Rear active toe elimination Options

[wortdog]

Some of you were interested in the rear active toe thing I mentioned last night, so here's a link with some information on it:

http://www.taboospeedshop.com/atil.htm

[turbohcar]

So... what it's saying is the active toe link setup is actually worse for drag/autocross/rally than what it would be without the active toe link? And their suggestion for eliminating this is a set of Galant VR4 control arms? I think I'm getting a little confused.

[wortdog]

The GVR4 control arms are identical to DSM ones, which is the problem. DSMs don't have a hydraulic steering rack in the back to hold the wheels straight. This allows the toe to change when the suspension travels (like bump steer).

One possible fix is here:
http://www.taboospeedshop.com/atile.htm

[RacerX11]

We did that fix on Eric Stemler's old Talon (I think this car is in Kou's stable now).

Marty

[turbohcar]

Very interesting stuff. I never knew these cars had this feature. I too am interested in how much this mod would cost. On a side note, what are the advantages of having an active toe link for regular driving? I am assuming that it helps with cornering?

[wortdog]

On a side note, what are the advantages of having an active toe link for regular driving?  I am assuming that it helps with cornering?

The advantage to the stock way is that it makes the car understeer so much that it practically takes a supernatural act or some really ham-fisted driving to spin an AWD DSM on dry pavement. This makes Joe Average driver feel safer because the car feels more stable and less out of control during spirited driving, but in reality it reduces the maximum cornering force of the car.

[turbohcar]

I see....all very interesting. Thanks

[RacerX11]

If you are going to do this on a street-driven car, you need to be careful. The trailing arm is stamped and welded mild steel, but the toe link is cast iron. It is very dificult to weld cast iron properly. If you don't pre- and post-heat it properly, and use the correct filler material, you will end up with a piece that is very likely to crack along the weld. With a high-powered DSM, this could be a dangerous recipe.

Marty

[wortdog]

Yes, that is an issue. If you elect to leave the rubber bushing in, and the welds fail, it just reverts to stock. The problem is that to properly weld to the cast piece, you have to ditch the rubber bushing. Then, if there's a problem with the weld, the rear wheels would be able to steer several degrees in either direction on their own.

[SCCA Stang]

does all this mean that the rear suspension is straight from the Galant VR4... if so, how difficult would it be to swap some rear spindles, add a hydraulic steering rack in place (the holes are already in place, thats how I interpretted the info on the Taboo page) and run some linkage.... whalla, AWD AWS DSM!!! cool thought even if it isn't feasable

[Forcus]

I was with it until the welding cast iron part.

My suggestion is the fabricate bracket that mounts to the stock steering mount on the rear-steer arm which then connects to the subframe mount, in effect eliminating the rear steer. Since the bracket is taking considerable lateral force it would have to be decently thick. Hard to tell what I am saying without a drawing. But if anyone is interested I'll do it and post it.

[turbohcar]

So, in essence Forcus, you are suggesting that you weld a piece of square cast iron and weld it to the cast iron control arms to keep them from moving backward or forward because the arms are moving at a diagonal direction. Now, if you were to weld in a horizontal piece of square cast iron, the arms wouldn't be allowed to move at the point of weld any more or less than the length of that bar? Seems logical to me but, I would probably still want to weld the arms to the linkage too for extra measure.

[Forcus]

So, in essence Forcus, you are suggesting that you weld a piece of square cast iron and weld it to the cast iron control arms to keep them from moving backward or forward because the arms are moving at a diagonal direction. Now, if you were to weld in a horizontal piece of square cast iron, the arms wouldn't be allowed to move at the point of weld any more or less than the length of that bar? Seems logical to me but, I would probably still want to weld the arms to the linkage too for extra measure.

No, no welding.

I figured that the way the rear steer was actuated or contained on the GVR4 was on that one mounting point on the arm. So to "lock out" the steering we should be able to use that one point.

Unfortunately, simply extending a short arm with rod ends to the subframe and creating a new mount would probably cause quite a bit of bind. In any case instead of extending it out, extend it forward to the current mount. Basically you are just inhibiting the arm from pivoting by tying in the rear part of the arm to the front and simply utlizing the mount already built in for your tie-in point.

Hell. If I have some time later I'll draw something and scan it.

[wortdog]

I'd probably just drill a hole right next to the pivot point(parallel to it) through both the trailing arm and the cast iron piece, throw a grade 8 bolt+nut in there and call it a day.

If the arm is too thin to support a load there, then I'd weld some strengthening plates onto it to spread the load from the bolts.

[SCCA Stang]

I'd probably just drill a hole right next to the pivot point(parallel to it) through both the trailing arm and the cast iron piece, throw a grade 8 bolt+nut in there and call it a day.

I like this idea!!! only maybe two bolts one at the opposite end of the arm and one at the pivot point, would be more supportive than just one at the pivot point

[Forcus]

I like that idea too. Much simpler than what I was suggesting. Or even a combination of the two if you wanted a rock solid arm.

Just curious if anyone was making anything to completely replace the arm. I haven't been under an AWD in years but it appears that the arm performs quite a few functions that would be hard to replace with a fabricated unit (without alot of extra machining involved). I was just thinking that that cast iron arm with all the add ons must be quite heavy.

[natedogg]

This makes me curious as to what they did for the evo. Maybe I'll get underneath and take a look tonight.

[turbohcar]

I was just thinking that Nate.