Surface finish on iso end caps, teflon wear

concours · Mar 6, 2012

I've aquired a retrofit kit to use the MKIII type adjustable iso's in my MKIIA. The end caps included have a 125 record groove finish that I think will wear the teflon washer in short order. So.... I took to polishing them on the surface plate with fine emery, and find that they are concave..

Surface finish on iso end caps, teflon wear

1up3down · Mar 6, 2012

Good tip!

Thanks for posting that, Concours.

swooshdave · Mar 6, 2012

Where did you get them from?

concours · Mar 6, 2012

swooshdave said:
Where did you get them from?

http://stores.ebay.com/Hokanson-Norton- ... 4340.l2563

concours · Mar 6, 2012

It's a sophemore machining mistake, holding that part can cause it to flex, the sequence of ops can cause it to relieve stress and change shape a bit.

dynodave · Mar 6, 2012

I've never heard of teflon being a suitable iso washer. Only some of the original bronze loaded teflon (IIRC NLA) or polyurethane.
Maybe these days they use delrin?
as a side note:
I know Carl Hockanson from the old days, but working on bikes using all these junk new parts must have wore him out.
He does not take referals any more.....I used to send him work....and now he sells parts. How could he keep working on bikes and charge a guy for a part then "fix" the new parts going on a job and make any money ? If he still works on nortons he must not be telling. He built vintage club roadrace winning commando's for many years. I pit crewed for him back in the 90's. He'd complain endlessly about the poor parts quality and had to fettle almost everything he touched on his race bike. The results spoke for its self. He did race, but in the hands of seasoned guest pilots his bike would leave the pack in the dust.

concours · Mar 6, 2012

dynodave said:
I've never heard of teflon being a suitable iso washer. Only some of the original bronze loaded teflon (IIRC NLA) or polyurethane.
Maybe these days they use delrin?
as a side note:
I know Carl Hockanson from the old days, but working on bikes using all these junk new parts must have wore him out.
He does not take referals any more.....I used to send him work....and now he sells parts. How could he keep working on bikes and charge a guy for a part then "fix" the new parts going on a job and make any money ? If he still works on nortons he must not be telling. He built vintage club roadrace winning commando's for many years. I pit crewed for him back in the 90's. He'd complain endlessly about the poor parts quality and had to fettle almost everything he touched on his race bike. The results spoke for its self. He did race, but in the hands of seasoned guest pilots his bike would leave the pack in the dust.

Dave, what do you think? grab the OD of these with soft jaws and take a cut to square it up?

swooshdave · Mar 6, 2012

Why not just lap them flat?

Cheesy · Mar 6, 2012

Ive just finished making some of those out of aluminium, they are not the easiest things to square up in a chuck.... All mine are different thicknesses to eliminate the shims and allow for the differences in ISO tube length. I also cleaned up the adjuster part as well, the back ones were not flat (wear from use somehow). Each end will have two UHMWPE washers, which hopefully wont expand too much, one has a hole that is tight on the threaded tube the other I heated and formed a flare that locates in the cap so all going to plan the relative movement will be between the two UHMWPE surfaces.

Dances with Shrapnel · Mar 6, 2012

concours said:
grab the OD of these with soft jaws and take a cut to square it up?

I would block them out on a surface grinder magnetic chuck with flat stock and grind off until flat. This is assuming the the inner rim is in the same plane as the inner surface. Easy enough to check with a depth gauge in a few spots.

splatt · Mar 7, 2012

concours said:
It's a sophemore machining mistake, holding that part can cause it to flex, the sequence of ops can cause it to relieve stress and change shape a bit.

Nay, its just what parting off tools do, measure with micrometer to see if its a uniform thickness and lap flat

rpatton · Mar 7, 2012

I think that if even if you start out with flat end caps that they won't stay that way for long. There isn't enough thickness to the flat load-bearing area, they cave in sooner or later. Considering how soft the stock PTFE washers are, I don't think it matters that much. I made a set of thicker caps and replaced the stock washers with acetal/teflon. I also put on an aftermarket headsteady. Between the two, I think the headstedy has more to do with the longevity of the Iso adjusters than anything else. It makes life much easier for them.

concours · Mar 7, 2012

Dances with Shrapnel said:
concours said:

grab the OD of these with soft jaws and take a cut to square it up?

Click to expand...

I would block them out on a surface grinder magnetic chuck with flat stock and grind off until flat. This is assuming the the inner rim is in the same plane as the inner surface. Easy enough to check with a depth gauge in a few spots.

Setting up the surface grinder now.. :mrgreen:

concours · Mar 7, 2012

There, that ought to do it...

john robert bould · Mar 10, 2012

concours said:
There, that ought to do it...

Get them hard chromed?

concours · Mar 10, 2012

"Get them hard chromed?"

That would work, but the surface finish usually needs retouching after that. Back to grinding, polishing only NOW it's "wicked hahd!" :lol:

Dances with Shrapnel · Mar 10, 2012

Once set up properly with a properly balanced engine (no rocking couple), there should not be much lateral load on these. In theory, the only loads are during turn in and turn out.

concours · Mar 13, 2012

Dances with Shrapnel said:
Once set up properly with a properly balanced engine (no rocking couple), there should not be much lateral load on these. In theory, the only loads are during turn in and turn out.

Agreed, not a lot of side load, but, lots of continuous MOVEMENT, and so, like the dreaded vibration that saws wire insulation, cables, etc., I beleive a coarse finish will, over time, gobble up whatever is next to it.

Surface finish on iso end caps, teflon wear

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