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Author Topic: Tapered roller bearings Yamaha RD  (Read 300 times)

Offline Ryan Stecken

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Tapered roller bearings Yamaha RD
« on: Sep 28, 2017, 10:17:00 »
Hey guys!

Just switching out the old bearings of my steering head to new tapered roller bearings.

I ran into two questions:

1.)Is it normal that the bearing shells which are to be installed into the frame neck have different "heights"?If yes which one should come on top?
2.)If I install the shell with the lower height (which is my guess for question NO1) the shell seems to stick out of the frame neck...is this normal?

Thanks!

Offline clem

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Re: Tapered roller bearings Yamaha RD
« Reply #1 on: Sep 28, 2017, 10:45:19 »
Yes they will be slightly taller. No problems though.

Sent from my SAMSUNG-SM-G930A using DO THE TON mobile app

"After every war there are soldiers who refuse to surrender. To this day there are still thousands who cling to their 30+ year old motorcycles, thinking that the war is still on, refusing to concede that the four-strokes have won"

1972 DS7 http://www.dotheton.com/forum/index.php?topic=45886.msg505995#msg505995
1983 CB550sc bobber http://www.dotheton.com/forum/index.php?topic=30599.30

Offline Ryan Stecken

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Re: Tapered roller bearings Yamaha RD
« Reply #2 on: Sep 28, 2017, 10:53:43 »
Is it normal that the shells have different heights clem?


How much torque would you apply to the fasteners on the stem?

thanks

Offline clem

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Re: Tapered roller bearings Yamaha RD
« Reply #3 on: Sep 28, 2017, 11:15:52 »
On mine, the bottom did not stick out but the top cup did. I don't remember which one is top and bottom but they are different. As far as torque, I just tightened the spanner nut tight enough to where it didn't bind but not loose enough to have any play. That may be wrong but I have no idea of an exact torque setting for that one.

Sent from my SAMSUNG-SM-G930A using DO THE TON mobile app

"After every war there are soldiers who refuse to surrender. To this day there are still thousands who cling to their 30+ year old motorcycles, thinking that the war is still on, refusing to concede that the four-strokes have won"

1972 DS7 http://www.dotheton.com/forum/index.php?topic=45886.msg505995#msg505995
1983 CB550sc bobber http://www.dotheton.com/forum/index.php?topic=30599.30

Offline jpmobius

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Re: Tapered roller bearings Yamaha RD
« Reply #4 on: Sep 28, 2017, 12:05:53 »
There is a factory seal that goes onto the steering stem first to seal the lower bearing.  The aftermarket tapered bearings I have come with a seal also, but I can't remember whether I use it or the oem one.  If I remember correctly there is a dimensional issue depending on the stack of components.  If the lower inner race is too close to the lower tree, the tree will contact the frame before the bearing is seated properly.  If the race is too far from the tree due to the seal being too thick, the stem will not project through the neck far enough and tensioning nut will not engage all the threads - which is nearly the case no matter what as the tapered bearings are thicker than the ball bearings they replace.  I can't remember what the best solution is, but install the lower outer race first and make sure it is completely seated in the steering neck.  Then take the inner and place it into the outer shell and measure the difference between the height of the bearing face and the steering neck.  You want to end up with the lower tree as close to the neck as possible without touching so the stem will project out the top as far as possible.  I can't remember what the best seal/shim combo is best, but do recall having to remove the new inner race from the stem to make changes which is sometime difficult as it is an interference fit.  Otherwise, as Clem has said, the upper race will stand proud of the neck.   I do seem to remember not being able to use a top seal as there is not enough space.  There is no correct torque, and again Clem's direction is fine.  I generally over tighten tapered bearings a bit to squeeze the grease from between the elements and then back off until the assembly moves freely.  There is very little load on the steering of a bike, so the compression of the assembly can be very loose as long as there is no play.  Most applications should be tighter, like the front wheel bearings of a car or transmission shafts because the loads are much higher and more compression is needed to make up for the resulting distortion.
Mobius


On a long enough timeline, the survival rate for everyone drops to zero.

1973 RD350 Yamaha build  http://www.dotheton.com/forum/index.php?topic=66498.0

Offline clem

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Re: Tapered roller bearings Yamaha RD
« Reply #5 on: Sep 28, 2017, 12:09:05 »
JP, I used the seal on the lower bearing but not the top. I was able to retain the thin upper bearing cover.

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« Last Edit: Sep 28, 2017, 14:26:22 by clem »
"After every war there are soldiers who refuse to surrender. To this day there are still thousands who cling to their 30+ year old motorcycles, thinking that the war is still on, refusing to concede that the four-strokes have won"

1972 DS7 http://www.dotheton.com/forum/index.php?topic=45886.msg505995#msg505995
1983 CB550sc bobber http://www.dotheton.com/forum/index.php?topic=30599.30

Offline Ryan Stecken

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Re: Tapered roller bearings Yamaha RD
« Reply #6 on: Sep 30, 2017, 18:05:46 »
Hey guys!

Thank you so much for your input!
It all turned out very well!
In the end I had to remove all the stock bearing pieces,re used the rubber seal on the bottom (was soft and in good shape)greased everything very well and torqued it.
Due to the upper cup sticking out a bit there were fewer threads available but plenty to get it to torque properly!
Had a testride today and I'm very happy with the result.
Thanks for the help!


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Offline jpmobius

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Re: Tapered roller bearings Yamaha RD
« Reply #7 on: Sep 30, 2017, 19:36:19 »
JP, I used the seal on the lower bearing but not the top. I was able to retain the thin upper bearing cover.

Sounds right to me - I looked out in the shop and seem to have a couple of top seals so I'd say that is what I have done as well.
Mobius


On a long enough timeline, the survival rate for everyone drops to zero.

1973 RD350 Yamaha build  http://www.dotheton.com/forum/index.php?topic=66498.0