of compensation movement at one end of the chassis as its a massive wheelbase.

Which B2B are you going to use? 17.67mm or 17.75mm? Exactoscale sell both as well as something like 17.87mm for S4.

 

I hope there is a bit of compensation movement at one end of the chassis as its a massive wheelbase.

Aaaaahhhh this is making things sound complicated. I thought there would be one standard - get a b2b and set them up - that's three standards you've quoted!!! Which one do I go for?! Not something to drop on a newby - I'm sure I can get it to work but that does sound off putting - I'm an engineer by back ground so like precision, but don't like ambiguity!

As for compensation the Pacer chassis drive wheels are fixed, but the trailing truck is pivoted and has a degree of movement up and down too so I'm fairly confident. The other thing to bear in mind is this is just an experiment really - to see if I like it. I'll be buying a length of EM and a length of finescale OO track to play with as well to determine track standards for future projects

One thing I do like is the fidelity of the tyres and flanges on the P4 wheels - beautiful to a man used to RP25 and coarse OO

Aaaaahhhh this is making things sound complicated. I thought there would be one standard - get a b2b and set them up - that's three standards you've quoted!!! Which one do I go for?! Not something to drop on a newby - I'm sure I can get it to work but that does sound off putting - I'm an engineer by back ground so like precision, but don't like ambiguity!

 

One thing I do like is the fidelity of the tyres and flanges on the P4 wheels - beautiful to a man used to RP25 and coarse OO

Hiya James,

Don't worry too much about being quoted three different numbers. They are, in order:

17.67 - the MINIMUM acceptable BtB under P4 standards

17.75 - the MAXIMUM suggested BtB under P4 standards

17.87 - the BtB for S4 modelling, which if you hadn't heard of the difference is a true scaled down set of dimensions.

Although you've seen the superb visual benefits of P4 wheels, there are still slight variations from 1:76.2 dimensions for practical and manufacturing purposes. There are a few cracking S4 layouts out there - google Ray Hammond's Buntingham for one - but it is very much the hair-shirt end of the Scalefour Society.

The Society Digets on track standards recommends going to the higher end of the BtB as this will give less slop through pointwork, and a generally better ride. I'd go with the 17.75 one if I were you.

However, the main thing (as with much of P4 modelling) is that once you've made your choice and bought a gauge, it doesn't matter if it is expressed to four decimal places, it Just Works.

FWIW, my BtB for P4, as scribbled on a corner of my workbench, is 17.78mm, as measured on a digital mic. That's just what the Society gauge was when I bought it years ago, and that's what i;ve used ever since!

HTH de-mystify things,

Flymo

A bit late now but if you needed to drill out pinpoints a little then the freebie from Ultrascale - 26mm Pinpoint axle Bearing drill http://www.ultrascale.co.uk/mis0001.php# is rather good.

 

Seconded... An excellent piece of kit for the job - which is one that you don't realise is needed until you see how much RTR and kits can vary from each other in this vital dimension.

Flymo

Thanks chaps. I've placed my order with Len at Exactoscale (a friendly and helpful chap - explaining the b2b differences too!) Went for the trackwork (just fast-track this time round as I'm learning and impatient!!) and the gauges and b2b. Also got some of the OO fast-track to determine what to use on future projects as I have so much OO stock.

I think I really need wooden sleepered f/b rail for Rose Hill but to get me going the concrete stuff will do to try things out.

??75 worth of stuff though so I'm thinking very very hard about whether the sound and DCC for Chrimbo option might be another slippery slope too far!!! I've enough expensive hobbies as it is (mountainbiking, web-design, photography, video editing and playing my guitar!).

Hehe sorry for dropping the numbers on you, it does show though that even P4 allows some tolerance in the numbers and that you can just set calipers to 17.7mm to get it running while you await the B2B. Glad Len and Flymo gave you the exact details though.

Slop in the trailing sounds like it should give you the required movement, it was a complete rigid system I was worried about.

Wait till you see the wheel to track interface and the nice 3/4 view you can do .

Rose Hill is going to have no backscene at the buffer stop end so you'll be able to get a nice view down the track

Thanks Craig!!

I'm looking forward to all the stuff arriving next week. I don't think this will be a complete P4 conversion - too much expensive OO for that - but we'll take things as they come and see where it leads me!