In search of high-speed stability

[LittleBlueGT]

My rear toe was positive as well, mostly on the RR wheel.

 

The toe adjustment on its own couldn't pull it enough. They used the 2x4 as a lever and got the toe into the negative, more then enough, then they loosened the toe bolt and allowed it to come back a bit and got very very close to 0 toe.

 

It looks like you are having the same problem. FWIW my car has never been in an accident, or hit any huge potholes.

 

I mentioned that is has been good for over a year to show that it appears that the "force" they used worked and has stayed.

[Guest]

So they were actually bending lateral links using a 2x4 ?

[SBT]

So they were actually bending lateral links using a 2x4 ?

A 2x4 wrapped in a rag and stuck through the spokes in the stock (OEM) wheels? Eee Gads!!!

SBT

[Underdog]

Yeah, I'm surprised someone as anal as LittleBlueGT would allow that!

 

I guess if it works, it works... However I plan on trying to bring the camber back in line with the 4BoxParts links and if that doesn't help fix the toe, then I'll have to dig in deeper.

[BrownBoy]

I'm thinking of getting the Whiteline Roll Center kit and some higher caster LCA bushings. When you decided on the AVO parts, were there any reasons to why you picked them over the Fulcrums or the Perrins? I don't want to do perrin, as I'm sure the NVH of the metal bushing will be felt in the cabin. I was hoping to get the Fulcrum SuperPros, but no one seems to stock them anymore

[Underdog]

Well I bought the control arms used with the AVO bushings preloaded. IIRC, the only difference between SuperPro and AVOs were a slight diameter change for press-fit into the arms. I couldn't tell you which is better, but supposedly AVO has revised their bushings since, so I'm not sure the differences are applicable anymore.

 

I don't think you can go wrong with either...

[LittleBlueGT]

Yeah, I'm surprised someone as anal as LittleBlueGT would allow that!

 

I guess if it works, it works... However I plan on trying to bring the camber back in line with the 4BoxParts links and if that doesn't help fix the toe, then I'll have to dig in deeper.

 

I got the links too, but waiting for the install, same reasoning.........

[Underdog]

After installing the trailing arms, the dealer (a different one than a few weeks ago) insisted on giving th car an alignment. This one turned out considerably "better". First a comparison of the previous alignment as set by Dealer A, and read by Dealer B.

 

Dealer A Settings - 6/6/08

Left Front.............Right Front

Camber: -1.1°......Camber: -1.3°

Caster: 6.6°.........Caster: 6.3°

Toe: -0.01°............Toe: -0.01°

 

Front:

Cross Camber: 0.2°

Total Toe: -0.02°

 

Left Rear...............Right Rear

Camber: -1.1°.......Camber: -1.6°

Toe: 0.22°.............Toe: 0.31°

 

Rear:

Cross Camber: 0.6°

Total Toe: 0.53°

Thrust Angle: -0.04°

 

-----------------------------------

 

Dealer B Readings - 6/13/08

Left Front.............Right Front

Camber: -1.3°......Camber: -1.1°

Caster: ----.........Caster: ----

Toe: -0.01°............Toe: -0.01°

 

Front:

Cross Camber: -0.1°

Total Toe: -0.00°

 

Left Rear...............Right Rear

Camber: -0.9°.......Camber: -0.9°

Toe: 0.24°.............Toe: 0.45°

 

Rear:

Cross Camber: 0.0°

Total Toe: 0.69°

Thrust Angle: -0.10°

 

---------------------------------

 

Dealer B Settings - 6/13/08

Left Front.............Right Front

Camber: -0.8°......Camber: -0.7°

Caster: ----.........Caster: ----

Toe: -0.08°............Toe: -0.05°

 

Front:

Cross Camber: -0.1°

Total Toe: -0.04°

 

Left Rear...............Right Rear

Camber: -1.0°.......Camber: -0.9°

Toe: 0.08°.............Toe: 0.06°

 

Rear:

Cross Camber: 0.1°

Total Toe: 0.14°

Thrust Angle: 0.01°

[Long Island Legacy]

Well i Just read this whole Thread.

 

Underdog looks like Dealer A has a poor mahcine compared to dealer B who seems to get way different readings that what you thought you had.

 

How did you source the Spec B Trailing arms for the rear. Can you post a Part# and how much did they run you. I looked into it a few days ago and each side was over 300 for the arms. i'm very interested in doing this setup for my car as well as the upper rear control arms that are also on the spec b.

[SBT]

Well i Just read this whole Thread.

