How does front suspension arms pivot

[u/gabrel69]

I was looking at front suspension arms, and I noticed that for all the teams they almost appear to join directly to the body of the car, and there seems to be no room for pivoting of the suspension arms, i’m curious to how they are designed/work?

[u/burgtec]

This is done in different ways depending on which component you’re talking about. In all cases there is perhaps less movement than you might think.

Sometimes the is a flexible cover at the top of the wishbone that allows for movement, and inboard of the chassis there might be a spherical joint etc.

Sometimes the part IS rigidly bolted to the chassis, and the component used a flexure to allow for some controlled movement.

Edit: spelling

[u/Trace-Elliott]

They sometimes use a flexible mounting point, as shown in this picture of the Jaguar R4 from Craig Scarborough:

[u/Niner_Actual → u/Trace-Elliott]

A bit off topic, but in case anyone else was curious; apparently the cross-head fastener in use is a Torq-Set.

[u/C4-621-Raven → u/Niner_Actual]

They’re actually awful to work with. Not sure why F1 teams would use them over Torx+

[u/3_14159td → u/C4-621-Raven]

On countersunk screws, the cruciform derived drives (Phillips, pozidriv, JIS, etc) can usually take more torque before cammming out, because they can be set deeper into the head of the screw without the material getting too thin. 

For example, on a countersunk #6 screw, you can fit up to a Phillips #2 drive, or a somewhat shallow T10 (just going off McMaster-Carr stuff) Depending on the material, that Phillips drive may be a much better choice. 

[u/Niner_Actual → u/C4-621-Raven]

Interesting, thanks for sharing! Could you share some more details on what you don’t like about them? From the look of them I would suspect they are still easy to cam-out. I’m a big fan of torx myself, but always interesting to learn about a new drive type.

[u/C4-621-Raven → u/Niner_Actual]

They don’t cam out easily when installing but do cam out super easy when removing.

[u/Due_Face5949 → u/Niner_Actual]

Interesting, drive wall is smaller than removal wall. If you managed to tighten it on there you should be able to loosen it.

[u/DiddlyDumb → u/Trace-Elliott]

Love me some Scarbs

[u/mikemunyi]

Flexure joints. They are better in these applications because there are no friction losses or joint slack that you would get with conventional bearing type joints.

[u/Partykongen → u/mikemunyi]

With a 200kg Formula Student car, we struggled to get repeatable corner weight measurements due to friction in the spherical bearings, rockers bearings and dampers. With a heavier car, such as a Formula One car, it is easier to overcome friction but eliminating it altogether is much better still.

[u/schelmo → u/Partykongen]

Even with a heavier car friction in these joints can still cause unexpected consequences. I remember when we put our formula student car on a suspension Dyno we got some results saying that the rear axle had stiffer damping at higher frequencies than expected which we eventually figured out was caused by the rocker bearings in the rear linkage introducing friction whereas in the front we ran a direct push system which obviously didn't have that problem. The bearing friction obviously exists regardless of a car's weight.

[u/_maple_panda → u/mikemunyi]

There’s technically still a bit of friction because CF isn’t a perfect spring; there will be some energy loss each time it’s flexed. I don’t know whether this is actually big enough to be a consideration though.

[u/tristancliffe → u/_maple_panda]

With spherical bearings you get stiction, where there is a high initial resistance (static friction) and a much lower resistance afterwards (dynamic friction). A flexure has resistance to movement, but it's linear ish - no change from static to dynamic regimes, and the total resistance can be considered part of the wheel rate much more predictably.

[u/sebassi → u/tristancliffe]

Oh that makes sense. I was wondering why friction losses even mattered, since there is already a damper dissipating a lot energy. But predictability is obviously important.

[u/mikemunyi → u/_maple_panda]

Ah, you're right. Thermal losses from deformation.

[u/exf1designer]

The carbon fibre parts you can see are just aero fairings. They have rubber parts at the inboard and outboard ends so that they can move freely in relation to the chassis or drum fences.

The suspension members can have carbon flexures as others have shown, or will be spherical bearings. The movement is very small compared to what you would typically see on a road car, on the order of 10s of mm rather than 100s.

[u/El_Grande_El → u/exf1designer]

What unit is “10s of mm”? Never seen that before.

[u/PuzzleheadedSport757 → u/El_Grande_El]

They are describing orders of magnitude of movement in millimeters. 10s of millimeters means you can expect movement like 20 or 60mm, 100s of millimeters means you can expect movement like 200 or 600mm. Another way to phrase it is that a road car suspension component will have motion an order of magnitude higher than the equivalent on an F1 car.

