Suspension uprights?

[PlatinumZealot]

Ok here is an update.. I made the upright lighter also made it one piece, cut off some of the control arm tips, made the bearing spacers smaller. Redid the mounts.

Some dimensions have to remain big because I am making the arms for a vehicle that can weigh up to 1200kg.

The upright is now just over 2 lbs (or 2.5lbs?? i forgot).

1000lbs applied to this arm. stress is very low. max is 1600N/cm^2
I didn't do any fatigue calculations yet.. so i think that it can stay that low, want it to have a long life.



New upright, i forgot to deal with the arm that connects the tie rod. This is the rear arm. The front will be different (ackerman angle etc).. for some reason i think it needs some webbing on the side..haven't tested that area yet.

[PlatinumZealot]

Now another question..

Where on the upright do I put the mount for the push rod?

[marcush.]

the last post I found a bit confusing...I first think through my concept and juggle the bits and pieces around in my head to arrive at the best possible layout
to get the wanted chararacteristics and avoid unwanted behaviour.If you let things
come towards you and tackle the problems as they creep up you tend to get into comprise spirals trying to retain things you have invested a lot of time effort and money already.So research , ideas and experience are the starting point not the CAD or drawing board.
Never I would start drawing up the thing and detailing it out before knowing where to put everything basically... so what´s your idea concerning hub ,bearing,bearing retention,how do you make sure the bearings run always(!)with the correct preload
(bear in mind different expansions for the hub and the upright etc, Brake disk,disk attachment ,Caliper mounts ,Wheel and tyre dimensions..

As for the ceramic bearings there is a halfway house with ceramic ball bearings at a fraction of the cost of complete ceramic ones .
You would of course go for angular contact ball bearings for reasons of friction anyways,and then maybe think about the possibility of ceramics.Also which sort of bearing seals (there is a whole shitload of friction to be found in seals so with
this is really an area where you can make a difference not resorting to the basic stuff.)

Ideally you were starting with the data of the tyre you are going to use.Assuming there is no such thing as tyre data coming from the supplier you have the first task in setting up something to test empirically (skidpad) what the tyre likes and needs to perform and start to design your vehicle around those basic needs.(camber,vertical load vs slip angle etc)
last word on staking: spherical bearing are obtainable with staking grooves (for example suffix G -Grumman stake - in Aurora bearings ,suffix V for NMB etc..)Staking tools are commercially available ,the staking process allows for a secure bearing retention without stress risers.

speaking of stress risers :I would concentrate on avoiding massive crosssection jumps in all components looking at your components theres lots of these .the better you get this sorted the more evenly the loads get distributed -so of course this is a win win situation -saves material ,more endurance.Think first about it,then design,will also not extend the machining time into bizarre figures...With exotic materials you have to sesort to HSM and if you have to pay for it you will quickly learn it is of paramount importance to be smart and keep the machining hours low (More than one part machined in one go ,reducing setup time
avoid tool changes..)

[mep]

Now another question..

Where on the upright do I put the mount for the push rod?

I think you should tell us what you want to do.
Do you just want to make a nice looking CAD model or do you really plan to build a car or parts of it?
When you want to do the second choice than you should tell us first what kind of car it will be.
For this you must pay much more attention on the things you are doing
and you will have to start from a basic concept.
You should invest a lot of time into vehicle dynamics, weight distribution, suspension layout.
When you have done this first, you will not come up with a problem like:
"Oh where do I place my pushrod now".
Next thing is the angle of the wishbones to get proper suspension kinematics.
I am not sure whether you don’t have any problems with your bearings rotational angle when your wishbones will have some angle.

[Jersey Tom]

Why not mount it to an a-arm?

Upright needs some serious DFM. Like, a lot.

[PlatinumZealot]

I wanted to keep as much loads of the A arm as possible, they are very skrawny ~20mm. So I chose to place load on the upright but I just don't know where exactly. Towards front or the back, near the wheel bearing bore, near the bottom CA mount?

I think you should tell us what you want to do.
Do you just want to make a nice looking CAD model or do you really plan to build a car or parts of it?
......

The car is being designed to spec for race series in the Caribbean. I have no funds to build it right now, I just want to lay down some designs for the future if ever there comes a time when I can build the car. The basic concept is a RWD front engine race car, similar to a Panoz or a Gillet Vertigo.



I modeled the frame and tested a crashbox.
viewtopic.php?f=6&t=7170


There is time limit and I suppose the final car has to be affordable..Mainly just a home project. So It's sort of a concurrent design right now since I have never designed a race car before.

My design style is to first start with the geometry, then add all the Kinetics. Drawing in CAD right now is just getting me familiar with how the geometry has to be setup. things like clearances and limitations. I hope to use the weight ditributions, spring, shocks tyre data etc to direct the geometry. Like a Plug and play sort of thing; all of the dimension right now are changeable.

the last post I found a bit confusing...I first think through my concept and juggle the bits and pieces around in my head to arrive at the best possible layout
to get the wanted chararacteristics and avoid unwanted behaviour.If you let things
come towards you and tackle the problems as they creep up you tend to get into comprise spirals trying to retain things you have invested a lot of time effort and money already.So research , ideas and experience are the starting point not the CAD or drawing board.

