Correcting Front Suspension

[marleyskater420]

I was going to give a really long explanation but to be honest it's will more benificial to post info so that other can do the math themselves rather than rely on someon else to figure it out for them. Here are a few links that I think members might find interesting and I'm also posting the calculation for figuring bumpsteer and camber change. This may be overly complicated for some but it will provide the best explanation for someone that is willing to do the work.

Ackermann steering geometry - Wikipedia, the free encyclopedia

Bump steer - Wikipedia, the free encyclopedia

Camber Change - Static & Dynamic - Tire Traction - Tech - Circle Track

OptimumK Help

This one may confuse you some but it's a lot more of an advanced engineering board and I doubt that many here would be members. I am however. LOL

Automotive suspension engineering - ISO8855 toe and camber angle definition into rotation matrix form

Automotive suspension engineering - Yaw damping

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Vehicle Dynamics, SLA Suspension camber change and bump steer example 5/11/09


Determining Camber angle and bump steer
Setup all the suspension points in space, with origin at upper pivot. P2=(0,0)
Determine coordinates of remainder of points as
a. P0=(-1,-9)
b. P1=endpoint of lower A-arm, (10,-9)
c. P3=Endpoint upper A-arm, to be calculated, (10,1)
d. P4=Origin of tierod, (-0.5,-4)
e. P5 = Endpoint of tierod, (10,-4)

Calculate R1=|P3-P1| and R1 = |P3-P2|
Set up equations for C,D,E,X3,Y3
Calculate X3,Y3 for initial positions and determine signs
Increment q for +- 10 degrees and calculate P3
Calculate camber change, body roll, and net camber change
Setup Chase 2C using P1 and P4 to determine P5
Calculate P5 optimal from P1 & R15 using spindle angle calculated above
Bump steer is determined by the difference between optimal and actual P5 DIVIDED by the ratio of tie-rod-arm length to wheel radius

Show that





DWF +DWR = DW = Zcg/t*Fy in all cases.
Define each of the terms in the above equation and discuss the limiting cases for each, .i.e. when do terms collapse and what do they mean?

Derive the relationship w = 188/x ½

Calculation of roll Gradient
Swaybar: 24.8mm F, 23.5mm R, Calculate roll rate example

On the calculating camber angle and bump steer equation is there a diagram to go along with it, or is that all the information given? How can X3/Y3/R15 be calculated if they aren't given? Or is part of the example missing?

Same with the other equations- did you pull these from a book where each character is defined? I'm going to have my physics/mechatronic engineering buddy help me with this stuff, but it looks like some of the equations are missing? (Ex: DWF, etc...where is this equation pulled from in order to allow a basepoint of where to start?)

Or is X/Y3 the degree/angle on the X and Y axis? R15 being the relationship of baseline R for the swaybar, then add 15deg roll gradient?

Could you link to where you pulled these equations from please? I'd like to work through these with my engineering buddies and see if I come up with anything remotely correct. I'd really appreciate it!

Thanks!

 

[charlief1]

On the calculating camber angle and bump steer equation is there a diagram to go along with it, or is that all the information given? How can X3/Y3/R15 be calculated if they aren't given? Or is part of the example missing?

Same with the other equations- did you pull these from a book where each character is defined? I'm going to have my physics/mechatronic engineering buddy help me with this stuff, but it looks like some of the equations are missing? (Ex: DWF, etc...where is this equation pulled from in order to allow a basepoint of where to start?)

Or is X/Y3 the degree/angle on the X and Y axis? R15 being the relationship of baseline R for the swaybar, then add 15deg roll gradient?

Could you link to where you pulled these equations from please? I'd like to work through these with my engineering buddies and see if I come up with anything remotely correct. I'd really appreciate it!

Thanks!

The equations are complete except for the diagrams. It's basic automotive engineering that is on my computer. I bounce some of my info to several of my friends in the field and they've provided me with the info I'm looking for. That's one of the reasons I'm on the eng-tips board as well as speedtalk. I don't know everything so I go to extension classes when I can as well as ask questions of those in the industry that are willing to talk to this lowly merkanik.:biggrin:

If your friend would like more info have him join the board and send me a PM with his info. I'd be more than happy to foward the research I've been doing since college. An engineer on the board would be welcome I think, especially one that would contribute to threads just like this one. One good basic source for info is the Bosch Automotive handbook. It also has info on joining ASE (Automotive Society of Engineers) which will help out with designs and technology. I still need to come up with a renewall fee since mine has expired now.

You also have to understand that MTSU has a lot of sponsorship through several automotive corporations like Nissan and Saturn. I got to deal with several of the top engineers in the field for several years and they helped my knowledge and understanding of chasis dynamics. Even to this day I can call some of my old instructors and get refferences so I can either call or email for info as well as pass info on to. One of the Nissan engineers took some of the info I gave him on the rear suspension of the Altima and corrected several flaws I caught in the rear suspension.