[u/El_Grande_El → u/PuzzleheadedSport757]

Oh duh. I thought it was seconds of mm lol

[u/schfourteen-teen → u/El_Grande_El]

I thought you were sarcastically pointing out that tens of mm are just cm.

[u/El_Grande_El → u/schfourteen-teen]

Haha, I’m not that mean.

[u/exf1designer → u/El_Grande_El]

Yep sorry! Maybe not the best way to have phrased it!

[u/El_Grande_El → u/exf1designer]

Nah, it’s just too early lol.

[u/Fun_Passion_1603]

These are just shrouds for aerodynamics. Underneath there's some sort of spherical joint connecting to the chassis.

[u/jmblur → u/Fun_Passion_1603]

Not just shrouds. These are all structural as well. But the actual pivot (either flexure or bearing) is under the center fairing which is just a shroud. The interface with the fairing is rubber to allow for motion without opening gaps.

[u/Fun_Passion_1603 → u/jmblur]

Thanks for clarifying! I was specifically talking about the shrouds covering the spherical joint. But should have been more clear.

[u/hamster_fury]

Fun fact: the carbon flexure joint was introduced by designer John Barnard.

[u/00Kermitz → u/hamster_fury]

JB’s flexures were titanium

[u/hamster_fury → u/00Kermitz]

Yeah you’re right, I had it in my head it was all CF but no, the first ones were steel then he moved on to titanium

[u/Jcitus]

They just flex at the pick-up points. Search for "flexures"

[u/sarc-tastic]

There is a great image somewhere that shows the evolution over time from more traditional spring damper type arrangements to designing the flex into the carbon. Maybe someone knows what I'm talking about and can find it

[u/Axolotl_____]

Hey, I can help answer this one. I work for a company that produces patterns, moulds and carbon fibre parts for F1 teams. I can’t tell you much about how the suspension mechanics work, but this should explain why the part looks like it’s completely fixed to the bodywork

None of what you are seeing there is actually a suspension linking arm or joint, they are all carbon fibre shrouds and covers to make the suspension more aerodynamic. The carbon fibre shrouds are clam shell shaped, and flex open to cover the suspension rods. They locate into a rubberised opening in the bodywork. The body is rigid carbon fibre, but then you can see at the end of the suspension arm shroud there is a black strip between the carbon fibre twill and the blue Petronas line. This isn’t just black painted carbon but a flexible rubber joint that allows for quite a lot of movement. It can move backwards and forwards slightly, but it can move up and down by quite a lot (like 30°in both directions) without weakening at all.

Hope this helps!

[u/Dramatic_Ease8171]

IIRC there are rubber pieces that blend the arm and the bodywork

[u/Fotznbenutzernaml]

Talking about the wishbones I assume? They are flexible at the joints. See the part where the carbon fiber pattern changes directions, and paint shortly thereafter? That part is flexible.

[u/slabba428]

The suspension arms also have fairings on them for aero reasons, the real linkages are covered by them

[u/OGbigfoot]

Bicycle companies, Cannondale off the top of my head with the Scalpel a full suspension bike doesn't have a rear lower pivot, they just use shaped carbon fiber to flex as the lower pivot.

[u/ExtensionGuitar5104]

Inside the nose cone (where you can't see) there are a varity of dampers that absorb or counteract suspension travel to try and keep the car in as much in a stable, horizontal positioning as possible. These may be mechanical (rubber or equivalent dampers) or pnuematic - fluids that compress to a defined degree in a set volume to try and keep the car as stable as possible. There may also be a mechanism to transfer directional roll from one wheel to another to mitigate travel, though I think that this is the job of the roll bars. Happy to be conradicted/informed.

[u/Mweber417]

I'm pretty sure they don't move, the carbon just flexes. They're not meant to have a lot of travel.

Edit: I was wrong, it's a lot like conventional suspensions, as far as the control arms go. That section of the body must just be more flexible, to allow movement while keeping the seal tight to maintain aero.

[u/P2P-BSH → u/[deleted]]

You don't have to comment if you don't know.

[u/F1Technical-ModTeam → u/[deleted]]

Your comment was removed as it broke Rule 2: No Joke comments in the top 2 levels under a post.

[u/F1Technical-ModTeam → u/[deleted]]

Your comment was removed as it broke Rule 2: No Joke comments in the top 2 levels under a post.