Twin Turbo.

I have made some progress on your brackets, but I need some more dimensions for the offset camber bracket. Because my diff is different I don't have a good reference to take dimensions from. Take a look at the pictures.

Bracket Drawing

Twin Turbo's Model

Mark.

P.S. In testing my links, it my be hard to read the dims on the drawing. You may have to save the picture on your computer so you can open it in a program that will let you zoom in.

 

That's looking really good.

Note that the bracket is not ready, it still needs an extra set of those mounting ears to clamp the rod ends & spacers in between.(the things outlined by dimensions J & K)

The dimensions that I do remember (don't have the bracket here) are:
A = 2"
C = about 4mm
B = 3,5"

D,E,F,G & H are stock dimensions, they are from the stock bracket.

I can give you the exact location of the stub axle center, when looking at dimension A, 1,5" of it is in front of the diff/lid parting line and 0,5" is behind it. The distance from the parting line to the stub center is exactly 2" so that makes that the center of dimension A is 2.5" from the stub axle center.

The final pos. of the inner rod end on the camber bracket will be set w/ spacers, that's why the other pair of ears are not on there yet.

For those other dimensions I will have to measure the bracket but don't have it handy. Maybe someone can measure theirm 80-82 diff? E & F are the through bolts that bolt the bracket to the diff.

 

I slid under my 80 and removed the heat sheild for access to the bracket and this is what I came up with:

D is 14.25"
E is 9.75"
F is 7.25"
H is 1"
G is 2.5"

And I also measured the following:

When the Trailing arm is parallel with the ground the rod end on the hub is 1" further forward of the rod end in the bracket. As the suspension moves down (rebound) the rod end at the hub moves further forward with the arc of the trailing arm.

My car has rod ends with square brackets that center the rod end in the bracket slot. The dimension from rod end to rod end across the bracket is 12.75"

On the 80 there is a lot of room forward of the bracket to locate another rod end as a second parallel arm (required separation dimension of the two innner rods?). However you can only move the rod end about 1 inch further rearward from the center line of the bracket because of clearance problems with the leaf spring (only applies to leaf spring set ups not coil overs). Since the 80 locates the bracket further back than 79 and earlier there may not be a need to locate the rear strut rod much further back and have it line up with the rear of the hub lower if a through bolt is used in the two strut rod type of system.

Still not sure if I should look at the two lower strut rods or add a link to the diff rear and located to the Trailing arm like the C4. The two parallel strut rods seems like an easier approach as long as the front can be mounted to the hub assy and allow for mounting the shock it is off center position.

 

FLEX -

Any chance in getting this file once it is completed? I would love to explore the possibility of fabricating a system like this myself a some point. I have a full version of SolidWorks. I gotta give you props for doing that, as an engineering student, that fascinates me. Wish I was that good with the software. I dont want to "rip off" all your hard work, but if you wouldnt mind, I would love a copy.

Thanks

Joe

 

A few things I think need to be considered:

If the trailing arm is replaced with two arms how does the length impact the arc of the suspension as it trys to move the wheel fore and aft. Should the arms be as long as possible.

How high or low should the arms be mounted on the frame to reduce suspension torque effects (car squatting)?

I also got a chance to look under the new SuperPerformance Daytona coupe and notice that the lower suspension was a lower strut rod and a diagonal arm to the frame just behind the seats is just like one of the images from TT. Was wondering if a link was made from J-bar would it clear the battery box?

Also notice the upper link was an a-arm with very little space between the two bushings. Looked like it would just fit in the vette. What would the minimum distance between the two a-arm bushing need to be to still control fore and aft movement?

 

This would be an excellent project for me to work on once I get a welder Very nice work Flex

 

Dave,

The length does influence the fore/aft movement of the wheel in respect to the wheel well, the longer the arm the less this movement, suspension travel also has influence on this, it's all about keeping the change in the horizontal component over the angle change to a minimum. A long swing arm is preferred.


With an IRS you can't get a lot of anti squat anyway, unlike w/a live rear axle, that's because the diff is mounted to the frame, can't do anything about it. Max. anti squat you could hope to get would be around say 25% or so. Then there's also something that I'm not sure about what it's called in English, maybe anti bump? It's about when you run over a bump, since the bump moves from front to rear, if the wheel moves backwards when the suspension travels up the bump promotes suspension bump, when however the wheel moves forward it actually has to run into the direction of movement of the obstruction reducing bump. Anyone know what this is called??

I don't think I quite understand your comment about the daytona stuff. I think you mean a toe control rod and a 2nd rod that runs to the pinon area?? If you use something like that, basically a triangulated a arm at the bottom, then a small arm (even a single one w/ rigid bushings that only rotate, and can't twist like a spherical joint) would be needed to control the hub, witha setup like that there is no fore/aft movement if there's no "caster" in the system (the hub hinges are in line above each other)

 

TT

My bad for not making the Daytona comments clear (too much of a hurry)

The Daytona chassis uses a triangulated lower control arm just like one of the pics for the white frame corvette used for discussions in this or a previous thread. My thought was that after looking at the 80 and lowering the strut rod pickup points on the diff it is feasible to make a triangulated lower control arm than would not hit the battery box at full compression. The comment on the J-bar was that if the rod did come too close to the box, a J-bar could be used. The J would give more clearance in the middle of the bar, however the end links would still be in line.

What really surprised about the Daytona was that the upper a-arm had only about 4 to 5 inches between the bushings which is much closer together than a front control arm. If this would work then an upper arm may fit between the boxes and the spare carrier. How would one calculate the minimum distance between the upper a-arm bushings to take the fore and aft load and still fit in the space?

This arrangement still needs a separate toe link

 

Are you talking about this?
http://www.corvettefaq.com/redir.asp?site=563

 

Flex, any new developments?

 

Flex.......

Can you just ad the top bracket and the two extra strut rods parallel to the stock strut rods or is that not doing anything to help keep the wheels vertical?

 

not parallel, you want a camber curve to gain neg. camber, that's why stock the lower rods are not parallel either. When the suspension moves into bump (the outer tire during cornering) the wheel gains neg. camber so that with body roll the tire contact patch is as large as possible (if everything is set up correctly), this will give you the max. cornering speed.