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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:HMMM:. 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?
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.Quote:
Originally Posted by alan levin
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:3dSMILE: .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 bitsQuote:
Originally Posted by custom*or*bust
Thanks to all for your replies.Quote:
Originally Posted by IC2
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
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.....Quote:
Originally Posted by Mike52
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
you used paper:D yep i laid mine out on the shop floor, were i am at now is low and just back of the oil pan crank center line were they intersect like you said i only have some holes lower front two hole lower back bar 5 or so and upper top front one and 5 on the upper back on the rear end never move it no need to :DQuote:
Originally Posted by Dave Severson
Main reason I made all the adjustment holes was cuz I put a bunch of engine setback in the car and want to be able to play with the handling a bit on the road course down by Omaha....and maybe the road around the lake!!!!!:eek:Quote:
Originally Posted by pat mccarthy
dave when you say track bar ? better the a pan hardbar ? your talking a track bar .@ bar crossing the lower two bars working the lower bars mount point s at a cross angle holding the rearend in track with frame off the lower front point of bar and crossing the back rear end mounting point from the other lower bar at lowest point to hold track ? .pan bar many push the rear end abit but if angle is right not much . but with the track bar you see load and unload work thru the rear end at lowest point. l had both with tub out car so the track bar may work better with a car not tub . yes a watts is the best but shuffing that under a car your going to look like a jungle jim set. just my two bits worth i know nothing:)
I run a parallel 4 link with a track bar in my Model A. The track bar is mounted to the left lower fwd 4 bar mount on the chassis and traverses over to the right lower aft 4 bar mount on the rearend housing. With this type setup there shouldn't be any lateral (side to side, left to right) movement of the rearend in relation to the chassis. The position of the lower 4 bars to track bar, makes 2 triangles that are parallel to each other. One is supported through the rearend housing, the other through the chassis itself. Since all the 4 bar mounts are fixed and parallel to each other, there should be no lateral travel between the chassis and rearend even while the rearend is moving up and down through is arc. I don't believe there is any loading and unloading work through the rearend as stated earlier. I can remove the my coilovers and move the rearend up and down to the extremes with no binding/loading at all. If there was any lateral movement, it would have to come from the 4 bar mounting plates that are welded to the chassis, flexing. Possible but not likely. In my opinion this is a better setup vs. a panhard bar. The only drawback is space, and while doing gear changes.
I have encountered the death wobble twice. The main reason for me was I was trying to run the lightest coilover spring rate possible, and run the least amount of rebound possible. The fix was either more spring rate or in my case I dialed in more rebound. Problem solved.
As far as Triangulated vs. Parallel, the OEM's have used the triangulated for eons for a reason, they are fairly easy to install with the space constraints considered. No panhard bar or track bar to deal with. It's built into the geometry of the triangulated mounting system. In a hot rod I don't think you can go wrong either way.
I chose parallel 4 link with a track bar because it fit the build of the car!
Keith
Reason I prefer the track bar is that it moves at the same rate and in the same arc of travel as the lower bars... Things do move around down there a lot when you drop the hammer with some sticky tires or slicks. As 31 mentioned, the track bar forms 2 triangles which are the strongest support of any geometric shape, and whatever deflection there is in the ends or the tubes themselves (yes, they do deflect under load) the movement is in the same direction of travel and arc on the lower bars and track bar with all the torque being applied to the forward mount points of the lower bars. A panhard bar actually transfers torque to the frame rail where the end is mounted. Probably more of an issue with us gear bangers then with the automatics, and not really an issue on the street cuz if you have enough horsepower to make deflection an issue on the street it will just blow the back tires off anyway......
well i will beat the dead horse on this :D.then i will be done. track bar can flex most of the pro street kit use a 1/2 bar that is to small for the street i feel you try to stop side to sid movment thru the lower bar to one point at the lowest point on the other side lower point. there is a better way ???yep. i do not car if it is triangulated .this is at the back end so by the time your at the front wheels the car will track washy and loose i built car s with them for racing only drag cars .but for the street i look at a bar independent of any lower mounting points that is hook to the frame higher up . closer to the mid point of the frame .center to were most of the weight and force is .a bar seeing the load strait on mounted points on the same plane as the axel side to side is the rear end is loaded guys like track rods there EZ to put in .but you will never see one in a car that runs around corners for a living panbar may jack the rear end some but your grabing the frame more to the center of whats going on? so then there a watts the best way to go if you can get it in there ok now i am done beating the horse .. good day
..YEP ... i thinking we maybe drive are stuff harder on the street then some do :D daveQuote:
Originally Posted by Dave Severson
Yuppers, Watt's link will always be the best and for me the preferred....Even though sometimes getting all those pieces in place above and behind the rear differential is kind of like putting a jig saw puzzle together and you get to make all the puzzle pieces!!!!---which I think is the good news!!!!!!!:whacked::LOL::LOL::LOL:
PS--Dead horse thoroughly flogged and laid to rest......
I wish I could of run a Watt's Link, no room for me.
Those Model A's are like packing 10 lbs of crap in a 2 lb sack!
Keith
Quote:
Originally Posted by blwn31
Yep - I know all about filling blivits:
http://i70.photobucket.com/albums/i8...finalasm12.jpg
I had a three link in my Monza---absolutely no bind anywhere from 3 points and used a y link from lower frame to a slider point under center of pumpkin arae