Author Topic: Head Bearings  (Read 555 times)

Offline AndyD

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Head Bearings
« on: April 01, 2020, 07:34:19 AM »
Just about winning a battle to get head bearings fitted on the 400 and am a bit baffled that it is so awkward.
Went for the All Balls kit which seems to be the most common offering and I have read lots of threads about problems of reduced thread for adjuster nut so tried to proceed as carefully as possible.
Spent ages again Googling on this before starting but there seems to be no definitive answer anywhere regarding the spacers etc.
In the end I found that only the thin spacer on the lower bearing could be used otherwise the top thread is virtually non-existent.
Even with this, it is only just enough and if the dust cover and washer are both fitted the amount of thread is very small.
One thread on the US site showed flattening the raised teeth on the adjuster screw and omitting the spacer (and I think dust seal) to get a bit more thread.
I'm going to play some more with this still but it just seems crazy that a common replacement part is so tricky and maybe dangerous as I guess there needs to be at least a reasonable thread for the adjuster screw to fix properly.
Any thoughts?
Cheers,
Andy

Offline ka-ja

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Re: Head Bearings
« Reply #1 on: April 01, 2020, 09:50:13 AM »
I don't know what is happening with modern kits, but fitting taper roller bearings never used to be a problem, I think the "washer" causes a lot of the problems.
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Offline Erwin83

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Re: Head Bearings
« Reply #2 on: April 01, 2020, 04:26:06 PM »
I fitted 2 of these kits recently and I recognize the information on the interwebz that it's indeed a bit 'awkward' in the top, especially with the outer bearing protruding out of the frame quite a bit.
Nevertheless, by using common sense during installation (not all washers / rings / caps are needed) I was still able to fit the top nut with enough windings to keep things safe (3+ windings easily).

I wonder if there is any difference in thread length or position of the thread on the stem, between de 350f and the 400f.
350f is certainly not as tight as I was lead to believe before tackling this job...
CB466f - KTM 1190 advR

Offline Bryanj

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Re: Head Bearings
« Reply #3 on: April 01, 2020, 04:52:38 PM »
Now my brain is addled(Guinness) but when we fitted these back in the 70's i dont remember any washer or the top outer sticking up, perhaps the older ones were more "indivisualised" than now?

Offline AndyD

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Re: Head Bearings
« Reply #4 on: April 01, 2020, 05:57:42 PM »
Agreed - it's all a bit baffling.
Having fitted tapered rollers on quite a few bikes recently, none have had any issues at all and just fitted.
The 400 ones are a nightmare but I've now got them fitted with the thin washer at the base - without this I think the lower yoke would snag.
By not fitting any spacer or seal at the top I can get just over 2 full turns of the adjustment screw which feels quite secure but still doesn't seem quite right.
I'm fitting these for now to get the bike together and assess how it all comes together so not too worried if they need 'revisiting' later on.
Just really surprised how these can presumably be sold in quite significant numbers but don't really seem to work - somehow it seems they should really just be 'shorter' overal so there is more thread available at the top.
Oh well, on to the next problem...
Cheers,
Andy

Offline waffey

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Re: Head Bearings
« Reply #5 on: April 01, 2020, 09:30:37 PM »
Done mine this week with a kit supplied from DS. Thick washer on the bottom of the yoke. I had plenty of threads left for top nut...%u2026...for what is worth!

Seeing the comment below, I did the same, I removed the ridges from the adjuster nut. Sorry, should of said before.
« Last Edit: April 02, 2020, 09:28:58 PM by waffey »
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Offline Erny

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Re: Head Bearings
« Reply #6 on: April 01, 2020, 10:22:14 PM »
Just about winning a battle to get head bearings fitted on the 400 and am a bit baffled that it is so awkward.
Went for the All Balls kit which seems to be the most common offering and I have read lots of threads about problems of reduced thread for adjuster nut so tried to proceed as carefully as possible.
Spent ages again Googling on this before starting but there seems to be no definitive answer anywhere regarding the spacers etc.
In the end I found that only the thin spacer on the lower bearing could be used otherwise the top thread is virtually non-existent.
Even with this, it is only just enough and if the dust cover and washer are both fitted the amount of thread is very small.
One thread on the US site showed flattening the raised teeth on the adjuster screw and omitting the spacer (and I think dust seal) to get a bit more thread.
I'm going to play some more with this still but it just seems crazy that a common replacement part is so tricky and maybe dangerous as I guess there needs to be at least a reasonable thread for the adjuster screw to fix properly.
Any thoughts?
Cheers,
Andy

Andy, I'm one of guys who fit top bearing by "flattening the raised teeth on the adjuster screw"
Did on my 2 bikes (750 K7, 550 K1) it is just perfect (now several thousands miles done on them). On both I used AllBalls kit that contains needed washers and seals. I recently replied to similar thread here http://www.sohc.co.uk/index.php/topic,21563.msg192923.html#msg192923

Key is to use proper washer on the bottom bearing to get the same height (+/- 1mm) compare to OEM bearing.
Then, as top taper bearing is usually higher than OEM, either adapt adjuster nut (grind flanges) or you need to adapt headllight ears (compensate gat by O rings or washers) provided you have enough thread to fix top nut.

 
CB750K7 US model (1977)
CB550K1 US model (1975)

 

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