8258 Crane Truck - rear steer?

[andythenorth]

If you have an 8258 crane truck nearby, have a look at the rear axle. Does it look like TLG designers left the possibility open to mod it to rear steering axle?

Would be a nice easter egg. Real life example would be something like this: http://www.ditzj.de/html/en/trucks/scania/arrighettir164g.html

[Zerobricks]

I think routing steering axle through gearbox is very hard...

[DLuders]

On the 8258 Building Instructions on BrickFactory, I'm looking at electronic Page 134 below. Is there any ROOM to do rear-axle steering control? Perhaps you could rummage around those Building Instructions and post a picture showing that it could be possible.

[andythenorth]

Is there any ROOM to do rear-axle steering control? Perhaps you could rummage around those Building Instructions and post a picture showing that it could be possible.

Hey, it's now a challenge

I have no idea if it's possible without serious modification, but I'm going to have a look tonight

[JunkstyleGio]

@ andythenorth:

Good luck. Would be a nice mod if you succeed!

[Seluryar]

sorry to steer this topic off discussion, but is there a good chance this model will be available on the lego shop site in december? preferably at its current price?

[DLuders]

sorry to steer this topic off discussion, but is there a good chance this model will be available on the lego shop site in december? preferably at its current price?

You can get the 8258 Crane Truck NOW for $149.99 from Shop.Lego.com: http://shop.lego.com/ByTheme/Product.aspx?p=8258&cn=57&d=70 .

Edited September 23, 2010 by DLuders

[Seluryar]

You can get the 8258 Crane Truck NOW for $149.99 from Shop.Lego.com: http://shop.lego.com/ByTheme/Product.aspx?p=8258&cn=57&d=70 .

i know this, but i wont be able to buy it until december.

[dr_spock]

Good luck waiting until December.

It does look like it could be modified for rear axle steer.

[mostlytechnic]

Last year the 8258 was out of stock well before Christmas, so I wouldn't count on it being available in Dec.

[Seluryar]

Last year the 8258 was out of stock well before Christmas, so I wouldn't count on it being available in Dec.

oh well, theres always amazon, but they want $50 more than what lego.com wants

[Pauger]

http://www.bricklink.com/search.asp?q=8258

[andythenorth]

I'm looking at the truck again, I reckon I can see a clear path for an axle through the gearbox. It's a convenient gear spacing from the existing steering gear as well. However it needs the tricky addition of some liftarms.

Routing through rear of the truck actually looks harder - to do it cleanly anyway.

Also, I noticed it would be a trivial mod to make opening doors. It just needs some pin joiners moving around, no big changes. Maybe TLG never tried it, but more likely it's hard to latch them - they'll swing open, particularly when tilting the cab

[Jetro]

The doors are indeed extremely easy to open. It was one of the first things I changed when I started modding the truck:

http://www.eurobricks.com/forum/index.php?showtopic=37724

[andythenorth]

Tried and failed to mod this to rear steer

There is a path through the gearbox for an axle to transmit steering control.

However there's no way to gear from the existing steering to the axle without a major rebuild of the gearbox area. I tried using universal joints, but these parts contain too much slack and so the rear steering action is delayed / slack.

Defeated for now. I might try again though

[DLuders]

@ andythenorth: Yeah, there isn't a lot of room to do much (from Barteek97's Brickshelf gallery):

[andythenorth]

@ andythenorth: Yeah, there isn't a lot of room to do much (from Barteek97's Brickshelf gallery):

No there isn't

Routing is possible with universals. The result isn't great. The steering angles are correct, but there is too much slack in the system. I also had to:

- lengthen the chassis 2 studs at the rear

- move the rear axle back 1 stud to allow the wheels to turn without contacting other parts

- move the motor back 1 stud (it's attached to the rear axle)

I'm going to leave the mod in place for now. If I double the rear wheels on the third axle I'll need to narrow the chassis and the steering mod will need removed

[Zerobricks]

No there isn't

Routing is possible with universals. The result isn't great. The steering angles are correct, but there is too much slack in the system. I also had to:

- lengthen the chassis 2 studs at the rear

- move the rear axle back 1 stud to allow the wheels to turn without contacting other parts

- move the motor back 1 stud (it's attached to the rear axle)

I'm going to leave the mod in place for now. If I double the rear wheels on the third axle I'll need to narrow the chassis and the steering mod will need removed

What about putting the steering axle under the gearbox and routing it to steering system via 3 16 tooth gears (one of them being a clutch one where engine shaft is). It should work!

Edited September 27, 2010 by Zblj

[andythenorth]

What about putting the steering axle under the gearbox and routing it to steering system via 3 16 tooth gears (one of them being a clutch one where engine shaft is). It should work!

I'll look into it. Routing past the diff will be tricky. I might rebuild the rear of the chassis anyway though, to fit double wheels on the third axle.

The easy way to do this would be steering using PF m motors & hockey stick springs

Edited September 28, 2010 by andythenorth

[Zerobricks]

Here's a dirty pic how to easy implement rear steering:

Black rectangle si the steering rack, propelled by a gray 12 tooth gear via blue axle. The blue axle crosses 3x 16 tooth gears, the middle one being a clutch one and hanging on motor axle.

Edited September 28, 2010 by Zblj

[Seluryar]

just had some good luck this morning and i was able to order this set from the lego.com store :D

[Seluryar]

is it possible to operate this set without power functions?, i forgot to order batteries and wont be able to buy them for several weeks, can you hook up a power adapter to the battery box and run it that way?

[dr_spock]

is it possible to operate this set without power functions?, i forgot to order batteries and wont be able to buy them for several weeks, can you hook up a power adapter to the battery box and run it that way?

The battery box uses 6 AA batteries. You should be able to buy them anywhere. Someone has modified the battery box to run off a power adapter before. I can't remember where I saw it. It might have been Brickshelf.

[DLuders]

Someone has modified the battery box to run off a power adapter before. I can't remember where I saw it. It might have been Brickshelf.

Here is that modification: http://www.eurobricks.com/forum/index.php?showtopic=44984&st=0&p=787616&hl=battery&fromsearch=1entry787616 .