 

Underdog looks like Dealer A has a poor mahcine compared to dealer B who seems to get way different readings that what you thought you had.

 

How did you source the Spec B Trailing arms for the rear. Can you post a Part# and how much did they run you. I looked into it a few days ago and each side was over 300 for the arms. i'm very interested in doing this setup for my car as well as the upper rear control arms that are also on the spec b.

 

Was thinking the same thing about the alignment specs. Not sure I trust any "dealer" to do suspension alignments correctly.

 

BTW - Here's the Spec B Suspension AND Aluminum "bits" compliments of Opie and his www.thel7.com:

 

2006 Spec B Suspension Part Numbers - Struts and Springs:

20310AG400 - Front RH Strut

20310AG410 - Front LH Strut

20320AG000 - Front Strut Mount (2) needed

20322AG010 - Front Strut Dust Cover (2) needed (or reuse OEM)

20323AG000 - Front Spring Seat (2) needed (or reuse OEM)

20330AG720 - Front Coil Spring (2) needed (or reuse OEM / or add aftermarket)

20365AG260 - Rear Shock Absorber (2) needed

20370AE000 - Rear Strut Mount (2) needed (or reuse OEM)

20372AE000 - Rear Shock Dust Cover (2) needed (or reuse OEM)

20375AE000 - Rear Rubber Spring Seat (2) needed (or reuse OEM)

20380AG540 - Rear Coil Spring (2) needed (or reuse OEM / or add aftermarket)

Aluminum Arms:

20202AG160 - Front RH Control Arm

20202AG170 - Front LH Control Arm

20252AG021 - Rear RH Trailing Arm

20252AG031 - Rear LH Trailing Arm

20250AG000 - Rear Forward Lateral Link (2) needed

20250AG030 - Rear RH Upper Lateral Link

20250AG040 - Rear LH Upper Lateral Link

 

I source all of my parts through www.1stsubaruparts.com or www.subaruparts.com depending on which has the better price. For JDM P/N's (also found on theL7 site), you can source those through www.jdmparts.com and other Japanese Market-oriented sites.

SBT

[Underdog]

Well i Just read this whole Thread.

 

Underdog looks like Dealer A has a poor mahcine compared to dealer B who seems to get way different readings that what you thought you had.

 

How did you source the Spec B Trailing arms for the rear. Can you post a Part# and how much did they run you. I looked into it a few days ago and each side was over 300 for the arms. i'm very interested in doing this setup for my car as well as the upper rear control arms that are also on the spec b.

 

It seems to me like the right rear was the primary offender, all the other reading seem +/- comparable. The camber being way out of whack (-1.6°) would definitely throw off the toe reading, and since the Tech A didn't seem to even touch the rear toe adjustment, it ended up being even worse when the camber was reading properly.

 

All readings are now within the specified range per the readout from North End Subaru, for a "2005 () - 2006 2.5GT Spec.B". When I install the adjustable lateral links and rear "upper" links, I will have it realigned (3rd time within 2 months) at a performance shop. I will shoot for zero toe all around and -1F/-1R camber at first, but then shift a bit more negative camber to the front axle if the car still understeers.

 

My records & receipts are at work right now, so I won't be able to give you the number I ordered until Monday. I found my info on this site, and probably made a thread about it... I purchased the trailing arms and upper links (among other things) through KOP for a competitive price. I thought the rear "forward" links were the same as the GT, but I'm replacing them with the 4boxparts adjustable links for the camber adjustment anyways.

 

I would place the aluminum components lower on the list than almost any other suspension mod you could do. The front arms may be slightly higher than the rear because it's a good opportunity to put in bushings and/or balljoints, slightly reduce unsprung mass, and have marginally stiffer/stronger control arms. For the front arms, rear arms, and rear "upper" links it was probably close to $2000 in parts and labor. The difference is subtle, and I am very satisfied, but I wasn't expecting a huge change, just an academic one. They do seem to take some of the impact harshness out of the konis/swifts, but I need to log some more miles with them.

 

I'll check back soon with more info, and the weight of the steel vs aluminum trailing arms.

