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Old 28-May-2004, 13:24
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ziggi ziggi is offline
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Front end ain\'t right after Yoke change (update)

Please help - I've taken the day off to ride my bike !!! I changed the top yoke yesterday for a more bling item. Today the bike feels very different on the front end. I'm fighting the bike to keep it in a straight line and it feels like it wants to lean over all the time. In a straight line it feels unstable.

I just took off the top yoke I had and put on the other one. It was a bit tight but all went on ok. Forks are 4 rings showing through yoke on both sides. I never slackened off the bottom yoke. I did need to apply the front brake to get the top yoke to fit on properly.

What have I done - it really does feel very different - must have done something wrong! Nothing else changed on front end. No suspension settings changed anywhere. Nothing changed on rear or any other chassis part !!

I've come straight back home because it's just not right.

Oh and i'm on the normal 24.5 degree steering angle. The steering lock still works so I don't think I've put it on the 23.5 degree angle by mistake.

[Edited on 28-5-2004 by ziggi]

[Edited on 29-5-2004 by ziggi]
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Old 28-May-2004, 13:36
748mart 748mart is offline
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have you checked both old & new yokes have the same hole centres, it sound as if this new one has made the fork ange steeper.
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Old 28-May-2004, 13:39
neil748r neil748r is offline
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Ziggi,

Might be a silly question but did you compare the new yoke to the old one before you fitted it?

If it was a bit tight to fit, it may be that the offset between the forks and steering stem is slightly different from stock. For example, if the offset is greater than stock, that would have the effect of changing the fork rake and shortening trail which would make the bike feel a bit unstable.

Hard to diagnose accurately without actually seeing the parts in question but worth checking out IMO.

Out of interest, who supplied the yoke?

Cheers, Neil.
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Old 28-May-2004, 13:42
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ziggi ziggi is offline
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erm... I bought it off Jasper who had it on his 748. Could that be it! Is there a difference in the 748 Yoke and 996S yoke? And no I didn't even think to check which is typical of me!!
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Old 28-May-2004, 14:22
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Harv748 Harv748 is offline
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mmmh...does sound strange.

I wouldn't have thought it possible to have made any changes in the steering head angle, just by changing the yoke.

Its the actual steering head tube that is rotated to adjust the head angle, and you would know if you had done that!

Just offer your old one upto the new one you have and see if the hole centres are the same...I'm sure they will be but it will rule that out.

Sounds to me that something else has been altered without your knowhow as you changed the yoke.

Have you refitted the steering damper? Are the clip-on pins located correctly in the small indentations on the back of the yoke. Did you loosen the stem nut when removing the yoke in any way?

Uhmmmmm....can think of anything else
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Old 28-May-2004, 14:46
DJ Tera DJ Tera is offline
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you won't be able to change the geometry just by replacing the top yoke - think of it as just a way of linking the forks to the steering damper and you'll see what i mean.

You may have loosened the headbearing somehow, or the steering damper is rubbing on the tank or something else

I seriously doubt you have altered the geometry - would be one hell of a cheap way to do so!

[Edited on 28-5-2004 by DJ Tera]
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Old 28-May-2004, 14:55
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Harv748 Harv748 is offline
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I'm betting that in the excitement of fitting the bling bling new yoke, he's forgotten to refit the steering damper (either at all or properly?)...would explain all of the symptoms suggested.

If not...soza
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Old 28-May-2004, 15:17
neil748r neil748r is offline
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I'm pretty sure the top yoke for a 748 is the same as for 996S. Just checked the parts cat and it's the same part number.

Regarding changing steering geometry, a different top yoke CAN alter the geometry! It's a bit hard to explain but I'll do my best.

Imagine if you will a vertical line, that's the line down through the centre of the steering shaft. Now, if the offset between that line and the line down through the centre of the fork legs is identical for both yokes then the forks will be parallel to the steering shaft. Now, imagine altering the offset of only the top yoke. The forks are no longer parallel to the steering shaft.

So, if the offset on the top yoke is even marginally different than the offset of the bottom yoke, by the time you translate that over the length of the fork legs, it will have made quite a large difference to the trail.

This is what I suspect is going on in your case. It would also explain why the new top yoke was slightly tight to fit on as the holes in both the top and bottom yoke would not be in perfect alignment (axis wise).

Ducati use a similar principal to allow adjustment between 24.5 deg and 23.5 deg rake. The difference is instead of playing with yoke offsets, they adjust the overall angle of the steering shaft in relation to the headstock on the frame.

My advice would be take the top yoke off again and compare against the original. Bear in mind that any difference would only have to be very slight.

Cheers, Neil
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Old 28-May-2004, 15:38
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Harv748 Harv748 is offline
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But surely if the centres were different then then the yoke simply wouldnt fit?

If the distance has changed, and the new yoke fitted, then either the forks have been bent to fit or the stem nut ( and associated bearings etc) have been forced...both very difficult to do I would have thought?

Still going with the steering damper!!!

AAaawww...my head hurts

[Edited on 28-5-2004 by Harv748]
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Old 28-May-2004, 15:46
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ziggi ziggi is offline
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Thanks for all your replies and yes my ohlins damper is fitted

First thing is Jasper now has my original yoke so I can't compare it. To fit this new yoke I have to offer it up - it won't go straight on so I have to hold the front brake and push the forks down and push on the yoke so it fits on the centre nut. Any other way and the centre nut don't line up with the middle yoke hole.
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