Does anyone have the spec's for rebuilding front idlers on a 4G/2T D4 regards Andrew

I don't have much info. The D4 rail height started out at 3.53 in. high then went to 3.66 in. so the 0.69 in. tread depth for a new idler is probably for the higher rails. Bearing clearances should be pretty standard.

Hi Andrew,
was in at WA today and tried to get onto Andy McCall to see if he had any of the old Aluminium undercarriage checking gauges. From S/M July 25 1955 P/No for D4 gauge is 6H1984. May have to try and get drawings.
Also the tread height is measured from the top of the center rib, may be there is some unworn evidence to gauge a possible height. Don't quote me, looking at a ruler seems like around 3/4" to 1" might be ok. Perhaps check the D4 I restored, located in the demo yard, as a guide next time you or I are there. Kinda dont want to turn up too often as I might have to put on the overalls again.
Cheers
Eddie.

Thanks Eddy, I was also trying to get get a measurement of how wide at the top rib as they seem to all wear there, Regards Andrew.

Hi Andrew,
just found old 1977 CTS (Custom Track Service) Hand book. Seems for all D4 idlers are same spec.. Especially see idler image at bottom left of page, it shows dimensions for SPOKED Idler.
Hope this is what you were after.
Cheers
Eddie B.