karcher85

Im working on a new project of mine. A 79, and ive been looking into suspension and options and im trying to get a grasp on a lot of information ive been seeing. One thing I read about is binding, binding when the car gets lowered.

2 questions,

what parts exactly bind? and what's the reason?

Is it the watts? By switching to a panhard, can that get rid of it?
Or is the lower arms the issue when binding? Causing snap oversteer?

do they really bind when just lowering a little? like 1" -1.5"? or is the case when "slamming"?

thanks
I'm new to this live axle stuff and it's taking a little time to get used to it. I come from the world of miatas

j9fd3s

iTrader: (3)

if you lift the rear of the car and just look at it you'll see.

the rear end is on 4 links and a Watts link. the bottom links are parallel to each other, which is fine.

the upper links are not parallel to each other though, they point inwards. so when the car rolls the axle has to twist in relation to the body. the axle doesn't literally bend, but the whole housing rolls forward and to one side.

the watts is ok, except that when the axle twists, it binds the watts up.

to do all this movement, the bushings have to twist, and new bushings are soft, old bushings are hard, and urethane doesn't flex, rood ends tear the body....

the problem really depends on the way you drive, for instance if you just drive around on the street, you won't have a problem, even if its lowered

karcher85

I see. Well I'd be doing some light tracking with the car so this is something I should look in to then.

RxTex

iTrader: (4)

I don't know how much lower the rear of my car is than stock, but probably a good 4 inches I'd say. I have coilovers on the front with a RB sway bar camber plates and illuminas and am running a modified eibach 175 spring and tokico illuminas in the back with hardly a bump stop.

One of the first "modifications" I made to my car was removal of the stock rear sway bar. The car use to feel as though it would bind and rebound during hard sustained cornering. Even before adding a bunch of other suspension parts, removal of this made the car settle much more nicely into a corner, with little adjustment having to be made mid-turn as before.

Our spec 7 car also runs no rear bar...

I'm sure plenty will disagree, but I drive my car hard, and am only speaking from my experience

diabolical1

iTrader: (3)

some ... maybe. however, most people that seem to know what they're doing with the rear suspension on these cars delete the sway bar or simply keep the stock one. i don't know if i would say that it's the consensus, but you're certainly not in scant company with your experience.

you know, i remember Rx7Carl explaining this to me quite a few years ago (i can't remember if it was in a thread or through PMs) but i have to say, this explanation was awesome. that's not to say Carl's was bad, his was awesome, too. he made an someone obtuse in suspension geometry understand it and remember it to this day, but yours was much simpler and concise.

j9fd3s

iTrader: (3)

my car ended up at the low end of the stock ride height spec, and on the track i get mild understeer... so it doesn't hurt to look back there, but you don't really need to do anything, except

i usually don't run a rear bar either.

thanks! i guess i spent too long laying under the car staring up

MosesX605

It never made much sense to me, since the rear sway should limit suspension binding, but when I was autocrossing my race jalopy it was nigh undrivable with the bar on and a dream with it off. I ended up running a RB front bar and no rear bar and that combination was eminently controllable: almost neutral with a tendency towards understeer until the rear end broke away.

If I'd been a better driver, it would have been quite competitive.

mustanghammer

iTrader: (3)

I seem to be drawn to cars with crappy OE rear suspensions.....

Bind = An Artifical Spring Rate Increase

That is why an RX7 with the stock 4 link/watts setup doesn't need/can't use overly stiff rear springs and a rear sway bar. Because as the suspension moves the effective spring rate is changed as the suspension goes into bind. This is a problem because it is hard to predict and measure. Makes tuning a race car a bitch.

Remove the bind and you will need to install stiffer springs and maybe a rear bar. But the trade off is NOW you know the factors that are affecting body roll. If the car rolls too much - install stiffer springs - easy peazy.

My other favorite car to race/autox is a fox mustang and the four link in those car is worse than an RX7. To the extent that spring rates over 300lbs are undriveable with the stock four link. However if you install a torque arm, Steeda 5 link or DIY three link, spring rates can easily be doubled to control the same amount of body roll.