I got some adjustable length compensator arms to make rear toe adjustments easier. I was wondering whether I could get the suspension geometry closer to stock (my car is lowered 1.75 inches) by mounting these differently. Refer to these pics as the driver's side of the car looking at it from the rear.


This is how they're intended.


Would this make an improvement?


Or this...?

What I'm talking about is the fact that the rear suspension has more toe change in it's arc of travel when the vehicle has been lowered and realigned compared to stock.

 

It doesn't matter what the shape of the arm is. The ONLY thing that makes any difference is the distance between the two bushing centers. The arm could be an "S" and it would still function exactly the same (as long as it doesn't interfere with anything).

By using an adjustable length arm (like shown), you will be altering the geometry of the rear end. If your vehicle is just lowered with no camber kits, then your geometry is still stock (just in a new "range"). It's not altered until you start changing the length or position of any of the pivot points. This is what takes you away from OEM..

Generally speaking, a shorter UCA will give you more camber gain during compression (if starting from parallel to ground). The only thing that you cannot predict, is the change in bump steer from altered arm lengths and/or mounting points. This is where "Mock-up" testing & measuring are supposed to come into play (though most don't do that).

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by suspendedHatch &raquo;</TD></TR><TR><TD CLASS="quote">
What I'm talking about is the fact that the rear suspension has more toe change in it's arc of travel when the vehicle has been lowered and realigned compared to stock.</TD></TR></TABLE>

what you need to remeber is that you most likely increased your spring rates also, the the range of travel is decreased.

I don't know you suspension setup, and i don't really deal with street cars. But this is why race cars run alot of static camber (even if it is a camber gaining suspension system).

run them like they are intended and leave them the same length as the stock arm. As 94eg! said you will change the dynamic toe curve when you start messing with the length of that arm.

 

Well they're GSR trailing arms on a Civic. I'm not sure if they're bent, my car's bent, or there's something going on with all the aftermarket/modified **** I got on there, but the adjustment is maxed out and still slightly out of spec. Hence the adjustable length kit.

I can't picture in my mind how the length of the arm makes much difference compared to sliding the whole arm, especially when it's just going to be a thread or two... maybe I'd feel differently if I had a model of the suspension in hand. But to me it's worth it if I can get it exactly right as compared to anticipating the slight toe change you get just torquing the bolt down.

So what if I welded a plate over the oval plate, and moved the bolt hole down an inch? In other words...

 

My apologies, but for some reason I thought you were talking about the UCA. The same stuff applies to the compensator arm though. The only difference is that it would effect dynamic toe curves, not camber...

That mod you showed would change everything about the handling of your car. Honda actually made that change after the 88crx. Every model year after 88 has the comp arm mounted to the chassis lower to the ground...

Moving it even further is an idea I myself asked about a year or so ago, and I was given this link that explains that particular mod as well as how the dynamics of the civic/integra rear suspension really works...

It's long, but it's a good read for sure...

On the other hand, if your just trying to get your toe settings within spec without having to cut, weld, or take it to a collision repair shop, then adjustable compensator arms are most likely a much cheaper/easier alternative. Unless your racing, the slight difference in dynamic toe shouldn't be noticed...

 

o wouldn't weld that plate on there, funky things start to happen if you mess with toe.


Something is bent most defently.

It certianly might not make a HUGE difference, but it does.

think of it like a lever, you can move the mounting point around with out causing trouble but once you change the length of the arm then your in another ball game.

I didn't really get it untill my freind had his 1994 integra on a left and showed me how it would change things, and i still can't really explain how, i just know that it does. And it isn't something i would venture into. With some research you might be able to find out what it will do, then you could feel confident in maybe moving ahead and making the changes.

 

OH. At first I thought you didn't know what the hell you were talking about.

I read that link a while back. All the pics are broken though. It reads like theory without application. I want specifics.

All of us already messed with the dynamic toe by lowering the car. My idea is to get the dynamic alignment angles back to what they were at the stock ride height. I've done a couple other custom mods that do nothing other than fool the suspension into thinking it's stock, with very positive results to handling and ride quality. This is alot more fun/interesting than buying your standard **** off the shelf, even if most of my ideas don't pan out.

Even with the car on the lift, you have to have someone jump up and down inside the car to get an idea of what's going on. I'm thinking about welding the plate on and cutting a hole for the stock position, then measuring the dynamic toe change and compare the two mounting points. But first I think I want to come up with some better slip plates. Cracked up, greasy spare kitchen tiles start to suck.

 

Well, the stock suspension design is setup to understeer. This is not really a desirable "sports car" trait. When Honda built their "sports car" version, they used stiffer bushings (in key locations) and larger rear sway-bar to help counteract this effect...

It works...

The only problem with jumping up & down to see how the suspension works, is that your not able to observe the actual "dynamic" effects of the rear suspension. It's the lateral loading of driving the car through turns that causes the civic/teg suspension to react differently under different circumstances...

It's these loaded effects that RR98ITR is discussing in that thread that make it such good reading (not so much the theory)...

 

you seem to think that great evils come from lowering a car, when in fact it's really not that bad. Yes things are effected but, the toe, and camber changes are not bad. In fact having toe change less is a good thing.

bumb steer is also an issue, but not somthing that should keep anyone from lowering there car.

 

You don't know what I'm thinking. I got nothing against a reasonable amount of drop, so long as it actually improves handling. I'm just not satisfied with bolting a bunch of $tore bought $hit on a car and calling it a day. I bought this car to experiment on. I derive a great deal of satisfaction if I can tweak it some little way, by putting washers between the two pieces on the outside bolts of the front lower control arms, by spacing the upper spring perches, by putting an adjustable proportioning valve on the rear brake lines and tying the front lines together, by reinforcing the seam welds, by squirting a hardening foam into the empty gaps in the unibody... not that many people know what the hell I'm doing. And on everything I've tried, people cautiously warned that my car would surely explode. But if it does, I'll just take my stock EF Si to work. And if it doesn't quite explode, yet doesn't improve anything, then I'll put it back to the way it was. So far so good.

I READ that other thread. I've read a lot more than that. I guess I'm not so easily impressed. I gleaned a some usable information... that lengthening the comp arms will slightly decrease the amount of dynamic toe change; and that moving the inner comp arm mount down will put you back on the same part of the toe arc as the stock ride height. I'll give it a shot and measure the alignment angles at different degrees of compression. Yeah it doesn't tell the whole story, but it betrays the footnotes.