wheel question for N&W j class 4-8-4

[Andy Fekete]

i may get a spectrum n&w j kitbashed into a CNR U4-a class northern but the u class had 77 inch white-walled drivers and the j class had 70 inch drivers. does anybody know if i could replace the stock wheels and if yes where might i be able to get a set of 77 inch white-walled wheels

thanks for all the help and support.
Andy fekete

[RAM]

I don't have a J, but I am sure that you would not be able to replace 70 inch drivers with 77 inch drivers.  I am sure that there is not enought room between the drivers.

[SteamGene]

At 1:87, how much difference is there between the two prototypical diameters?
Gene

[Virginian]

Seven scale inches of course, Gene !
If someone is contemplating this "bash", I would think the wheels would be the easy part.  The J's boiler is a lot bigger one than the Canadian's.  Might want to try the body off an old Bachmann Plus series J.  I have never seen whitewalled drivers for sale.  If you want them that way, you may have to paint them.  You do realize you are going to have to fabricate all the rods to mate 77" drivers (or 80s or 79s) on the J chassis unless you luck out and find drivers with the same crank radius as well, I hope.

[Nigel]

.....You do realize you are going to have to fabricate all the rods to mate 77" drivers (or 80s or 79s) on the J chassis unless you luck out and find drivers with the same crank radius as well, I hope.

VGN; I have to disagree with you on this one, the crank pin to crank pin distance on the rods is the same as the axle to axle spacing, and independent of the crank pin radius.  Sketch it out.

[Nigel]

...where might i be able to get a set of 77 inch white-walled wheels

http://www.greenwayproducts.com/a_drivers.shtml

[Virginian]

You are absolutely correct about the rods Nigel.  I must have had another one of those senior moments.  Andy, I sincerely apologise for dispersing bad information.

[SteamGene]

Exactly, Virginian.  amd 7 scale inches = 0.08 inches.  I'm not sure my micrometer is that accurate
Gene

[ebtnut]

The critical issue is the space between the driver flanges.  If the gap is greater than the 7 scale inches, you might get away with it.  7 scale inches is about 3/32", if that helps any.  Couple of things.  You might use slightly smaller drivers, like 76", and/or use blind drivers on the two center axles.  May not be prototype, but it will help in getting the loco around sharper curves.