My method is to one part at a time, my style is ideas> research > sketch > basic calculations > CAD > sketch again > CAD.... Right now is just about the upright and Control arms.

Never I would start drawing up the thing and detailing it out before knowing where to put everything basically... so what´s your idea concerning hub ,bearing,bearing retention,how do you make sure the bearings run always(!)with the correct preload
(bear in mind different expansions for the hub and the upright etc, Brake disk,disk attachment ,Caliper mounts ,Wheel and tyre dimensions..

Those will fall into place I have never done this before so everything has to fall into place somehow. I just keep a trusty notebook to keep track. Other than how wheel bearings look (type max load life etc) everything else about I have to learn while i do this project.

Ideally you were starting with the data of the tyre you are going to use.Assuming there is no such thing as tyre data coming from the supplier you have the first task in setting up something to test empirically (skidpad) what the tyre likes and needs to perform and start to design your vehicle around those basic needs.(camber,vertical load vs slip angle etc)

The vehicle is to be versatile so it has to use many tyres.. there might be an optimum tyre yes.. but I don't have much knowledge about tyres right now. I just assumed the maxium G's expected to design these parts. But when I reach that brigde (the whole dynamics part of it) all the tyre data will definitely be used.

last word on staking: spherical bearing are obtainable with staking grooves (for example suffix G -Grumman stake - in Aurora bearings ,suffix V for NMB etc..)Staking tools are commercially available ,the staking process allows for a secure bearing retention without stress risers.

Ok, thanks.. just found out what bearing staking is.. this means I need grooved bearings if I am to choose this method. And the End of the control arms might have to be thinner (or bigger bearings to meet the thick arm).

http://www.aurorabearing.com/Files/auro ... l-data.pdf

http://www.autosport-bearings.co.uk/ima ... tool-1.jpg

speaking of stress risers :I would concentrate on avoiding massive crosssection jumps in all components looking at your components theres lots of these .the better you get this sorted the more evenly the loads get distributed -so of course this is a win win situation -saves material ,more endurance.Think first about it,then design,will also not extend the machining time into bizarre figures...With exotic materials you have to sesort to HSM and if you have to pay for it you will quickly learn it is of paramount importance to be smart and keep the machining hours low (More than one part machined in one go ,reducing setup time
avoid tool changes..)

I considered some of these suggestions but I can't do so many jobs at once! Because of me designing the whole car parts might not be the best quality

[Jersey Tom]

I'd start by taking the upright design more seriously from the get-go. The concept right now is unrealistic to manufacture.

With regard to where to put the a-arm pickup... wherever works out in terms of stressing the thing, packaging, and installation ratios.

[PlatinumZealot]

It was inspired by this one, except the mounts are one piece.
and the flat faces are cut through that's it! Mine might look funky dimension wise though..but I think the features a very similar. Is it the area where the cylindrical part meets those triangles that you are talking about?


http://www.angerole.com/diary.htm

[Jersey Tom]

[PlatinumZealot]

Yeah i know, that's because I usually fillet the edges last.

I went ahead and made a less funky version similar to one you posted..

The pushrod mount is integrated to the lower right, the pushrod is suppose to slant away from the driveshaft. I also made the mount for the upper CA and toe adjustment link separate like the one you posted.. I JUST realize that this allows the King Pin angle to be large enough without making an extra thick upright.

Unfinished.. I made this in like 30 min.. second time around seemed to go much much smoother.



I will still develop the funky one though.. see what could have been.

[mep]

Ey just one thing, this is your front suspension right?

Anyways have you ever thought about what happens when you want to steer
and you have your pushrod connected to the upright of center of the steering axle
This will affect each other.
This means steering your car will be impossible.

Try to make a concept first:
What kind of car, kind of engine, location of engine, tire, gearbox,….
Then make the basic layout of your suspension.
This means you just make a CAD skeleton for the suspension, but with all the important parts:
A-arms, pushrod, steering rod, upright, damper, anti roll bar.
When you have this you can think about whether the locations are realistic and how you can make the parts in detail.
Your way is Ok for learning CAD but you will fail to make a proper car by this.

[ringo]

No I think he is building the rear first.
I have seen some of his work, he has some of those things you mentioned sorted out already.

[PlatinumZealot]

Ey just one thing, this is your front suspension right?

[-X Rear upright.

[marcush.]

attaching the push/pullrod to the upright looks sensible to me ,putting the lower pickuppoint of the rod exactly into the steering axis willallow for no forces acting on the steering in bump or droop but to achieve this .

I can´t see the point of following two concepts in upright design.
You should try to keep it simple ,doable with your recources and believe me if it´s right than it also looks right,simple as it is.

Why do you have those long studs to fix the Calipers? I´m pretty sure for their weight these will be very weak ,espeacially in x direction(vibration coming from brakes?)

Speaking of constraints we have not seen the space available in your rim and the brake assemply ...

[tok-tokkie]

Jersy Tom, I do some cnc machining but don't follow that fully. Are you saying that if you use a 6mm cutter then the maximum depth should be 18mm? (I apprecaite that you are going to go down to that depth in several passes.) I am more or less self taught so am interested.