Yamaha 9.9HP reverse gear and bearing fit (should it be tight or loose?)

[Kevin_Kondo]

Hello there, I am new to this forum.

Just purchased a yamaha reverse gear for 9.9HP outboard engine (parts no. 6E7-45571-00-00) and noticed that I can install the bearing onto the gear without using any tools, I was expecting this would require tools and some hard work.

When I put the gear with the bearing facing down, the bearing would just drop off. Is this normal or would it have some adverse effect on the engine?

[99yam40]

I have never worked on one of those 9.9s before,
but what did it take to remove the old bearing?
That should give you some idea of what the fit should be like

[Kevin_Kondo]

Thank you 99yam40, I didn't pay attention to it when I took it off, only noticed it's not normal ( comparing to other bearings I've worked with that have a tight fit) when I was installing the new reverse gear. I will just go ahead with it and see how it goes.

[TownsendsFJR1300]

If that gear is spinning loose on the bearing that bearing isn't going to work properly and you'll have excess play resulting in excess wear. It should at least be snug (some application with a hammer and proper tool).

I'm assuming your assembling the bearing to the gear the way the manual calls for.

You can also enter your year and model # after clicking on the RED "Purchase Yamaha Parts" in the upper rt of this page to see the assembly order.



THE OLD BEARING, HOW DOES IT FIT COMPARED TO THE NEW ONE??

[99yam40]

I would measure the new and old bearings and the gears
Or try to find the specs to compare.

Maybe Rodbolt will chime in.
give the model # of the motor , but I think all the 9.9s used the same gear

[zenoahphobic]

One, always take pictures (mobile phone whatever) before and during dismantling.

Two, always compare new with old before reassembling, use calipers, vernier guage and measure if not fitting properly to determine whether component just out of tolerance, or majorly different.

It seems the inner race diameter is too large.

Just a bit of a preach, sorry.

[Kevin_Kondo]

Thank you guys for helping out new guy here!

TownsendsFJR1300: I didn't change the bearing, it is the reverse gear that I changed. It requires no tool to put it together with the bearing. It doesn't have the snug feeling but it isn't loose neither. I measured the inner diameter of the bearing and the outer diameter of the new gear, they are 25.0mm +/-0.00mm and 25.0mm +0./-0.018, from my understanding the outer diameter of the gear should be 25.0mm +0.005/+0.012mm to produce the "snugness".

99Yam40: I measured the old gear also, it is 25.0mm -0./-0.018mm. Since the old and the new gears agree on the tolerance I guess this is how it is supposed to fit.

zenoahphobic: Thank you Zenoaphobic! Lesson learnt! I will definately keep those in mind!

[99yam40]

If the gears are the same then maybe the bearing is what is out of tolerance for the proper tight fit?

Why were you changing the gear?

Hopefully everything is OK and will work for years for you.