Home made 4 link almost complete. seeking PHB advice

[RNation0001]

Hey guys, i been working off and on building a 4 link suspension for my 67 camaro for some time now. getting very close to being done and in the next week i need to mount my panhard bar. after completion i will do a whole big writeup but for now i have some question. this is just a cruiser that sees a couple of events thoughout the year in which i would like to do the autocross course.

I know level with ground at ride height is nominal however it creates packaging problems by forcing the frame mount to be excessivly long. i dont like that due to the forces that will be applied on it. what is the max angle you would run on it. mine is approx. 12 degrees and heres some pics to show what i mean

IGNORE THE OLD BRACKETS I STILL HAVE TO CLEAN IT ALL UP AND PAINT IT WHEN IM DONE.

https://static1.pt-content.com/images/pt/2014/04/IMG_2850_zps0e5e4c58-1.jpg (http://s1015.photobucket.com/user/RNation0001/media/CNC%20Stuff/IMG_2850_zps0e5e4c58.jpg.html)

https://static1.pt-content.com/images/pt/2014/04/IMG_2849_zpsaad2cdbd-1.jpg (http://s1015.photobucket.com/user/RNation0001/media/CNC%20Stuff/IMG_2849_zpsaad2cdbd.jpg.html)

https://static1.pt-content.com/images/pt/2014/04/IMG_2845_zps0725ec21-1.jpg (http://s1015.photobucket.com/user/RNation0001/media/CNC%20Stuff/IMG_2845_zps0725ec21.jpg.html)

https://static1.pt-content.com/images/pt/2014/04/IMG_2851_zps726674c6-1.jpg (http://s1015.photobucket.com/user/RNation0001/media/CNC%20Stuff/IMG_2851_zps726674c6.jpg.html)

[bret]

Here's why the panhard bar must be level at ride height: as the suspension goes through its travel...about 3" in each direction, up and down...an un level panhard bar will induce a lot of lateral movement into the rear suspension, giving you a VERY uncomfortable feeling, especially at speed. To demonstrate this, have a buddy raise and lower the rear end housing while you hold the (frame) end of the phb against a fixed point that simulates your intended frame mount. You'll find that you can't...the end of the panhard bar will want to migrate laterally as you raise and lower the rear end. The more radical the angle, the greater the lateral migration. It could be calculated mathmatically, but I'd guess at a 12 degree angle and a 30" bar, you'd see as much as .500" of lateral movement. If you level it up at ride height, you'd get that down to around .100".
The longer the phb the more unlevel you can tolerate, but in most cars like Camaros, you just can't get a long enough bar under it to allow any unlevelness.
Reinforce the frame mount, whatever it takes. (And it will take a lot)

[RNation0001]

Thanks alot, funny the ridetech guys responded first cause id say 75 percent of this setup is ridetech parts that I modified slightly. i do plan on heavy reinforcement of the frame rails i never realized how thin that was til i started cutting and welding on it earlier this year. i plan to use some plate steel to reinforce the rails and also using a bar between the two frame rails as well as other reinforcements. i guess i will try raising the axle mount another inch and lowering the frame mount another inch in my CAD and cutting them out on the cnc router i built for another mock up. can anyone give me an estimated amount of force applied to the panhard bar? im assuming its a great amount when cornering which is why i wanted the mounts to be short as possible for leverage reasons.

[minendrews68]

I may be wrong, but I don't think the parts made out of particle board will hold up very long.............................................. I'm sorry, just had to.

[RNation0001]

bahahah yea i dont think id make it out the driveway. im going to try to CNC another set and offset all the dimensions by 1/4" and attempt to use it as a stencil for a plasma cutter. never tried it but hoping it will work.

[benno505]

wouldn't you use a watts link in that setup, I have a 4 link in my charger and it does not run parallel with the diff if your looking from the sky down, it mounts on the frame probably 4 foot in front of the diff then the other end goes to the bottom opposite lower control link, that way the panhard bar can not push the diff left or right as the suspension travels.

Or if you are destined on that setup, I am pretty sure the panhard bar needs to be level with the diff to prevent left to right movement of diff

[RNation0001]

how does ur charger ride with that type of trackbar?? i had debated on doing something like that but seems like i remember seeing something about that being better for straight line but not great for cornering?? which truthfully im after a better ride quality than anything. the previous owner cut all the original leaf spring brackets off the axle and also the car and put a ****ty older ladder bar setup on the car which made it ride horrible.

[MrQuick]

Saddle the frame rail and tie into that shock cross member.

[RNation0001]

hey thats a great idea sir. pretty close to what i was going to do but i was gonna tie into the other frame rail. doing it like this should make it much easier for me if the geometry works out. i know the upper shock mount bar are a little forward of the panhard but i will definitly be checking into this as soon as i get home.

THANKS for the suggestion

[19,69camaro]

If your going to be running the PHB behind one of the coil overs I would highly suggest running past the other coilover as close to the drivers side brake as possible in order to minimize the lateral movement of the axle.

