2nd try for the pics.

AHH CRUD!! This stuff is HOSED!

zero toe:
http://www.crossfire.homeip.net/twinnie/ackzerotoe.gif
http://www.crossfire.homeip.net/twinnie/ackzerotoe2.gif

toe in:
http://www.crossfire.homeip.net/twinnie/acktoein.gif
http://www.crossfire.homeip.net/twinnie/acktoein2.gif

toe out: http://www.crossfire.homeip.net/twinnie/acktoeout.gif
http://www.crossfire.homeip.net/twinnie/acktoeout2.gif

[Modified by Twin_Turbo, 8:29 AM 5/9/2003]


[Modified by Twin_Turbo, 8:30 AM 5/9/2003]

 

Here's to show we have no (or very little) ackermans. Judging from this pic it's about 0, I'll check this afternoon. I'll do some more measuring to see if the knuckle lies in the same plane as the ball joints... hold tight :)

Here's the pic:

 

o.k. so who's for just cutting off our existing front ends and grafting on a c-4 or c-5 front? :crazy:
TT, if i'm understanding the new theme of this thread, is it even possible to have 'ackerman' with our design? from your diagram it seems that our steering linkage would need to be somewhat free to pivot, unlike how it currently is with the pitman/idler arm setup. am i close to following this?
as for the spindle extenders, i personally am never going to trust a welded spindle. i simply will never NOT think about it at 120mph at buttonwillow so i'm just not going there. i do have an idea which i think would be reasonably inexpensive to fab and accomplish the same thing. i have IM'd my thoughts to a couple of people for their opinion who have yet to get back to me (ahem!).
i still think the best option would be to relocate the inner pivot point further down but it just looks like a major clearance issue.

 

Interesting subject. Now this seems like a simple solution, do you guys not like this approach :confused:

 

So to get ackerman, we'd need to have somewhat of a free floater steering system? Like the tierods float a little longer then they should be, so one side can slide out the other in, in the corner? But then we're not talking about a tierod! Maybe a Rod end on one side, and a welded on stop on the side closest to center?

But that would make the out side tire open up... it would give you an ackerman angle, but wouldnt pull the inner tire (From the turn stand point) closer to the center of the car... so it probably wouldnt help at all :crazy:

 

I've got another question/comment... Once you get the tire on one side absolutely flat, would you not be picking up the front inner tire (to the turn) if you get enough g's with no rolling of the body?

I seem to remember the 80's racing porches getting one tire up in the air in the turns, but there motors in the rear.

At this point I'm holding my hands over my ears going LA LA LA LA LA... i'm over my head, but would love to figure this one out! :crazy:

 

I don't think we want ackerman, seems to darty for me. It's only used inn them Brit Taxi's ;) and in RC cars I think. It's perfect for in town driving, short turning radius.. and so on.

To get ackerman you just have to install different steering arm so the line ball joint-steering ball joint isn't parallel to the car centerline anymore, simply said, a steering arm which places the ball joint more inward

The center pivot you see is just the steering rod setup of the pic, the same applies for a center link like we have and rack & pinion steering

So.. to make it ackerman it has to be like this (the blue stuff), the red is the non ackerman plane.



Why don't you trust a welded spindle? Don't you trust the other welded stuff on your car? look at the flimsy welds on the trailing arms for example.

As for the best option, locating the inner pivot down is a PITA since the frame is not flat there, secondly by lowering it you WILL need longer armd or you will have way too much negative camber. This because you have to quite significantly lower the pivot point to be any good.

Now, since longer arms are almost certainly required, why not mount the arms on the OUTSIDE of the frames, then you can use short ones at any height you want without chopping the tuff up. You only need to weld in a flat plate (because the edges of the frame are bent over) and remove the little reinforcement tab of the shock mount. The only thing is tos elect a correct length arm. Too long and you won't be able to set enough neg, camber because the cross shaft resting against the frame is max. neg. camber (whereas in stock it's max. pos. camber)

decisions decisions.... :)



[Modified by Twin_Turbo, 12:27 PM 5/9/2003]

 

Anyone have the specs for our suspension's currently? A-arm length etc?

Or maybe just some pictures?

Thanks
:cheers:

 

Read norval's post about the coleman extended bushings. They are not a direct fit. The ownder of the race car modded his VB&P arms and since it doesn't really fit too well had to weld the ball joint on the outside. Everytime he removes it he needs to grind away the weld. Not a real problem but I want it done some better way that that. If the aftermarket upper arms fit then you could use those ball joints since the arms are available drilled for the mini ball joint pattern.

 

yes me :) I have the measurements on them.

it's all in millimeters though






[Modified by Twin_Turbo, 12:24 PM 5/9/2003]

 

Do we know the ID of the hole for the upper ball joint?

Thanks

:cheers:

 

... found a suspension anylizer... my pea brain cant figger out most of this stuff http://www.performancetrends.com/SuspAnzr.htm

 

Interesting thread on an engineering discussion board... http://www.eng-tips.com/gviewthread....d/60/qid/12793

 

about 1&3/4"

 

Yeah, I have seen that before. Perf. Trends has a nice engine analyzer too. .. but once you look at the price. I'm not buying that :)

 

Ouch! my eyes my eyes! They must be making a killing! :eek:

 

Twin turbo, great pics on the A arms. Those will go a long way towards computer simulation. If you are feeling really industrious how about getting the pivot points on the frame all measured and then someone can run some stuff on their suspension modeling software.

Norval, I should have been more specific regarding the roll center and ride quality. In a straight line, you are right, there is no effect to ride quality by the roll center. But in a corner, the roll center changes and the closer it gets to the center of gravity, the less the car will roll and the stiffer the front will get. Circle track magazine was explaining that if the roll center and the COG coincide in a corner, the suspension will be rock solid. Hard to imagine, but I'll take their word for it. Ask your coworkers thoughts on this.

I got this off a document on setting up chassis for racing.

With the Corvette rear suspension, the roll center is determined quite similarly to the front suspension with unequal length A arms Here the axle half shafts and the camber control rod are the two lateral locating mounts for the suspension, so they are considered as the A-arms lines are extended from the two locating arms to their intersection point. Then a third line is extended from the intersection point to the tire centerline Where the third line crosses the centerline of the car is the roll center (marked with an X) In the stock Corvette the rear roll center height is 26 inches, the front roll center is 3 1/4 inches high and the center of gravity is 16 1/2 inches.

Unfortunately the document is incomplete. I am trying to convince the person in possesion of it to share, but so far no go. I'll let everyone know if I get it. It is called "The Trans Am and Corvette Chassis" but the sections on corvettes, except what I posted above, are missing.


As for relocating the A-arm mounting further outward and using a much shorter A-arm, be aware that this would significantly increase the range of motion that the ball joint must be capable of. Not sure if ours have that much range, and I have seen ball joints break when stressed to hard. I think the taller spindle is still the way to go.

Chris

 

You guys remember the caddy in Hotrod magazine? The one that was whipping up on the Camaro's? He moved the upper a arm rearward, and the lower forward... kind of like the setup on AC cobra's. If i remember correctly, the lean in the suspension is the reason for why they could do the 0-100-0 :cheers:

 

Okay, I'll start measuring. Am I the only one w/ a bare frame + suspension?? ;) :D

 

Have you guys thought about a mcpherson strut setup for our cars? Chop out the inner fender, weld in a hoop similar to the race car twin turbo posted...

Or maybe just a coil over?