Author Topic: A nice puzzle pic...  (Read 373 times)

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Offline Rex

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A nice puzzle pic...
« on: 19 Oct 2017 at 17:29 »
This is a Mk 5 head set top race and housing.
Who can see the obvious error?

Offline eddie

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Re: A nice puzzle pic...
« Reply #1 on: 19 Oct 2017 at 17:39 »
It looks as if the inner cone has been mismatched with the earlier style cup. The late type head bearing is a cup and cone whereas the early bearing was a deep tracked thrust bearing with 2 identical tracks (part number 2016).

  Eddie.

Offline Rex

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Re: A nice puzzle pic...
« Reply #2 on: 20 Oct 2017 at 17:35 »
This bike came to me with a reputation for tank-slappers, and sure enough, the head-set was iffy. Tightening it caused a strange self-centreing action, and loosening it until that problem was no longer evident meant that the head-set was too loose to ride it safely. The test ride was very short and very disconcerting.
When stripped for inspection it became clear what was happening; two errant balls had obviously been dislodged the last time the bearing was assembled, and had lodged up at the top of the housing in the old hardened grease. In this position they were preventing the cup and cone bearing from being adjusted and appear to have been happily wearing away the housing (see additional bearing wear like a huge smile beneath the race).
Given the depth of the groove worn, this has been like this for many years, so I wonder how many previous owners and riders have thought "this Douglas handles like a pig, I'm going to sell it on"?
Equally the ace mechanic in the dim and distant past who left it like this can't have much "feel" for how the steering ought to have felt after regreasing or whatever he did. :?

Offline Hampshirebiker

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Re: A nice puzzle pic...
« Reply #3 on: 21 Oct 2017 at 08:57 »
Not guilty me lud. Glad the culprit has been found. You may recall my post when the problem first manifested its self. Is it not repairable?
Dave.

Offline Rex

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Re: A nice puzzle pic...
« Reply #4 on: 21 Oct 2017 at 09:18 »
Doesn't need repairing as the wear groove has no impact at all on the action of the top bearing. The pic isn't very clear, but the top bearing housing has quite a depth to it, and the bearing track is probably a good 10mm vertical distance from that witness mark.
All back together and working just fine now, for the first time in ??? years?

Offline yosemite

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Re: A nice puzzle pic...
« Reply #5 on: 01 Nov 2017 at 18:37 »
Thanks for the idea,  my t35 had a serious problem with the steering, suspected all sorts of causes and though the handling hadn't quite degenerated into a tank slapper it was getting  close, I saw this post and decided to check the head first, when I stripped the steering head there was an errrant ball wedged in the hole for the grease nipple. I suspect that the weight of the forks and bottom yoke cause problems when trying to support them and align the top race, resulting in the mislocation of a ball (or three). I know this happened to me the first time I tried and ended up lifting the forks into positon  by supportin them on a block of wood on a trolley jack and then fitting the balls and top race.
took the bike out for a test ride this morning  and problem was solved and am looking forward to taking it out for a good run.
Thanks
Yosemite