New universal install, limited steering

[linklemming]

Been loving my new Wraith Spawn RTR although I should have just bought the kit as Im upgrading it anywho.

One thing I really dont like is the limited steering angle. I thought I would go 4WS but decided to try upgrading the front driveshafts to universals first.

With the dogbones, I just set the steering EPA so the dogbones wouldnt click at full steering lock (55% on a GT3C). I did not check for the behavior I mention below.

Install was pretty straightforward. The 'only thing' I did not do is put loctite on the diff side of the axle that is shown in the kit manuals. Not sure what that would do(other than remove slop) except to make the axles impossible to remove later on.

The increased steering angle after the install was awesome. I was able to increase EPA to about 75%. Just putting around, I loved the change.

Something I noticed was that with increasing steering angles, I seemed to be experiencing binding when throttle was being used, basically causing the front end to start hopping (when holding the car off the ground)

This only happens when I put the wheels/tires on. With the wheels off I can go full throttle and apply steering until the servo binds due to the steering links hitting the axle housing(temporary EPA as a reference). It seems to me that if the universals were binding I would see it with the wheels off as well. Putting on either wheel causes this problem immediately. I even tried putting on just the wheel hub only but didnt see the issue when I did this. The wheels/tires are not touching anything when this problem occurs

With the wheels/tires on and the driveshafts disconnected, there is no universal binding either. I can spin the wheel by hand as fast as possible or just turn the driveshaft portion at the diff.

I did discover that I didnt have my driveshafts aligned and fixed that, the behavior got better but its still limiting steering angle.

At this point, I have EPA set to 45% and dont have the issue at this setting. That being said, I only have 20 degrees steering angle. I see people mention that this is just the nature of solid axles/locked diffs but 20 degress seem pretty low to me and pretty much the same as the dogbones.

Total drivetrain lash at the tires seems to be +/- 1/2 inch just rolling the car forward/backward.

Anything obvious I am missing

Yes, I did search, about 6 hours on youtube, google and rccrawlers

[TacoCrawler]

Common error by many, so thought it should be asked.

Are you sure that you aligned (Phased) the drive shaft's correctly ?
^ assuming you had taken those apart.

The WB8 DS's have alignment markings on the plastic shafts.
But if they're aft. mkt.
then ensuring that the universal pins align with each other, will work.

from your description it sounds more like shaking then bind.
but hey... I'm just guessing here.

[linklemming]

Originally Posted by TacoCrawler

Common error by many, so thought it should be asked.

Are you sure that you aligned (Phased) the drive shaft's correctly ?
^ assuming you had taken those apart.

The WB8 DS's have alignment markings on the plastic shafts.
But if they're aft. mkt.
then ensuring that the universal pins align with each other, will work.

from your description it sounds more like shaking then bind.
but hey... I'm just guessing here.

Not sure what the 'technical terrm' is...Ive seen many

Didnt see alignment marks on the driveshafts but in the wraith kit manual, they seemed to show that the pins needed to be aligned. The wraith spawn manual doesnt show any of this but I made sure my assemby looked identical to what was shown in the manual(pins vertical).

I did align/phase the driveshaft. Basically made sure the all the slots were the same on assembly(vertical).

[351Beno]

The inner tire rubbing the links? If you dont have stops that can happen.

[WHITE-TRASH]

As the angle of steering increases the tires will begin to speed up and slow down as they rotate.

[maslin]

Originally Posted by linklemming

Something I noticed was that with increasing steering angles, I seemed to be experiencing binding when throttle was being used, basically causing the front end to start hopping (when holding the car off the ground)

How's it drive when you aren't holding it off the ground?

I'd put this one in with "my car sits crooked on the shelf!"

Drive it, it probably works just fine.

[Brandon]

Its the anatomy of a U-Joint that you are seeing.

