Technical question for Mr. Gadgets and other drive builders
 

Any way to stop the pinion bearing/race from going bad when running big power to an XR?

This is the second time in the past 4 years I've seen this; see below... Every winter I replace the bearings in the lower, gears every other season. I was running the caged pinion bearing but I've recently been told the Mercury bearing is superior and that the caged bearing tends to "grab" the race and tear it up when running big power?

only 20-30 hours on this bearing set.... I'm going to use the Merc needle bearing but thought I'd run this buy you.

Thanks in Advance!

Frank

You are most likely running props out of the water (surface riding) Pinion shaft starts to move around not enough support in lower bearing area on Bravo lowers. Also check run out on pinion shaft.

Without a doubt, get rid of that caged Imco bearing and use a Merc bearing. Far better bearing. Just remember, you have to change the race to a merc race and since you are running an Imco vertical shaft, you have to put a small taper to the inside of the race, where it will touch the step on the vertical shaft. Otherwise, the race will not seat all the way flush to the step on the vertical shaft.

5 1/2" propshaft depth, it's not surfaced. I'll double check the run out when assembling.

BMax HT's, they're not radiused but thanks for the suggestion.

What I meant by saying surface riding was not prop shaft depth, but with the high HP and running at high speeds and trim & transom lift the bullet rides very close to surface of water. The prop shaft has two good size bearing to support prop shaft. The pinion shaft has good support on top of shaft but not on bottom where your having the problem. Also make sure the pinion bearing is tight in case, sometimes a little green loc tite helps

Frank,
I am not sure about the Bmax lower bearing. I know it is caged, I have only seen pics of them. But with the Imco caged lower bearing they decided to go back to the Merc bearing. And the shafts are radiused at the steps.
Will the Merc bearing fit into the lower housing, if it will I would use it. If there is another bearing that isnt caged I would use it. There is more support with more needles. The myth is the caged are better, run cooler, but they also have less load capacity, as I have been told, by bearing people.
One thing to check is the shaft runout and the runout of the bearing on the shaft at the lower end. I have found the shaft to be good, but when the bearing is pressed on, it has more runout out.
But I have never seen a bearing on the vertical shaft wear like yours. But I have not had an opportunity to work on the Bmaxes..

Hope this helps.
Dick

Most likely you do not have enough clearance to the race do to the bore in the case, it seems that the bore has a slight taper and it reduces the bearing size so you loose the proper clearance for lubrication. I have seen this before and the fix is to re-bore the housing or you can have the race put on a center grinder and have it clearanced. But you will need the proper tools to check for how much the bearing has changed from on the bench to in the case.

Also make sure that the top of the bore has a nice flat surface for the bearing to seat on when it is pull up into the case.
Also the Bmax vertical shafts is a little under sized at the splined end and the gear fit isn't as close as it needs to be so the gear has a touch of run out and this can also cause bearing issues.

A new shaft is in the works.

With Bmax closed it will be very important to keep the parts you have maintained.

Thank you all for the input, we'll have to see what happens next winter with the Merc bearing installed! :coolcowboy:

PS, the yellow arrows are the aftermarket caged bearings.