P85 Premature Button Failure

[JustinMan43]

While changing weight arm bushings last season , I noticed once of my rollers was collapsed.

Had a shop go through it and put all new rollers and buttons in it.

I had 5 of the 6 buttons fail (some got “crushed” and one had fallen right out) at about 500km

Had the shop put new buttons in again switching mfgs and it failed this weekend after 70km.

Any ideas on what would be causing this other than poor parts? I never did put a feeler gauge on on the button to sheave clearance myself but assuming it was within reasonable tolerance (< 10 thou, spec is 2 thou I’m told) I’m not sure how they would fail/fall out.

Would excessive crank run out or a poorly balanced clutch cause it? Maybe but not in 70km?

 

[Rhodesie]

While changing weight arm bushings last season , I noticed once of my rollers was collapsed.

Had a shop go through it and put all new rollers and buttons in it.

I had 5 of the 6 buttons fail (some got “crushed” and one had fallen right out) at about 500km

Had the shop put new buttons in again switching mfgs and it failed this weekend after 70km.

Any ideas on what would be causing this other than poor parts? I never did put a feeler gauge on on the button to sheave clearance myself but assuming it was within reasonable tolerance (< 10 thou, spec is 2 thou I’m told) I’m not sure how they would fail/fall out.

Would excessive crank run out or a poorly balanced clutch cause it? Maybe but not in 70km?

severely out of balance clutch. maybe the movable sheave bushings are sacked and its put excess load on the spider. may be worth the cost to get a new one. ugly price but better than an engine rebuild.

 

[JustinMan43]

severely out of balance clutch. maybe the movable sheave bushings are sacked and its put excess load on the spider. may be worth the cost to get a new one. ugly price but better than an engine rebuild.

Sounds like maybe they didn’t index the movable to the fixed sleeve properly? The only casting marks are the X on the cover and spider itself right?

 

[Rhodesie]

spider, moveable and cover have index marks. When i break one down i use a sharpie and mark everything.