 

[83hurstguy]

If you'd like some data without the headache of measuring and calculating, this is about all I've ever seen posted online for a G-body:

Savitske Classic & Custom

 

[charlief1]

To make this a little easier, here's some links for free downloads so you can do your own calculations. Each chasis is different and although the G body chasis was mass produced each one needs to be mapped out for the best performance.

While Marcus has given some nice pics of the chasis under dive conditions he doesn't have the info on the static position.

I do have some data that I'm not to let out quite yet because it hasn't been published yet, but once it is I have permission to put it out. It varies just a little from the link posted above. It is much more accurate because the data was gotten off a metric G body chasis measured in a shop just for this purpose, and is being used to manufacture chasis parts for them. I'd trust the person making the parts a whole lot more the SC&C because they actually make the parts in house rather than purchase the parts from some one else and claim that they made them.

Performance Trends

http://www.neohio-scca.org/comp_clinic/hand_out_reprints/Vehicle Dynamics2007.pdf

 

[motorhead]

LOL Sorry about that. There just a point where you have to make a very serious point.:biggrin:

But, some people might see you as an a$$hole in doing so.

The AFX spindles are designed for a G body but don't do all that's claimed of them so it's really not worth the money at all.

Sssshh! You are effecting someone's bottom line... Everyone ignore him and buy the expensive parts, it is easier than fixing the driver.

That's it from me, I am sitting this one out... for now!

 

[charlief1]

But, some people might see you as an a$$hole in doing so.

Well I'll take this as a good thing then. I don't buy from someone because they can tell me that their parts are the best, I buy the parts which will work best from the knowledge that I have and take the time to learn how to make what I want.:biggrin: None of the vendors will ever get rich off me since I do most of my own work.

As far as being an ass goes, kinda the way you were commenting on the 87 pro tuoring thread, right?:biggrin:

Sssshh! You are effecting someone's bottom line... Everyone ignore him and buy the expensive parts, it is easier than fixing the driver.

That's it from me, I am sitting this one out... for now! View attachment 147670

Well I would like a little clarification on a few things reguarding the AFX spindle before you go please. I belive this quote is classic pertaining to the AFX spindle. If you'd like to actually use the book I would like some clarification on this one little blurb that's not exactly clear to me. Please, I really would like to have a scanned page to refer back to in case I'm making a mistake here.

If you want, I can send you some scanned pages I took from my book that explains why you don't really need the AFX spindles, and why the lowers aren't a real necessity.

 

[marleyskater420]

The equations are complete except for the diagrams. It's basic automotive engineering that is on my computer. I bounce some of my info to several of my friends in the field and they've provided me with the info I'm looking for. That's one of the reasons I'm on the eng-tips board as well as speedtalk. I don't know everything so I go to extension classes when I can as well as ask questions of those in the industry that are willing to talk to this lowly merkanik.:biggrin:

If your friend would like more info have him join the board and send me a PM with his info. I'd be more than happy to foward the research I've been doing since college. An engineer on the board would be welcome I think, especially one that would contribute to threads just like this one. One good basic source for info is the Bosch Automotive handbook. It also has info on joining ASE (Automotive Society of Engineers) which will help out with designs and technology. I still need to come up with a renewall fee since mine has expired now.

You also have to understand that MTSU has a lot of sponsorship through several automotive corporations like Nissan and Saturn. I got to deal with several of the top engineers in the field for several years and they helped my knowledge and understanding of chasis dynamics. Even to this day I can call some of my old instructors and get refferences so I can either call or email for info as well as pass info on to. One of the Nissan engineers took some of the info I gave him on the rear suspension of the Altima and corrected several flaws I caught in the rear suspension.

Thats what I need, is the diagrams please. I appreciate the help! I am also unfamiliar with the terms like "DWF" "DWR", are these something along "dive wheel front" (referring to angle?). Could you explain what they mean, because I have no idea, and I can't ask my physics buddy (hes a car guy too, but we both had no idea what these meant) to help me cause I didn't know what those terms meant.

Thanks maistro!

 

[charlief1]

Thats what I need, is the diagrams please. I appreciate the help! I am also unfamiliar with the terms like "DWF" "DWR", are these something along "dive wheel front" (referring to angle?). Could you explain what they mean, because I have no idea, and I can't ask my physics buddy (hes a car guy too, but we both had no idea what these meant) to help me cause I didn't know what those terms meant.

Thanks maistro!

Have you friend join the forum so that more info can be aded to help the thread. He can PM me his info and I can email the info over to him, or you can PM his contact info to me. Either way it would work.

I'm changing providers so I may be offline for a few days while I wait for everything to be hooked up, so if I don't respond right away, I'm sorry. You know how they are about getting things set up.

 

[marleyskater420]

Have you friend join the forum so that more info can be aded to help the thread. He can PM me his info and I can email the info over to him, or you can PM his contact info to me. Either way it would work.

I'm changing providers so I may be offline for a few days while I wait for everything to be hooked up, so if I don't respond right away, I'm sorry. You know how they are about getting things set up.

TBH I wanted to try to figure this out myself and then have him check it. He's a busy guy (he just came down to interview at Stanford Labs) so I wanted to try this myself, and then send it to him to double-check when he gets some free time.

