Random, I know, but I was just reading the manual from BAT for Merkur and realized something.
I don't really like McPhearson strut suspensions.
Why did they deviate from two A arms and shocks?
I can't imagine that it is cheaper and there is no performance advantage.
So why?
It is cheaper - you buy it assembled from a supplier that you squeezed down to barely marginal profits with your 900lb gorilla tactics... and then you pay only one monkey with a nut driver to install it in 5 minutes.
A-arms require more than one monkey and cannot be pre-assembled.
In reply to Giant Purple Snorklewacker:
You really think it is cheaper? With a proper sub-frame design you could pop in a double A arm with a one armed monkey and a nut driver.
Your probably right, though.
FlightService wrote: In reply to Giant Purple Snorklewacker: You really think it is cheaper? With a proper sub-frame design you could pop in a double A arm with a one armed monkey and a nut driver. Your probably right, though.
Well, I suppose I should not have stated that like it was a fact. That is my guess because it seems like whenever a double A arm setup appears - it gets cut for cost purposes in the next model run. (See Honda Civic and Accord for references)
It is worth noting though that Porsche and BMW both make some pretty damn fine handling cars out of them so I guess maybe they are not inferior in applications where there is enough height to use them and they can be prevented from binding under load. If that is the case - cheaper and effective "enough" might apply.
Less parts, less engineering, smaller packaging... absolutely a McFearsome is cheaper.
I suspect they are cheaper, as you get to lose half the control arms and associated pivots without adding any new parts. They package better as well, as they're not as wide as a double wishbone.
I am just thinking of the engineering that has to go into the strut.
Nice 6 DOF and multiple loading directions and methods. One would argue volume but then you go back to if I put that volume in a traditional shock set-up I would have to believe the cost is close.
But you all are probably right, cheaper wins everytime with mass production.
FlightService wrote: But you all are probably right, cheaper wins everytime with mass production.
That's why entry-level cars still sport rear drums, when high-level trim versions have discs. There's a reason for the price difference and its' name is profit.
ReverendDexter wrote: smaller packaging...
+1 It gives more space for transverse engines in FWD applications
FlightService wrote: Random, I know, but I was just reading the manual from BAT for Merkur and realized something. I don't really like McPhearson strut suspensions. Why did they deviate from two A arms and shocks?
You mean, like, in the 50's?
Originally, it was a speed-of-assembly thing. (as related to me by a guy who dated the daughter of one of the Ford UK people who was responsible for the Ford... whatever it was) I don't know if that particular car had non-adjustable suspension, but by having the mounting points spread so far apart, tolerance stack doesn't affect alignment very much. I can think of very few control arm suspensions that have no factory adjustment, and they are relatively new vehicles, while it's more likely than not to be non-adjustable for struts. No adjustment means less steps on the assembly line, as well.
Later, they found that they could make the chassis a whole lot lighter because the loads are spread out more. An A-arm suspension is trying hard to twist the frame rails (or whathaveyou) so that needs to be beefed up. (Beefinated?) Struts, on the other hand, basically just hang the car by the strut towers, and the crossmember just deals with lateral loads.
In reply to Knurled:
Why not when. LOL
Sheet metal flexes (which is why weld up our race cars put strut tower braces that tie to fire wall, build tube frame car, give up and go boat racing, but I digress.)
I don't buy the FWD packaging bit, because they are completely assembled before moving up from the bottom of the car and all bolted together. You need to align the McPhearson struts just like an upper control arm.
We all know how much OEMs care about us and ease of maintenance.
I really believe some one, some where, said "Hey, I can knock a $1 off an assembly on that car." The A arms guys said "whatever." A billion units later the A arm guys are in the retirement home going, "I once was a supplier, I once was a supplier."
McPhearson guys are parting with Paris Hilton.
FlightService wrote: McPhearson guys are parting with Paris Hilton.
You mean parting out Paris Hilton? Not much of value there, honestly.
Knurled: I hadn't thought about the beefination but that makes sense for the trend shift to unibody cars. Once the big honkin frame was gone they had to either beef the subframe artificially or spread the load. Makes sense to me.
In reply to Giant Purple Snorklewacker:
You obviously haven't seen her home movies. Not much reason to stick around really. Pun intended. 
JoeyM wrote:ReverendDexter wrote: smaller packaging...+1 It gives more space for transverse engines in FWD applications
That's totally true, but why in the hell does the 911 use them? More trunk..er..bonnet space? Then again, why do they hang the engine off the rear axle? Its it stereotypical Germanic one-upmanship? "Ve kan build ze betah ka ewven dough it haz pogo stiks for a suspenseon ahnd Kardashian-like mass distribuution!"
Engine off the rear axle:
Pogo stix front suspension:
Giant Purple Snorklewacker wrote: Engine off the rear axle: - Real IRS, and anti-squat can launch like live axle
Ask a super stock racer to set up his rear end with as much anti-squat as you can get with an IRS. You can get huge amounts with a stick rear end if you want, sure it isn't streetable at that point, but anti squat isn't even close between a stick rear end and an IRS.
Just to quibble, it's 'McPherson' not 'McPhearson' (named after Earle S. MacPherson, who is credited with perfecting the design in 1920's)
MacPherson Struts were in use in rear drive cars LONG before their use in front-drives.
McPherson was a Chevy Engineer. My memory is that GM patented the design in the late 40's (Coulda been the 20's..)
First companies to use it in production were.....Ford of England and Porsche....
(GM was ruled by NIH Beaners even then....)
Rog
To people who complain "Why did Porsche use it?"...
Consider what they were using before they made the 911.
Then consider that they are such a ridiculously conservative company, they stuck with air cooling WELL past its sell-by date, and they still make cars with the engine in the worst place possible, simply because that's the way it's always been done, therefore that's how they're going to do it.
they can't be all bad. Colin Chapman would not have used them on the rear of the Lotus Elite.
...and that's why they are properly called Chapman Struts if they're on the rear.
Well to be fair to Porche, they also created 924, 928, and Cayenne. But as long as folks are willing to pay for a 'real Porche', they will make them.
Colin used them in pursuit of simplicity, light weight, low cost, and 'because he could'.
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