Nope - I had the old stuff. My Vettes are not setup to "squat and hook" on the drag strip. I am a "cornering junkie" - with the Guldstrand and the BFG GFORCE tires I can do 1.02 G on the skidpad - which is good enough for amateur road racing. BTW - I still use the VB&P stuff - I just upgraded the rear suspension to the Guldstrand 5 Bar - good bye to the stack trailing arms.

Hope to see ya when I get up to Canada..

:steering: :banghead: :steering:

:lurk:


[Modified by shawn_cake, 4:58 PM 4/21/2003]

 

Shawn, I'm about to order the Guldstrand. Looks like there is a 2 month wait. Did you have to use a C4 wheel bearings, or can you run the C3 bearings? Does it change the tire offsets or width of tire that you can run?

mark


[Modified by 81vette, 9:24 PM 4/21/2003]

 

Lol. you guys jacked my thread! Well there isn't much that happened since last update but here goes... After thorougly looking for rod ends I finally made a decision to go with the LXM8-10 from rodendsupply... they are 1/2" bore and 5/8 thread. You can see them at:

http://www.rodendsupply.com/cat/page05.htm

The static load on those is 12,807lbs and should probably hold on. I almost went with the XM series since the body uses 4130 steel instead of C1045 but the cost made me decide otherwise. The ones I'll be using cost 10.91$ each which is really affordable for the strenght they have.

Still looking for coil-over shocks.... Looked at the hal qa1's but they are pricy. If any of you have suggestions. I'm looking to get as close to 100$ per shock as possible.

 

We merely kept the discussion going in your absence :)

Have you got any sketches or drawings or anything showing the design you're planning on going with?

 

I'm going with the same design greenwood did which is:

http://www.greenwoodcorvettes.com./S...a/FiveLink.jpg

I might actually change the front t-arm (shortened) brackets a bit but thats pretty much it. I've reviewed that design several times and it appears very good. Everything is easy to fabricate and from my knowledge of physics, it should give a good performance. Now that I'm done collecting prices (or almost) I'll be making the brackets.. then the next step will be to take measurements for the rods (didn't get any response from greenwood).

 

Yesterday I mentioned I wanted to modify the greenwood concept a bit and this is what I came up with:

... tried to put the image but I can't from my free host.. so here is the link to a temp homepage with the pics:

http://lohkay.faithweb.com/5link.htm

You will notice a few changes. The lower front link now bolts to the t-arm right underneath the upper link instead of going to the strut mount. The reason for this is to put the 2 links in line (it wasn't in the greenwood design since the strut mount is offset by 1" inwards). The upper and lower links will be seperated by 5" at the t-arm and at the front frame bracket so they will be parallel. Another change I made is the way the shock mounts to the strut bracket. Since my lower link isn't connected to that bracket anymore, I was able to bolt the shock right onto it.... now the image doesn't show the bracket at the right angle cause I didn't have the proper software to do those kind of changes.

I'm interested in hearing any feedback you guys have about those changes.


[Modified by Lohkay, 8:43 PM 4/23/2003]


[Modified by Lohkay, 8:52 PM 4/23/2003]

 

This thread needs to get saved into the faq pages!

:cheers:

 

Lohkay,

What you did there is kind of what the C4 suspension also has. However, there the struts are not inline.

I like it :)

 

Lohkay,

I would think there is some advantage to having the upper and lower trailing links being as far apart as practical. Having them both mount to the modified trailing arm might put them too close together.

Just a thought.

 

I thought about that and figured that with 5" between the rods, I should be alright. But unfortunatly, I got into some financial problems...coupled with my estimate of the cost, I'll have to post-pone this project. For those wondering how much my estimate was... it would've cost me ~700$. Thats all the hardware including both coil-over shocks, springs, rod ends and jam nuts. I was going to fabricate the brackets myself so I didn't add that. I was right by saying the shocks would be the costly item on my list. They take more than half of that estimate. I tried to find shocks that would fit my application under 100$ and didn't even come close... 130$ was the lowest. Its still way under the ~2100$ asked for the gulstrand kit. But higher than my 400$ target.

If anyone wants to try it out based on what I did so far, email me and I'll give you the work/research I did so far. As for me, I'll get back to it as soon as I have a few spare coins! :lurk:

 

I'm trying to think of a reason that the trailing links need to be closer to each other in plan view than they are.

The trailing links, in side view, establish the side view swimg arm. That's the effective point about which the suspension operates when viewed from the side. In this suspension design, they really don't do a thing for toe and/or camber, since those have their 'own' links.

In rear view, the lower camber link and the halfshaft take care of camber and that's relatively unaffected by the other links.

In the plan view, the upper toe link pretty well takes care of toe. It's in toe that the trailing links shoudl have the most impact. What they'll be doing is re-orienting the 'caster' of the wheel, effectively rotating it about some point as viewed from the side. The trailing links (if they're not parallel to each other in the side view) will be rotating the hub as viewed from the side, and they'll want to affect toe if they're not perfectly perpendicular to the toe link, but the toe link is restricting that.

What's troulbling me at this point is that the suspension seems overconstrained. Toe & Camber links take care of toe. Trailing links trail, but also can affect toe. Seems that the suspension has the potential for being bound up if there aren't some bushings in there that take care of that.

Hmmm.....
Just some thoughts.

