Thread: Parallel or triangulated 4 bar, which is best?

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Looking for opinions to help settle a debate. What are the pros/cons for using a parallel 4 bar with a panhard bar vs a triangulated 4 bar, both with coil over shocks, on the typical '30s boxed frame with 9" Ford axle? Is there a 'best' choice or is this like the Chevy vs Ford debate?

Mike

Both work well but i prefer the triangulated plus it gives you the option of making it look old on an early car by useing a wishbone as the bottom link.

It can also be used with the triangulated bars mounted at the bottom but the name escapes me now

One drawback is it can be tricky to get exhaust pipe through.

Mike,
I found an old article that lists several pros & cons of the two approaches that might help. http://site.streetissuecustoms.com/4linkFAQ.html

While they are both good, I prefer the triangulated as the panhard bar on the parallel 4-link allows the differential to swing in a slight arc from left to right as it moves up and down. On Jeep TJ's they reverse the directions on the front & back panhard bars (one right side frame, one left side) to keep things straighter as you articulate, but then Jeeps are meant to have big suspension travel. With IFS you would see a bit more mis-alignment as the suspension travels (front stays straight, back arcs a bit), and I am interested in keeping things going straight where I point them and not introducing lateral movement that can be avoided.

If sold on parallel bars, a Watts link will eliminate the panhard bar if you have room behind the diff to install one and don't mind the look.

I have triangulated 4 bar now and intend to keep it, was built that way 40+ years ago using coil springs. However I now have exhaust running all the way to the back and indeed the triangulated has made for some tight fits. I am thinking of replacing the coil springs with coil over shocks. Opinions?

Jack.

I chose the 4 bar simply to have some added room under my 'A' chassis for exhaust. When I was all done - wouldn't have made much if any difference. My preference and what I would have chosen for sure had I used a '32 chassis for my car would be the triangulated set up. As far as what works better on a street driven car - toss up as far as I'm concerned

if you have room triangulated with this system there no need for a track rod or panhard bar. parallel 4 bars is ok with panhard . if your running coil overs they can added to things in the way as well so its a toss up. like others said .. but i do like triangulated i remade my GTO re work it with all new points bars and a ford 9 . at the time guys i knew told me i was nuts just go parallel 4 link bars but it hooks very good and i can really drive it hard in to a corner with no need for a panhard bar to hold track

Any thoughts on a vette rear under a model a vicky?

Originally Posted by alan levin

Any thoughts on a vette rear under a model a vicky?

Why isn't this a new thread? It does not seem to have anything to do with Mike's question about parallel vs triangulated 4-links. Perhaps Bill can move it??? Just noticed that you did start a new thread, double posting your question..... I'll post my answer in the other posting.

I work in a late model race shop part time, we use parallel 4 link settups on our cars because it allows near-infinite adjustment for bite on accelaration and in corners. We use a J bar for side to side stability. I think if your just cruising or on the strip, the trianguleted setup would be cleaner under the car, But your adjustment woould be limited. I hope this helps, and I hope Im correct, there ar3e lots of people who know more than me. Have fun

Originally Posted by custom*or*bust

I work in a late model race shop part time, we use parallel 4 link settups on our cars because it allows near-infinite adjustment for bite on accelaration and in corners. We use a J bar for side to side stability. I think if your just cruising or on the strip, the trianguleted setup would be cleaner under the car, But your adjustment woould be limited. I hope this helps, and I hope Im correct, there ar3e lots of people who know more than me. Have fun

well all most i have trianguleted set up i made so i have many holes to move bars to on frame and rear end and upper bars are ajustable for pin angle . to so you can get that if you want it on a good day on the street it pulls air under the front wheels .i am thinking your taking a track bar .J bar ? that not a good deal on the street you want the rear end to hold track thru center line of were the frame is going in a turn .you do not get a firm feel going in a turn with just a track rod .over streer big time.i almost lost a car with one . great for track they suck on the street panhard way better just my two bits

Originally Posted by IC2

My preference and what I would have chosen for sure had I used a '32 chassis for my car would be the triangulated set up.

Thanks to all for your replies.

Dave, if you don't mind me asking, why would you use triangulated 4-bar over parallel 4-bar on a '32 chassis, is that what's on your 'A' chassis? That's the type of answers I'm searching for, why would someone choose one style over the other. BTW, I have a TCI Stage III IFS chassis also.


I'll tell you one of the things mentioned in the debate that I found troubling. One of the guys said that a parallel 4-bar equipped chassis is more susceptible to getting into a 'death wobble' type of motion at speed and the only way to stop it was to slow down cautiously. I've experienced a death wobble on a motorcycle before, it's a very scary feeling especially when you're only on 2 wheels!! Has anyone else heard of or experienced this in a parallel 4 bar chassis set-up? (Please no replies about other motorcycle experiences, let's try to stay on topic)

Thanks again,
Mike

I've ran, built, and installed both.... Oh yeah, when talking parallel 4 bar, are we talking equal length or unegual length bars???

Equal length, parallel 4 bar is easy, as others have mentioned it frees up room for the exhaust over the top of the differential. With a triangulated 4 bar it takes some careful planning to get everything in place, but it can be done.

As Pat mentioned, triangulated 4 bars often get a bad rap for no adjustability...which is true with the majority of store bought kits. But a bit of fabricating (and properly applied math and geometry) a trianulated 4 bar can also claim "infinite adjustability". Not very meaningul or useful in a street car, but in a drag car it means there is only 1 adjusment position that is correct, and an infinite number of adjustment points that are wrong!!!!!!!

A panhard bar is designed to take your parallel 4 bar (equal or uneaual length arms) and push everything totally out of alignment and bind up every non-heim jointed connection point in the rear suspension!!! If you want to do it right, use a Watt's Linkage and keep things in alignment!!!! A track bar is a bit better, but still leaves the rear end doing the Watusi on every compression and rebound!!!!

"Death Wobble" in a 4 bar only occurs when someone thinks their street car is a drag car and install heim joints instead of bushing for the rod ends....Then neglects the necessary maintenance and lube required on heims and half of the heims are locked up on the thru bolt and the other half are loose, sloppy, and worn out cuz they're a cheap junk heim bought when the builder decided to save money!!!!

So, IMO a triangulated 4 bar is for cruizin', an equal length parallel 4 bar is good for street/strip use, and an unequal length 4 bar is best left for drag use only....

Dave, thank you soooo much for your explanation, that's what I was hoping to see!!

Mike

Originally Posted by Mike52

Dave, thank you soooo much for your explanation, that's what I was hoping to see!!

Mike

Most welcome Mike. Someplace in my gallery here on CHR there's some pics of a triangulated 4 bar with a bunch of adjustment holes I'm fabbing up for my 'maro.... the geometry works great on paper,,,,but unfortunately the car is now on my round-to-it list and I can't tell you how well it works.....

death wobble ho yes i been in a car like that. guys mix up a fast for just realy bad chassis work .that scare the crap out of you if you have any brains .. guy i did work on his stuff pick up a nice shiny death ride tub out blown BBC with a unequal length 4 bar put in up side down short bars on bottom and pin angle off when you took your foot out of it bad thing happen i never did more then look and said what the $*ck