[Underdog]

Okay, here it goes:

 

20202AG160 - Front RH Control Arm - Bought from Legacy_Otaku, used with AVO bushings ($237.50)

20202AG170 - Front LH Control Arm - Bought from Legacy_Otaku, used with AVO bushings ($237.50)

20252AG021 - Rear RH Trailing Arm - Bought from K.O.P. ($296.17)

20252AG031 - Rear LH Trailing Arm - Bought from K.O.P. ($287.55)

For reference:

 

20250AG030 - Rear RH Upper Lateral Link - Bought from K.O.P. ($57.75)

20250AG040 - Rear LH Upper Lateral Link - Bought from K.O.P. ($57.75)

4BoxParts Adjustable "Forward" Lateral Links - ($175)

 

Differences:

Front Control Arms:

Steel 7.5lbs - Stamped and Welded Construction

Aluminum 6.5lbs - Cast/Forged Construction

 

Rear Trailing Arms:

Steel 17.8lbs - Cast Construction

Aluminum 11.2lbs - Cast/Forged Construction

 

Upper Lateral Links:

Steel 4.9lbs - Cast Construction

Aluminum 3.3lbs - Cast Construction

 

Rear "Forward" Links:

Not yet measured.

[Underdog]

^Updated weight of steel vs. aluminum upper links.

 

Okay, I'm going in for an alignment tomorrow and my suspension mods are complete.

 

Konis/Swifts

Aluminum Control Arms, Trailing Arms, Upper Links

Adjustable Camber Rear Links

Cusco Lower Arm Bars - Front & Rear

AVO RSB Mounts

AVO LCA Bushings (+ Caster)

Whiteline Roll-Center Adjustment Kit

 

I'm going to aim for zero toe all around and have them max out the front negative camber with the stock bolts (<=-1.3). However, I'm not sure what to have them dial in for rear camber... This is my daily driver and I want the car to handle neutrally, but I don't want to push the balance towards oversteer. Snap-oversteer is one thing, but I'd like to keep the steady state balance towards the understeering side. Any suggestions??

 

Also, if -1.3 degrees is going to mess up my front tires, please say so. I ran it for a while and the car felt great, nice and stable. Not really sure about these alignment settings, and I don't have the time/facility to do it by trial & error.

[BrownBoy]

I'm going to aim for zero toe all around and have them max out the front negative camber with the stock bolts (<=-1.3). However, I'm not sure what to have them dial in for rear camber... This is my daily driver and I want the car to handle neutrally, but I don't want to push the balance towards oversteer. Snap-oversteer is one thing, but I'd like to keep the steady state balance towards the understeering side. Any suggestions??

 

Also, if -1.3 degrees is going to mess up my front tires, please say so. I ran it for a while and the car felt great, nice and stable. Not really sure about these alignment settings, and I don't have the time/facility to do it by trial & error.

 

You should be fine with the -1.3* if you are able to zero out your toe. As far as the rear, with no adjustment possibilities, I was running -1.1* or so (-2.3* front w/ coilover camber plates) with a pretty good feel. The rear toe wouldn't completely zero out for me however (I have no idea why). It's been a pretty good alignment, and I've been happy with, except now my LCA bushings are torn, and the car feels like crap. I really need the Roll-center adjuster and the AVO +caster bushings... :sigh:

[Guest]

Differences:

Front Control Arms:

Steel 7.5lbs - Stamped and Welded Construction

Aluminum 6.5lbs - Cast/Forged Construction

 

Just 1 lbs. difference? I thought it was like 3 lbs.

[Underdog]

Yup and that is rounded, favorably, from results on a scale with X lbs xx.x oz resolution.

 

Remember, the aluminum parts must be designed more rigidly than steel arms due to the lower yield strength. Less weight + more rigid suspension + slight strength increase... no wonder Vimy loved them.

 

I'm gonna need the alignment before I can say for sure how the results of the modifications match up to my expectations.

[Underdog]

The technician just called me up and said he was getting ready to put it on the rack. I had specified 0 toe all around, and -1.0 -> -1.2 front camber, -0.8 -> -1.0 rear camber. The tech recommended that the toe should be toed-out by 1 or 2 minutes (.01-.03 degrees) so that under power the toe would come in to zero. What do you guys think?

[LittleBlueGT]

The technician just called me up and said he was getting ready to put it on the rack. I had specified 0 toe all around, and -1.0 -> -1.2 front camber, -0.8 -> -1.0 rear camber. The tech recommended that the toe should be toed-out by 1 or 2 minutes (.01-.03 degrees) so that under power the toe would come in to zero. What do you guys think?

 

 

I think you will not notice that small of an amount, I also doubt the equipment they are using is accurate enough for that small of an amount.

[Underdog]

Quite possible on both counts...

 

I don't want the car to be twitchy, at all. I'm very very focused on the steering inputs when I'm driving, probably to a fault. I had been driving with the toe at -0.01 in the front for a while and it did not seem to cause problems.