Would that be cool if you sent the stuff to me? I like challenges and its been awhile since I've used geometry/physics, so it'd be nice to try it, then send it off to my bud and have him correct my work. I'll be sure to post up how far off I was

If I send you my email would that work?

Thanks!

 

[motorhead]

Well I'll take this as a good thing then. I don't buy from someone because they can tell me that their parts are the best, I buy the parts which will work best from the knowledge that I have and take the time to learn how to make what I want.:biggrin: None of the vendors will ever get rich off me since I do most of my own work.

As far as being an ass goes, kinda the way you were commenting on the 87 pro tuoring thread, right?:biggrin:

Charlie you and I are from the same school of thought on this one. One man's ass, is another man's messiah depending if he likes the message being spoken or not.

 

[marleyskater420]

Charlie you and I are from the same school of thought on this one. One man's ass, is another man's messiah depending if he likes the message being spoken or not.

Its usually the things you like hearing the least about yourself that aid you the most in personal growth.

I've found that true in myself many times!

 

[charlief1]

Well I'm back online but a lot slower on my system. This is fairly advanced math Marley and it gives me problems sometimes. I can send it to you but I have a feeling that you'll end up getting help with it. Since your friend is an engineer and physicyst he should understand the math pretty easily.

 

[marleyskater420]

Well I'm back online but a lot slower on my system. This is fairly advanced math Marley and it gives me problems sometimes. I can send it to you but I have a feeling that you'll end up getting help with it. Since your friend is an engineer and physicyst he should understand the math pretty easily.

Send it over. Worst that can happen is I ask him for some help, but in doing so hopefully I'll learn something. I figure by the time thanksgiving comes around (when hes back in town) I'll have given it a good shot, and be able to go over with it in person. At least that's my goal.

I'll let you know how it turns out! Thanks for the help.

 

[49-blues]

i plan on using stock modified spindles for LS-1 rotors and C5 calipers from flynbye -what tubular arms would be best for my combination to ncorrect the geometry problem.?

 

[Hy82e]

I'm also in the middle of trying to figure all this out so I'll share some of my notes with you just dont confuse me with somebody that knows all the what's and why's.

The easiest and cleanest way when using a stock(ish) spindle is by picking up the phone calling Marcus at SC&C and ordering his Stage 2 plus kit. If you have the $$$, cause it comes at a premium. I'll be honest if i had the funds i would have already ordered my set.
The Stage 2 kit he offers comes with SPC adjustable upper a-arms, and .5" tall Howe upper and lower ball joints. Now with the Stage 2 plus kit you'll get the xtall Howe ball joints. I don't don't know what length Marcus uses, but Howe offers a .9" over stock shaft p/n 22369a. But I can't say that is the one Marcus uses. I do know that the SPC a-arms he orders differ from the ones you might pick up at summit or other parts source. He gets them to assemble them so that they optimize the g body tall ball joint format. I do not know the specifics.

UMI
Spohn
BMR
are some other companies making tubular upper a-arms built to take advantage of the .5" tall upper ball joints while improving camber and castor angles, but I don't know if these were designed to use a tall lower ball joint too. I know they work because there are guys using them. These are not going to adjust to variances from car to car since they at least for now are not adjustable, so traditional methods of lineing up the car are used.

Now if if you are in the same boat as me and cost is not the main concern, but a huge restriction there are some options.

The tubular a-arms circle track guys use for there g body are shorter than the stock arms and allow you to align car without using a ridiculous amount of shims to get the camber and caster angles needed. USUALLY a 8" long arm will allow everything to come together.

Gbodyparts. com
Speedway
are some companies you can get these at. The down side of these are, that while they are built tough they are not built to meet the standards of a daily street driven car. The biggest draw back probably being the bushings on these are steel on steel, and while they are greasable they are not rebuild able.

Another company

UB Machine
builds these same arms for the same racing purposes, but build them to order. So if avoiding the one size fits all option is a concern these guys can help you out. The bushings are not rebuild able, but they have an option for nylon lined bushings. And even though they are not adjustable. They will build them at whatever length and offset you may need to help cut down on shims needed for alignment. The trick is figuring out the correct dimensions for you application.

For ball joints we have a few companies producing these in a tall variation.
Pro forged
AFCO
Qa1
and so on. I do not know if any of these guys are making an xtall ball joints.

 

[49-blues]

Very informative. Will all tubular arms let you use regular coil springs or coil overs if you wish?

 

[Hy82e]

The upper a-arms do not affect or come in contact with either coil springs or coil overs. The car is held up by the tension of the spring between the frame and lower a-arm. The upper a-arm is non-load bearing. The main purpose of its design is to hold the spindles pivot point (ball joint) in position and to control the up and down motion of the suspension.

Almost all of the companies I mentioned above make lower a-arms as well. I have no plans of swapping the lowers so I have no notes on them.

I will add that when adding the tall lower ball joint it will lower your ride height .5" - .75". So keep that in mind when choosing springs.