Front Driveline issues near steering lock

[photon_trap]

This is driving me nuts. I just installed a set of VP knuckles and C blocks and as I am attempting to re-set my steering servo end points end points I find I have an extreme case of what seems to be some sort of driveline binding anywhere near full lock. As I run it up, (on work stand) everything is fine when going straight, but when you get to a certain point turning L or R, I get a severe "irregularity" (for lack of a better term). What was smooth rotation turns into a almost crunching mess.
I have seen something similar with worn bearings in the front but all his stuff is new or in very good shape.
With the the wheels off it is barley noticeable, but with wheels on (even loose) it appears... Also, it does he same thing, regardless of where the suspension is in it's travel.... At first I thought I was exceeding the limits of the CVD in terms of angle but it starts at what seems to be about 2/3 of its range.
I did have the Diff apart (100K cst) but it seems fine doing what you would expect a diff to do.
Any insight is appreciated, staring at it and thinking does not seem to be helping - Ha!

 

[Jus]

It's the CVD's. It's a little less noticable when you're actually driving it but still happens. Especially at higher speeds. I notice it even more with my front end locked up. Just the nature of the beast.

 

[Calderwood]

In rc CVD is a slang term. As far as I know there aren't any true constant velocity joints smaller than 5th scale. When operating at an angle there is considerable acceleration and deceleration as the pin oscillates.

 

[ROLANDROCKSHOP]

it's normal..

oil and clean them each run and it'll be fine.

Im still on my stock/factory set of cvds..on 3s.

 

[photon_trap]

it's normal..

oil and clean them each run and it'll be fine.

Im still on my stock/factory set of cvds..on 3s.

Ok, thanks all...
I'm sure there's no oil in the area so maybe that's part of it.
It just puzzles me why i never say this before.
Do Vaterra's (less than)CVDs have some special design "feature" that makes them especially prone to this? I get none of it with my other kits.

There is enough of this that it actually causes differential action due to the intermittent drag. I have looked for witness marks and cant find exactly where its rubbing and found nothing so, it adds up, the issue is inside the joint.

Another strange thing is that when I hold the axle and CVD in my hand and spin it, it feels fine. I don't know how to explain this.

Anyway, I will add some oil and set my endpoints as wide as I dare and go from there. Thanks again, at least I'm not at all alone -ha! FWIW

 

[ROLANDROCKSHOP]

it's due to the design of the front A-arm setup..

at full droop it's close to being maxed out(cvd angle) then throw in the steering issues and its doubled.

It works..but..it has some quirks.

 

[photon_trap]

but cycling the suspension up and down has no effect strangely.

 

[photon_trap]

Just out of curiosity, anyone ever measure how much steering lock (in degrees) they get before they get CVD binding issues? Mine seems very shallow and binding is downright violent at full lock (even after oiling)

 

[Farmers00]

I have the exact same issue. Its not a droop issue. Its just the limitation in the CVD. I recently replaced one of mine and took the new one and replicated the rotation in my hand and could feel the bind at a certain point. I even have a youtoube video of it and a thread some pages back on here. It just happens at full lock. I haven't found a CVD alternative yet.

https://www.youtube.com/watch?v=DL8P5JtBKwI

 

[photon_trap]

Thanks dude, Yea, I see I am not alone and, as it is with no alternative CVD, I'm stuck like everyone else. I just can't believe Vaterra can't build a better joint - My other IFS kits have no problems and I would guess their turning radius is even tighter.
Anyway, I'm gonna re-adjust the endpoints to where the "irregularities" are reduced to a tolerable level. I was just wondering how mine compared to others and why i never noticed it before.... I find things like this difficult to tolerate but I guess I have no choice. Grrrr

Another mystery is why with the wheel and tire removed, it's barely noticeable.....

 

[Farmers00]

I noticed that too but I would assume because there's no centrifugal force of the wheel and foam to add to the vibrations / weight. I only ever crawl with mine so its really not noticable but at full speed you can tell and its probably putting loads of wear on the cvd. Just keep a few in stock lol. Surprised as well that for a rock racer, Vaterra hasnt patched this yet. Kind of a big issue. But I also dont really like the front rockers on the suspension. Feels too bindy. Cool idea, but at the end of the day, could do without. Also would have saved them all that hassle with Traxxas. But aside from those minor complaints, I have yet to have anything bad happen. I'm 100% stock except for front locker and I've only broken 2 CVD's (which is bound to happen eventually)

Heres my original thread about it. http://www.rccrawler.com/forum/vaterra-twin-hammers/452844-wheel-wobble.html