 

Lohkay,

How about putting the coil-over addition off till later. Continue your design with an eye towards utilizing the current transverse leaf spring and shock locations. The coil-over brackets could be added later. That would know $260 from your cost, assuming you had a working setup currently....

 

ddecart,

I think the rod ends on the trailing links would allow the toe to be controlled by the "upper toe link". Even if the trailing links pull/push the wheel towards the front/rear of the car, the "upper toe link" and the halfshaft should create a specific toe change over that distance. The rod ends would just pivot to accomodate this.

One point you mentioned was the parallelism of the trailing links to one another. If they are not parallel, and cause rotation in the hub, then I could definately imagine a "twisting" of the halfshaft and toe link. As the toe link rotated, its effective length would change, which would toe the wheel. If you look at the Guldstrand setup, the location of two "camber/toe" links is located below the halfshaft and equi-distant spaced from the centerline of the wheel bearing. I would think in this case when the links "twist", one end on the hub side goes up, the other down, cancelling each other out (almost). This movement would probably still affect camber, and if the two links were not the same length (static toe setting), then the movements would not quite be equal and opposite to one another.

Also, with the trailing links parallel, wouldn't you lose any possible anti-squat from the suspension? Even though the wheel hub doesn't get any reaction forces from halfshaft torque, I would think the force from the wheels transmitted through the trailing arms to move the car forward could produce some anti-squat if the trailing links were angled. Also note that the Guldstrand setup does not have parallel trailing links, and seems to have a horizontal upper trailing link, while the lower seems to be angled upward from the hub to the frame.

I think another point would be to look at the Greenwood setup and the relationship between the halfshaft and the toe link and what change in toe would be caused by the distance the trailing arms pulled/pushed the hub toward the front/rear of the car. The length of the toe link and its position would affect this relationship.

A little wordy, and I wish I could just draw a picture... Thoughts? Comments?

 

Good stuff guys. I thought about going with the tranverse + shock but in the stock system, the trailing arm is limited in movement downwards when it hits the pocket's lower edge. I'm afraid that with the trailing links located where they are, it would give a LOT of movement downwards... would be a bitch to jack. Actually I think the shock would be the limiter but isn't that a lot of pression (caused by the spring)? If you guys can convince me I wouldn't have any problems with that, I'll surely continue with the project as the main problem was the coilover cost.

About what you said on the toe change caused by the trailing links, I don't think it would happen because your toe is controlled by the upper and lower links and both of them rotate (shorten) when the trailing links go up.. so theorically, if they are both the same length, the toe shouldn't change. If they aren't (toe/camber setting) then it should affect it but I don't think by much... most probably a lot less than stock system. :lol:

Its a lot of things to think about when you try to visualize the suspension travel and possible changes in toe/camber/caster.

Hope to hear good ideas on the leaf spring variation! I just hate the idea of not doing this. :(

 

Don't worry for a sceond about the shock. Shocks are used for rebound stops, ALL THE TIME. They take one hell of a lot more load than they will during jacking.

Have you got any dimensions for the link locations (x, y, z)? I'd like to model the suspension and spit out some toe & camber curves.

 

Lohkay
Sorry, you lost me there. Which upper and lower links are you refering to? I would think toe would be controlled only by the halfshaft and the link directly rear of it that connected between the X-member and the rear of the modified trailing arm (the "hub"). The effect could certainly be insignificant. It should be easy to figure out with some real world lengths to the links.
Just out of curiosity, why did you relocate the bottom trailing arm link? From the picture, it would seem that the top link would be horizontal, and the bottom link angled downward from the hub to the frame. Is that what you were planning, or still two parallel links?

Also, I was thinking... Are you going to cut up your trailing arms to make the suspension? They are not so cheap that I wouldn't consider fabricating something in their place so that you could keep them... In case you ever need to go back. Just some thoughts...

ddecart
What program do you use to map out the suspension behavior?

shawn_cake
I'd love to see some pics of that installed guldstrand 5-bar suspension... :D


[Modified by 75 BBC Stingray, 11:36 PM 4/27/2003]

 

It's called sSNAP (Static Suspension non-linear analysis program). I'm a bit rusty and it'll take me a little while to model it.

 

Hope you're right. :) About the dimensions, I don't have 'em all right now...still working out a few details on the brackets. As soon as I get all the final dimensions, I'll let you know cause I'd be really interested in the model you'd produce. You only need the position of each rod end compared to the others? Bracket dimensions too?

75 BBC Stingray
The reason I changed the design is for a few reasons. First, I didn't like the idea of putting the coilover shock on that small bracket connected to yet another bracket thats connected to the stock shock mount. In my design, I get rid of one bracket. Another thing is that when you look at it from above, the 2 trailing links aren't in line... don't know how much it would affect the suspension but I felt it wouldn't do any harm. As for getting them parrallel from a side view, I understand it removes any anti-squat but that anti-squating puts a LOT of pression on those rod ends. Besides, I think the spring should handle that (be it transverse or coilover) and not suspension components.


[Modified by Lohkay, 12:07 PM 4/28/2003]

 

damn this is good info :lurk: sounds like a prospective group purchase opportunity :yesnod: :nonod: maybe so? What was the lead time for delivery?

 

I ordered the Guldstrand 5-link about two weeks ago, and the wait time was 2-3 months. :cry


Mark