nicjasno

Youtube, yes, I will try to use what lego uses, to enable people to build everything themselves. Only 2 moded parts if all goes well, 2 gears in the gearbox.

The gearbox this model deserved (just the stack):

No amount of ackerman can save this. Pivots too far away from wheels, negative caster..

You can make a macpherson with the porsche wheels. Just can't have the strut inside the rim. I plan to keep the lego landrover exterior and redo the rest properly.

The spring needs to be therefore mounted further away from the center of the rim. My future plans:

I can see right away what the problem is. The angle of the spring is too extreme and the top pivot is a complete disaster. Use the small turntables like in the 240z build in the other thread.

Thing is that ladder chassis like this have a natural tendency to torsionally twist, even when made out of steel. That's why automakers went from body on frame constructions to unibody construction. Because a unibody by design twists less than a body on frame design. In trucks and heavy equipment, this is factored into the suspension and is not an issue. In cars you want more precision and safety of the survival cell.

What's the point of suspension then? I usually have a ballpark figure spring setup while designing and then adjust the final spring rate once the model is complete. The suspension is fun to play with when you can get some lean into it. Thing is, once you have used a HoG setup on a suspension with proper geometry (caster, kingpin..) you will never want to go back. Suddenly one has feedback in the steering, which feels amazing :)

Looking at the angle of the steering link really hurts. :P What is going to be between the suspension? And why does it need to be so stiff? I am very curious.

I strictly separate the drivetrain from the chasiss. The drivetrain needs to be completly removable. This way you can easily fix/modify it and it does not bind with the chassis/body. Also i build my bodies as unibodies. So a complete shell, where the exterior is part of the load bearing structure. This way i maximise torsional rigidity and minimise weight. Unnecessary weight can be a models worst enemy.

Me and @Gray Gear got into an interesting discussion about this topic and i thought i'd make a thread for it, so we can expand on it and not pollute the originating thread with it. I'd love to see the heavy duty chasis @Gray Gear ws talking about to continue this. Here's one of my approaches making an acurate and strong front part of the car (my lego bmw e30 attempt): Liftarm frames and panels are a great way to make everything stiffer in a lighter package. I can not recommend them enough.

I suggest we make a new thread for this, to not pollute the OPs build thread with this discussion. I'd like to see the chassis you are talking about.

Everything can be achieved with perfect steering geometry. It's just how much thought you are willing to put into it. Myself, if i have to do a double wishbone setup i prefer to position the steering links on the oposite side of the springs. Like here for example: The datsun suspension here basciaclly just needs the yellow shock absorbers and it's good for the intended model.

I disagree. That datsun suspension is a perfect example.

Building strong and accurate are not mutually exclusive. And i get no satisfaction from a model if i don't get the suspension right.

So now you have bump steer then.... Even worse.

By doing this you have created a "toe out" situation, where your wheels point out on both sides slightly. Because of the toe out, you get a fake ackerman effect, but you have bigger issues, when driving straight forward. Add to this all the slack that you get in lego suspensions and it is not a great setup.

There's much more that you will need to engineer here. Take what is good and don't change just for the sake of change.

Ackerman is overrated anyway. This setup will do fine. If you move the steering links so that they are not paralel to the wishbones, then you will get toe in, which will be even worse than no ackerman. It is a concept, ofc. I have no idea how the rest of what you have planned looks like, but i had to design a bit of the front subframe along it, in order to have a frame to attach the suspension onto.

There are many ways. In lego you have to be carefull with that because you don't have the option to fine tune the length of the steering links with a threaded connection. Usually the ackerman is achieved by geometry. You can have the steering link either in front or behind the front axle. If in front, the steering link pivots must be closer to the wheels than the main pivot, if behind, they must be closer to the cars center line.

Here's the link to the entire galery: http://imgur.com/a/J1soFtO

I'll devise a plan. This thing deserves it.

I really love it.

Finally someone with a vision! I hope you give her caster aswell. Also, make sure the steering links are paralel with the wishbones.

I am making a 28 tooth myself as soon as i get my hands on them. Then a small 4 speed gearbox can be made.