Input speed vs. output speed varies as the angle increases. Wikipedia made this easy to share

https://en.wikipedia.org/wiki/Universal_joint

[Brandon]

Also, this video was posted on our Facebook a while ago. Definitely helps explain whats happening.

https://www.facebook.com/axialinc/vi...3791634495873/

[TacoCrawler]

as far as Axial universal axle shafts... there are angle limits



some may attempt some dremel work to net more
but doing so can weaken the universal's strength.

[linklemming]

Thanks for all the info guys, I was going crazy trying to figure out what was causing this.

I had no idea universals did this (new to crawling).

[TheBigRigger122]

Originally Posted by linklemming

Thanks for all the info guys, I was going crazy trying to figure out what was causing this.

I had no idea universals did this (new to crawling).

Same here man!

[351Beno]

If your only getting 20 degree of steering keep working. My wraith and xr10s with universal can well over that with no hop or binding. I did have some sets that i had to grind a bit off the ears because they would hit. Some pics or video would help.

[linklemming]

Originally Posted by 351Beno

If your only getting 20 degree of steering keep working. My wraith and xr10s with universal can well over that with no hop or binding. I did have some sets that i had to grind a bit off the ears because they would hit. Some pics or video would help.

As I mentioned in my original post, there is no binding of the universal up to where the servo stalls due to linkages hiting the axle housing(probably 50 degrees). With the driveshaft off I can spin the wheel by hand, no problems. I can also remove the front wheels and go full throttle/full steering(50 degrees) with no issues.

Also, the wheels are not hitting anything.

Its definately the acceleration/braking of the wheel as shown by the video/graphs posted by Brandon. It is speed based getting worse with higher wheespeeds.

Only other thing I can think of is the drivetrain lash in the diff amplifies this accelration/braking effect.

[Soldat Vaillant]

Originally Posted by linklemming

As I mentioned in my original post, there is no binding of the universal up to where the servo stalls due to linkages hiting the axle housing(probably 50 degrees). With the driveshaft off I can spin the wheel by hand, no problems. I can also remove the front wheels and go full throttle/full steering(50 degrees) with no issues.

Also, the wheels are not hitting anything.

Its definately the acceleration/braking of the wheel as shown by the video/graphs posted by Brandon. It is speed based getting worse with higher wheespeeds.

Only other thing I can think of is the drivetrain lash in the diff amplifies this accelration/braking effect.

the wheels and tires add a lot of weight (load) to the knuckle bearings, if one or more of them are worn or sloppy it could be changing the angle of the stub axle end of the universal when the tires are off the ground. without the wheels and tires the axle can move around a little and find it decent center to run smoother. big out of balance nature of crawler tires aren't helping. this isn't much of a problem when your driving, unless you spend a lot of time at full throttle with the wheels turned while flying though the air.

[maslin]

Originally Posted by Soldat Vaillant

this isn't a problem

Well said.

[winnerone23]

Originally Posted by TacoCrawler

as far as Axial universal axle shafts... there are angle limits



some may attempt some dremel work to net more
but doing so can weaken the universal's strength.

Not picking on you taco...

The axial uni's Do have angle limitations.. In Stock form.. (See above pic)

The main issue with the is.. The ears hit the inners and the edges of the ears. Hit the edges of the ears.



So 2-3 options...
1. Sand the tips of the ears off, just to get a little smoother..

2. Buy Dlux modded uni's

3. Do a little work..
Drive skinny pin out. (Make sure you clamp the bottom ear, tightly)

The rest just comes apart.

Dremel or hand file, the outer ears (not a Ton, just enough).. Then file the inner, where they contact.

Then clean up with WD40 and put back together..

These are mine. While they are overkill (for visibility and show) I have never had one break!

From 1.9 mrc, to the Sexo.(3500kv XL on 4s @ 30mph) and every rig I own, in-between.
You can't over steer and bind them! Lock them in a drill and get 80° out of them.

Yes, they speed up and slow down, still..
But won't bind and break.

The only uni's I ever saw break, comes from too much steering and Stock uni's..
They bind on themselves and that's how they break.

[northern hooligan]

@ linklemming, your question/dilemma also just helped me out.

