[LOLSTi]

Originally Posted by cliff257

oh yeah i like to cheat and get all the answers from you guys. kinda of like cliff notes.

[Guest_1u53r]

More discussion on the OP's questions can be found here:
http://forums.nasioc.com/forums/show...0#post16602650

[LOLSTi]

busted

[cliff257]

haha you guys are so funny and hey i started that thread and yes i read that. haha funny though. but you gotta love that 935 on the front of your book. i will have to purchase solely for that.

[Guest_1u53r]

Fred Puhn's book is a good one. It is missing some explanation in necessary places, but it's a great start if you ask me.

I think he has a far better grasp of the physics involved than Carroll Smith in Tune To Win



Both are good books, but it is all too common in Smith's writing for him to dismiss something as unimportant when the subtext is clear that he merely doesn't understand it. The impression I get from the two authors is this:

Fred Puhn = classically educated engineer, with practical experience
Carrol Smith = practically trained engineer, with only the education he has needed along the way

As such, their approaches are somewhat different. Puhn seems more like a physicist translating high level concepts to your level and Smith seems more like a good-ole-boy mechanic telling you what he knows.

Another one I've read is Allan Staniforth's Competition Car Suspension: Design, Construction, Tuning. It's decent and has a TON of pictures of past and present era race cars, but is a lot less applicable to road-going vehicles than the others.


I'm currently in the middle of reading Milliken & Milliken's Race Car Vehicle Dynamics. Make no mistake about it, this 1000page heavyweight is an engineering textbook and if you don't have a strong grasp of physics and calculus, you will not understand it.

[cliff257]

nhluhr whats the deal on one website (nasioc) you are a guru and here (iwsti) you are retired. retired from what if i may ask? you seem to have much knowledge on the subject. either way you have helped me out thanks

[Guest_1u53r]

Retired from being a fulltime moderator here.

I'm just here for the beer and women and the occasional tech talk nowadays.

[RainMaker]

Originally Posted by nhluhr

I'm just here for the women.

Because they are everywhere. I can't even move in here without rubbing up against one.

[Turninconcepts.com]

Originally Posted by AnorexicSTI

Shim it in which direction? It mounts with a D bracket on the passenger side and a similar bracket on the driver side... do you mean putting washers underneath so the rack sits further away from the subframe it bolts to?

It's a little more than washers, but you have the basic idea. The thing is you can't just stack a couple of washers on there, and call it a day.

You need to properly shim the whole mount area so the bushings still make full contact, but at same time you have to know how thick to shim in relation to the setup of the car.

[cliff257]

i assume spacing the rack along with the tie-rods would be the best way to go to the help with bump steer??

[jaydubya]

Originally Posted by cliff257

i assume spacing the rack along with the tie-rods would be the best way to go to the help with bump steer??

Yeah, I believe the rack spacers move the steering rack down, which moves the inboard end of the tie rod down. The tie rod extenders move the outboard end of the tie rod up.

I believe the goal is to have the tie rod parallel to the a-arm.

Many racing classes don't allow one or both of these changes...

On a strut suspension you generally don't want the a-arm orientation with the ground to go past parallel with the ground. As you lower the car the inboard part of the a-arm drops while the outboard part sits still. So at some point of lowering it hits parallel with the ground. The bad things that happen when the a-arm angle goes downward from outboard to inboard include detrimental changes to the camber curve and moving the roll center farther below the center of gravity. The latter induces more roll in corners. On the other hand, you also are dropping the center of gravity, improving aero, etc....

I'll second nhluhr's recommendation of Fred Puhn's book for concise explanations of these phenomena.

[mxpop]

My first Porsche was a used 1982 911 that the previous owner had just lowered. It looked great but was a total handfull at speed, esp on eneven pavement.

After some research, I found out that it needed the steering rack to be raised by as much as the car was lowered (with aluminum blocks). It not only had bad bump steer but it had toe out!

After the adjustment and alignment, my car handled so well that it actually wasnt as interesting to drive anymore!

Bottom line is that almost anything you do to change the stance/attitude of your car will have some other effect on something else. Do your homework because a good handling car is better than a powerful car that cant handle.