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Dear folks,

Don't know if this forum is in need of 'yet another AWD front steering', but decided to post it anyway since it may have some interesting features to share:

- Compact 5 stud high modular design

- Strong, double suspension per arm

- Embedded cross block, to prevent bending axles

- Adjustable steering arms to enable toe-in and toe-out (and as a side effect, prevents damage when crashing)

- Ready for (2.4 GHz RC) servo steering ;)

 

I needed a flat front module to fit my chassis, but didn't want to use the 'old' 3 stud high Wheel Hub (50301). It simply has too much friction in the turns and breaks too easily. 

Furthermore I wanted to use the universal joint (61903) in stead of the cardan cup (92906). Since I'm putting significant torque on these joints, and it turns out the universal joint is much stronger. However, this does requires the wheel arms to pivot 1 stud wider than using the standard config.

Using the 5 stud high 11949 front wheel bearing and bound to a maximum height, I needed a way to fit suspension within this height. Very happy with the result. 

Anyway, have a look if you're interested. Happy to hear if anything can be improved.

https://www.flickr.com/photos/153697698@N03/sets/72157695812709340

Edited by janssnet

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The steering axle with the black connector (32039) is not robust at all! The black connector can easily move along the axle or even slide off the axle under load!

Edited by Yevhen

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Give it a try, you'll be surprised! I will post a video when the rest of the car is ready.

For now, you may want to check this out, an earlier version using the same steering-bar.

 

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46 minutes ago, janssnet said:

Give it a try, you'll be surprised! I will post a video when the rest of the car is ready.

For now, you may want to check this out, an earlier version using the same steering-bar.

 

Yes I've watched the video. And you're making the same mistake here. The red connectors are not locked  on the steering rod, so they can relatively easily leave their positions under load.

Edited by Yevhen

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Seconded. The connector that holds the steering link is completely unsecured, it will slide under any serious load. Also, I strongly suspect that your "embedded cross block" on the driveshaft is pressing on it when suspension works. Plenty of room for improvement in this design.

Edited by Sariel

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Totally see your point and thanks for responding. I was in doubt myself while building, if this would hold. Turns out it does. Even at high speed. 

My (highly speculative) assumption: When driving, the wheel puts pressure on the steering arm, which then puts pressure on the connector holding the steering bar. Since the angle between the steering arm and the steering bar is not 180 degrees there is also a force pushing the connector 90 degrees backwards. The result is enough friction not to start sliding.

Let's see if I can put a camera on this thing while doing a next test drive. May take a few weeks though.

Hope you appreciate, if this construction holds, that it enables toe-in and toe-out and it protects parts when crashing.

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14 minutes ago, Sariel said:

Seconded. The connector that holds the steering link is completely unsecured, it will slide under any serious load. Also, I strongly suspect that your "embedded cross block" on the driveshaft is pressing on it when suspension works. Plenty of room for improvement in this design.

Thanks for your remarks Sariel. I will surely have a serious look at the 'steering connectors'. 

Regarding the cross-block. I can assure that it works perfectly, no friction is introduced when suspension is active. The reason for this is, that the pivot points of the driveshaft are 100% equal to the pivot points of the 'wishbone' arms. Therefore the cross block continues to stay completely in parallel with the driveshaft. The drive-axle does move left and right through the cross block when suspending, but there is enough space left to do this (hence this cross block 32557 and not the regular cross block 42003).

Hope this helps. Happy to show if there is wear-out on the axle after a serious test-drive.

 

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47 minutes ago, Sariel said:

 

 

31 minutes ago, janssnet said:

 

 

Edited by Yevhen

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2 hours ago, janssnet said:

Thanks for your remarks Sariel. I will surely have a serious look at the 'steering connectors'. 

Regarding the cross-block. I can assure that it works perfectly, no friction is introduced when suspension is active. The reason for this is, that the pivot points of the driveshaft are 100% equal to the pivot points of the 'wishbone' arms. Therefore the cross block continues to stay completely in parallel with the driveshaft. The drive-axle does move left and right through the cross block when suspending, but there is enough space left to do this (hence this cross block 32557 and not the regular cross block 42003).

Hope this helps. Happy to show if there is wear-out on the axle after a serious test-drive.

 

It isn't the question of pivot, it is due to the distance between the driveshaft and the wishbone, what is changing by the travel of the suspension. As further the suspension is from the neutral position as smaller the distance between the paralel elements.

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3 hours ago, Attika said:

It isn't the question of pivot, it is due to the distance between the driveshaft and the wishbone, what is changing by the travel of the suspension. As further the suspension is from the neutral position as smaller the distance between the paralel elements.

