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Jack_Hagerty
Moderator

Smithology: Four thousand words about suspension

I was an English-Lit major in school, with a minor in Journalism. Call me stupid, but I love a good abacus. I also love the frequently-asked-questions “FAQ” format of topic dissection. Largely because this is simply how my brain works when unpacking certain subjects—Question A leads to Question B, and then Problem C suddenly becomes apparent, so oh, hey, you start thinking about Item D, and that raises the notion of Digression E, and so on. So we’re going to use Truth of the Week to chase that format for a bit, see what happens. This process will be at least 40 percent more appealing than it sounds. Promise. This week’s topic is simple. Consider the following five words: You can be too stiff. Roll that idea around in your head for a moment. (This is a family website, so keep it clean.) Lean into the notion. Imagine questions. Now imagine those questions on this page, in bold text. In 3… 2… 1…

 

Read the original article: https://www.hagerty.com/media/?p=107425

10 REPLIES 10
audiocage
Detailer

Brilliant!  And yet, you're only up to Item D...

TheStick
New Driver

Awesome! I would love to read a technical article - maybe by Don Sherman - explaining the various types of suspension designs and pros/cons. For example, we are told that the new GT3 is going from a strut based front suspension to double wishbone. I'd love to understand the details between the two designs and what makes one better than the other.

Jack_Hagerty
Moderator

I'll ask Don if he's willing to do it. This is a great idea.
Geschwindigkeit
Passenger

I grinned! I laughed! I cried! A beautifully intentional stream of consciousness - I'm most grateful.

 

Nigh a decade ago, I decided it was high time to put some starch back into the rusty '89 E30 BMW I'd recently purchased (as apparently every part of its suspension was still original). In went stiffer springs, thicker (and adjustable) sway bars, firmer dampers, a few polyurethane bushings - you know, the works. After dealing with the prior festival of body motions, I was practically quivering with anticipation for the first post-overhaul road test. 

 

Spoiler alert: the car was undrivable. 

 

Stiffening the suspension ended up magnifying other weaknesses that were previously masked by the car's overall gooiness. When I turned the wheel even slightly to the right, the back end of the car would do a scary lean to the left as the suspension loaded up before the car began to move. On the highway, this was functionally like having more than a full quarter lock of steering dead zone. It was frightening. What happened was that the rear subframe bushings, which I'd not touched as part of the suspension work, immediately became the softest point of the entire setup, and did all of the compressing (and steering, it so happened) before anything else came into play. Replacing those helped, but that ended up making the 65 series tires the weak point. Swapping *those* with bigger wheels and shorter sidewalls helped too, but the target just kept shifting.

 

This is a long aside. I guess my point is that experience sure is a good teacher, and there sure is an awful lot to think about in terms of suspension setup and design. Thanks for turning this ethereal concept into a corker of an epic poem, Sam!

 

PS: These articles (and finding Baruth! Sherman! Robinson! here too at Hagerty) have been the high point of the pandemic. Such a tonic after watching the old rags deteriorate into cut-rate clickbait sources written by 'influencers.' Truly, thank you.

audiocage
Detailer

And once you've got everything else sorted, the biggest variable of all is the Spacer.  The Spacer is mounted between the steering wheel and the seat.  It makes a big difference when you take out a bad one and put in a good one.

Swamibob
Instructor

Sam:

 

Wonderful monologue, or even Soliloquy?  Great thoughts and information.  As the Great and Powerful philosopher Swamibob once said; when asked any number of questions:  "Yes there is a better way".  He also said:  " Sometimes you need to ask a different question".  

The idea of stiff vs compliant brought me back to a longstanding feud between followers of **bleep** Gulstrand and Herb Adams.  Gulstrand was firmly in the camp of stiffer springs (no, those aren't really stiff enough) and small anti-roll bars to tune with.  Adams was far more in favor of compliant suspensions that soaked up pavement angle changes and kept the tire face following the ground and used larger bars to control body lean.

Both were considered Guru's of the GM F body (that's Camaro's and Firebirds for the uninitiated).  Both had followers and both had great knowledge of suspensions.  I've driven cars set up both ways and I have to say; I liked driving the Adams style cars a good deal more than the Gulstrand.  A really stiff car can work really well on a very smooth surface, but I've found the more compliant car works much better when confronted by any sort of uneven pavement.  I also hate having to wear a mouth guard to drive my car.  it's just not cricket.  🙂

Looking forward to further Professorial bliss!

TheWatson
Passenger

I got most of this and enjoyed it - or anything else Sam-Bob puts out there.  This sentence, however, lost me: "Too-stiff springs generally make a car abrupt in limit response and overly sensitive in a different fashion, the tire seeming to “spike” into slip at the slightest delta from driver or pavement."

FordNorm
Passenger

Hi Sam. I finally took the time to track you down after leaving R&T. Good to read your ramblings again. I will apply this to my vintage Ford iron.😎

DUB6
Gearhead

You're gonna have to call ME stupid, 'cause I can't for the life of me see the connection between English-Lit and an abacus...

However, I enjoyed the article and there are a lot of truths in there.  The biggest among these, I believe, is that one must experiment, try, try, try different things, observe what happens with each change, in each environment, and realize that no one answer or calculation or setup will fit every time.  Each car is different, temps change things, road surfaces are variable, and as mentioned by @audiocage , the "spacers" can throw everything off.  So there is no magic formula for suspension setup, just as there is no such formula for engine setup.  You just learn all you can about what affects what, so you won't make things worse, and then keep tweaking until something gets better (and you understand why).  Sooner or later, you'll develop a catalog of what to do for different situations and will experience some success.

hyperv6
Engineer

The things people make the greatest mistakes on a car are too big of a Carb, Cam, Compression, Gear, Springs, too stiff shocks.

It is a given man6 think bigger is better.

GM for years would slap bigger springs and bars on a car to make it handle. It worked but it still did not ride well snd it removed your fillings.

Now a good example where GM learned how to really set up suspensions was on the GM Performance Division cars they did. I owned in. John Hennessy the SCCA. Hampton and GM engineer taught them how to set up cars.

My HHR SS was a perfect example where John took the pedestrian HHR suspension and lowered the car, added soft springs with shocks that were better valve for the suspension. The Sachs shocks were key in firming up the suspension but still giving yield in the suspension. The bars are balanced not to be too harsh and control the body roll.

 

The bushings also play a roll. Deflection can create issues in deflection and control. 

 

But good geometry is the foundation all this needs to be based on. 

The secret for a good suspension is to get good balance and get all parts to work together.