The Ford Barn

yachtsmanbill · 10-27-2013, 06:13 PM

Youll need a lathe with a 4 jaw independent chuck for adjustment... 3 jaw universals are inherently inaccurate... so with that you need to start at a known accurate point which I used the inside bore and gear running faces as "accurate". Talk to your machinist pal; he'll explain that the runout measured from 3-9 o'clock is the X axis, 6-12 is the Y axis and the bore centered to the whole shebang is the Z axis is. Accuracy is pretty critical at this point. Without fixturing, and a granite surface block to measure from, youll have to trust that the factory had and maintained the XYZ part. So now, yer lathe guy withdraws the indicator with the carriage on the machine and mechanically moves it to the ring gear flange. At this point he'll measure the X-Y difference and that's the runout on that part. If you are in fact out .012" he'll take a skim cut and true it up. If its good, like
<.005" Id let it go, but that's your call .000" is best. If he doesn't want to cut or grind the finish true, at least take a stone and swipe the face for upsets around the bolt holes. The lathe guy will concur. ws

10-27-2013, 06:13 PM	#39
yachtsmanbill Senior Member Join Date: Dec 2011 Location: Two Rivers, Wi. Posts: 1,406	Re: Something let go in the tranny Youll need a lathe with a 4 jaw independent chuck for adjustment... 3 jaw universals are inherently inaccurate... so with that you need to start at a known accurate point which I used the inside bore and gear running faces as "accurate". Talk to your machinist pal; he'll explain that the runout measured from 3-9 o'clock is the X axis, 6-12 is the Y axis and the bore centered to the whole shebang is the Z axis is. Accuracy is pretty critical at this point. Without fixturing, and a granite surface block to measure from, youll have to trust that the factory had and maintained the XYZ part. So now, yer lathe guy withdraws the indicator with the carriage on the machine and mechanically moves it to the ring gear flange. At this point he'll measure the X-Y difference and that's the runout on that part. If you are in fact out .012" he'll take a skim cut and true it up. If its good, like <.005" Id let it go, but that's your call .000" is best. If he doesn't want to cut or grind the finish true, at least take a stone and swipe the face for upsets around the bolt holes. The lathe guy will concur. ws __________________ " Warning; the following contains content that the anal retentive may find offensive - please skip on to the next posting!"