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Steering Head Bearings, Evo


trapezeartist
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There has been a bit of movement on the steering head ever since I got this bike, so this week I decided to do something about it. Being taper roller bearings, I expected it to be just a matter of adjustment.

I took it all apart and cleaned the bearings. The roller races felt good and the bearing surfaces looked nice. I re-greased and started to re-assemble. I have the Top Team triple clamps and spindle, which may be slightly different to standard. Having got it all back together I dropped it on the ground and checked it: worse than before!?

Blaming myself, I took off the handlebars and loosened the top clamp again. I was able to get a bit more movement on the adjusting nut (the one that is tightened with a C spanner) and then re-assembled. Still sloppy. I went through this a couple of times more with increasing frustration so finally decided to really tighten the bearing. So I wound the adjusting nut down hard and then eased it back a touch. I checked the steering wasn’t tight and then re-assembled yet again. With the bike back on the ground I found there is still play! What am I doing wrong?

When I pull the front brake on and push forward on the handlebars I can here and feel the movement. Looking at the area of the top bearing, there seems to be 1mm+ of radial movement. Grrrrrrr!

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Place your finger on the area between the pinch nut and the top triple clamp and rock the bike to feel for motion. Some standard Beta top triple clamps pre-18 had too much clearance in the spindle hole. Tightening the nut would help for a few hours but the only way to fix it was to shim the spindle. I don’t know about the Top Trial clamps but if they don’t have a pinch bolt that might be your problem. I chased that clunk for months tightening the bearings and re-seating the head bearings over and over until I figured that one out.

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Probably not but worth checking it’s not just play in the floating front disc bobbins you are feeling, especially if you are feeling for movement with the front brake on and rocking back and forth. 

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Thanks for the suggestions, but I can see the movement at the top bearing. I woke up early this morning thinking about the problem. I'm wondering now if the thread on the spindle is too short, so tightening the adjusting nut is just tightening against the end of the thread instead of against the bearings. It would explain why the steering doesn't really bind up even when it is tightened hard. If that's the case I imagine I'll have to remove the spindle from the bottom clamp (I don't know how it's fixed there) and pack it with a washer or two. I won't have time to dismantle it all again now before the weekend so I'll ride it as is on Sunday and take another look next week.

BTW Dan, there is no pinch bolt on the top triple. It's sandwiched between the adjusting nut and the top nut. It is a pretty good fit and I don't think that's likely to move.

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I’ve seen this on a new Evo before. There was slight play in the headstock even after tightening the stem nut on to the top yoke (obviously after the top yoke pinch bolts had been slackened). There was not enough adjustment on the threaded stem to remove the play. 

I contacted Beta UK who said that some of the Evos were fitted a shim washer between the top yoke and the inner race of the top tapered bearing. I used a 20x35x1 washer, Beta part number 00277348 which sorted the problem.

Edited by dabba
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On 4/26/2019 at 9:36 AM, b40rt said:

Sounds like your tightening against the outer, rather than the centre. A spacer missing / incorrect size ?

Not tightening against the outer (that would generate noise and friction), but yes there probably is a spacer missing.

On 4/26/2019 at 9:38 AM, crashmonkey said:

Is the outer race a tight fit in the headstock tube? should be a press fit.

 

Yes.

On 4/26/2019 at 12:24 PM, dabba said:

I’ve seen this on a new Evo before. There was slight play in the headstock even after tightening the stem nut on to the top yoke (obviously after the top yoke pinch bolts had been slackened). There was not enough adjustment on the threaded stem to remove the play. 

I contacted Beta UK who said that some of the Evos were fitted a shim washer between the top yoke and the inner race of the top tapered bearing. I used a 20x35x1 washer, Beta part number 00277348 which sorted the problem.

The std Beta and Top Team designs seem a bit different, but I think I could find a home for a washer like you suggest that might work. I’ll have a rootle around in my fixings box to see if I’ve got a suitable washer. If not, I’ll try to get that part no from Beta UK.

Edited by trapezeartist
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I pulled it all apart again this evening and confirmed that the nut was bottoming on the thread. I forgot dabba’s Beta part so  I’ve ordered a couple of ordinary M20 washers on flea bay. They will be 3mm thick which is a bit OTT but I’ll give it a go.

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