Rate My Suspension

[Alasdair Ryan]

Ok so as you may know I am not really a car builder,but I wanted to attempt a front axle with double wishbone suspension,I also wanted to attempt the camber thing and the other thing found

on steering.I know or am aware that the technic steering parts prevent us from making a 100% accurate replica.

Perhaps those builders how have built similar set-ups can make some suggestions for improvements?

Edited June 23, 2016 by Alasdair Ryan

[Saberwing40k]

I'd say you've got it pretty good. I don't know how useable it would be, but it looks about right. Also, you're talking about caster angle, which you have. Now just comes the small matter of getting the wheels to go straight...

[Alasdair Ryan]

Due to me offsetting the suspension arms it is pulling the end of the axle in-towards the centre when the suspension is at it's lowest,but is about level when it is at it's highest.is it supposed to be like this?

Edited June 23, 2016 by Alasdair Ryan

[AkiyamaWataru]

Hey Alasdair, can you post a picture taken from directly above the wishbones?

As you are building a driven suspension one hint: your cv-joint could be pulling the u-joint from the wheelhub. I had the same problem with a similar setup. Easiest solution is filling the gab between the u-joint and the cv-joint with half bushes und bushings.

What I'm wondering: how do you keep the attachement point of the lower wishbone fixed to the attachementpoint of the upper wishbone and the chassis? It looks kind of wierd and wobbly.

[nicjasno]

Poor. (yes, i'm being honest here)

You got all the engles wrong.

And you added complexity to a simple layout without adding anything to it, like caster angle, kingpin inclination or anything else.

The driveshaft is also at the wrong angle.

And the hub itself is also not good, because it pushes the wheel further from the pivot points.

[TheMindGarage]

Looks OK so far. I've only very recently explored camber and castor angles. For camber angle, I use an "L"-shaped beam extending one of the suspension arms very slightly. Effectively the suspension arm goes from being x studs long to sqrt(x^2+1) studs thanks to Pythagoras. For castor angle, your method seems pretty good. Normally, I do it the other way and mount a suspension arm half a stud off-center.

[PorkyMonster]

I think the 1x7 bent liftarms shouldn't be used here as it'll mess up all geometry...

how about trying with straights or right-angled ones?

[Alasdair Ryan]

Here is a photo if it from above.

https://1drv.ms/i/s!...zpCahbQR4mFipSh (photoblob is down)

What I'm wondering: how do you keep the attachement point of the lower wishbone fixed to the attachementpoint of the upper wishbone and the chassis? It looks kind of wierd and wobbly.

I don't quite know.

As you are building a driven suspension one hint: your cv-joint could be pulling the u-joint from the wheelhub. I had the same problem with a similar setup. Easiest solution is filling the gab between the u-joint and the cv-joint with half bushes und bushings.

I have moved the bush and disk/wheel in towards the hub so there is now less play.

Poor. (yes, i'm being honest here)

You got all the engles wrong.

And you added complexity to a simple layout without adding anything to it, like caster angle, kingpin inclination or anything else.

The driveshaft is also at the wrong angle.

And the hub itself is also not good, because it pushes the wheel further from the pivot points.

I was curious to what you might say,I did watch your videos you made about the subject.

Looks OK so far. I've only very recently explored camber and castor angles. For camber angle, I use an "L"-shaped beam extending one of the suspension arms very slightly. Effectively the suspension arm goes from being x studs long to sqrt(x^2+1) studs thanks to Pythagoras. For castor angle, your method seems pretty good. Normally, I do it the other way and mount a suspension arm half a stud off-center.

So just to be clear move the dark brush grey which is not off seted by the angled liftarm out by 1/2 a stud?

I think the 1x7 bent liftarms shouldn't be used here as it'll mess up all geometry...

how about trying with straights or right-angled ones?

I used them thinking I could get my offset,but it does seam like it is going to prevent me from tying the two steering arms together.

Edited June 23, 2016 by Alasdair Ryan

[AkiyamaWataru]

What I can see now:

1. No Kingpin Inclination
   
2. No Caster. The wheelhub is usable for caster creation but you should move the upper wishbone a bit to the back of the car.
   
3. Maybe changing Camber but it looks like in the wrong direction. If my knowledge is correct you don't want less camber when the suspension compresses. Normaly you lean on the outer wheel and compress it's suspension. If you do that you are working with camber to increase the contact patch of the tire.
   

Try building a Mockup-Chassis to place it. think about shock attachment.

If you want I'll post a picture of my suspension later. I'm still working on it. It is a driven and steered doublewishbone supension as yours.

[Alasdair Ryan]

Ok, So I need to start again.

If want caster,camber and toe do custom made hubs work better than those produced by lego?

Edited June 23, 2016 by Alasdair Ryan

[TheMindGarage]

Ok, So I need to start again.

If want caster,camber and toe do custom made hubs work better than those produced by lego?

You can still get virtually everything you want with LEGO's hubs. You can also use a custom hub built from LEGO pieces like you did in your earlier pics - these work just as well.