Thank you Attika. I did the math and you guys are 100% right. 

When in neutral position, the driveshaft is 15.94mm under the upper wishbone. When suspension is active, putting the arms under (for instance) 10 degrees, the driveshaft is 15.70mm under the wishbone. 0.24mm difference :((

It's just that I don't like the wheels to toe-in when putting torque on differential. The longer the arms of the wishbone get, the more this seems to be the case.

Do you have another solution for this?

5 hours ago, janssnet said:

Thanks for your remarks Sariel. I will surely have a serious look at the 'steering connectors'. 

Regarding the cross-block. I can assure that it works perfectly, no friction is introduced when suspension is active. The reason for this is, that the pivot points of the driveshaft are 100% equal to the pivot points of the 'wishbone' arms. Therefore the cross block continues to stay completely in parallel with the driveshaft. The drive-axle does move left and right through the cross block when suspending, but there is enough space left to do this (hence this cross block 32557 and not the regular cross block 42003).

Hope this helps. Happy to show if there is wear-out on the axle after a serious test-drive.

 

You may have seen my previous remark regarding the cross-block. You are 100% right. There is friction when the wishbones go up and down.

Regarding the 'steering connectors'. I couldn't resist doing a short test. Please have a look . (Did add 2 extra bushes for extra safety).

https://www.flickr.com/photos/153697698@N03/44893400601/in/album-72157695812709340/

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13 hours ago, janssnet said:

Regarding the 'steering connectors'. I couldn't resist doing a short test. Please have a look . (Did add 2 extra bushes for extra safety).

https://www.flickr.com/photos/153697698@N03/44893400601/in/album-72157695812709340/

Could you not also add a half bush on the outside of that connector just to add a little more friction on the outside? Granted you might need to stock up on them as they may be prone to falling off if they are at the very end of the steering arm axle. Looks a sweet project though, can't wait to see more :classic:.

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Project is ready. If you're interested to see the results, please have a look at some of the pictures here. (Warning, contains modified and non-LEGO parts).

https://www.flickr.com/photos/153697698@N03/albums/72157702072230814

Album also includes a short video of the car on an RC race-track. And guess what .... the weakest link turns out to be construction of the wishbone arm :(  Thanks for warning Sariel!

Steering axle did a fine job BTW. Speed test showed 84.5 km/h, without hardly any wear out on the axles. Thanks to the silicon spray. Will do a video soon. 

 

 

Edited by janssnet

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It's quite cool but I highly doubt that is 70 km/h, more like 30 or 40. I know this since I have a brushless short course truck that does 70 and is heaps faster. I used to use an app like that and it is terribly inaccurate, do the test again with a GPS speed recorder then we can find the true speed of the model. Good work nonetheless

I think that the steering system is fine as long as you use some epoxy or super glue.

Love the foamboard body design though

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23 minutes ago, MattL600 said:

It's quite cool but I highly doubt that is 70 km/h, more like 30 or 40. I know this since I have a brushless short course truck that does 70 and is heaps faster. I used to use an app like that and it is terribly inaccurate, do the test again with a GPS speed recorder then we can find the true speed of the model. Good work nonetheless

I think that the steering system is fine as long as you use some epoxy or super glue.

Love the foamboard body design though

Thanks Matt, appreciate your comments.

I'm in doubt if I will do a next version: back to the old 3 stud-high wishbones for stronger steering and lower placement of motor and accu for better balance. If I do a next version, I will do a GPS measurement.

Problem is though, that there is no space for the steering servo if the chassis base is lowered, unless the base is made wider (like normal RC cars). Any ideas?

Additional problem, with a wider base, I can't use the LEGO hull any longer as a body :((    And I still like the LBOW idea .... a LEGO Boat On Wheels (the body is made of an 54779 LEGO hull).

 

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47 minutes ago, janssnet said:

Thanks Matt, appreciate your comments.

I'm in doubt if I will do a next version: back to the old 3 stud-high wishbones for stronger steering and lower placement of motor and accu for better balance. If I do a next version, I will do a GPS measurement.

Problem is though, that there is no space for the steering servo if the chassis base is lowered, unless the base is made wider (like normal RC cars). Any ideas?

Additional problem, with a wider base, I can't use the LEGO hull any longer as a body :((    And I still like the LBOW idea .... a LEGO Boat On Wheels (the body is made of an 54779 LEGO hull).

 

Please don't give up on the Sbow I love the idea. Maybe buy third party or order 3D printed custom elements off shapeways. 

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