Body Posts Crossmember

[skom25]

Hi,

Rear Body Posts in my TT-02 feel bit too flexible, because they are quite long. I wonder, if that kind of part will stiff them?

I have mixed feelings.

[Pylon80]

I keep saying I want to make a thread with my TT-02 tinker mods but I never get around to it 😞

Maybe that is helpful, here is how I make my body posts considerably stiffer and always nice and centered:

Since I'm OCD, back when I first built my rally car I couldn't stand how the rear wheels would never fit the body perfectly left and right, since the TT-02 posts are always moving side to side a bit. With a long turnbuckle you get basically a truss structure (like a bridge) and you can micro-adjust your wheel fitment side to side with the turnbuckle. Mr. OCD is happy.

[BuggyDad]

The M-08 has a similar solution out of the box but it has some depth, and so it not only links the posts left to right but holds them vertical as well.

An easy 3d print design would achieve this on the TT-02. Thin sheet material like that CF, sitting on body clips, would do little more than link left to right, I'd suggest (which the shell is already doing). You could perhaps modify the CF to clamp the posts somehow but I think a print would be better and much cheaper. 

I may be able to check tomorrow but I have a feeling I even have a rough 3d print I just grabbed off thingiverse to do exactly this on a TT-02. 

[turbofan]

if you can accurately measure the distance between the center of each post and the thickness of a post, I would like to give it a try and 3d print one for you

 

[Pylon80]

The problem with all the horizontal crossmembers like the M08's is that they merely create a "deformable parallelogram" so they hardly do anything for the stiffness. A diagonal cross member like the ones you see on 1:1 roll cages are working both in tension and compression to effectively stiffen the body posts.

[BuggyDad]

4 minutes ago, Pylon80 said:

The problem with all the horizontal crossmembers like the M08's is that they merely create a "deformable parallelogram" so they hardly do anything for the stiffness. A diagonal cross member like the ones you see on 1:1 roll cages are working both in tension and compression to effectively stiffen the body posts.

I think the idea of them is to add just enough stiffness to take out the visible body wobble but no more, might as well have the parallelogram still deform in a crash - it might just save something else?

[turbofan]

[skom25]

10 hours ago, BuggyDad said:

The M-08 has a similar solution out of the box but it has some depth, and so it not only links the posts left to right but holds them vertical as well.

An easy 3d print design would achieve this on the TT-02. Thin sheet material like that CF, sitting on body clips, would do little more than link left to right, I'd suggest (which the shell is already doing). You could perhaps modify the CF to clamp the posts somehow but I think a print would be better and much cheaper. 

I may be able to check tomorrow but I have a feeling I even have a rough 3d print I just grabbed off thingiverse to do exactly this on a TT-02. 

Will they fit TT-02 Body Posts? I mean, is width the same for both?

[BuggyDad]

1 hour ago, skom25 said:

Will they fit TT-02 Body Posts? I mean, is width the same for both?

No. M-08 holes more widely spaced. But anyway you'd be buying the whole parts tree just for this one part. 

Here's the 3d print on my budget rally TT-02. 

Side by side next to one without, it has much less body wobble. It was off thingiverse or some such. I wouldn't have modelled it like that (would go for something more like @turbofan's first one) though, it's a bit lazy. 

[skom25]

Thank you.

I will go for part from first Post or just make my own from plexi.

[turbofan]

will be making some of these, in case you wana try it message me

 

 

[Otis311]

I just whipped up a cross brace in FreeCAD. It's up on Thingiverse if anyone wants to try it. TT-02 Body Post Brace . Basically the same as Turbofan's above, not a rip off I promise as I have been working diligently in CAD for the last couple hours.

 

 

[turbofan]

this prototype made a difference but not sure it's much, the main issue is that these posts are very soft, it's now 26mm high, so ether has to be taller or maybe Pylon80's approach is more mechanically sound as it cross braces this soft post more securely

[Otis311]

It's true this seems like a losing battle with the posts that are inherently bendy. The Squash Van has some braces included that may help a little but the body on that truck still flies around like crazy. I think the key here is to make the holes in the brace fairly tight fitting to eliminate any movement. The brace I just printed is about a rigid as I would want.

[chris.alex]

A few days ago I implemented the Pylon80 variant and am very happy with it. It is not only very stable, but also infinitely adjustable. 

[skom25]

I bought part from first kit. Now Body Posts are really stiff and body is centered. Good upgrade for not too much money.

[Pylon80]

On 3/23/2024 at 3:24 AM, chris.alex said:

A few days ago I implemented the Pylon80 variant and am very happy with it. It is not only very stable, but also infinitely adjustable. 

Awesome and glad I could help  You can't go wrong with triangles in structures. Bicycles... welded airplanes and race cars... the Eiffel tower... All a series of triangles attached to more triangles.