Cheapie XR steering conversion

[Hardline]

I did my first steering conversion using plastic c-hub & knuckle and promptly upgraded to VP Wraith pieces because the plastic knuckle wouldn't rotate far enough due to the twin tie-rod arms hitting the housing.

Now I want to do a low-cost build on another car but still need better steering. And I've got those original plastic pieces just sitting around. Since both the draglink and tierod will install to the front of the axle, I wonder how successful it would be to just cut off the plastic tie-rod arms and do both the draglink and tierod off of aftermarket arms (RCbro etc) on the front only. Any reason this wouldn't give me the same steering as the VP stuff, only not as strong?

[MRCrackhead]

I've been running the plastic knuckles for a long time on my mini with no issues at all.

Low budget in mind, I did the same to my AX10 and have had no issues either.

The VP knuckles will give you more steering than the plastic knuckles because the arms mount much higher on the knuckle.

Whatever steering arms you run, the rod end will be the first thing to contact the axle housing. The higher mount on the VP's allow the rod end to pass above the axle tube. That's what gives them the edge.

Depending on what you're trying to accomplish, the plastic knuckles (with the double arms cut off) will give you a LOT of steering. More than most setups will allow without major rubbing issues on links/shocks.

Best part is, you've done most of the work. Upgrade to VP's when you can.

Check out my build threads if you'd like some pictures/ideas.

AX10
Ugly Betty

MRC
Mary Shelley's MRC

[Hardline]

Originally Posted by MRCrackhead

The VP knuckles will give you more steering than the plastic knuckles because the arms mount much higher on the knuckle.

Whatever steering arms you run, the rod end will be the first thing to contact the axle housing. The higher mount on the VP's allow the rod end to pass above the axle tube. That's what gives them the edge.

Thanks. Assuming the plastic arm-mounting surface is lower (not suggesting otherwise, just haven't looked), why couldn't you just put spacers under the arm to bring it up the the VP arm height? And then they'd be identical. Unless the VP arm mount is not in the exact same location when looking straight down on it.

But as you suggest, it may not be important because something else my stop my steering before the rod-end hits.

[Haastnooit]

I got my steering setup exactly like you describe above ... I am using stock Axial XR10 c-hubs, knuckles and (short) Axial zero ackerman knucklearms. The c-hubs are clocked one spline past stock max castor.

http://www.rccrawler.com/forum/axial...suduone-9.html

On page 9 you can see some steering angle pics ... I think steering is pretty good for this setup. Using some longer knuckle arms will probably add some extra degrees to the steering angle. I still have to try, got some RcBros extende VP knuckle arms ready.

[MRCrackhead]

Longer steering arms won't give you more steering.

Different lengths change the amount of throw the servo will need to turn the knuckle.

Longer arms give the servo more leverage, but too long and the servo will not travel far enough to complete the lock to lock cycle.

Zero ackerman arms are 90 degrees from the point of pivot. Whether the arm is 10mm long or 10km long, when it pivots, it will hit the axle tube at the exact same degree.

The 10km arm will have to move a long way to get there, but the knuckle will be traveling exactly the same.

[Hardline]

Haastnooit, I looked at your pics and I couldn't be sure but it looks like there might be some unused travel on your steering horn. When you're at max angle, can you see what's stopping the tire from turning further? Check it with the links connected and again disconnected. That will tell you if the linkage or servo travel is part of the limitation.

[Haastnooit]

Steering angle is at max with current setup, on the driverside the nut below the knuckle arm hits the axlecase and on the passengerside it is the rodend of the steeringlink that hits the axle case. I use the short Axial zero Ackerman steeringarms, you can see them on page 1 and 2 in my thread. Current arms are real short, longer arms could improve my set up

[MRCrackhead]

Originally Posted by Haastnooit

Steering angle is at max with current setup, on the driverside the nut below the knuckle arm hits the axlecase and on the passengerside it is the rodend of the steeringlink that hits the axle case. I use the short Axial zero Ackerman steeringarms, you can see them on page 1 and 2 in my thread. Current arms are real short, longer arms could improve my set up

Bolt longer arms on and hold your breath until it helps increase your steering angle.

After you wake up from passing out, it will all be crystal clear.

[Hardline]

No, longer arms could possibly result in increased angle. If they move hardware or rod ends further from making contact. But as you say, longer arms will need to travel further so will need a longer horn or more swing on the servo. It's pretty much a case by case basis. Hard to tell if you don't have the assembly in your hands.

My XR steering seems to be limited by the pulsing that comes with universals operating at high angles. That's after clearancing everything so nothing is hitting or rubbing. Since the four tires don't pulse in phase, that means some tires need to turn faster than others, resulting in wadding and bind. I don't know any way around that except a true CV joint and what we call CV joints aren't.

