Survey: Steering Binds At Full Lock?

[JC3]

Doing a survey. When at full lock either left or right and moving forward, does your X4 show any signs of binding, clicking, crab walking, or as some may say scrub steering?

I'm trying to determine if this is a portal axle/CV joint thing and therefore something particular to the X4 or if it is just an anomaly found on some X4's. This can pertain to stock or modified X4's.

Let me know if you have experienced this or better yet found a way to resolve it.

[nodnarb0822]

It's a common issue, over extending the CV joint. Adjust the servo endpoints and it'll be solved. https://youtu.be/tFO29GV28yA

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[Inspector86]

I have five TRX4s and not one of them has displayed any problem with the CV joints binding at full lock. However, I do make a point of keeping the CV joints lubed and have my servo end ponts set.

[JC3]

Originally Posted by Inspector86

I have five TRX4s and not one of them has displayed any problem with the CV joints binding at full lock. However, I do make a point of keeping the CV joints well lubed.

Would you say that you are conservative with your steering endpoint settings as mentioned above or are you looking for all of the steering you can get? I set mine so that there is still some clearance between the inner portal cover and the steering yoke but still have what can only be described as some sort of binding/scrubbing. My friend sets his the same way and has no problems.

[JC3]

Originally Posted by nodnarb0822

It's a common issue, over extending the CV joint. Adjust the servo endpoints and it'll be solved. https://youtu.be/tFO29GV28yA

Thanks for the link. I did watch the video looking for any answers.

[neilus]

Mine does it. If i have 45 degrees of steering it's terrible (but only with the truck in the air). On the ground i would describe it as 'acceptable'. I'd need to turn the steering down to less than 40 degree for it to go away. I've left it at 45 degrees and drive accordingly.

[HumboldtEF]

You're grouping a few different things into one category to which they dont belong. What are you specifically asking about? Binding? Clicking? Or scrub radius?

these all separate subjects to some extent.

I'm just going to ignore crab walking because nothing crab walks without 4 wheel steering.

Anyway I'll assume your worried about something like this: https://www.youtube.com/watch?v=3g4d7gRlV0A

What you see in the video above is totally normal and nothing to be worried about, its just how a CV's act. Once on the ground they wont be near as bad.

[JC3]

Originally Posted by HumboldtEF

You're grouping a few different things into one category to which they dont belong. What are you specifically asking about? Binding? Clicking? Or scrub radius?

these all separate subjects to some extent.

I'm just going to ignore crab walking because nothing crab walks without 4 wheel steering.

Anyway I'll assume your worried about something like this: https://www.youtube.com/watch?v=3g4d7gRlV0A

What you see in the video above is totally normal and nothing to be worried about, its just how a CV's act. Once on the ground they wont be near as bad.

You're right, I've made a jumble of the description of the problem. I'll stick with tire scrubbing as it seems most accurate.The more I learn the more I think that there are two aspects to this. One is CV related and the other the issue of locked diffs. My truck is the Sport so the diffs are locked. I want to mention that these problems don't bother me, and I consider them minor, I'm just trying to get more info.

The video shows one aspect of it, the wobble at full lock. Attributing this to the CV's makes sense to me but I'm kind of surprised that it's even an issue. As you said, it's barely noticeable when the truck is on the ground and only happens momentarily at the steering extremes. I'd like to think I can alleviate it with some creative tuning on the CV's themselves. A work in progress for now.

The other aspect is the tire scrub due to locked diffs. Now that I understand why it happens I also figured out why my friends X4 does not do it. While I only have under-drive gears in the rear of my truck, he has over and under-drive gears in his. His front wheels are able to pull the truck forward without the rears pushing on them and trying to force them out. Some people want to attribute the scrub on the X4 to the portals, however, I'm not sure that they are right about that and the diffs seem more like the culprit.

I'm not suggesting that everyone get OD/UD gears to alleviate the problem, as OD/UD's aren't good in every application. For dedicated crawlers like ours, both or one or the other are fine.

[HumboldtEF]

I can attest to the underdrive/ovedrive combo improving steering on the TRX4, with it the front end does the pulling so to speak more than getting pushed around.

I dont think it has much if anything to do with portals its just the nature of fully locked diffs. The outside wheels have to travel farther than the inside wheels when turning and something has to give so this inner tire tends to slip or skip around as it keeps pace with the outer tire.
And as for coming up with a fix you might save you're self the trouble and except it as it still hasn't been fixed in 1:1 in all these years (well yes it has its call unlocking the diffs lol). I though I've heard that Universal type axles do this a little less than CV axles, though I dont think there's a universal axle available for the TRX4.


I really love this old video on differentials, it does a great job of simplifying the concept and showing its inner workings. (and this concept does apply to crawlers)



https://www.youtube.com/watch?v=yYAw79386WI

[JC3]

Yes, I've watched that video before. Many of those old time videos do an impressive job of explaining things.

And as for coming up with a fix you might save you're self the trouble and except it as it still hasn't been fixed in 1:1 in all these years (well yes it has its call unlocking the diffs lol). I though I've heard that Universal type axles do this a little less than CV axles, though I dont think there's a universal axle available for the TRX4.

I believe a DCV (dual CV) would fix it. I use them on my touring cars to resolve that very issue of wobble and steering limitation. As you said though, not likely that one is available for the X4's and implementing it would be quite a challenge given the space limitations. Maybe Traxxas will come out with a hop up kit! lol

[HumboldtEF]

Thats interesting, I've never seen a DCV before.