Needle bearings

[tonyfalkon]

Is there a specific reason why manufacturers don't use/incorporate needle bearings on the transmission or axles or even driveshafts for that matter in rigs that are 25 or more inches in length ? Are there any cons to using it instead of 2 or more ball bearings in place ?

A few months back, about 3 - 4, when I was incorporating the recessed 3 bearing mod on the differential drive line, I came across a needle bearing with 15 x 21 x 12 mm dimensions which is the same length as the 3 bearings I'm installing. Naturally I ordered the bearings but with the installation of some other mods such as using the front center driveshaft on the rear then using the HPI boot to cover it (still water resistant BTW with no binding, getting caught or crumpling) and the recessed 3 bearing mod, the needle bearings sat for a while. I wanted to see how the other mods are affecting the rig before I put it in another modification.

After about 75 hours of testing and no catastrophic failures, its time to use the needle bearings instead of the 3 bearings. I will use it regardless in the front/rear axles I just wanted to see if you guys know something I don't, from what I have read about needle bearings they are actually sturdier and more stable than using 3 ball bearings.

[Tzicul]

The problem is you don't have the inner ring that the pinion sits on and rotate together with it. So the pinion will rotate against a still surface. I considered this mod some time ago and I didn't figured it out how to resolve this. Maybe you will

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[Pete9]

Originally Posted by tonyfalkon

Is there a specific reason why manufacturers don't use/incorporate needle bearings on the transmission or axles or even driveshafts for that matter in rigs that are 25 or more inches in length ? Are there any cons to using it instead of 2 or more ball bearings in place ?

...

After about 75 hours of testing and no catastrophic failures, its time to use the needle bearings instead of the 3 bearings. I will use it regardless in the front/rear axles I just wanted to see if you guys know something I don't, from what I have read about needle bearings they are actually sturdier and more stable than using 3 ball bearings.

Generally, needle bearings are used when the only load is radial (basically, a force outward from the center of the rotating axle out directed out perpendicular through the outside of the bearing). Ball bearings, because of there spherical shape, can handle both radial loads but also axial loads (forces that apply along the direction of the axle, either forward or backward). Balls can roll both along the outer race and also along the inner and outer edge of the cage. Needle bearings suffer from greater friction when there is any axial load (like from your axle shifting a little bit back and forth inside the bearing).

I'm really curious how well the needle bearing will work out. I think it's worth a try. If the amount of play in the axle or driveshaft is very small, needle bearings might work, and be much tougher than even 3 ball bearings. On the other hand, they might generate a bunch of friction, and therefore heat, and melt your diff housing. Can't wait to hear your results!

[tonyfalkon]

Both valid points tnx gentlemen, I've test fitted it, rolled and wiggled it plenty of times and as far as I've seen/experienced the bearing just drops in not tight or loose either. Rolls as smooth as a ball bearing, Im not really worried about dirt and water ruining it because of the HPI boot that I have in place in the front and marine grease on the opening. The axial forces that Pete mentioned is where I am a bit concerned, I drilled down the screw holes so the screws can be lowered, hence recesses 3 bearing mod. I implemented that in anticipation of the backlash to prevent the pinion moving a lot closer to the differential than it needs to be but since I was using ball bearings I was confident they will hold. Using the needle bearing however I'm not sure if lowering screw holes would even matter.

To keep the pinion from backlashes or axial forces that would affect the needle bearing, there should be a limiter on the opposite side to keep the pinion from moving forward, which technically would make it more complicated than just using 3 bearings in the first place. I think I'm over thinking it again either that or I'm getting ahead of myself yet again. I guess I won't know until I start bashing it on the field, immana try the simple approach first and go from there.

If you guys think of anything else I may have missed or may have not considered please lemme know, it may take me month to post some results, I need at least 12 hours of bash time before I'm convinced if this is worth further pursuing or just table it.

Tnx again T and Pete.

[thatguy]

The contact patch of the bearing face. The more contact the more friction.