Moving the upper suspension wishbone back half a stud will give you castor (and I think kingpin inclination as well). As for camber, I think AkiyamaWateru is referring to the idea of suspension camber varying as the suspension compresses. I don't think it's essential - with LEGO vehicles the effects of all these are negligible. But if you want it as a technical highlight, I would build a mock chassis as suggested and play around with different linkages.

[AkiyamaWataru]

MindGarage just a note for you. You don't get Kingpin Inlcination by moving the upper wishbone a bit to the back. The upper wishbone has to be moved a bit to the center of the front axle. That givs the inclination.

For Camber: the effects on lego cars are neglectible i think. And mostly not visible.

[Alasdair Ryan]

Ok, I will start attempt two and get back to you.

[Choops]

looking at the suspension from the front the arm pivot points on the chassis should be closer together than at the wheel hub. When you draw a line thru the suspension arms Where these lines meet is the roll center. As a car leans over when turning this roll center helps keep the tire square to the road.

http://www.speeddirect.com/wp-content/uploads/2013/02/roll-center1.jpg

Steve

[Didumos69]

Perhaps a good idea to read some easy background info: http://www.motoiq.com/MagazineArticles/ID/1982/The-Ultimate-Handling-Guide-Part-8-Understanding-Your-Caster-King-Pin-Inclination-and-Scrub.aspx

If you want all angles to be proper, then this could also be a source of inspiration: http://www.eurobricks.com/forum/index.php?showtopic=92099&st=150#entry2503499

Edited June 23, 2016 by Didumos69

[TheMindGarage]

MindGarage just a note for you. You don't get Kingpin Inlcination by moving the upper wishbone a bit to the back. The upper wishbone has to be moved a bit to the center of the front axle. That givs the inclination.

For Camber: the effects on lego cars are neglectible i think. And mostly not visible.

I see. I wasn't quite sure what kingpin inclination was - I'd hardly heard of it.

All of the effects are negligible, and if they are clearly visible, then they've been overdone and the car will handle badly. The only advanced geometry that should ever be obvious is Ackermann steering.

[nicjasno]

All of the effects are negligible, and if they are clearly visible, then they've been overdone and the car will handle badly. The only advanced geometry that should ever be obvious is Ackermann steering.

Far from it. The effects are clearly visible on cars in real life. Park your car with wheels at full lock and go see what happens. Then imagine the car leaning into a corner.

[Saberwing40k]

Far from it. The effects are clearly visible on cars in real life. Park your car with wheels at full lock and go see what happens. Then imagine the car leaning into a corner.

Well, for real cars, that is true. Question is, are the effects needed with Lego cars/vehicles? I personally don't think so, but it's good to have them, if you are working at a scale that allows them to be implemented.

[AkiyamaWataru]

Far from it. The effects are clearly visible on cars in real life. Park your car with wheels at full lock and go see what happens. Then imagine the car leaning into a corner.

I meant it in comparisson to the scale. I have seen the camber on Mk2 VW Golf on the rear end and stuff. It was meant for lego as Sabewing said

[nicjasno]

The effects are very well felt on the steering of a model. And operating a model via HoG with good suspension geometry is a very rewarding expirience.

I made this here in a hurry:

Edited June 24, 2016 by nicjasno

[Alasdair Ryan]

Nicjesno,does that design incorporate the caster,camber and toe,I see you have a full stud offset from the top and bottom arm,I though it was only 1/2 a stud?

[nicjasno]

This includes everything. The pivot of the universal joint would ideally have to be half a stud more towards the wheel, so it'd be on the imaginary line between the upper and lower balljoint.

I didn't bother with the steering. Too much effort at such late hour. Just remember that the steering links have to be paralel to the lower wishbones. Both from the top view and from the front view.

Edited June 24, 2016 by nicjasno

[Alasdair Ryan]

Thanks.

[Didumos69]

The effects are very well felt on the steering of a model. And operating a model via HoG with good suspension geometry is a very rewarding expirience.

I fully agree. And I would like to add one more thing: Lego is all about making 'models'. And to me (sorry, I have an engineering background) 'model' means: Simplification of a system (or thing) that brings about one or more aspects of that system's (or thing's) nature. Models allow us to zoom in on certain aspects while leaving other aspects out. So it's all about what exactly do you want to tell with your model. Even when something isn't really noticable when playing with a vehicle you can still have a good reason to implement it.

I made this here in a hurry:

This small design sort of has it all .

[PorkyMonster]

I made this here in a hurry:

Nice little design, but I think there's a need to refine further for camber to be reasonably useful, unless I've missed something...

All of the effects are negligible, and if they are clearly visible, then they've been overdone and the car will handle badly. The only advanced geometry that should ever be obvious is Ackermann steering.

Just to share my view (I'm no expert in all these, btw), my assumption has always been that if real cars need these stuff, then it'll make sense for models to have them - ON ONE CONDITION though : whether we want our model to travel in the same speed and road conditions (to scale, of course). In other words, u'r right if there is no plan to drive the models at realistic speeds and roads . Unless, as what Didumos69 said - the purpose is to 'model' these aspects for the sake of 'modeling'.

Edited June 25, 2016 by PorkyMonster