[RNation0001]

ok guys i have redesigned both brackets and got the bar level if i remember correctly the axle bracket mounting point is about 3 inches above the axle centerline where it was 1" abovewhich im happy with. also lowered the frame mounts by two inchs and already cnc'd the templates and cut them out with a plasma cutter in 5/16" steel. still got some work to do but i will take photos later today and post them. as far as extending past the other coilover i may if i have enough tubing. as it sets right now the panhard is about 29" long and i was wrong the angle was closer to 8 degrees not twelve which meant i had about 3.98 inchs difference between the upper and lower mount. should be almost dead nuts now

[wendell]

I'd work to get your pbar lower. Shoot for even with the axel w/ adjustment lower. Not knowing anything about your 4L, tires or goals, you might want to burry the rRC as low as possible.

[RNation0001]

ok guys heres the almost finished product just have to do my reinforcements to the axle and frame brackets. lemme know what u think. its pretty level just doesnt look it

https://static1.pt-content.com/images/pt/2014/05/20140504_181817_zpsegv3rxmb-1.jpg (http://s1015.photobucket.com/user/RNation0001/media/rear%20end%20saga%202013/20140504_181817_zpsegv3rxmb.jpg.html)

https://static1.pt-content.com/images/pt/2014/05/20140504_181805_zpso7n4tgkw-1.jpg (http://s1015.photobucket.com/user/RNation0001/media/rear%20end%20saga%202013/20140504_181805_zpso7n4tgkw.jpg.html)

[parsonsj]

I'd work to get your pbar lower. Shoot for even with the axel w/ adjustment lower. Not knowing anything about your 4L, tires or goals, you might want to burry the rRC as low as possible.I'm with Wendell. That high PHB will cause a high roll center, which will give your car sudden transitions and oversteer. It'll be fine for cruising, but you'll have trouble tuning the rear suspension with springs and shocks because the PHB's high roll center will dominate the kinematics.

The ideal location is below the axle centerline.

[jerome]

Here are some clamp-on panhard bar mounts (http://ubmachine.com/panhardbarmounts.html) that I wish I had found before fabricating my own.

Here is how I reinforced my frame-side mount and made it adjustable:

https://static1.pt-content.com/images/pt/2008/06/6101162289-1.jpg

Here is the axle-side mount:

https://static1.pt-content.com/images/pt/2007/12/610180206-1.jpg

It appears that you have your frame-side and axle-side mounts reversed. In order to counteract driveshaft torque while cornering, you should have it the other way around:

Frame attachment on driver's (L) side and rearend attachment on passenger (R) side

In a left hand turn, the frame rises on the L side and panhard bar slopes down from L to R. The panhard bar is loaded in compression and increases downward force on the R tire.

This only works when the panhard bar is level.

In a right hand turn, the frame drops on the L side and panhard bar slopes up from L to R. The panhard bar is loaded in tension and increases downward force on the R tire.

Under acceleration, the driveshaft rotation increases downward force on the L tire. The panhard bar orientation is designed to offset this driveshaft force.

[RNation0001]

thats a lot to digest. lol however it may be a little late for that but cause its all welded in but truthfully this is the first real suspension project ive ever done, also the biggest fab and welding job ive done. and truthfully its only for a learning experience. all i can hope is that it rides decent and maybe performs a hair better than the stock leafs ( would have went back to leafs but it would have been almost as much work. ) and although i havent had a chance to see how much better it is over the really poorly done ladder bars i can done tell an improvement for the most part. I do things the hard way, i try it, learn from it and re-try it so im sure in the next year or so i will be taking yalls suggestions and implementing them into a redesigned suspension.

[jerome]

thats a lot to digest. lol however it may be a little late for that but cause its all welded in but truthfully this is the first real suspension project ive ever done, also the biggest fab and welding job ive done. and truthfully its only for a learning experience. all i can hope is that it rides decent and maybe performs a hair better than the stock leafs ( would have went back to leafs but it would have been almost as much work. ) and although i havent had a chance to see how much better it is over the really poorly done ladder bars i can done tell an improvement for the most part. I do things the hard way, i try it, learn from it and re-try it so im sure in the next year or so i will be taking yalls suggestions and implementing them into a redesigned suspension.

I've been in that spot before many times, with better ideas after something has been built. I wouldn't worry about it, it won't make a meaningful difference in the enjoyability of the car, and it is probably only a marginal performance advantage that you wouldn't really notice unless you were really driving at the limit. Enjoy the car!

[BillyShope]

RNation0001, don't be too concerned with all this late advice. Yes, it's unfortunate when you find you could have done a tad better on the original design, but you're not all that far off and you should be proud of your accomplishment. An asymmetrical rear suspension...such as a 3link...would have taken care of the driveshaft torque problem, but I'm not advising you to go to that trouble for your purposes. As for the increased rear roll stiffness, don't worry about it. That's easily accounted for. Purchase a copy of Millikens' "Race Car Vehicle Dynamics." You obviously would appreciate it.
shopeshop.org

[RNation0001]

Thanks for the encouragement guys. im still working on it right now but it shouldnt be but a week or two before i can take it out and beat on it a little and see how its going to do and when i do ill get a video.

[BuzzKillian]

I know you are just asking about the PHB, but I couldn't help but notice the lower mount for your coil-overs. Are you just using the bolts for mock up?

[RNation0001]

yes im going to be using a lathe to make some heavier duty coilover spacers if i cannot find something suitable that i can purchase.