3 link for my 65 falcon

[baggins]

is the hammertone you used made by rustoleum? also is it just the regular black tone?

[Bryce]

Thats pretty close to what I did. Jim is cool about selling the parts you need. Aluminum rod ends? Or just the bars? Cant wait to see the pics. JR

yes aluminum rod ends. they still have a steel ball. they can take the same loads but half the weight.

Jim is really cool. I have been emailing him this week.

[Bryce]

is the hammertone you used made by rustoleum? also is it just the regular black tone?

yes it is. regular black ends up a little gray.

[Bryce]

update.

so the 9" housing with the 4.11 gears is in. im running it with the stock leafs and lowered it 2.5". I modified the housing so i can use clamp on leaf pads and change them out later for my lower link/ coilover brackets.

i am currently working ona desing for the upper coilover mount and watts link, then the sway bar and finally the upper third link mount on the chassis side. as i build this i hope to continue to drive the car.

so to make it a better driver i modified some clamp on traction bars from summit. it works really well. over 100% antisquat. good for the strip and not much else. but it will be fun.

the 4.11s were a huge difference stepping up from the 2.80s. WOW.

[BillyShope]

Have you given any consideration to the cancellation of driveshaft torque effects with the 3link? (This might be a bit late, as I noticed the first thing you did was weld on the upper link attachment point to the rear axle.) As I'm certain you're aware, the driveshaft torque tends to unload the right rear during forward acceleration. Jaguar overcame this inherent asymmetry...with a RWD beam axle car...by building a cancelling asymmetry into the 3link used in the Le Mans-winning C-Type competition car.

I have a spreadsheet for determining the proper geometry at my site (Page 18).
http://www.racetec.cc/shope

[Bryce]

yes i have thought of that. One of the cars in my garage, a intermeccanica omega, has that type of rear suspension. It was a holman moody designed car with an intalian body and ford running gear. I kinda like the idea.

I have already commited to the centered upper link. and i have looked at all your calculations. very helpful.

my idea is to run a huge sway bar for drag racing and this will cancel the engine torque. while also preloading the passenger side.

[BillyShope]

my idea is to run a huge sway bar for drag racing and this will cancel the engine torque. while also preloading the passenger side.

While this will help equalize rear tire loading during forward acceleration, it can never do the job alone. This is because there will always be considerable roll stiffness at the front of the car. Either static preloading or unequal spring rates across the front will be necessary. You're going to a lot of extra trouble, all of which would have been avoided with the asymmetric 3link.
http://www.racetec.cc/shope

[Bryce]

i could always add it on later and run both brackets and change bars and see if there is a difference.

[Bad Bird]

Is it possible to cancel the driveshaft torque in another fashion, such as using a panhard bar?

[Bryce]

Is it possible to cancel the driveshaft torque in another fashion, such as using a panhard bar?

panhard is only for side load under suspension compression. not for driveline torque. I think only a swaybar or offset upper link will cancel it.

[BillyShope]

I think only a swaybar or offset upper link will cancel it.

The high rate swaybar will never totally cancel. In addition, it should be disconnected before the car is driven on the street.

There is, however, another way...besides an asymmetric rear suspension...to dynamically cancel driveshaft torque. Different rate springs can be used across the front. In other words, if the spring rate at the right front is greater than that at the left front, the effect...during forward acceleration...is the same as with an asymmetric rear suspension. Adjustable coilovers will be required, of course, to statically equalize the rear loading. Again, there is a setup spreadsheet at my site.
http://www.racetec.cc/shope

[MoparCar]

Does anyone have a "good" picture of the factory five offset 3-link they offer on their kits? It has tight packaging, but I've never found a really good picture or details. Their offset link connects rear of the axle tube instead of at the top or front.

[parsonsj]

Different rate springs can be used across the front. In other words, if the spring rate at the right front is greater than that at the left front, the effect...during forward acceleration...is the same as with an asymmetric rear suspension. Adjustable coilovers will be required, of course, to statically equalize the rear loading.

