Angle of suspension brackets

[Ceboe]

Hi,

I ve used the search function to get an answer to my question but I didn't find anything so I'll just ask it here.
Why do a lot of teams put the front suspension brackets an an angle, and not horizontal? I've seen this with teams like delft and other monocoque teams.
In the picture below it maybe clear what I mean.
Does it have something to do with anti-dive?
Why can't they just put the bracket horizontal or in the plane fromed by the top suspension A-arm?

[Tim.Wright]

Probably to increase the possible articulation angle of the arm. For example, a rod end might be limited to 14deg of misalignment about axes transverse to the bolt hole before it mechanically binds up. If your control arm needs 20deg you can rotate the rod end so a component of the rotation is about the bolt hole axis which is effectively unlimited in terms of the angle it can reach without binding.

As to why they don't rotate them completely 90deg, i have no idea.

[Markus]

Tim, rotating the bracket will increase the local bending load on the monocoque, so you don't want to rotate it more than you have to.

[Big Bird]

I think there is an equally interesting question - why do we assume such brackets should be horizontal??

Or vertical for that matter...

[Georgy Arutyunyan]

I think that spherical bearings work better when subjected to radial load. Axial maximum allowed load is only about 10% from allowed radial load, if my memory says me right.
So I believe that it is better to mount brackets horisontally, bacause this way the loads from braking and accelerating will act as radial forces.

[Thijs]

...because this way the loads from braking and accelerating will act as radial forces.

Are you sure that's different for rotated brackets? FBD FTW

Our reasons for rotating the brackets are simpler than you may think.
As a hint for Ceboe, here are some pictures of DUT09 ('horizontal' brackets) and DUT11 (rotated brackets):

DUT09:
http://dutracing.tudelft.nl/wp-conte.../dut9_fsg3.jpg

DUT11:
http://dutracing.tudelft.nl/wp-conte...s-dut11-03.jpg
http://dutracing.tudelft.nl/wp-conte...n/img_9457.jpg (wheels are in droop here)

Thijs

[Z]

I think there is an equally interesting question - why do we assume such brackets should be horizontal??

Or vertical for that matter...

Or that you NEED 16 of them.

Plus another 4 for the spring-dampers. Oh, and must not forget the other 4 for the rockers. Must have those rockers...

So that's 24 so far, each with 2 holes to mount them to the chassis. So that's 48 accurately positioned holes in the chassis that need jigging. Or maybe you should mount them with 4 bolts each, for more optimal bolt loading? Yeah..., 96 accurately positioned holes...

Hmmm..., now what else can you add, so that you can claim that your latest car is "optimised for simplicity and reliability...".

(And let's be honest, you will be saying that, won't you?)

Z

[Big Bird]

Z, you forgot front and rear toe control. And I guess that each of these 2 force members have outboard points too. And that the independent arcs that all these links swing through necessitate outrigger bearings for the steering rack (and we should all assume such a thing is a necessity...) , and plunge and articulation for the driveshafts.

So many holes, and relative motions, and components, and deviations from assumed component rigidity, and manufacturing processes, and potential sources of assembly error, and tolerance errors, and non-linearities, and failure points, that all have to line up to get this car thing to act like it does in the simulation...

[Sormaz]

Z, you forgot front and rear toe control. And I guess that each of these 2 force members have outboard points too. And that the independent arcs that all these links swing through necessitate outrigger bearings for the steering rack (and we should all assume such a thing is a necessity...) , and plunge and articulation for the driveshafts.

So many holes, and relative motions, and components, and deviations from assumed component rigidity, and manufacturing processes, and potential sources of assembly error, and tolerance errors, and non-linearities, and failure points, that all have to line up to get this car thing to act like it does in the simulation...

simulation? what simulation?

[Tim.Wright]

Z, you forgot front and rear toe control. And I guess that each of these 2 force members have outboard points too. And that the independent arcs that all these links swing through necessitate outrigger bearings for the steering rack (and we should all assume such a thing is a necessity...) , and plunge and articulation for the driveshafts.

So many holes, and relative motions, and components, and deviations from assumed component rigidity, and manufacturing processes, and potential sources of assembly error, and tolerance errors, and non-linearities, and failure points, that all have to line up to get this car thing to act like it does in the simulation...

Our 2008 car was built almost entirely out of shims to counter that problem.