Is this wobble on steering normal...? (Video linkage)

[RCFinger]

Hi!
Still on my ET48 2.0 first build, really taking my merry time with it.. Lots of waiting for Batteries, Charger, Cables, Transmitter and paint paint PAINT! So many lovely colours, such a small body. Paralysed by choice...
Anyway, Hooking things up testing and setting the Transmitter, ESC and Servo, i noticed the front wheels do this really weird, and at times quit violent wobble/oscillation near the full lock point of steering. It sounds awful too.
I have watched videos including the Joe Bornhorst one. I'm happy i set it up ok, getting full steering without the servo pushing any further.
The wheels are balanced, even though it's going to be a basher, can't hurt right! When the car is off, there is a ton of play on the inside wheel near the end points.
Any help massively appreciated, the car is a engineering marvel, I never got the "Shelf Queen" thing before but i'm starting to understand now..

Here's a short video, probably explains it better!

 

[RustyUs]

Depending on how far the inside spindle is pulled, there could be very little leverage on it, and causing what you see. Do you have the steering stop screws installed?

 

[RustyUs]

I actually went through this with my SCT410 2.0 when setting up the steering endpoints and big knobby tires rubbing.

 

[RCFinger]

Hi, Thanks for the reply!

I see in the thread link, you said:

"The inside steering linkage has no push/pull (leverage) on spindle at that last bit of throw."

I 100% agree and had noticed this too. The steering stop screws are fitting as per manual. There is about 5mm of clearance at the closest point, so no rubbing.
I also tried some DE Racing Speedline Plus dish wheels (thanks to jeremiahrobles) that i was going to mount some Backflip 4s tyres, but don't have any glue yet. Suffice to say, still the same issue.

 

[RCFinger]

While trying to diagnose the issue, i have noticed how the wobbling affects the the driveline, I don't think the video does it justice, it gets quite violent!
I appreciate the chassis is designed to flex and the centre front driveshaft must accommodate for this, but how much should it move? I get about 4mm, feels a lot.
Also should there be any front to back movement with the centre diff (within the mount) or should it be zero?

 

[Matthew_Armeni]

You might have assembled the CV joint incorrectly. Please read through this thread to see what I mean.

 

[RCFinger]

You might have assembled the CV joint incorrectly. Please read through this thread to see what I mean.

Hi, Read the thread you linked to, thanks. I had the whole frontend off and checked through things including the bulkhead being screwed into the chassis 100%. Everything seemed fine.
Here is a photo of the CV Joint, looks correct to me.
Cheers!

 

[YourConfused]

Looks like shims are needed. Does the wheel move side to side where the cv axle stub goes through the bearings? Might need shims between the wheel hex and outboard bearing. Is there play in the steering assembly? If the balls are inserted the wrong direction, when assembling your steering rack tie rod end links, I can damage the plastic causing excessive play. Mine have looked that wobbly after lots of abuse or when i had excessive play in areas that needed shims.

 

[YourConfused]

Hi, Read the thread you linked to, thanks. I had the whole frontend off and checked through things including the bulkhead being screwed into the chassis 100%. Everything seemed fine.
Here is a photo of the CV Joint, looks correct to me.
Cheers!

View attachment 10699

It's interesting to see wear on your cv like that since it is new. Unloaded suspension, suspended car on a stand, will make things look worse than they actually are though. You could temporarily adjust your droop screws to simulate weighted suspension angles and drive line angles for a test to see what difference that makes.

 

[RCFinger]

Does the wheel move side to side where the cv axle stub goes through the bearings? Might need shims between the wheel hex and outboard bearing.

I have shimmed it with 0.2mm shim. Really helped on the rear.

Is there play in the steering assembly? If the balls are inserted the wrong direction, when assembling your steering rack tie rod end links, I can damage the plastic causing excessive play. Mine have looked that wobbly after lots of abuse or when i had excessive play in areas that needed shims.

Could you explain this bit? I'm not sure i remember a right or wrong direction. When the wheels are turning it is the steering link that has visible "chatter".

