measured the roll center of front suspension - Page 3

thundering02 · #31 07-29-2005, 12:31 PM

My friend here owns an AE86 and he was looking at roll ceter adapters and he found something you get you drop springs in and then install under the shocks but just above the steering nuckle and it provides all the results and none of the down sides because it moves everything porportionally. http://cgi.ebay.com/ebaymotors/AE86-...QQcmdZViewItem

mbtoloczko · #32 07-29-2005, 02:29 PM

Quote:

Originally Posted by thundering02

My friend here owns an AE86 and he was looking at roll ceter adapters and he found something you get you drop springs in and then install under the shocks but just above the steering nuckle and it provides all the results and none of the down sides because it moves everything porportionally. http://cgi.ebay.com/ebaymotors/AE86-...QQcmdZViewItem

Not that easy with the SVX. Suspension is different.

thundering02 · #33 07-29-2005, 03:56 PM

Oh I wasn't sur does anybody have a good pic front or rear of the shock tower and steering knuckle maybe something similar can be adapted?

Subafreak · #34 07-29-2005, 05:32 PM

Quote:

Originally Posted by mbtoloczko

Having the ball joint a bit lower than the control arm pivot is probably the best. The roll center will be closer to the CG, and by having the ball joint a little lower, the front suspension can undergo the maximum amount of camber compensation as the car leans in a corner.

People equate lowering the car with less of a tendency to lean during cornering. Lowering the car will reduce the tendency for the car to "jack up" during cornering because it does drop the roll center. This isn't a big problem though because at stock ride height, the roll center is already only about 2.75" above the ground. Lean is controlled more by the distance between the roll center of the car and the CG of the car. If the car is slammed by say 1.5" at the front, the roll couple (distance between the roll center and the CG) is going to be much larger than before the car was slammed, and the only thing that keeps the car from handling worse than before the car was lowered will be an increase in spring rate. With your GC springs, you could actually drop the car by 1.5", and it will probably handle better than stock. If you changed the drop to 0.5", it would probably handle better though.

For a mild increase in spring rate (such as my strut springs), I wouldn't recommend a 1.5" drop because no matter what is done with the roll center, the car will lean into the bump stops way too soon which also kills handling. For your GC setup dropped 1.5", it would be interesting to see how the car handles with the ball joints lowered.

Well I will have to see where I'm at right now, and what the stock ride hight is and reset my springs from there. I will probly go for .5 to 1" lower than stock just to keep as much suspension travel as possible. I will also have to look into spacing the ball joins a little to readjust the roll center.

I finnaly got the article so I could read for myself but there are some questions I wonder about. If the shorter the roll couple the better, than what if the RC and CG lined up perfectly? It also says the front to rear RC can be used to tune the cars handling. On our cars what effect would leaving the rear at stock hight but lower the front 1" without a ball joint spacer? Or would it really not matter becouse with stiffer springs and the new lower CG in the front that the differance in RC wouldn't be noticable? Or do they can suspension tuning a "black art" for a reason?

mbtoloczko · #35 07-29-2005, 05:33 PM

Quote:

Originally Posted by thundering02

Oh I wasn't sur does anybody have a good pic front or rear of the shock tower and steering knuckle maybe something similar can be adapted?

Some sort of extension needs to be added to the balljoint shaft so that the balljoint sits further below the steering knuckle. I have a couple ideas but haven't tried anything yet.

Tiamat-red · #36 01-24-2007, 07:10 PM

Old thread I know but did we ever figure out if this was possible?
Or, rather, easily possible?

svxsubaru1 · #37 04-17-2007, 07:17 PM

I know this threads been dead for a while but it seems like a worth while upgrade. I found a pic on nasioc of a ball joint extension for a STi i know it wont directly work but it seems like the same basic design could be used for the SVX, its pretty much what i had in mind and it doesn't seem like it would be that hard to make, but we would still need to relocate the sterring rods to get rid of the bump steer that would be introduced by moving the ball joint. Heres a link to a nasioc thread covering them. http://forums.nasioc.com/forums/show....php?t=1085646

Tiamat-red · #38 04-17-2007, 09:41 PM

I too was interested in this mod.
But now I'm more interested in that pic.
I can tell instantly that nothing on that car would ever be compatible with mine.
I don't even know how that car runs at all.
How do all the parts even function without a nice coating of grime, dirt, oil, and muck.
That car obviously doesn't even have the self venting valve cover gaskets like mine. And without those how do all the suspension components remained lubricated with fresh oil?
Apparently the newer cars have taken a step backwards.

mbtoloczko · #39 04-19-2007, 06:56 PM

Quote:

Originally Posted by svxsubaru1

I know this threads been dead for a while but it seems like a worth while upgrade. I found a pic on nasioc of a ball joint extension for a STi i know it wont directly work but it seems like the same basic design could be used for the SVX, its pretty much what i had in mind and it doesn't seem like it would be that hard to make, but we would still need to relocate the sterring rods to get rid of the bump steer that would be introduced by moving the ball joint. Heres a link to a nasioc thread covering them. http://forums.nasioc.com/forums/show....php?t=1085646

Ball joint extensions are now made for the Evo too. Its definitely a good mod for people looking to maximize traction on lowered cars. Someone just needs to engineer a solution for the SVX.

Tim · #40 04-19-2007, 10:01 PM

So bump steer is an inherent characteristic of the SVX regardless of the suspension setup used?

I noticed my bump steer getting much worse as my struts die one by one...

Trevor · #41 04-20-2007, 12:18 AM

Quote:

Originally Posted by TE1221

So bump steer is an inherent characteristic of the SVX regardless of the suspension setup used?

I noticed my bump steer getting much worse as my struts die one by one...

My 92 SVX, imported used from Japan, is absolutely neutral in all respects relative to handling. It most certainly does not bump steer, in any shape or form. This factor is an absolute credit in respect of design. If the car was otherwise I would not own it.

jman050 · #42 04-20-2007, 09:05 AM

whats bump steer?

mbtoloczko · #43 04-20-2007, 12:07 PM

Quote:

Originally Posted by TE1221

So bump steer is an inherent characteristic of the SVX regardless of the suspension setup used?

The ball joint extensions aren't meant to alter bumpsteer. Their main purpose is to restore the camber curve on cars with MacPherson strut suspensions that have been lowered significantly.

Trevor · #44 04-20-2007, 05:02 PM

Quote:

Originally Posted by jman050

whats bump steer?

When the steering/suspension geometry is such that, on hitting a bump in the road, as a result the car car "steers" off the intended line.

sicksubie · #45 04-20-2007, 05:16 PM

Quote:

Originally Posted by mbtoloczko

The ball joint extensions aren't meant to alter bumpsteer. Their main purpose is to restore the camber curve on cars with MacPherson strut suspensions that have been lowered significantly.

So without extensions on a lowered car will you get uneven tire wear? Tom is building me a set of Koni/GC's this summer. I would be very interested in what getting an extension made entails.