Inner c bearing? Are they necessary?

[cooterwrenchen]

Ive been RC crawling since the ax10 came out. Recently I was at a crawl cession and a guy was say he hasn't ran them since switching from dog bones to uni's. Is he alone in this? I mean I consider myself fairly knowledgeable about crawlers and this is the first I've heard of it. In a way it makes sense you might get more steering without grinding on your brand new axles. Any thoughts?

 

[cooterwrenchen]

Seriously? I didn't think it was that stupid if a question obviously some else must have tried this. I mean Chevys don't have a Bearing there probably other trucks as well

 

[Scotski]

If you are referring to the inner bearing on the steering knuckle, I fail to see how having 1 bearing instead of 2 will be better. The stress put on that one point will result in binding and wear, either of the axle, the bearing or the bearing seat. A bearing only has so much angular stress it can withstand before binding.
2 load bearing points reduces angular stress as well as supporting a much higher load. Also, how could having more bearings cause grinding on your axle unless the bearings are crap to begin with? In my opinion, running with less bearings is more likely to cause undue wear than with more. Perhaps the single bearing can support the load enough depending on what bearings you are using.
If you want to get 1-2 degrees more steering and are willing to take the chance of ruining parts, then that is the question you have to ask yourself. If that helps you win a comp then maybe it's worth it to some, but for myself, I look at the cost factor both in money and labor repairing the damage.
When you refer to a Chevy, I am assuming a full size vehicle. The difference is that a real vehicle has much tighter and stronger components. For example, the u-joints actually have bearings vs. pins without bearings(which have a lot of play most times and just rotate metal on metal). They also tend to have roller bearings and not ball bearings which again can support more load.

Just my thoughts. Hope this helps or maybe garners other opinions, whether professional or speculative."thumbsup"

 

[meatmonkey]

I think he's talking about the bearing inside the C-hub that the inner axleshaft resides inside.

Although I have heard people will shoe-horn XR universals into regular SCX knuckles by ditching the inner wheel bearing and getting creative with shims. I personally feel that this is a bad idea because there's no way the single smaller 5x11 bearing will survive without help from the now-removed larger 10x15 inner bearing.

As far as the C-hub bearing goes, theoretically when the universal joint is "tight" (this is why 1:1's get away without this bearing, although Toyota's and others have used brass bushings in this location) it isn't needed since the inner shaft is located off of the center axis of the U-joint.

However, once the U-joint wears and develops slop the only thing centering the inner shaft is the C-hub bearing. If the inner shaft is allowed to move off axis due to loose U-joints and nonexistent bearings then all sorts of bad binding and angular oscillations occur when at full steering lock. This is going to result in excess wear in the U-joint and the wheel bearings and potentially the interface between the inner axle and the differential's spool.

I don't see how you can gain steering angle simply by ditching the C-hub bearing? The ears of the XR universals require clearancing well before the bearing is a concern.

 

[vwmopar]

He probably has a Ford.

 

[cooterwrenchen]

The guy that was telling me at this has one some big events here in Northern California and Nevada, that's the only reason I gave it any thought. I know my uni's bind before full lock and I was thinking without the bearing in the inner c I might get full lock to lock without grinding the uni's

 

[Scotski]

That's what I was talking of, Meatmonkey. Seems in crawlers they call it a C-hub, but I have referred to it as a steering knuckle since I started RCs 20 years ago. Personally, if you need 1-2 degrees of steering or any angular displacement to win a competition then you may want to work on driving or approach skills or maybe even different rig setup. Just my opinion though. I am not a competition crawler and my scale driving skills are nothing to brag about lol.

 

[hibbs]

Why not take it out and see if it makes your steering any tighter? Mark off on the floor your turning circle to the right and to the left. Take the bearings out and recheck. If it makes it better, consider running it for a bit and checking for wear. Worst case you're out a few dollars for replacing worn axle housing? Maybe the axles or hubs. Share with us and let everyone know what you find.

 

[cooterwrenchen]

I think I will after the holiday. That's a good idea, I don't think it where the housings but it might cause that outer two bearings to wear faster than necessary. Threes and I think it should work fine is because a lot of 1.1 axles are like this.

 

[Highmark]

They serve to help support the inner axle and to help keep dirt out of the axle case. They also the inner axle and universal joint from deflecting under load. But the axle will still function without them as the bearings in the knuckles and at the locker/tang area do the majority of the work and support wheel/vehicles weight and inner axles.

A good way to visualize this is imagine torquing a long rod that is supported on both ends - if it's uniform it will fail in the middle. If you only support the bottom and torque from the top it will have an asymmetric failure as the entire rod moves around because it isn't supported. In real life this situation wouldn't be as noticeable because it is supported by the universal joint but it should give you an idea of the extra forces (beyond turning the wheel) that it's putting the joint through.

BUT the bearings shouldn't have anything to do with getting more steering out of a properly setup rig. When setup correctly, the universal should pivot on roughly the same axis as the knuckle (it gets kind of weird with 8* knuckles but the concept is still applicable), but if it isn't then the entire axle is forced to move in and out, and also side to side (where the bearing your asking about should keep it from doing so). This is the situation where you would get more steering but obviously this is far weaker.

 

[chino63]

They serve to help support the inner axle and to help keep dirt out of the axle case. They also the inner axle and universal joint from deflecting under load. But the axle will still function without them as the bearings in the knuckles and at the locker/tang area do the majority of the work and support wheel/vehicles weight and inner axles.

A good way to visualize this is imagine torquing a long rod that is supported on both ends - if it's uniform it will fail in the middle. If you only support the bottom and torque from the top it will have an asymmetric failure as the entire rod moves around because it isn't supported. In real life this situation wouldn't be as noticeable because it is supported by the universal joint but it should give you an idea of the extra forces (beyond turning the wheel) that it's putting the joint through.

BUT the bearings shouldn't have anything to do with getting more steering out of a properly setup rig. When setup correctly, the universal should pivot on roughly the same axis as the knuckle (it gets kind of weird with 8* knuckles but the concept is still applicable), but if it isn't then the entire axle is forced to move in and out, and also side to side (where the bearing your asking about should keep it from doing so). This is the situation where you would get more steering but obviously this is far weaker.

Great job describing how things work right there. What about a description of lateral movement vs. torque angle under load and how it is affected by scrub radius, gear ratio and caster. I'm having a tough time visualizing that.

 

[snapon boy]

When I built my son s dingo I forget to put those in about a month later the outside bearings failed. Before they did the front wheels had lots of wobble.