Dia Compe Headset woes

Seals easy to test, you just remove it.
Quite likely the races are a bit worn and new bearings make it more noticeable. The bearing is doing a full rotary bearing job, it stays in one position and only moves a fraction left and a bit right. Until you get of the bike and let the steering twist. So, they get hammered in to one spot over time over bumps and not worn smooth like wheels and bottom brackets.

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Matty538":3oyog41n said:

Can't help thinking your lower seal is the wrong way round but I may be reading it wrong. I recently had problems with my headset knocking although it was an impact headset. The problem was I didn't install the lower seal because it's all chewed up after the previous owner installed the wrong bearings. I've been unable to find a new seal so tried to make do with what was left of the old one. In my case the seal is stepped, kind of like an L shape. The seal sits on the crown race and then over hangs downwards creating a seal with the bottom of the crown race and the bottom headset cup.

Click to expand...

I think the lower seal is the wrong way around, too. The lipped part should go over the crown race, lip pointing downwards, and the lip helps to stop the seal slipping sideways on the race - it should fit snugly over the crown race. The flat surface points upwards so that the bearing cage sits on a flat surface. The exploded view on page 2 is not very clear about that. However, it could be that the whole headset is knackered as well.

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Thanks for all the replies guys!

To answer a few of the comments/questions -

- The cups are filled with bearings. Initially I removed 2 as I had read elsewhere but this sounded worse. Reading elsewhere online it suggested if there was wear that you could 'cheat' your way around this by filling the bearings so that they did not get 'stuck' in any pockets of wear made by the old bearings. Having a full set certainly sounds better then when there are 2 less in there

- I suspect the cups to be original and the bike has never been repainted

- Bearing size was determined by online research and a response I received to a question on this forum

Which really leaves 2 main options - the headset is worn OR the Crown Race seal is fitted the wrong way round. At the moment the flat, wider part of the seal is facing down towards the Crown Race and the narrower part facing toward the bearing. From whats being suggested this could be the wrong way round so Ill swap it over and report back.

Appreciate all the help and advice so far