[HELP] Steered, Driven, Independent Suspension

[Canmorite]

Is it possible to create a steered, driven and independent suspension (without the use of special ball-joint parts) that is closer than 3 or 4 studs to the wheel? I've tried searching but every design I've seen the pivot point is at least 3 studs away from the rim.

Thanks!

[Saberwing40k]

Yes, it is. I used 42000 wheel hubs to do this.

[nicjasno]

That uses special parts.

[Saberwing40k]

It thought he meant stuff like the hubs and wishbones from 8070. Besides, my design could be adapted to use standard parts.

[Canmorite]

Yes, it is. I used 42000 wheel hubs to do this.

I know it can be done with those hubs, however I am trying to see if it's possible to replicate that design with normal parts... so far I haven't had any luck as the joints are too wide.

How do you think your design could be adapted for regular parts? I am thinking of getting 42000 specifically for the suspension bits.

[Saberwing40k]

getting 42000 for bits like this is a good idea, as while my design can be adapted, it is really difficult to get an assembly like this,and have it be strong.

[Silcantar]

Having spent a fair amount of time trying to do this myself, I would say that no, it's not really possible. The real limiting factor is the length of universal joints. You can get a bit closer to the wheel with CV joints, but you're still pretty far from the ideal pivot position, since the steering axis has to pass through the joint.

[Technyk32231]

You can use kingpin inclination.

[Hrafn]

Yes, it is. I used 42000 wheel hubs to do this.

I'd love to see this. Do you have a picture or something? I can't seem to find it on past forum posts

Thanks!

[Thirdwigg]

What do you mean by normal parts? This has all features except for an independent suspension (live axle), but could be adapted to do so with ball joint arms (but not within 3 studs).

I have found by letting the differential float, you can get the axle more narrow since you can remove two Ujoints. See here. This has worked well, and can be added to the above idea.

What is the width of your vehicle (overall)?

[Hrafn]

I have found by letting the differential float, you can get the axle more narrow since you can remove two Ujoints. See here. This has worked well, and can be added to the above idea.

When I tried a floating 3L diff (leading to a u-joint and then a CV, and using 6L wishbones pivoting so they act like 5L ones) I had two problems. First, the diff would move away from the driving gear when the wheels were stuck. Second, that situation led to the diff teeth getting mashed. How did you avoid those issues, or are they not a problem with the 4L diff?

[Zerobricks]

What about a tatra-like axle? By using only one U joint and driveaxle to swing about?

[Thirdwigg]

When I tried a floating 3L diff (leading to a u-joint and then a CV, and using 6L wishbones pivoting so they act like 5L ones) I had two problems. First, the diff would move away from the driving gear when the wheels were stuck. Second, that situation led to the diff teeth getting mashed. How did you avoid those issues, or are they not a problem with the 4L diff?

In the picture of the car, you can see a small frame that connects the differential with the bevel gear. The same principle can be seen here with the 3L Diff. It works enough for a XL motor to drive it.

What about a tatra-like axle? By using only one U joint and driveaxle to swing about?

This also works well.

[Hrafn]

In the picture of the car, you can see a small frame that connects the differential with the bevel gear. The same principle can be seen here with the 3L Diff. It works enough for a XL motor to drive it.

Ah, now I see what you did, that makes sense. The diff there isn't really floating, it has support on each side. I was trying to have a diff supported only by the u-joints on each side, which didn't work.

[Thirdwigg]

Ah, now I see what you did, that makes sense. The diff there isn't really floating, it has support on each side. I was trying to have a diff supported only by the u-joints on each side, which didn't work.

Right, but the support is not fixed to the chassis, so it can move. I hope it helps.

[Hrafn]

Right, but the support is not fixed to the chassis, so it can move. I hope it helps.

It helps me understand what you did and why, yes, thank you. I had misunderstood what you meant by a 'floating' diff.

[Zerobricks]

In the picture of the car, you can see a small frame that connects the differential with the bevel gear. The same principle can be seen here with the 3L Diff. It works enough for a XL motor to drive it.

This also works well.

Looks like de dion-like suspension

[Saberwing40k]

Actually, De dion suspension is nothing like this.

[Lakop]

I've just looked up De dion suspension. Interesting. The above car set up is great.

H

[Canmorite]

Having spent a fair amount of time trying to do this myself, I would say that no, it's not really possible. The real limiting factor is the length of universal joints. You can get a bit closer to the wheel with CV joints, but you're still pretty far from the ideal pivot position, since the steering axis has to pass through the joint.

Thanks - I remember trying this about a decade ago but not getting any closer than 3 studs... same situation now!

You can use kingpin inclination.

Well that only too hours of reading and videos... might be able to make it work, though, thanks!

[Hrafn]

The closest I've ever gotten to the rim was 2.5 studs using 62.4x20 wheels; with larger hubs it might be possible to get closer. Note that this construction uses 10.2mm ball joint parts (not the smaller tow balls used in dedicated suspension parts) which work but are more fragile.

The suspension has a number of issues (friction, awkward placement of drive axles, no differential, very limited steering lock, etc.) but at least it's narrow.

EDIT: yes, it can be used with the 44772 (Technic Racing Medium) wheel to get a pivot point 1 stud away from the edge of the wheel. However, the CV axle then only protrudes 1L into the wheel, which isn't enough to keep the wheel on reliably.

Adding 2 wedge belt wheels and some pins would give you a pivot point 2L away from the edge, but make things sturdier.

Edited January 14, 2014 by Hrafn

[Thirdwigg]

You will need a reinforcement when you add a shock, otherwise the green connectors will slid off of the axles when a load is applied.

[Hrafn]

You will need a reinforcement when you add a shock, otherwise the green connectors will slid off of the axles when a load is applied.

Good point, though I've found that if you increase the axles to 5L and add a 1x3 thin liftarm on the top and bottom, the ball joints will pop out of their sockets under pressure way before the lime connectors start to slide on the axles.

This was just a spur of the moment sketch to convey the basic idea in case someone found it useful; since I'm not currently building anything that uses wheels of this size I haven't tried to develop it further. Certainly it needs more work if it is to be practical.

EDIT: A more robust setup with the CV joint is possible (though the steering connection is a bit wobbly), but the wheel still doesn't want to stay on with only 1L of CV axle connection:

If we switch to a u-joint, this next hub gives a 1.5 stud offset from the edge of the wheel, but it's a bit less robust and I'm not sure how to attach the steering link:

The u-joint design is theoretically subject to the problem of the lime connectors sliding off the axle, but again in practice the ball joints pop out first - and it takes quite a bit of force to pop them out. I wouldn't use it for a truck but it might serve for a car.

Edited January 15, 2014 by Hrafn

[Rockbrick]

I like Zblj's idea, with a large enough wheel and deep offset then centre point steering would be possible