Opinions on my panhard bar setup, please.

Roll center is sort of a misleading term as it affects other things. If you watch Nascar and hear of a driver *****ing about no forward bite, watch when the car pitstops many times you'll see a guy putting turns into the panhard bar effectively lowering it. The panhard bar probably started in a neutral position even with the axle line. Your panhard bar is too high. I'm not go to pull out the books and go thru the formula to prove it you but it's simply too darn high and to me it could be dangerous in the right situation. Don't beleive a old fart and do whatever youn want to.

 

What 2OLD2FAST is referring to is usually referred to as rear steer. Normally it's only something that you hear circle burners referring to , I hadn't thought of that aspect but he is correct.

 

Like has been said before, but what the heck I'm new so I'll say this: cycle the suspension without the shocks/springs, if nothin binds and you can live with the lateral displacement, unless you're worried you won't get the pole at watkins glen or something it'll sure work on the street. You would probably benefit from adjustable mounting to the frame, to provide some tunability once you get rolling, as others have suggested. That will allow you to level the bar once the car is on the ground, which is optimal, and then adjust for any over/under steer tendencies that arise. As for bump, it is true that a longer bar will react nicer. However, what you've come up with is very tidy and i think worth a shot. Best of luck!

 

My opinion is...if you know something isn't as good as you can get it from a performance (over pretty) standpoint, and the required improvements are reasonably easy to apply...why not just make the improvements?
A longer, flatter and lower Panhard could have been easily made and put into place in the length of time this thread has been up!

I think what you have now will work but what the guys mention will work BETTER.

 

Ok guys this is my take on this, I dont like high mount panard rods as they promote too much body roll and too much scrub during bump situations. This setup is compromised because of the short bar length also. The closer you can keep the panard rod points thru the center of the axle the better your car will drive. Now you can run a short bar but the shorter it is the closer to the horizontal center of the axle the better off you will be. It doesnt necessarily have to be straight it can be a J bar if you need additional clearance.

In this case I believe that this set up will generate too much side scrub when the ch***is hits a bump this will cause a tracking issue or the driver will actually feel the ch***is wiggle . I have diagrammed this out the black lines indicate the travel of the rear axle under two wheel bump and the red outline is the axle under one wheel bump. If you simulate the operating mode by reviewing the arc travel of the panard rod pickup points and see the issues that develop as the vehicles travels down an unsmooth road. This doesnt have to be a pot hole plunge it can be a simple expansion joint edge bump. My take is to move the panard rod to a more friendly position.

 

Would adding an anti-roll bar lessen the scrub? Certainly it would aid the roll situation, and could be mounted out of the way.

 

But that would mean fitting a anti roll bar at the front too. The OP has all the correct info posted here, up to him if he takes the advice on board.

 

There are literally thousands of rods out there with exactly the same setup you are running. It's not the "best" but it will work fine.

Did you design the suspension to use all the travel available in the frame notch? If so, I think I see another potential problem....

 

What you have looks OK but it is not preferred.
I'm going along with **** Spadaro and Acme30 comments.

The thing is it will probably work in normal range of smooth driving, but should you happen to get out of shape for whatever reason, you will want all your **** working with you and not against you in a split second situation.


You are in a great position to fix and improve what you have since you are still in the build stage and now you have some good information which will ***ist you to do some corrective work.


Your skills appear to be good and it seems you are willing to take on board helpful comments.


I had a 1990's Japanese vehicle which ran a rear panhard bar and it was setup pretty well to the book, but even that would develop a ch***is wiggle during crossing some of those 4 way intersections where the road is kinder hollwed out for the rain water to drain away and dips hard.


So make the changes and you will be much happy knowing you have done it the best possible way.

 

The roll center is the center of the bar.

 

What?

Tell me how that works.

 

ROLL CENTER
that would be a good thing to adress on handeling

i used to use a piece of 2x6 square tube and weld on LR of stock cars angled down behind axle tube
on rr of frame welded a down piece off the frame to align with other and and this extendet above the frame as much a stuck down and off the top of this run a cross bar to the other frame rail to take the tork of the bracket

after seeing this i would say to go and look at a couple good dirt track stock car builders product

i would think if you ever want to do any autocross a low roll center would be what you would want
there are also stock car books on handeling that may be good refrence

i built a ton of stock cars using sway bars off street cars and mounting them in the right places and they worked