[MRCrackhead]

Nobody is selling longer arms and advertising how much more steering they'll give you.

Because they won't.

Longer arms are even referred to as "torque arms" because they give the servo more leverage.

VP knuckles get the link ends ABOVE the axle. That is the ONLY way to get better steering.

I don't know how to explain it any clearer than my post above.

45 degrees is 45 degrees one inch from the knuckle or one mile........

It's still 45 degrees.

[Hardline]

Sigh. Nevermind.

[Haastnooit]

[MRCrackhead]

Originally Posted by Hardline

Sigh. Nevermind.

I was typing my post while yours was posted already.

I agree that if a different arm lands right in a "sweet" spot, it could eek out a degree or two.

Not many of those on an AX10 housing. It's fairly straight.

Agreed on the universals too.

Also, I've had my steering working at ridiculous angles and it's not a help at all.

The outside tire just folds under and makes a mess of things.

[Hardline]

I think locked axles are doomed from the start regards smooth, extra tight turns. We just do what we can do. Some of my clubbies are pretty good at dynamically throwing a 180. Mine's heavier and not too agile that way.

Ronald, I can see from your sketch that 71 degrees beats 64. Can't really figure out what that's all about. But I believe you...nice sketchwork.

However if that means you currently turn wheels at 64 and plan to increase it to 71, I just don't think the universal will behave at those angles. Mine starts behaving ugly at less than 60.

[Haastnooit]

Originally Posted by Hardline

Ronald, I can see from your sketch that 71 degrees beats 64. Can't really figure out what that's all about. But I believe you...nice sketchwork.

However if that means you currently turn wheels at 64 and plan to increase it to 71, I just don't think the universal will behave at those angles. Mine starts behaving ugly at less than 60.

The drawing is only to show a increased angle when rotating a longer knuckle arm around the center (blue knucklearm is startposition) before ending the possible movement by an obstacle (5mm line offset to center) ...

It is NOT my current setup or desired setup ...

[Hardline]

Okay, trying to understand what's happening. Best I can make out is there is some angle loss due to the width of the arm at the link mounting hole. The further the link mounting hole is from the pivot (ie longer arm), the fewer degrees loss due to that same width. Surprising increase in angle for something seeming so minor. Whether that has real world impact on our crawlers is another matter.

[MRCrackhead]

Guess I was wrong.

Sorry for wasting your time.

Just didn't see any difference running various length arms on my rig.

I'll look closer at it for sure when I get home.

[Hardline]

Originally Posted by MRCrackhead

Guess I was wrong.

Not really. I think most of these details are almost in the noise. Only in an unusual case could you get any significant gains by going with longer arms (plus longer horn to make them work). It's almost always a matter of finding what's currently stopping you and dealing with that.

For me it's the universal itself. I have a set of D_Lux-clearanced XR axles here and have ordered another pair of stock XR. I want to chuck both in a lathe and see what angles they run smooth at. One of the vendors posted a vid of how far his special universals would go and I can't really figure out why one universal would out-do another assuming both were properly clearanced.

[MRCrackhead]

Originally Posted by Hardline

My XR steering seems to be limited by the pulsing that comes with universals operating at high angles. That's after clearancing everything so nothing is hitting or rubbing. Since the four tires don't pulse in phase, that means some tires need to turn faster than others, resulting in wadding and bind. I don't know any way around that except a true CV joint and what we call CV joints aren't.

I'm curious about the pulsing too.

On my MRC the locker allows you to put the u-joints 90 degrees to each other. One tire is going slow while the other goes fast, then vice versa.

I didn't notice it helping, or hurting the way the vehicle handled or steered.

I ultimately switched it the next time I was in there for some maintenance. Now they are the same orientation.

I switched it after realizing Axial rigs all come that way and there are smarter people in this world than myself (see above posts for an example of my ignorance).

Very curious as to why they are that way, and did I have the mini setup better with them turned 90 degrees.

It seemed less obvious the way they were before because both tires weren't accelerating/decelerating at the same moment.

[MRCrackhead]

Originally Posted by Hardline

For me it's the universal itself. I have a set of D_Lux-clearanced XR axles here and have ordered another pair of stock XR. I want to chuck both in a lathe and see what angles they run smooth at. One of the vendors posted a vid of how far his special universals would go and I can't really figure out why one universal would out-do another assuming both were properly clearanced.

I'd love the answer to this question too.

My uni's are shaved just like "the cool kids" are doing. But they still seem to behave as you describe.