Bravo XR Rolling load Torque?
 

Guess this would be a question for Mr Gadgets.

XR lower rolling load torque per Merc should be 3-5 inch pounds. Is 2.5'ish on run in parts ok?

Just had one checked because it had some end play after a rebuild, they pulled it apart and reset at a claimed 3.5 lbs stating that the race might not have been fully seated in the carrier. When I checked it it myself it was at 5+ lbs and the needle was very unsteady, was very jerky and would vibrate as you rolled it around. Took it elsewhere for a second opinion and was told it acted too tight, we have backed it off right around 2.5lbs, same as the other untouched drive, and it feels fine now. Ran it this past weekend and after some long and very hard runs I'm not seeing a great deal of rise in the res level. Running 75/110 Amsoil Extream in a 1.50 Bravo XR. Both lowers now have a very silky smooth feel to them.

Am I good to go here?

To check the rolling torque you would have to remove the lower so you are not turning anything else. The 3-5 you speak of is just for the vertical shaft with out the prop shaft installed. After the prop shaft is installed the total rolling torque for both shafts is 11-15 inch lbs depending on new or used bearings and if you set it to low side of spec or high side of spec.

which shaft are you referring to? prop shaft ?

Yes,the rolling load torque taken at the prop shaft with a fully assembled lower not installed on the upper, all run in parts, nothing new except the keyed tab washer and seals. Only taken apart to inspect after the upper gears chit out. This thing felt tight at 5.5, I can't imagine what it would feel like at 11 - 15. At the 2.5 both these lowers feel silky smooth, no end play, and seem to run well with very little heat build after long hard runs.


By the way is the Prolong product their SHD Oil Stabilizer? Or the regular engine treatment product?

Thanks Mr G, value your input.

Sorry for the delay in answering.. I have been working 5am to 11pm most days.. just not enough time in the day..

Rolling torque on propshaft is 8-12 new bearings, and 5-8 old. I set it without a clamp on the vertical shaft bearings, but with the case loaded.
If you feel any jerky or see the needle bounce, the bearings have dirt or are damaged, usually. With no preload, I see about 2.5 with good seals on the shaft.
That being said, if you have no wobble in the shaft and it runs free. Then it should be ok. But I would like to see it tighter. The bearings will loosen and it will be a problem.
I would run it at the 5, but if the bearings are used, they probbably have dents in them. And I would replace them and start from scratch. So you know you are getting a good preload reading. If you do run it... loose like that. Keep an eye on it, check it everytime you come in for end play and up and down.
Hope that helps.
Dick

I guess you learn something every day. The guy that did the drive originally, Merc certified tech, and then reset the lower to correct the loose prop shaft, the in/out play, told me rolling torque was to be 3-5 per the manual specs. Guess it's time to buy my own manual and do some reading. Would the spec for an XR lower be different than a regular Bravo unit?

When I put the torque wrench on it my self the needle did act jerky. Would bounce a pound or two as you rolled it around. My thought was dry, as it was upside down for over a week while I prepped and repainted it, adding some lube seemed to help a little. But it still felt tight when compared to the other one which has never been touched and has been trouble free. I was in the water on monday after a couple hours run time and and the prop felt good as far as end play, not a real high tech check method, but it was not moving in and out like before.

Thanks for the help.

Ragged

Yeah, B1 and XR propshaft rolling torque are the same. The jerky needle indicates dents in the race of the tapered bearings. With all the metal the Bravo produces, it is a wonder the bearings last as long as they do.
I use RP oil to assemble my drives and it will hang on the bearings for a while. If they are dry, you get a completely different feel when you check it..

Dick

So would the jerky feel be caused by the bearings that sit on each end of the prop shaft? Thinking I should go ahead and replace them and the races, or would I be wise to just replace all the bearings in the lower, including the ones on the vertical shaft, and be done with it?

Makes sense that there might be something wrong with the bearings or races, in that there was some end play in the prop shaft which is what led to getting into this in the first place.

Bump .................. Mr.G ???

Sorry.. been over run with work lately

If it were mine, I would replace all the bearings, but you will have to recheck setup afterward. Some races will change the height of the vertical shaft, and hence the lash.
If you spin it with load on the vertical shaft, it could be those bearings also. I feel it is a waste of time to not change them all.
Dick