This book just got published a few weeks ago and is written by one of the founders of JRZ. Should be pretty informative and current.

http://www.amazon.com/Vehicle-dynami...4012225&sr=8-1

 

He goes way back. He's like the original Yoda from Koni in the 1960's - 1970's. He can be believed to actually know things. As for communicating them usefully - we'll see - I ordered mine just a few minutes ago.

Here's his own site: http://janzuijdijk.com/

Scott, who has orange shocks from one of Yoda's apprentices...they're kinda like a light sabre with a remote reservior...

 

Jan is a real nice guy,as most Dutch are!
Not nice enough to help me out,but most Hollanders are penny pinchers anyhow....<-- Coming from a Dutchman

 

And this is $130 cheaper than the Miliken book so I can actually afford it.

 

$22.73 shipped with USPS slow poke shipping.

http://www.authorhouse.com/BookStore...x?bookid=65879

 

I ordered it straight from Amazon along with a can opener I needed, so free shipping. 1.24 savings woot

 

I will be checking this one out..

 

I bought this book earlier in the week from Amazon.com and it just arrived in the mail today. I immediately opened it up and began reading nonstop. Well, I just finished reading it and I can say that it is very difficult book to follow due to nonexistent editing, poor english grammar, and many mispelled words. In addition, Jan includes only the bare minimum of graphs, formulas, and line drawings. However, if you read between the lines and already have some understanding of dampers in particular and car suspension systems in general, you can easily locate the useful nuggets of information. But I warn you, it takes some work to understand the author throughout the book so it is by no means a passive reading experience.

I give it three stars out of five for content.

 

Thanks for the review Johnny. This one will have to wait for me.

 

Johnny, you just ruined my day! I ordered it like 5 minutes ago and then I found this.

 

Don't worry Claude...If a couple of issues of Motorsport cost $20 and are worth it, then this book certainly is. I'm just working my way thru the last few chapters and while I can certainly second many of the criticisms I've seen here and heard elsewhere, it's worth reading. Johnny Mac is right when he says there Are nuggets. And think about how relatively scarce nuggets are.

Scott, who can turn his damper ***** all he wants and can't tell a thing...well, the car is on jackstands after all...

 

My copy arrived today. Any other books to look at on this subject after this one?

 

If there were, we wouldn't have been so excited and disappointed by this one.

Scott, who thinks the whole subject is about as easy and intuitive as the pronunciation of the authors last name, except for once you've heard it you can probably repeat it, not that anyone else would know you were saying it right, and not that that would help the next time you encounter some inscrutable name, which sorta reminds of the subject again..."Try more low speed compression"....there, that's the book.

 

How much does RCVD get into it?

 

Not much on dampers. But it's a must have book. Not perfect, but it has a ton of good info.

 

Just finished reading my copy. I agree with John on the grammar and editing issues. I'm not quite sure what the publisher was going for.

There is a decent chunk of good info and it re-affirms a lot of the data that is currently being collected by autoxers as they move away from OTS shocks into more custom/high dollar shocks.

If nothing else the book makes you want to go out and buy some JRZ's...

 

Good to see some honest reviews of the book. I haven't gotten mine yet as Jan promised me he would mail me a signed copy (excited).

If anyone has questions they need clarified, please feel free to ask.

Best,

Bryan

 

Yeah, too bad JRZ doesn't make an off the shelf RS for Integra or CRX. However, I do know they can build a set of dampers based on a sample damper installation (i.e. top mount down to fork - in my case) that you send them.

 

I've been meaning to write something about the book but haven't got through the last ten pages for a few weeks. Most of you covered the main points. Compression damping and gas pressure are important.

All in all, I would absolutely recommend the book at anyone. There were definitely new points apart from those two I learned which are very significant (like non-preloaded stack, etc). Chapters 4,5,8,9 can probably be skipped entirely, maybe a couple others too.

There was one point I didn't quite get. Why would a car with a high motion ratio like macstrut need much less low speed damping but more in mid to high speed than something like a Honda/double-wishbone for which it's much lower. The point of motion ratio is to account for damper velocity difference relative to wheel rate..

I saw some plots of JRZ RS Pro's for an Evo recently, the range of adjustment in your dampers is just insane, compared to others like even Penske.

 

Hi Bryan,

For those of us who don't know you (like me), can you tell us about yourself and what you do at JRZ. I'm sure there are those of us who would like to ask you some questions if you're willing to take them.

Scott, who has been going thru his archive of articles researching a nagging question (unsuccessfully I might add), and along the way re-read a bunch of articles on dampers including one by Jan Z...

 

I sent the drawing with correct dimension for RS about 3 weeks ago. Just got the final drawing back from them last week. We should be getting the RS dampers sometime next week. It is for one one of our customer who will start racing Honda challenge this year.

 

My apologies, I'll introduce myself. My name is Bryan Hise and I work for JRZ Suspension Engineering as their US Representative. I've been with the company for about a year and a half, before that I worked for one of their major importers for 2 years. Day to day, I do everything from set up dealers, rebuild/revalve at the shop, design work, provide customer support, or am at the track supporting series from ALMS to Drivers Ed days. My phone is on 24/7 for our customers. The shop is located just south of Baltimore, MD, and yes the snow last week was diabolical.

What Jan is getting at with various suspension designs like McPherson, multi link, wishbone, etc is that they have different motion ratios. To be clear, there are three terms we're working with here: the motion ratio, the wheel rate, and the damping ratio. The motion ratio is the proportion of wheel movement to shock and/or spring movement. The wheel rate is the spring rate measured at the tire which can be expressed as wheel rate = spring rate * motion ratio^2 (to be precise, also account for the tires own spring rate in the form of a series spring calculation). The damping ratio is a relative term of how much damping is in a system. Keep in mind that the simple damping ratio calculations found online are only valid for linear systems. Most high performance dampers are not linear. Many of the approximate terms people use we feel is both mathematically and functionally incorrect.

So when we design a valving, we have to take all three of these factors (plus a few more) into consideration. The bottom line is that you want a certain amount of damping at the wheel relative to that wheel rate. So for suspensions with different motion ratios, the dyno graphs will look different but at the wheel things are relatively similar. Another consideration is the unsprung mass of all of these varying assemblies. Damping of the unsprung mass is central in our design theory.

We build our dampers with considerable range for a number of reasons. The first being that the spring rates and applications our dampers find themselves to varies widely. Second, it is much more effective to make good chunks of change with a click when tuning. For specific clients who know exactly what they need, we can make the range tighter for fine tuning.

Please feel free to PM for my mobile as well.

Best,

Bryan

 

I wish I could afford some RS for my new car...

 

This is sooo coool a real life JRZ guy on our website!




That was funny I laughed A funny shock joke lol

 

Hi Bryan,

First - Welcome to Honda-Tech. Second - no need to apologize. Third - refer to the First.

Thanks for the down payment on our acquaintance, but we (ok, I) want more. Where do you come from? Are you from one of those racing Universities? Are you ex-FSAE? You didn't just pop out of an MBA program and land in the back of a trailer revalving shocks at ALMS races. What's your story? Who are you? Might you stick around and be our friend if we make this place interesting enough?

Then, "Sooooo, you seem to have found the only online discussion yet of Jan's book in the USA..." or have you? This board has a checkered past, but remains inhabited in a low key fashion by some pretty serious (and some unserious) club racers and even an aspiring "pro" racer or two or three. Are there any other places you know of that we don't for this kind of endlessly fascinating and exasperating tech?

Sincerely,

Scott, who has a typing impediment that makes me do this when I sign my posts...