XR4Ti Archived Tech Articles

    Damper Technology Discussion - The effect of dampers, also know as shocks or struts, on performance handling and racing, and what the damper really does.

Post Date:    Wed, 18 Apr 2001
Subject:      Re: question about Rapido's lowering spring kit
List:         merkurowners@merkurowners.org

Steve wrote:

> The settings are not there to give one a choice of firmness but 
> rather to compensate for wear as the shock ages....WHOoooaaaa! 

Very interesting.  I'm running my Spax dampers (the proper term 
for a shock or strut) at 6 of 10 on the front.  I can't remember 
my rear setting right now.

My next dampers will be rebuildable/revalvable.  The idea there
is that they will essentially never wear out, and if I make 
changes to my spring rate or car weight or throw on some 
superlight wheels, then I won't sweat the affects on the dampers.

FWIW, I've come to believe that the second most important item on 
a race car (autocrossers included) is the dampers (the first most
important being tires). 


Post Date:    Wed, 18 Apr 2001
Subject:      Re: importance of dampers 
List:         merkurowners@merkurowners.org

Greg wrote:

> OK, but why?  Explain your rationale.

Sure thing.  As Grayson pointed out, damper technology is still 
behind the shroud of black magic to us unlearned novice racers.
I've read five or six books on racing technology and car 
development/setup and I've always focused on the damper section 
because I find it so intriguing.  The most significant thing 
I've read is regarding the FIA's ban of active suspension in 
Formula1 in the early 90's and the resulting effect it had on 
damper development.  Damper technology apparently skyrocketed 
in 1994 or so.

Erik wrote:

> Probably because the "dampers" do 
> more to keep the tires attached to 
> the ground in a balanced fashion 
> than any other component (except 
> gravity).

As Erik pointed out, the dampers really are directly responsible 
for keeping the car attached to the pavement.  My rationale lies 
in the fact that the tires must stay in contact with the road to 
maintain grip, obviously.  While it's the springs providing the 
force, it's the dampers providing control.

The dampers have a lot of work to do.  In autocross more so than 
in "racing" (roadracing), the car is almost constantly in a state 
of transition.  There are very few settled moments.  Even in the 
straigtaways, you are busy exiting from the previous corner then 
setting up for the next corner.

Any autocrossers out there ever spun out in a slalom?  I have.  
The slalom is probably the most transient portion of any autocross 
course.  The car is switching back and forth between cornering 
directions.  This is when improper damper settings are really 
going to show their ugly face.

This isn't to say bad driving form isn't the cause of spins in 
slaloms.  But if there is too much weight transfering too fast 
(ie improper dampers) there is going to be trouble.

Remember, the damper isn't supposed to control movement, it's 
supposed to control how fast that movement happens.

Jack wrote:

> All three of the Solo components 
> require top grade traction. 
> Naturally, this means tires that 
> can hold well, but even the best 
> tire can't stick if the suspension 
> (springs and "dampers") are weak. 
> Wheel hop, severe body sway, and 
> "nose diving" (weight transfer 
> under braking) are some of the 
> problems poor suspension can cause 
> or aggravate.

He's got it covered here.  The tire isn't going to do it's 
job if the suspension can't keep the tire on the road, *and* 
properly loaded.

To sum up, I've got a few projects planned for my racer.  
First, I'm going to redo the engine.  I need more power and 
better general mechanical condition.  If it weren't for the 
lifter tick and the piston slap, I'd be just happy with
the power the engine has, and I'd move on to my second task.
That's dampers.

I'm currently running Spax adjustable dampers from BAT.  I 
think the part number is M401AL.  The standard Spax adj. is 
listed as M401A, as I recall.  The "AL" is the shortened 
stroke version designed to work with BAT's -40mm lowering 
springs which I'm also using.

The plan is to chuck the Spax adjustables and the -40mm 
springs at the same time and replace them with a great 
coilover damper.  I'm thinking that ShockTek, as mentioned by 
Grayson, is the way to go.  Not only will the spring rates be 
changable and the ride height adjustable, but I'll also be 
able to have the dampers rebuilt as needed and revalved.  
Revalving allows you to tune the suspension more precisely.  
So if I decided to install a 3.8 SuperCoupe motor in my XR, 
ala Godfrey, I'll be able to compensate for the sudden 
reduction in weight in the front end of my car.

Finally, I read in Grassroots Motorsports sometime last 
fall/winter, that the hot ticket for the extremely competitive 
world of National/Pro level autocross in stock class was 
expensive dampers ($1000-$1200 per damper).  Often the dampers 
would be rebuilt between each event.  Heck, I've had the same 
dampers on my racer since 1998 and the wear isn't grossly 
noticable. Apparently there is enough wear on a damper after 
one event for a rebuild to have an effect on the function of 
the damper.

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Published by Chris Anglin.