Ridetech OUT, 4 link Watts-link in.

[Tweak]

In an effort to clarify things a bit. ridetech has recently re-engineered their rear suspension mostly by changing the upper links to converge as they run forward from the axle. The new upper links are longer.

Thanks David
Any chance I could get those dimensions and run them threw my cad model?

[David Pozzi]

I'm guessing their changes were for better roll center movement but I really don't know for sure. I don't have access to dimensions or a car near me. I did drive the old version at an autocross a few years ago at Del Mar Goodguys event and I did very well with it and I liked how it handled. I was able to hop in and turn a great time with no difficulty. I did not drive it on the street.

I think with the original shorter upper links, the geometry "sweet spot" was going to be at one ride height only and if you run a different ride height it will not be so good. The original was designed as an easy bolt in or optional weld in, with minimal to no cutting. That has it's limitations on what can be achieved.

I'd like to see what you come up with in a four link. A Watts link can be easily adjusted to move the rear roll center so that's a nice benefit.

[Tweak]

I'm guessing their changes were for better roll center movement but I really don't know for sure. I don't have access to dimensions or a car near me. I did drive the old version at an autocross a few years ago at Del Mar Goodguys event and I did very well with it and I liked how it handled. I was able to hop in and turn a great time with no difficulty. I did not drive it on the street.

I think with the original shorter upper links, the geometry "sweet spot" was going to be at one ride height only and if you run a different ride height it will not be so good. The original was designed as an easy bolt in or optional weld in, with minimal to no cutting. That has it's limitations on what can be achieved.

I'd like to see what you come up with in a four link. A Watts link can be easily adjusted to move the rear roll center so that's a nice benefit.

1st image shows where I am so far.
Diff is at my ride height, front lower arm is ride height and OEM location front, rear pickup of bottom arm is middle hole on ridetech weld on bracket
The top arm front pickup point is where i get the most gains and losses, this position is Inside the frame rail and doesn't require cutting into floor. Not that im apposed to doing so if required.
I have the diff at 90deg. so its easier to measure change, as its relative once I have set drive angle.

2nd image shows how much the axle moves forward threw 2" of compression and rebound
the wheel base shortens 2.9mm (0.12")

3rd image shows 1deg of pinion angle change at 2" rebound, however I think I can get this to around 0.8deg

4th image shows 0.5deg of pinion angle change at 2" compression, i will give a little back to the rebound with fine adjustment.

5th image interested me, you can see the angle change of the bottom arm axle pickup point has huge angle changes.

6th image shows axle movement forward with centre of axle at ride height and 2" of articulation
Watts link and arms hidden for easy viewing and measuring, but totally impressed with how it keeps the axle located threw all movement, vertically and articulation.


I really look forward to your views David as I'm pretty green when it comes to 4 link design.

[130fe]

Thanks David
Any chance I could get those dimensions and run them threw my cad model?

For someone that seems to bash ridetech (this and your last one), it just seems funny you want “their” numbers to run through “your” CAD model.

[Mark@lateral-dynamics]

I think you could benefit from playing around with a suspension analyzer to help with the geometry. Packaging should follow function.

In the first pic, and this is arm's length, I would not recommend having the lower links (in side view) dropping - at all - from rear to front. As you show, in modest bump, the rear moves forward, even 1/8" is something that "may" be felt as a rough ride depending upon the compliance of the link ends you use - with rod ends being the least forgiving in this instance.

I see that you have a lot of adjustment available, this is always a good thing. Pinion angle change is probably a third order consideration, I'd focus first on the overall envelope of Instant Center Length and Height, then calculate the resulting A/S. If your roads are rough, you will benefit from having LESS anti squat under hard throttle exit.

Ditch the driver's side upper link to create a 3-Link. 4 links with additional lateral restraint (Watt's in your case, or PHB) are over-constrained - it's actually a 5 link in this case.

Hat's off to you for diving in, this will likely be one of the most educational and hopefully gratifying things you can do to an early muscle car. Absolutely bad-a$$ to have a first gen Camaro in NZ!

[slammed68]

I think you could benefit from playing around with a suspension analyzer to help with the geometry. Packaging should follow function.

