R200 NLA Front Pilot Bearing

[ezzzzzzz]

BlueovalZ, I jumped ahead of all the other posts to state I'm in agreement with your observation. Any helical cut gear is going to try to walk away from it's mated gear under load. The pinion is no exception. In this case, the pinion bearings do experience axial (side) loads of some sort.

[rudypoochris]

Yes, but in this case we are talking about a bearing that is not going to experience much axial loading at all. All the load would go straight through the inner race.

 

My hybrid bearing is coming. It is rated to run with no lubricant which is nice. It doesn't reduce friction much over straight SS bearings, but some (spin down time compared to normal SS is twice as long at 5000 to 2000rpm using 1/4" ID 5/8" OD bearing). It does dramatically reduce wear and lowers temperatures apparently because the ceramic balls cannot create little welds to the peaks of the races under high load. Spin down time for the same bearing, talking full ceramic is 350 seconds as opposed to 35 seconds, from 5000 to 0 rpm. Would have cost me $215 instead of $105 though so I figure I will just be happy with the no lubrication required bit.

[JMortensen]

The ball bearing is not the only bearing in the diff. Most differentials don't even have a pilot bearing, and those that do often have it at the other end of the pinion gear (like a Ford 9"). The load from the gears driving on each other are enormous, and a ball bearing, especially a single row bearing, wouldn't be the best choice to deal with such loading. In my time selling diff parts I can think of only one differential that had ball bearings taking the thrust load, and it was an OLD (1940s or 1950s) GM one ton truck. It used a 4 or 5 row ball bearing that was hyper-expensive and hard to get. Everything else I've ever seen uses a tapered roller, and that makes a lot of sense because they are so much better equipped to deal with the type of loading we're talking about.

 

The tapered roller bearings take the load from the pinion trying to walk off the ring gear in the R200. When the pinion tries to push off of the ring gear towards the front of the case, it presses the tapered roller bearing with the blue race in the attachment. The blue race is pressed into the case, thus the case absorbs the load from the pinion. The pilot is just along for the ride. In reverse the smaller green race takes the load.

 

The "pinion bearing adjusting spacer and washer" define the preload of those bearings. Once that distance is set, nothing that goes on after them affects it (except a loose pinion nut--been there done that). The bearings are seated in their races, which are seated in the case and and that is where the forces trying to drive the pinion off the ring gear are concentrated. Unless there is some abnormal slop in the bearings or the spacer is wrong, the pilot is just along for the ride and is centering the incredibly long pinion in the housing.

 

The reason for the pilot bearing in this diff is the extreme length of the pinion gear. The difference is pretty extreme! See for yourself:

 

R series ring and pinion:

 

Ford ring and pinion:

 

[rudypoochris]

My hybrid Ceramic ball bearing came back. I am pleased with it. It has a different retainer, and the black ceramic balls. The unit rolls much easier than before (that could just mean larger tolerances though - although I feel no difference). So far, so pleased.

[Guest GaryZ]

Just wanted people to know that these are still available from Courtesy Nissan as I ordered a couple this week.

[Toni L]

Hi.What is the easiest way to replace that front pilot bearing? I have differential case taken away and oil seals, and I can see that front bearing is not tight. Do I have to remove drive pinion?