So I built a triangulated rear link suspension but ran into some clearance issues. I have changed the vertical angle at which the top link connects to the rear end. See pic 1 Pic 2 shows the other side that I haven't changed yet, it's pretty much straight on. And this is both from the rear. Do you think there is an issue with the link not being straight on, having it angled down into the rear axle the way it does
i see a few issues but before we get into them. does that set up even move? with those differnt rod angles and lenths the articulation will not follow a pararelel plane
How many times have you seen a Tie-rod end or a drag-link that is manufactured with a bend in it. A straight linkage has more structural integrity under compression or tension, but one with a bend in it will swivel exactly the same. A linkage is actually an imaginary line between 2 pivot points. I have seen J shaped panhard bars work successfully around a quick change rear. Have a good look at a modern car front door hinge [ or a trunk hinge ] they are normally J shaped for clearances and to get the pivot point in a more desirable position
That's the purpose of a triangulated four link. The different angles (in plan view) of the top bars compared to the bottom bars don't allow the rear axle to move left or right and eliminates the need for a panhard bar. What Kerry mentioned about curved links is true. Any shape link will act just as a straight one does, and doesn't change the actual geometry. It's not generally seen, but no reason a curved link wouldn't work...as long as it's strong enough. But I don't think you have to do that. To answer your question, I don't really see a problem. You have changed the geometry, but not a lot. Nearly all rear axles rotate a little bit (viewed from the side of the car) when the suspension moves up and down. The idea is to keep it to a minimum. The closer the top and bottom bars are to being parallel to each other, (side view) and the same length, the less the axle is gonna rotate due to suspension movement. But the top bars are almost always shorter than the bottom bars...just as yours are...the difference in length can be compensated for by the location of the attachment points to keep rotation to a minimum. You've increased the difference between the horizontal angle of the top and bottom bars, so at first glance, the axle will rotate a bit more than it would've with your first setup. But again...not all that much. Another factor is how much suspension travel there is. Naturally, if there's not a lot, then other related arcs of travel aren't going to be affected as much. I'd say that the main thing affected by axle rotation, would be the change in angle of the rear U-joint as you drive. Too far, and it'll bind. Looks to me that your axle is gonna want to rotate backward...top of the axle goes back as the suspension compresses. Not a bad thing...again, just a matter of limitations. If it was me, I'd make a simple model to mimic your geometry, so you can "bench-test" it. Just cut out a piece of cardboard to represent the rear axle. Maybe use yardsticks for the links. Push pins for attachment points. Set it up on a table or bench or the floor in the exact configuration you have for real. Also include your components (crossmembers) that pose the clearance issues. Now move your model axle up and down the approximate suspension travel and judge your clearances, how much the axle is gonna rotate, and how it affects the change in angle of your rear U-joint. Then experiment and adjust your attachment points to get the least possible rotation. I hope this helped a little. Good luck. One more thought. I'm not 100% on how the link angles affect traction ability at the dragstrip...but I know they certainly do. If you think this is a concern you'd have, I'd wait for some responses from drag racers here with hands-on experience.
I'd move the top link frame connector off the top of the frame to the inside of the frame. The top links normally are at least flat, or run slightly downhill. Yours appear to run uphill. Once you get the frame connector moved, if necesary move the rear housing attachment nearer the tube / center section attachment. I have a triangulated setup in my roadster and you have use significantly more verticle height space than most I've seen.
Thanks for the responses. I will look at the frame end location and how close to parallel those two pivot points are. I didn't think the actual shape of the arm shouldn't matter but I was worried. As far as drag strip performance at best this will be street light to street light.
Actually, you didn't change the vertical angle of the top link. All you did was change the shape of the link. The link mounting points are eactly the same as before. The new link shape may create more stress on some of the welds, etc. You may load the bushings in the front bracket much more too due to the new shape. The angles of the links, as viewed from the side, create an "anti squat" percentage. If top and bottom links are parallel and horizontal at ride height, you will have zero anti squat. Run the axle up and down through its travel and watch what the pinion/driveshaft angle does. You don't want this angle to change too much. And you don't want to bottom the driveshaft yoke in the trans or pull a driveshaft out. Also, rock the housing back and forth and feel for binding. Spend some time here. It is important that you not put brackets, links in a bind during suspension travel. Otherwise, you may tear a bracket out of the frame or snap a link. Just be careful here as you re-engineer your setup.