 

Regarding the machine accuracy... The readouts go to hundredths of a degree, although I'm certain there is some tolerance on that figure. Also, the tech (a trustworthy one) cared enough to call and ask, so I would think he would actually be able to do it.

[whitetiger]

The alignment should be taylored to driving style. A daily driver should have 0 toe all around with -.5 to -1 degrees in camber all round. this will give good stability while maintaining straight line brake performance and tire wear characteristics.

 

for an autox/track car you want somthing alittle different. For starters, you will want more camber all around. -2 degrees or more is not uncommon especially when running coilovers and r-comp tires. this level of negative camber will maximize cornering grip and highspeed stability while sacrificing tire wear and alittle straight line braking. people running this setup will be trail braking anyways. Also, you will want to toe-in 0.5 to 1 degrees up front an toe-out the same amount in the rear. the toe in upfront will increase steering response and turn-in while the toe outin the rear will allow the car to rotate alittle easier. this all makes sense when you think about how the weight transfers accross the car when cornering. the toe out in the rear will decrease high speed stability but not by much. Also, all the off zero toe will cause even faster tire wear but, in the interests of performance, tire longevity is not a top concern .

 

I run, if i remember correctly, 0 toe up front with -1.75 degrees of camber up front, .5 degrees of toe out and -1.75 degrees of camber in the rear.

[Underdog]

Cool, so it sounds like the few hundredths of toe out will make practically no difference for daily driving, and the camber is right around your range. I wanted to bias a bit more static negative camber to the front to help reduce understeer by increasing front end grip. I just hope he doesn't exceed a few (3) hundredths of toe, or I'm gonna have to push back.

[whitetiger]

^if you have offset caster bushings in the front LCAs then you actually need less static camber since more caster increases dynamic camber. the best way really to reduce understeer is just use better stickier tires and be smother on the brake and gas in to a turn. Our cars are fairly heavy and transfer alot of weight. If you can control front to back weight transfer then you will not ovewhelm or underwhelm the front tires and maintain optimal front end grip and the best way to do that is by driving correctly. all the other alignenmet and suspension stuff is secondary and mostly will change the way the car handles one that grip is achieved.

[whitetiger]

back on topic though, if all you care about is high speed stability, then moderate negative camber all around with toe in front and rear. the toe out in the back will hurt stability but it will hlp the back come around better in tighter turns with alot of lateral weight transfer going to the outside rear tire.

[Underdog]

Yes... driver mods are always a welcome suggestion. I know it's something I need to work at, particularly in conjunction with shifting.

 

The thing that sucks is such a large percentage of my driving is just commuting and I can't really justify setting up the car to be "race-ready". The suspension stuff has been 50/50 to improve performance as well as comfort, since I found the bouncy, floaty, understeering stock setup to be almost unbearable. Actually, this thread started just through my search to improve highway stability, and has since snowballed.

 

That being said, I do try to be conscious of keeping the car nice and balanced at all times, and I'm always seeking ways to improve my "technique". I will post back later this evening when I have the results of my latest alignment, hopefully it will be my last for a while.

[Underdog]

Before - 7/1/08

Left Front.............Right Front

Camber: -1.3°......Camber: -0.9°

Caster: ----.........Caster: ----

Toe: -0.60°............Toe: -0.45°

 

Front:

Cross Camber: -0.5°

Total Toe: 0.15°

 

Left Rear...............Right Rear

Camber: -1.0°.......Camber: -0.8°

Toe: 0.18°.............Toe: 0.79°

 

Rear:

Cross Camber: -0.2°

Total Toe: 0.97°

Thrust Angle: -0.30°

 

---------------------------------

 

After - 7/1/08

Left Front.............Right Front

Camber: -1.0°......Camber: -1.0°

Caster: ----.........Caster: ----

Toe: -0.02°............Toe: -0.02°

 

Front:

Cross Camber: -0.1°

Total Toe: -0.04°

 

Left Rear...............Right Rear

Camber: -1.2°.......Camber: -1.1°

Toe: 0.00°.............Toe: -0.01°

 

Rear:

Cross Camber: -0.1°

Total Toe: -0.02°

Thrust Angle: 0.01°

 

The camber is only highlighted red because it is out of the Subaru spec. I'm pretty happy with how it turned out and the car felt great driving home, especially after driving ~50 miles on the "before" settings. (The steering wheel was cranked like 20 degrees CCW going straight down the road!!!) I was driving on those settings because I had to eyeball things back into place after installing the front&rear lower bracing and adjustable links.

 

Another factor that probably made the car feel extra good was that I was driving the fiance's Yaris to/from work today...