 

[RustyUs]

Looks like shims are needed. Does the wheel move side to side where the cv axle stub goes through the bearings? Might need shims between the wheel hex and outboard bearing. Is there play in the steering assembly? If the balls are inserted the wrong direction, when assembling your steering rack tie rod end links, I can damage the plastic causing excessive play. Mine have looked that wobbly after lots of abuse or when i had excessive play in areas that needed shims.

I have shimmed it with 0.2mm shim. Really helped on the rear.

Could you explain this bit? I'm not sure i remember a right or wrong direction. When the wheels are turning it is the steering link that has visible "chatter".

Even though I've never seen a Tekno 1/8 manual state such a thing, a couple people have mentioned a right/wrong way to insert pivot balls into rod ends. The said "correct" way is to insert the pivot ball through the side of rod end with visible ring...

I highly doubt any right/wrong pivot ball insertion is causing your issue @RCFinger .

 

[RCFinger]

It's interesting to see wear on your cv like that since it is new. Unloaded suspension, suspended car on a stand, will make things look worse than they actually are though. You could temporarily adjust your droop screws to simulate weighted suspension angles and drive line angles for a test to see what difference that makes

What you see on the CV that looks like wear is the Dry lube i used, instead of a thin layer of grease. It's called Molyslip. It has a weird grey look to it when dry. I have cleaned it off and used some grease just in case.
I was aware that it was being tested on the stand, so after you mentioned it, I cable tied the arms so that they were level with the chassis, no improvement unfortunately

 

[WickedFog]

Even though I've never seen a Tekno 1/8 manual state such a thing, a couple people have mentioned a right/wrong way to insert pivot balls into rod ends. The said "correct" way is to insert the pivot ball through the side of rod end with visible ring...
View attachment 10711View attachment 10712
I highly doubt any right/wrong pivot ball insertion is causing your issue @RCFinger .

Yeah, rod ends on every kit I have assembled have had that mark for as long as I can remember. If you measure each side with calipers, you will see that side with the mark is bigger.

 

[RCFinger]

Yeah, rod ends on every kit I have assembled have had that mark for as long as I can remember. If you measure each side with calipers, you will see that side with the mark is bigger.

What measurements are you getting? I'm not seeing any difference (6.28mm)

 

[WickedFog]

What measurements are you getting? I'm not seeing any difference (6.28mm)

I didn't measure the Tekno ones. But that is the side that goes on the ball.

 

[RustyUs]

Yeah, rod ends on every kit I have assembled have had that mark for as long as I can remember. If you measure each side with calipers, you will see that side with the mark is bigger.

They may have a molding mark, but the only time I've ever seen any manual mentioning a pivot ball being inserted through one side vs. the other side of a rod end was... never.

I was hoping @Matthew_Armeni would have shed some light on the rod end subject/picture in post #11.

 

[WickedFog]

They may have a molding mark, but the only time I've ever seen any manual mentioning a pivot ball being inserted through one side vs. the other side of a rod end was... never.

I was hoping @Matthew_Armeni would have shed some light on the rod end subject/picture in post #11.

Yeah, it has never been mentioned as far as I remember in any of the kits I have built. I have measured them on other kits before and have seen differences though, for certain.

It was years ago when I first checked them because I did notice some were like impossible for me to press the rod end on the ball. But every time, if I flipped the rod end over, it snapped on there fairly easily. I didn't have shock pliers back then, so I was just setting the ball on my bench and pressing the rod end on with my thumb. But there was a noticeable difference, and it was the ring side on every one of the rod ends that was easier to press on. And since every rod end has that mark, I have been doing it that way ever since. I wish I knew why that ring is there, but I have just assumed it is an indicator to show you which side the ball should go in.

It wasn't until I started working in the racing industry that I actually saw something similar when we were making IndyCar wishbones (A-arms). We machined the rod ends, and sure enough, one side was machined bigger so the ball would press in. But these were steel of course. But after the ball was pressed in, a ring die was pressed around the outside of the ball to lock the ball in place by pinching the material around the ball. You would not believe how little material there is holding those balls in place on IndyCars.

So maybe RC adapted that "look" to show which side the ball goes in? I have no idea. But isn't it interesting that every rod end has that feature, and there has never been any explanation why?

So I though I would try to see if I could show the difference with an image, but it was clearly more visible when I changed the opacity back and forth. And the only way for you to see that is with a video.