In the first pic, and this is arm's length, I would not recommend having the lower links (in side view) dropping - at all - from rear to front. As you show, in modest bump, the rear moves forward, even 1/8" is something that "may" be felt as a rough ride depending upon the compliance of the link ends you use - with rod ends being the least forgiving in this instance.

I see that you have a lot of adjustment available, this is always a good thing. Pinion angle change is probably a third order consideration, I'd focus first on the overall envelope of Instant Center Length and Height, then calculate the resulting A/S. If your roads are rough, you will benefit from having LESS anti squat under hard throttle exit.

Ditch the driver's side upper link to create a 3-Link. 4 links with additional lateral restraint (Watt's in your case, or PHB) are over-constrained - it's actually a 5 link in this case.

Hat's off to you for diving in, this will likely be one of the most educational and hopefully gratifying things you can do to an early muscle car. Absolutely bad-a$$ to have a first gen Camaro in NZ!

Mark, is the lateral dynamics 3 link be re-introduced? if so there is the OP's solution.

[Tweak]

I think you could benefit from playing around with a suspension analyzer to help with the geometry. Packaging should follow function.

In the first pic, and this is arm's length, I would not recommend having the lower links (in side view) dropping - at all - from rear to front. As you show, in modest bump, the rear moves forward, even 1/8" is something that "may" be felt as a rough ride depending upon the compliance of the link ends you use - with rod ends being the least forgiving in this instance.

I see that you have a lot of adjustment available, this is always a good thing. Pinion angle change is probably a third order consideration, I'd focus first on the overall envelope of Instant Center Length and Height, then calculate the resulting A/S. If your roads are rough, you will benefit from having LESS anti squat under hard throttle exit.

Ditch the driver's side upper link to create a 3-Link. 4 links with additional lateral restraint (Watt's in your case, or PHB) are over-constrained - it's actually a 5 link in this case.

Hat's off to you for diving in, this will likely be one of the most educational and hopefully gratifying things you can do to an early muscle car. Absolutely bad-a$$ to have a first gen Camaro in NZ!

Hey Mark
thanks heaps for your input, I really appreciate it
its taken me awhile to get my head around anti squat, starting to understand

Do you think I should weigh my car to establish CG?
cheers
damien

[Mark@lateral-dynamics]

If you can weigh the car, by all means it is great data. But it's not really critical, you can estimate the CG height and fudge a typical 53% front weight bias. The numbers won't be perfectly accurate but it's good enough to see the changes when you go through the range of link locations. I personally feel it is far more important to consider the "SVSA" for link-stick axle rear suspension systems. Making it short and high off the ground will result in an increase in A/S but to the detriment of very hard braking (potential for wheel hop, just like the NASCAR into the hairpin at Sears Point), or under heavy throttle corner exit on rough courses/roads. 100% A/S means that the suspension is effectively "locked up" under full throttle, which means that the springs and shocks do nothing to soak up the bumps, which means the car can/will scamper. Note also that A/S is ONLY a condition when torque is applied, if you are just cruising down the road under light throttle it doesn't come into play and the suspension will react as you'd expect.

Best of luck, you'll get it.
M

[Tweak]

If you can weigh the car, by all means it is great data. But it's not really critical, you can estimate the CG height and fudge a typical 53% front weight bias. The numbers won't be perfectly accurate but it's good enough to see the changes when you go through the range of link locations. I personally feel it is far more important to consider the "SVSA" for link-stick axle rear suspension systems. Making it short and high off the ground will result in an increase in A/S but to the detriment of very hard braking (potential for wheel hop, just like the NASCAR into the hairpin at Sears Point), or under heavy throttle corner exit on rough courses/roads. 100% A/S means that the suspension is effectively "locked up" under full throttle, which means that the springs and shocks do nothing to soak up the bumps, which means the car can/will scamper. Note also that A/S is ONLY a condition when torque is applied, if you are just cruising down the road under light throttle it doesn't come into play and the suspension will react as you'd expect.

Best of luck, you'll get it.
M

Hey Mark

Found a good explanation on SVSA and how to calculate A/S
My car is predominately a street driven car, in saying that our rounds are what you would call canyon type roads. Would like to start doing track days soon.

What would you consider a good A/S percentage to aim for?
Approx 3200 lb car, ls408 545hp 490ft/ lb. chassis dyno Numbers.

Cheers
Damien