Of course, that's drag racing only, right? You wouldn't want asymmetric springs in a street, autoX, or road racing car.

jp

[BillyShope]

Of course, that's drag racing only, right? You wouldn't want asymmetric springs in a street, autoX, or road racing car.
jp

That's a very good question. I considered this when, at my site, I suggested that rates be chosen so that the front roll stiffness remained essentially unchanged. Oval track racers commonly run very different spring rates across the front and are still able to make the occasional right turn when required. I had a constructor friend (now deceased) who had the opportunity to do some testing on a sports car circuit with a car that was set up for El Cajon, a 3/8 mile asphalt track. He said he was very impressed and surprised with the handling of the car in both left AND right hand curves.

Certainly, the roll axis is going to be moved laterally, but whether that would make the car totally unmanageable is a question I cannot answer. Frankly, I doubt it, but that's just an opinion.
http://www.racetec.cc/shope

[MoparCar]

I found these picture of the factory five offset 3-link. What's the thoughts on the rearward (back of axle centerline mount)? Any disadvantages? Advantage I guess would be less upper arm into the passenger compartment. It would cause some gas tank issues. The small arm to the diff from the 3rd link mount is a stiffening brace only.

Anyway just some additional ideas. Is there an ideal amount of offset to the side for an offset 3rd link?

Wes

[Norm Peterson]

It results in minor changes to anti-squat. Not the amount at static ride height, which you could "force" to be at the same value as a same-length upper that mounted directly above the axle center. I'm thinking about the rate at which the anti-squat varies as ride height changes. I don't know offhand whether it would be a tiny benefit or a similarly small disadvantage, but I doubt that it would be enough to matter.


Norm

[BillyShope]

I found these picture of the factory five offset 3-link. What's the thoughts on the rearward (back of axle centerline mount)? Any disadvantages? Advantage I guess would be less upper arm into the passenger compartment. It would cause some gas tank issues. The small arm to the diff from the 3rd link mount is a stiffening brace only.

Anyway just some additional ideas. Is there an ideal amount of offset to the side for an offset 3rd link?

Wes

The rearward mounting allows use of a longer link, the obvious advantage of which is to minimize antisquat change with a given deviation from ride height.

I would define "an ideal amount of offset" as that which would provide complete cancellation of the driveshaft torque effect, meaning the rear tires would be equally loaded during forward acceleration. Since the link loads are proportional to the percent antisquat, the antisquat determines the suspension geometry. For a dragrace car, the antisquat should be at 100%, since this minimizes load oscillations at the rear tires and thus maximizes forward thrust. But, for an autocross car, this value of antisquat would almost certainly cause wheel hop problems during braking.

On Page 18 of my site, there is a spreadsheet which yields the geometry for total cancellation and allows the user to input the desired percent antisquat and such things as the rear mounting points of the links, including their horizontal relationship to the rear axle centerline.
http://www.racetec.cc/shope

[MoparCar]

Billy,
What am I doing wrong with your speadsheet? When I hit computer it always comes up with "NaN" in the answer spaces.

Thanks for all of your information. Very valuable.
Wes

[BillyShope]

Billy,
What am I doing wrong with your speadsheet? When I hit computer it always comes up with "NaN" in the answer spaces.

Thanks for all of your information. Very valuable.
Wes

I'm assuming you're using the spreadsheet on Page 18.

My first guess is that you entered too low a value for the desired percent antisquat. If there are insufficient vertical force components in the links, it is impossible to cancel the driveshaft torque. Even an autocross car should be able to tolerate 80% or so with no braking problems. The default values act as you describe when the antisquat percentage is changed to less than 51%.

If the above is not the case, does it do this with the default values? If so, it's a browser problem and I can't help you.

If the default values work, change one value at a time until you have a problem.

If all else fails, give me a call or post the numbers you used here.

I strongly believe, however, that my first guess captured the problem.
http://www.racetec.cc/shope

[LowBuckX]

I found these picture of the factory five offset 3-link. What's the thoughts on the rearward (back of axle centerline mount)? Any disadvantages? Advantage I guess would be less upper arm into the passenger compartment. It would cause some gas tank issues. The small arm to the diff from the 3rd link mount is a stiffening brace only.

Anyway just some additional ideas. Is there an ideal amount of offset to the side for an offset 3rd link?

Wes

Thats how mine is planned. But I didnt think to use axle clamps. Thats a score for me because welding the axle tube in not what I want to do incar.