Took the leap

[Gav]

There are plenty of Homebush Cobras on the road, so unless yours has been modified it should be fine.
The front end does look newer than the rest of the chassis though, was it in an accident or something?

[Baur323]

No accident, the previous owner swapped the Torana based front end for a Toyota Supra based from end. He showed me the old one, no damage. I also added some additional supports/triangulation.

[Gav]

As long as it's square and the geometry works it's all good.

[Baur323]

I think its looking okay, Front should load up to be almost parallel.

[Trickycoupe]

I will be the first to admit that I'm no expert but the photo of the front suspension appears to be shown at full droop.

I would want the suspension to be placed in that position at full static load, if not actually slightly lower at the outboard end so an imaginary line drawn through the lower inner pivot and the outer lower ball joint is horizontal / parallel to the ground when loaded.

Someone earlier stated it looked odd and I have to agree. Best to check the geometry now before going further and having to undo your good work.

[Treeve]

From what I can see here, I reckon you need to get an engineer on board right now, before you find yourself in a world of expensive hurt.

I no longer do ICVs, but if you were to bring this to me I'd be asking for a LOT of changes to that front end.

Treeve

[ICCARS]

Originally Posted by Trickycoupe

I will be the first to admit that I'm no expert but the photo of the front suspension appears to be shown at full droop.

I would want the suspension to be placed in that position at full static load, if not actually slightly lower at the outboard end so an imaginary line drawn through the lower inner pivot and the outer lower ball joint is horizontal / parallel to the ground when loaded.

Someone earlier stated it looked odd and I have to agree. Best to check the geometry now before going further and having to undo your good work.

Agreed Tricky, and I mentioned this point previously as the front upper wishbone is completely incorrectly positioned in relation to the lower wishbone and as can be seen clearly by this photograph, if both wishbones traverse any further into rebound then the front uprights will generate massive positive camber, then go into massive negative camber as the upper wishbone pivots over it's center point, plus toe in the front wheels at the same time. When loaded, any further movement into compression will generate massive negative camber changes and toe out the front wheels, so the relative positioning is completely off. I would be starting again on the front suspension with qualified and experienced guidance showing the way to set it up right.

[Antny]

That's a great photo perspective. If you can, remove the coil-over shock on one side, then raise and lower the suspension arms through it's full anticipated range of motion with a floor jack. Take a video of this from the front and from the side looking straight at the spindle. Let's see how/if the spindle angle changes much through the range of motion in the video. That should show if there are any geometry issues or not.

[Baur323]

Once again guys, thanks for the feedback. The suspension mount points are in exactly the same place (to the mm) of the Toyota Supra subframe, so I would be surprised if the geometry doesn't work. Let me try to video of the movement.

Regarding an engineer, any recommendations in the hills district?

[Antny]

Cool, the video should put this issue to rest one way or the other.

Who's spindles are you using? If not Toyota Supra, are the ball joint mounting points the same dimension as the Toyota? If not, the geometry will not be the same. If they too are from the same year Toyota Supra, then the geometry SHOULD be fine and you'll be golden.

[albanycobra]

you might just need longer shocks to get the required droop in the suspension.

[Trickycoupe]

Great idea to take a video.

While doing so however, start with the suspension at the correct static loaded ride hight.

Then, using the jack go into bump or droop and with a level or some measuring device to actually measure the camber change at known increments ie 1/2 to 1 inch intervals, just as you do when checking bump steer. (Ride height being the 0 reference)

Bump steer will be the next thing to be concerned with however confirm what you have functions within a known and acceptable camber change range first.

(Based on one of your earlier photos of the car sitting on the ground with engine fitted it appears you likley have in the region of negative 2 degrees camber)

[ICCARS]

Hi Stephen, this is a photo of the Supra suspension as it rests in full droop (or total rebound) - note the position of the upper "A" arm in relation to the lower resting control arm. Just FYI.

Cheers
Wil

[Baur323]

I think Antny has hit the nail on the head.... The axle stub is off a Torana. Did some searching and it would appear that the Supra stub is significantly shorter, thereby bring the top wishbone more parallel.

Would that make sense gents?

[Trickycoupe]

It does.

You have to keep in mind that suspension is generally designed as a complete package for a specific car, ride height, handling characteristics, etc.

So you either use all the appropriate bits and set up pivot points around the original donor locations which may or may not work on the new car or, you start from a clean sheet of paper and design in the bits that you want to use ensuring the geometry functions correctly.

Loads of good books on how it should all work are out there

I have seen loads of good handling cars ruined by owners excessively lowering them and wondering why the thing doesn't handle well any longer. Reason is the geometry has moved outide the bounds of correct function and bump steer has been introduced.

[ICCARS]

At least your making progress now mate, that's the main thing.. Good one.

[Antny]

OK, we're getting there. You just need to find the right spindles now. Or, move the upper a-arm mountings and replace the upper a-arms with fully adjustable arms to dial in the geometry. Easy stuff.