Are you pretty happy with the baseline settings on your Koni Yellows, or have you adjusted them?

I picked up a set and am wondering what you thought after a couple of months. My car is a daily driver, so I am looking to improve the ride and car control more than ultimate handling capabilities.

Mike

 

That's a damned good question, and I do not yet have an answer.

I have not yet found an approach to shock tuning that inspires confidence.

You and I have different goals, and in your position I reckon I'd simply make a series of small adjustments while driving the same favorite (and perhaps a little bumpy) road in order to find settings that make you smile.

In my case I don't give a fig about ride comfort, what I need is minimum time on course.

If the weather will cooperate what I'll probably do is set out a six cone slalom, and using GTech accelerometer data I will investigate the effect of baseline, and then +.5 turn, and then +1. turn (near to full stiff). I'll leave the rear alone initially until I have some idea of what the settings changes accomplish up front, and unless I have a problem out back I'll most likely never touch them.

My prejudice going in to this exercise (which may be utter BS) is not to fall into the trap of using too much dampening because it makes the car "feel tighter".

The challenge is that any test approach I can perform will involve relatively few elements, and so detecting measurable speed differences and isolating driver noise will not be easy.

Should be an interesting learning experience.

Cheers,

Charlie

Dennis Grant (FarNorth Racing) has been my best source for learning about shocks (and many other topics). With regard to shock tuning for the stock class however, Dennis does not say much:

"Setting Up a Stock-Class Car

The major limitation of a Stock-class car is that you have to run the OEM springs. That means that the proper practice of "set natural frequency with springs, damp at 65% critical" won't work.


The way I'd tackle the problem would be to adapt a strong, steel-bodied take-apart shock to the car and crank the gas pressure as high as I dared. Then I'd measure the spring force contributed by the gas pressure, calculate the revised natural frequency, and damp at 65% critical as per normal.


If that isn't an option, it is possible to "fake" a stiffer spring by going with more rebound, but there's an upper limit to how well this works. The more rebound, the slower the suspension will react, and eventually, it's effectively bound up. Furthermore, super-high rebound forces will eventually blow out seals (especially Koni yellows) so there is a durability issue as well.


My gut says that the upper limit is probably just north of critical. I have no data more solid than that. If you are knocking on 200% critical though, you almost certainly have way too much rebound."


References:

http://www.bimmerhaus.com/tech/shocktuningTN.html
http://grassrootsmotorsports.com/art...king-behavior/
http://www.rspeed.org/forums/motorsp...ning-info.html

 

Here's the B Spec muffler bypass - which arrived in the middle of a snowstorm, raising the question just how daft am I? Daft enough to grab tools on a wet concrete floor? Hmm.... I do really want to hear this...



So B Spec benefits H Stock - or at least that is the plan!

Hey, if it is louder it HAS to be faster, right???

Not to mention the weight loss - it's gotta be at least .2% right?

Cheers,

Charlie

 

I want to hear that in action...

 

Louder car = Faster car

Cleaner car = Faster car (at least that is what the slow guys in vintage racing used to tell me)

Just have fun. Time to put on the Carhart and crawl on the concrete.... (boy, that is easy to tell someone else).

Mike

 

I heard them in action when Grand Am (and the B-Spec cars) came to Laguna Seca. Those were the only sessions I didn't need earplugs for. Its weird having racecars go by so quietly. I couldn't say how it comperes to a regular Cooper.

 

Well, it is snowing there, so that means you are not driving and have nothing to do...So do you have it installed yet?????

 

LOL - I jacked the car, crawled under it, eyeballed the whole layout and then wimped out. The installation requires one clean and correctly located cut on the OEM system, and with my oddball tool collection and poor working position I determined the odds were against me.

So I've an appointment with a friend at a local shop next Tuesday, where the combination of a proper lift, good tools, and professionalism will ensure that I don't wind up making a mess... (bloody hell I've cut it several times and it is STILL too short! ).

I'm endlessly amused at my own impatience, which is a clue to the fact that I really do take much joy out of this whole silly preoccupation with parking lot racing in tiny underpowered cars!

Cheers,

Charlie

 

Do you have contact information for Hendrick? Email or Phone? I also contacted Turn 17 and Fast Toys as they are supposed to be coming out with a B Spec style by pass too...but have not heard back.

