Rear Suspension Type Ideas

[DynoDon]

So, let's say you have an early Mustang with full Global West front suspension and you could choose one of the following rear options, which would you choose, and why.
Street Driven with Auto X and Open Track Day emphasis

1. 3 link rear

2. Torque Arm Rear like the new TCI kits

4. Triangulated 4 link

5. Corvette C4 (already have one of these)

Take into account that the owner is a fabricator and can do any of these. Do not consider costs, as it is somewhat irrelevant in this case, since the owner can do all the work.

So let's hear it. Tell us your opinions. go for it

[MrQuick]

Since your Dyno Don, I'd build a long bar 3 link w/ watts link.

Vince

[onechev]

The torque arm works for all 3 of the apps you descibed and is easy to install. saw TCI at the rttc the camaro did well seens like it works in all the events. The 3 link wil require cutting the floor
which it sounds like you can do but why would you.

[silver69camaro]

3-Link or triangulated.

Definetely not C4.

[DynoDon]

3-Link or triangulated.

Definetely not C4.

Why not the C4 ?

And it sounds like you may not be a fan of the Torque arm either, reason?

I'm trying to learn here

[Bryce]

3-link with watts...

and dont call it a 5-link.

[DynoDon]

3-link with watts...

and dont call it a 5-link.

I won't! Tell me why you like this option best if you would

Thanks, Don

[MrQuick]

It offers great articulation, light weight possibility and huge range of adjustability over stock and after market 4 bars. Thats if you are not afraid of losing SOME back seat space. 4 links are a great alternative if you have packaging concerns.

vince

[silver69camaro]

Don, C4 suspensions have very little travel to keep geometry correct. If I were to do a IRS, it would probably be a SLA type.

Torque arms can work OK, but I prefer links due to the unsprung weight...but that's just my opinion.

[DynoDon]

Don, C4 suspensions have very little travel to keep geometry correct. If I were to do a IRS, it would probably be a SLA type.

Torque arms can work OK, but I prefer links due to the unsprung weight...but that's just my opinion.

Thanks, that's the kind of information I am looking for. And your opinion is valid and appreciated!

[Bryce]

I won't! Tell me why you like this option best if you would

Thanks, Don

The reasons I am doing a 3-link with a centered upper link:

Good articulation without binding, unlike a triangulated 4-link.

Adjustable anti squat unlike a torque arm.

adjustable roll center and roll steer, unlike a 4-link.

The 3-link can be designed to be great at all kinds of driving styles and situations.

Its the most universal.

[JRouche]

Four link!! LOL A parallel four link that is. Why wasnt that one of the choices? Prolly cause you loose the back seat. Thats a major factor.

But I like the parallel 4-link with a watts link. Some major adjustability and really nice locating of the rear end. And with proper rod ends there is NO bind and alot of travel. A parallel 4-link will prolly give you the most adjustments but with a cost of loosing the rear seats and the ability for getting into trouble with TOO many variables. But.... Packaging is a deal breaker, no doubt. JR

[exwestracer]

Torque arm offers the benefit of not having to build in a lot of structure where there is normally air (inside the car). Understand that you CAN do the work, but IMO the benefits of the 3 link do not warrant the extra effort in a unibody chassis. The 3 link is the best setup, but the torque arm isn't far behind. Of course, there are a lot of savvy guys out there going real well with leaf cars, too...

One advantage to the torque arm setup is the ability to have a pretty aggressive instant center for acceleration without having to pay the price fighting with brake wheel hop (brake floaters on the 3-link would solve that). The instant center isn't as easy to adjust, but if you've designed it right it shouldn't need to move much. Also the IC will stay put as the suspension travels, rather than migrating as it will with a 3 or 4-link. The unsprung weight of the torque arm setup is an issue, but the one I built for the "Vintage Viper" is made out of 1 1/4 X .095 4130. Plenty strong, and it doesn't add a lot of % of unsprung weight to that big 8 3/4" rear end it's attached to...

For lateral location I would go with a watts linkage simply for it's symmetry. Nothing wrong with a Panhard bar, but it will react a little differently in right and left corners. I'm still seriously toying with the idea of a reversed Mumford linkage and adj rear sway bar. Seems like that would be the best of both worlds (except for the unsprung again...)

[silver69camaro]

I'm still seriously toying with the idea of a reversed Mumford linkage and adj rear sway bar. Seems like that would be the best of both worlds (except for the unsprung again...)

That would be interesting. I'd only say be careful not to get the RC too low, it can be easy to do with a Mumford setup.

[Bryce]

A torque arm will have a limit to the upper range of the antisquat. Based on the geometry it may end up above the transmission. Thats if you need that much A/S.
Depending on link lengths you can have limited A/S change during suspension travel and limited pinion angle change. With a 3-link you can have a long SVSA, maybe even longer than a Torquearm.

But if you want to keep the rear seat your only choice is a really short length UCA with a 3-link or you need to go with a TA to reduce the compromises with suspension geometry.

If you were building a falcon (i think you are from a previous thread) you can get a much longer UCA than you can package into a 65 mustang.

Without cutting into the rear seat i can get at least a 14" UCA. Twice the lenght of a new mustang and longer that EVM 3-link designed for the 65 mustang.

[DynoDon]

Thanks guys, keep the ideas and theories coming. Plenty to think about and I appreciate the input

[exwestracer]

That would be interesting. I'd only say be careful not to get the RC too low, it can be easy to do with a Mumford setup.

Yeah, reversing it (bellcranks on housing) brings the ride height R/C (on mine) to about the bottom of the center section. I'm thinking that the adjustable rear bar will let me tune the lateral/thrust force edge of the traction circle a little better. Of course that's just a theory...

[DynoDon]

and longer that EVM 3-link designed for the 65 mustang.

Went to look at the EvM system and it appears that they closed the business.

[exwestracer]

Thanks guys, keep the ideas and theories coming. Plenty to think about and I appreciate the input

Don, couple other things to consider about 3-link type suspensions in a unibody chassis...

The links always exert force along their own axis (push or pull) so the upper link must be adequately braced front to rear. Many of the versions out there punch through the floor or add a mount above the tunnel. This area was never designed to carry that sort of load. The rear floor behind the seat is basically a big, mostly flat, panel...

Also, any sort of side angle built into the upper link will cause binding in the rear suspension. As the upper link goes into tension under power, it tries to straighten it's own load path, which pulls the housing sideways and binds the lateral locator. This was a lesson hard learned for me, as I chased this problem for 5 seasons on a supermodifed. I bring this up because I see them built this way every once in awhile. It may be convenient for packaging, but it doesn't work with big hp and big tires.

[AMC Racer]

Good articulation without binding, unlike a triangulated 4-link.

Why does the triangulated 4-link bind? It shouldn't bind unless using rigid bushings instead of sphericals?