steering stem runout query

[yamaman]

Just in the middle of converting my standard front end to the r1 (early type) and have noticed a 10 thou run out on the fazer steering stem. Any opinions on whether is an acceptable tolerance will be greatly welcomed.  Thanks in advance.

[sirgalahad3]

Good luck with the conversion. Pic when done hopefully?

[Screwdriver]

Ten thou from where to where?


How did you measure it?

[yamaman]

Cheers Sirg, will definitely post some pics mate.  So far the conversion is going well, I am building a complete R1 front end first and then just do a complete one for another swap if that makes sense?
As for the run out screwdriver, it is measured by holding one end in a lathe and turning it whilst measuring with a dial gauge.

[Falcon 269]

I wouldn't worry much about the runout.  When all's pinned and bolted up together, it'll pull itself square between the bearings, I reckon.

[Screwdriver]

Cheers Sirg, will definitely post some pics mate.  So far the conversion is going well, I am building a complete R1 front end first and then just do a complete one for another swap if that makes sense?
As for the run out screwdriver, it is measured by holding one end in a lathe and turning it whilst measuring with a dial gauge.

You'll be very lucky to get a good reading to ten thou. First off you have no idea how accurate the piece is machined on its centre, secondly, unless you have very carefully set it up in a 4 jaw, you're looking at probably 5 thou just in the 3 jaw chuck, assuming you will have calibrated the tailstock offset with a test bar. Finally the stem is an interference fit in the lower yoke, another large source of error.


So, no. I personally wouldn't worry about ten thou on a piece like that because it is tricky to measure down to that level of accuracy on a crude part and a "perfect" piece is going to be pressed into another crudely machined casting leading to even more possibilities for error. While error may be cumulative and it's always worth doing the best you can, any slight eccentricity in the stem is going to overshadowed by what happens when you press fit it. It's at that point you want to be setting the piece up in a jig and measuring for square/eccentricity.


S.