Theirs has a nice looking tip on it, but I can always add one of those if I need to.

 

Matthew Hair <Matthew.Hair@HendrickAuto.com> was kind enough to handle that purchase for me.

Send my regards,

Charlie

 

Well I am very pleased indeed with that Hendrick bit of plumbing, now that it's properly installed and rather thoroughly test driven.

I should think it lightened the car perhaps five pounds - far less than simply removing the spare, and perhaps added a horse or two.

But the real benefit is as I expected - now that I can hear the car it is much easier to drive smoothly, and suddenly my right foot seems much smarter.

And anyway, I had almost forgotten that the best toys go vroom vroom...

Cheers,

Charlie

Ps: Gordon added one more clamp to make the joint tight and strong - the band clamp that comes from Hendrick is a nice piece of kit but the extra strength was worth the few bucks. If it leaks over time I'll just have it welded.

 

Any pictures or video would be great.
Thanks

Tom

 

These are better than I am likely to create...

Cheers,

Charlie

 

Waaaay quieter than I thought it would be unmuffled. Hmmmm.....

 

Yep I think that passing sound at Devens will not be a problem...

Cheers,

Charlie

 

Does your car have one cat or two? A resonator? I'm guessing that you are very limited on what you can remove or replace........

Did you get some nice weather over the weekend to put some miles on?

Mike

 

Single CAT, one muffler right behind the cat and another chamber tucked just in front of the rear bumper. That latter chamber is now history.

The weather improves at an agonizing and teasing pace - it is New England.

Cheers,

Charlie

 

Hey Charlie,

Was wondering what you thought of the exhaust after having it on the car of just over a week..

 

It is excellent. Loud enough to hear, so my driving is a bit smoother. Not loud enough to even turn a head, so far from obnoxious.

Best exhaust mod ever for under $100!

Cheers,

Charlie

 

So I was trying to turn out my pets to the street corner in order to help the racing budget, but they weren't thrilled with the idea of being accosted by strangers and anyway the street corner hasn't been properly plowed yet... so much for my career as a pimp.

What's a fella to do? I jumped in the shallow end and pulled the trigger on the rain tires (the 195/50-15 R1R for the 15" Holies). They have to come up from Tennessee of course but I was assured I'd have them by the 30th for the Corvette Club event.

That's a start - and $570 poorer I now have only to find another $1,000 or so to put race tires on the pretty Panasport wheels that are stacked in the family room. Since my plan to make extra money came adrift I can only pray that will be possible by the 7th of April.

And oh by the way, the Corvette Club event sold out before I could register so my intention to test & tune that day will go unrequited.

Interestingly enough the car would be spot on for the proposed "Street" classes, except that I'd be looking at camber plates instead of Hoosiers. Too soon to say how that notion will play out, but my pets are all for it!

Cheers,

Charlie

Edit: A good friend has possibly found someone who cannot make the Bay State Corvette meet and from whom I could buy a registration, so perhaps I shall start 2013 on March 30th as intended -- I do hope so!

 

If I had a set of wheels in the family room, I wonder where I would be sleeping..........

Maybe you can stumble on a set of used tires for the panasports, just to get you off the ground?

Mike

 

Wheel, Tire and tool storage - that is what my parents garage is for...and you would think at 40 I wouldn't have that luxury...however the wheels are nothing compared to the STS Miata I had in there for the past few years. So my dad is actually happy that it is only a couple sets of wheels, some tools and misc spare parts.

 

LOL... to both of you.

Charlie

 

Now wearing the 195/50-15 R1R on the 15" holies, and I have several immediate impressions:

1. the car looks pretty funny with those little tires (23.9" diameter is much smaller than the OEM Continentals)
2. the gearing is noticeably shorter, so 3rd will get used on some courses
3. the tires are pinched on the 5.5" wide rims, so I shall have to find appropriate pressures to try and take the slop out of them
4. DAMN that rubber does grip!

All in all it is what I wanted - a really good rain setup that works fine on the street also.

Now I have to write that last BIG check - the purple crack ain't cheap folks.

Cheers,

Charlie

 

Charlie,
Always a fun read.

Question - Why the R1R over the R888? Just curious as I bought a set of the R888 for the track and was told that they would make a good wet tire.