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Rate My Fabricated Uprights
43655 - 16/4/14 at 08:54 PM

After agonizing months of designing, I'm at least pretty happy with the uprights
Any criticism on the design?
If they're any good maybe they'll be of use to others, I spent a lot of time looking at what others had done
CAD model here https://grabcad.com/library/fabricated-front-suspension-upright-1








SPYDER - 16/4/14 at 09:30 PM

Will they fit inside 13" wheels? What hubs are you using?


Slimy38 - 17/4/14 at 07:12 AM

The last pic suggests the brake disc is trying to occupy the same space as the upright?

To me the hub seems a bit too close to the upright, it doesn't leave much room for the 'top hat' design of most brake discs.

It looks really nice though...


HowardB - 17/4/14 at 07:29 AM

Have you thought of doing any FEA on them?


Doctor Derek Doctors - 17/4/14 at 07:32 AM

It depends what you want them rated in terms of. What was/is your driving design goal? Weight? Durability? Manufacturability?


designer - 17/4/14 at 08:57 AM

If you box in the upper and lower extensions they will be a lot stronger, even when made of thinner material.

The outer steering ball joint should be above the steering arm, just in case something happens at that end. More chance of it staying in place!

Personally I would use a stub axle bolted into the upright to make it a lot lighter and easier to manufacture.


davidimurray - 17/4/14 at 11:16 AM

A few thoughts

1) Why are the 'blocks' top and bottom for the wishbone set above the plates they are welded into, i.e. any bending is trying to pull the weld apart rather than sharing the load between plate/weld.

2) 0 Caster? I assume this is for race only use?

3) For your steering arm I would be tempted to extend both plates to the full profile and then weld a bush/sleeve between them. That way you are not just relying on the weld alone.

4) How do you tighten up the nuts inside the upright?

5) If racing have you considered using rod ends instead, you seem to have them inboard? You could then mount them all in bouble shear between plates.

6) What is your bearing arrangement and how will you pre load them. Also what are you going to do to secure the bearings. If welding, the housings would need machining after welding which is quite a big job!


h0nda - 17/4/14 at 12:27 PM

I agree with designer about boxing in the open sections, this includes, both the extensions and also the steering arm, by not boxing them in you will have more movement of your connection points to wishbones and steering arm. The boxing in is to reduce the displacement of those hard points. e.g. as they are now when braking the upright will twist about itself and give you at the very least toe changes.


43655 - 17/4/14 at 05:42 PM

nope, my wheels are 17"! they're 300mm between the pivot points top and bottom.

I'll have to check the disc; can always get a little less offset on the bell.

I can't get my head around Solidworks' FEA, so relying in what looks right, same as my whole chassis!

Driving will be mostly road, occasional track i guess. lightish weight but don't want to compromise strength

Can appreciate what people are saying about boxing in, still need to be able to get at the ball joint nuts though

Good call on the steering arm, not sure why I designed it like that

As for the spindle, you're proabably right. I started the design based on a bolt-on Audi A6 hub so i could use the same front and rear. Except i'll probably be making that from scratch too becuase 5x114.3 is a bit close to the edge on the hubs i bought.

no real reason apart from being a bit easier to design i guess, i see your point though and will look at extending the sideplates up. should get more weld between the two parts then too actually.
Just meant no caster in the upright itself, think there's 4-5 degrees when it's mounted
Ah i see what you mean on the steering arm, good idea thanks
I think they have castle nuts and a split pin so shouldn't need big torque. should be enough space for a socket in there as it is, but don't know how i would if the back was plated off too
Must admit i have reservations about the longevity of rod ends in shitty UK road conditions. The lower inners I'd planned to do as delrin bushes, the top inner joints would at least have rubber covers. I'll consider it
the bearing is a standard automotive sealed double-race bearing, no need to preload really?
was hoping that with a pretty thick wall (~5/6mm i think) distortion would be minimal, could have a 'mock bearing' in during welding perhaps. I could bore it out though, I'm a designer but still pretty handy on a mill and lathe

Hmm oh right, i thought it was beefy enough to prevent noticable distortion under use


Many thanks for the advice so far


43655 - 18/4/14 at 08:30 AM

how much ackerman angle do people run?
start with 'some' and tweak the rack position?


davidimurray - 18/4/14 at 09:53 AM

quote:
Originally posted by 43655
nope, my wheels are 17"! they're 300mm between the pivot points top and bottom.

I'll have to check the disc; can always get a little less offset on the bell.

I can't get my head around Solidworks' FEA, so relying in what looks right, same as my whole chassis!

Driving will be mostly road, occasional track i guess. lightish weight but don't want to compromise strength

Can appreciate what people are saying about boxing in, still need to be able to get at the ball joint nuts though

Good call on the steering arm, not sure why I designed it like that

As for the spindle, you're proabably right. I started the design based on a bolt-on Audi A6 hub so i could use the same front and rear. Except i'll probably be making that from scratch too becuase 5x114.3 is a bit close to the edge on the hubs i bought.

no real reason apart from being a bit easier to design i guess, i see your point though and will look at extending the sideplates up. should get more weld between the two parts then too actually.
Just meant no caster in the upright itself, think there's 4-5 degrees when it's mounted
Ah i see what you mean on the steering arm, good idea thanks
I think they have castle nuts and a split pin so shouldn't need big torque. should be enough space for a socket in there as it is, but don't know how i would if the back was plated off too
Must admit i have reservations about the longevity of rod ends in shitty UK road conditions. The lower inners I'd planned to do as delrin bushes, the top inner joints would at least have rubber covers. I'll consider it
the bearing is a standard automotive sealed double-race bearing, no need to preload really?
was hoping that with a pretty thick wall (~5/6mm i think) distortion would be minimal, could have a 'mock bearing' in during welding perhaps. I could bore it out though, I'm a designer but still pretty handy on a mill and lathe

Hmm oh right, i thought it was beefy enough to prevent noticable distortion under use


Many thanks for the advice so far


I must say it's great to see someone doing all this work and sharing it with us - I've been catching up with your other posts. Keep up the good work! One day I dream of doing the same and having designed other stuff before I know how every decision ends up being a compromise!

Just a couple of other thoughts -

You mention the castle nuts, I assume the joints are tapered? If so don't forget you will need to find a way to dismantle them - can you get a joint splitter in there? Also looks ok but can you get socket plus the ratchet head in there to tighten up? If not how much turn can you get with a ring spanner - looks ok but worth checking.

With regard to sphericals you can get dust boots to go around them but not cheap so off the shelf ones are good. Which joints are you planning to use? Have you checked the articulation on them across all the suspension settings? Where are your shocks mounting? Will your chosen joint take a load in both directions, i.e. if on bottom arm the shock won't pop the joint out of the cup. I have a distant memory of reading that the maxi joint is good in this respect which is why it is so commonly used.

For the stub axle bearings I assume you must have a shoulder machined inside the tube and a bearing either side to prevent the stub axle floating. The nut on the end of the stub axle then bears against the inner bearing to prevent float. Tube won't be particualrly round and maybe variable on diameter so. The bearign seats either side of the step will also need to be perfectly concentric which is quite tricky to do! Have done some before in the lathe and bored from one side and then backbored without changing the setup - was a right pain.

As I said keep up the good work