Topic: Broken Lower Steering Cone?

[azuredesign]

Hi,
I took the front end off of my '73 750 project to check and repack the steering bearings and found the lower cone fractured through.The other races looked pretty good showing much less wear. While it makes sense that the lower cone takes most of the forces generated on the stem, I was surprised to see the break, which was displaced enough that I could fit a screw driver between the two sides.
Is this a common occurence, and am I better off replacing with tapered needle bearings?
Thanks for any help,
Ben

[eurban]

Don't know how common of an occurence it is.  Perhaps your bike has been wrecked at some point or perhaps the front end was a good bit too loose at some point allowing for a good bit of back and forth smacking at the lower bearing . . . . By all means replace what you have with a new set of tapered bearings.   Given your current situation, the results should bring a smile to your face.

[Gordon]

Agreed!  Replace them with tapered roller bearings.  As a bonus, you'll find that the crack in the lower race greatly simplifies its removal from the yoke. 

[bryanj]

Common with impact damage and worth fitting tapers BUT inspect the steering stem where the race fits as i have found these distorted frequently after an accident.

[azuredesign]

Thanks to all for your responses. Unfortunately on removing the cone I found that the stem was indeed distorted, and I will have to replace the lower triple tree and stem. The inner fork tubes appear  straight when rolled on a flat surface, as well as the frame steerer tube. Is there any other damage I should look for?
Thanks again,
Ben

[Steve F]

I had the same problbem with my 750F when I got it.  I couldn't fit the tapered bearing race on the steering stem when I tried the conversion.  Turned out the steering stem was bent at the lower tree, and I had to replace the whole thing.  The PO said that the forks were replaced because of an "accident".  It appears that the mechanic didn't check everything really well when he put it back together.  Check yours out before you use it....it's YOUR life on the line.

[azuredesign]

Thanks for your advise Steve. I've been hanging my rear off of skinny seats for almost 40 years now, and I do think more about saving it than I used to!

Best,
Ben