Its all just tacked together so far, I think I'll take the springs out tonight and move it up and down with the jack and see how much the yoke angle changes. The link mounting points are parallel upper and lower the picture makes it look like they are not. I definitly do not want it to bind or cause undue stress
This isn't going to work very well. This is what a tri-angulated 4 bar should look like. the geometry should allow the rear axle to move up and down without binding and without changing the pinion angle. I built this set-up and have been driving the car for two years and it rides and handles great. The bars sit parellel to the ground with the body on and gas in the tank.
damn,, 40 billion rear drive Ford/Gm cars using triangulated four links are all ****ed up.......... For optimal drivability the bottom bars should be close to level, the uppers should point down slightly and the instant center (imaginary point where the bars should intersect) should be somewhere around the front u joint. Oversimplification for sure but that will get you in the ball park. As for the OP's question,, the redone bar will be fine as long as it is welded strong enough to not try to straighten itself out when you hammer it. Bent/curved/crooked suspension links only "see" a straight line so the shape of the bar doesn't matter.
Best advice for you without a bunch of math, in side view you should be able to draw a line through the front and rear bushings and they would point at the back of your cam in the engine. Oversimplified, but that's the gist of it.
I think your giving the rear end a BIG advantage over that top bar in picture 1. I also agree the top bar frame mount should be re thought. A lot of force here to control e****ially with a sticky tire.
Well as far as the potential for binding, I modified the other side and lifted it and set it down on the jacks. No issues, as far as the change in angle on the Yoke it was less than 2 degrees. My lower link bar is not perfectly level when the car is at current ride height. It has a 3 degree upslope to the rear end, the Upper link has a 6 degree slope down to the rear end (measured using the center s of the 2 pivot points). I did originaly have the mount points to the inside of the frame but it makes the upper link really really short. So I opted to move it above just to get a decent length upper bar. I know the upper bar is supposed to be shorter but at 12" long I figured it would really change the angle of the u-joint when it traveled, so this was the lesser of 2 evils in my mind.
Can you get the lower link level? Is the pinion/driveshaft angle staying close to ride height angle through its travel? I would keep the upper link as long as possible. I would put frame on jack stands and support the center of rear end with floor jack and rock the rear end housing up and down on one side as if the body was swaying to see if you feel any binding. You will be able to tell very easily. Just keep in mind how much travel the suspension will actually have.
The top bar is to low on the rearend. The top of that rearend is going to want to twist forward and bend those bars like a pretzel when you drop the hammer. I hope I'm wrong.
I'll bet he does too. I don't follow that one at all. The top bar is in the factory location where GM engineers placed it. The top of the housing will try to rotate in the opposite direction of the ring gear when he "drops the hammer". The top link he modified is going to try to snap the round tubing right off the plate steel.
66, I wonder about me sometimes. papastrk is right, of course. You didn't change the geometry from your first set-up.
I guess we will see. It seems to move up and down over a 5" range without any movement to the yoke angle, or binding in any way. The bottom bar will take most forces when launching the top bar when the brakes are applied and also when any lateral forces are imposed on the system, from the way I see it.
Well checked tonight lifting just one side and still no issues or binding but it is good to check these things. Actually pretty good range of motion. As far as strength goes I feel pretty confident I can reinforce if necessary Thanks again for the input on this one!
FYI damn rear ends mounts on a Chevy 10 bolt are not symmetrical! Posted from the TJJ App for iPhone & iPad
Please clarify this....maybe it's just me, but I don't understand. BTW, I'm quite aways from doing this same thing,but I have a tri-link & an S-10 Blazer 10 bolt going into a Brookville Model A ch***is is why I ask
I've been using this http://mysite.verizon.net/triaged/fi...rLinkV3.1d.zip to ****yse the 4 link design for the track roadster I'm designing. Works slick. There's also a 3 link version http://mysite.verizon.net/triaged/files/3LinkV1.0bBETA.zip
Google "Herb Adams" Then buy his books on Ch***is Design. Only SOME of what has been said here is true and accurate. And a lot of it only really matters if you are stuffing a bunch of horsepower through the rear. You are, however, on the right path, and near the end. Cosmo
Ups pirate, To clarify what I found was the whole ***embly on my 10 Bolt rear end is about 1" offset towards the p***enger side. Mines from a 75 Monte Carlo. Can't confirm what else Chevy did this for but I've found after mentioning it, others have confirmed their driveshaft and rear link ***embly is not centred on the car either. S10 I believe is centred but best to throw a tape on it to be sure. Posted from the TJJ App for iPhone & iPad
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