RideTech Triangulated 4 link, upper bars?

[Rod]

I'm building a rear suspension system for a 1963 AMC Rambler, Triangulated 4 link, watts link and sway bar, I'm using the ridetech universal triangulated 4 link kit and I know the kits upper bars are shown going outward towards the frame, but I see the Air bar kit, and prodigy bars upper links come from the axle towards the center of the car (I have no packaging issues so either direction will fit under the car) any suggestions? on an ideal direction?



towards the outside frame rails?


towards the differential center line?

[marolf101x]

The upper and lower images are how we build the majority of our AirBars (upper arm links to center of rear). This is also how the OE A-Body mounts are aligned as well.
(One note, image #1 will not work as the frame side upper mount is 90 degrees off. If you install it like this it will not move much before something breaks.)

The middle image is our AirBar for the Dodge B and E Bodies. Arms are different for clearance purposes.

I would suggest you model yours off the GM A-Body architecture or our F-Body AirBar as we have a TON of development time in those units and the results keep speaking for themselves.

Also, you do not need a lateral locating link when using a triangulated 4-link. The

[Gitter Dun]

I was going to say the same thing. Lateral locating device not required with triangulated four link. Set the axle in the car for ride height and then set yourself up for upper links and link attatchment. This would be easiest on a frame table so that you could square and plumb all dimensions acurately but I'm sure you already knew that.

[Rod]

I do know that i don't need a lateral locator on a triangulated 4 link, maybe I have it all wrong, that's why I'm just asking around. So in theory because of the design a triangulated 4 link doesn't need the watts, but I was thinking that a watts will lessen the bind on the 4 link and reduce some of the slight wander that I have felt on some other 4 link designs (i have felt the same wander on leaf spring cars also and have elevated the motion with the watts)
Thanks Guys the input is greatly wanted!!! keep it coming!!

[exwestracer]

I do know that i don't need a lateral locator on a triangulated 4 link, maybe I have it all wrong, that's why I'm just asking around. So in theory because of the design a triangulated 4 link doesn't need the watts, but I was thinking that a watts will lessen the bind on the 4 link and reduce some of the slight wander that I have felt on some other 4 link designs (i have felt the same wander on leaf spring cars also and have elevated the motion with the watts)
Thanks Guys the input is greatly wanted!!! keep it coming!!

My own opinion is that the upper links should meet at the axle, and be mounted as close together as possible. The convergence point of the upper links is the location of the roll center, and the further the links are spread apart, the higher and further behind the axle the roll center falls. Reversing the links places the roll center somewhere up around the middle of the car. This will cause some slight lateral movement of the axle housing in roll.

[MIKE67]

Ray, the Milliken's define the upper link convergent point as "lateral restraint point". The roll axis is a line thru that point and parallel to the side view lower arms (for parallel lower arms). The roll center is where the roll axis crosses the rear axle vertical plane. The problem is that the roll axis moves with the lower arms and to have some roll understeer the lower arms must slope down to the front of the car. This puts the instant center very low.
Having the upper arms converge at the frame mounting ends can result in some weird roll center positions depending on their side view angle.

[Rod]

this getting awesome!!! this is what I want, give me more guys, digging the info

[exwestracer]

Ray, the Milliken's define the upper link convergent point as "lateral restraint point". The roll axis is a line thru that point and parallel to the side view lower arms (for parallel lower arms). The roll center is where the roll axis crosses the rear axle vertical plane. The problem is that the roll axis moves with the lower arms and to have some roll understeer the lower arms must slope down to the front of the car. This puts the instant center very low.
Having the upper arms converge at the frame mounting ends can result in some weird roll center positions depending on their side view angle.

Thanks, Larry. I was thinking solely about the links converging at the axle. Shouldn't be posting from work anyway! LOL

[Gitter Dun]

What would be optimum horizontal angle for the upper arms? length? Length compared to lowers?

[MIKE67]

WOW! Now that is getting to the heart of the matter. Simple answer, it depends. It depends on what compromises you are willing to make. It depends on available room to package the suspension (or how much fabrication you are willing to do), how much anti squat you want, how much pinion angle change you can live with, what is the side view angle of the lower arms, how much rear roll steer you want and what rear roll center height you want. All of these affect each other, so there are thousands of workable combinations. If it was easy, anyone could do this stuff.

[exwestracer]

Upper link length is usually a packaging issue, as Larry pointed out. the "sweet spot" seems to be about 70-75% of lower link length, as measured in side view. This is the "effective length", not the actual length of the bars themselves.

[Gitter Dun]

Thanks guys....no intention on building one.....just have a great interest in suspension technology. I think ultimately....if I was to try and put something together it would run more down the lines of a 3 link with watts set up. My current set up is leaf spring with Fays 2 watts. Amazing what rear roll center height adjustment does for the front handling of the car.

[MIKE67]

I agree with the roll center adjustability. That is a problem with the 4-Link. It also usually has a high roll center. But, it is simple and usually easier to package.

[Rod]

Great Question Gaetano!!! like I said I love the info and I have no packaging issues building this car so if the upper links or link needs to protrude into the cabin floor so be it, it is a wagon!! so heres what I understand right now

1) lower arms must slope down to the front of the car
2) upper arms about 70-75% of lower link(arms)
3) angle of upper arms?

so are many here thinking a 3 link as opposed to a 4 link?

[Gitter Dun]

If it was me, I would do a 3 link with a watts. Rear roll center adjustability is something that I have just begun to do and like I said, it is amazing how rear roll center adjustment works in balancing the handling characteristics of the car. I have knocked a total of 4 seconds off my lap times at T-Hill with bypass config. just from adjusting rear roll center height. Got down to 2:04's in two track days and I'm not done tuning. I should be able to get in the 2:00 range on 100 tread wear tires.

[Rod]

ok ok ok so I should lean towards the 3 link, next tough question for everyone!!

centered 3 link or offset 3 link

[AMC Racer]

Have you considered a torque arm?

[feeble]

If you have to build it anyway, I would use the offset link.

[Rod]

Have you considered a torque arm?

I had thought about it....but? I have havnt had any chances to see one at the tracks in action, never rode in or drove one so that was one of the reasons I wasnt looking at those, I have rode in Kyles DSE car with there 4 link, rode in Mary and Deannas Hotchkis 3 linked car, Bretts new 68 Camaro(west coast version) ride tech car felt and looks smooth at the events with there triangulated 4 link, so Ive leaned towards the linked rears for the wagon project

[AMC Racer]

Torque arm seems a simpler way to go and was used stock in the later Camaro, etc. ... but if you're up for making the structure for the upper link and want the adjustability, a 3-link works. Control Freaks makes some Rambler / AMC stuff including a triangulated 4-link .... but if you're making parts yourself, likely can make something to suit for less $$ and get some adjustability.

http://www.freakride.com/2011_amc_suspension.pdf