This forum is great for all the info on here, I just bought the universal set myself and will install them in the future and after I get some hours on the wraith.

I just opened up the package and sure enough the ears do make contact. I will try option 1 - Sand, then if need be option 2 - A little work

@ winnerone23, thanks for the info/ fix tip.

[linklemming]

Originally Posted by Soldat Vaillant

the wheels and tires add a lot of weight (load) to the knuckle bearings, if one or more of them are worn or sloppy it could be changing the angle of the stub axle end of the universal when the tires are off the ground. without the wheels and tires the axle can move around a little and find it decent center to run smoother. big out of balance nature of crawler tires aren't helping. this isn't much of a problem when your driving, unless you spend a lot of time at full throttle with the wheels turned while flying though the air.

Yeah, I agree it isnt really a problem as most of the time when I am using high steering angle, I am going REALLY slow (i.e crawling). The only scenario I see is when trying to power up an traction limited incline with alot of throttle, sometimes it helps to go back and forth on the steering. I actually thought of doing some mixing effectively reducing steering based on throttle. It would be weird/scary when reducing throttle in a turn though.

Luckily I have a great crawler store within 30 minutes (crawlspace). I paid them a visit today and his suggestion was to dremel the knuckles just as has been suggested.

I will do that and report back

Just spent 30 minutes grinding down the knuckles, it is much better, I can get 30 degrees of steering now.

Going to try what winnerone23 suggested on the ears next.

Did some more grinding of the knuckles and took a file to the ears outlined by winnerone23 . I could actually see where there was rubbing on the ears so I just used a small file, no dissassembly and I am about 33 degrees now. I could probably go further but feel it will be a game of diminishing returns at this point.

My EPAs were at 45 before, now 60. I ran the dogbones at 54 so its not really that much of a gain for me 'steering wise' compared to the dogbones.

I do plan on 4WS soon so Im ok with what I have now.

I have decided to try the vanquish VVDs and see what I get with these as far as steering angle.

I will report back Monday when I get them installed.

It seems like I am going down the path of making my axial universals look like the vanquish VVDs. While the VVDs are twice the price, if I can bolt them on and get 45 degrees steering angle at full throttle, thats alot cheaper than 4ws and should be fine. If not, I can run the axial universals in the rear for my 4ws setup.

Its basically a what is my time worth question, Im probably 6 hours into solving a problem of making the axial universals barely exceed the steering angle of the dogbones. I know what my time is worth and I am way overbudget on this.

[WHITE-TRASH]

You either have a bad set of universals or you're having issues with something else. Straight out f the package universals are good for 50* with zero issues.

Vvd's are good for 50* also but they speed up and slow down exactly like a universal style shaft since they are not a true cv style joint.

I have broken a vvd but never a universal at the joint if that tells you anything.


I'd suggest pulling the shafts out of the housing and reassembling the knuckles and C hubs then cycling the steering. That will tell you if it's the shafts or not.

[Erik D_lux]

Originally Posted by winnerone23

Blah, blah, blah, yak, yak, yak, picture, picture, picture

Awesome write up Troy! I will be referring many to this!

To back up what Troy said, any time you remove materiel, you're weakening it but if done right, it does not matter as it will still not be the weakest point of the shaft.

I cant tell you how many modded shafts I have sold at this point and while some have broken, not a single one that I know of has broken at the point where I mod it.

Just what I consider an interesting observation.... its only the Wraith shafts that bind at the end of the ears (not the inside edges). The XR version does not have this problem.

When the ends of the ears do bind, I suggest letting them self clearance. They dont bind that hard and taking minimal material off this spot is important IMO.

The one down side to getting more angle is that if you do not run a steering stop, the shafts will allow you to steer too far and you will snap a shaft. A stock shaft limits the steering at 50* and wont let it turn further. This is not enough to fully bind the shaft. When you get 70*, it will fully bind and snap the shaft.

People really, really, really, really, really, really, really need to start making mechanical steering stops. I would venture to guess that a huge percentage of shaft failures are due to a lack of mechanical steering stops.