Alignment & Handling Balance

[LRegvall]

I'm trying to figure out a handling issue that seems alignment related and wanted to see if anyone has experienced the problem and can provide some insight. I have an '05 LGT wagon with BC Racing BR coilovers, an AVO 20mm RSB set firm, Goodyear Eagle GTs. My camber plates are set to be caster plates. I have around 8.5deg caster, -.75deg front camber,-1deg rear camber, -.03deg front toe, .01 rear toe.

 

My problem is a general understeer and lack of connection between front and rear of the car. When I drive, the car turns initially then hits a dead zone in steering feel/affect, then catches and turns too much. I then have to correct and back out steering input. I have to use the back of the car to avoid the problem - use a little steering input along with lift throttle or brake rotation followed by a hard throttle. Unless I use this technique, the back and front feel unconnected. The back end stays anchored unless I throw it around; the front won't rotate the car and ends up with this dead zone in the steering after which the excess slip angle (i.e., understeer) has to be unwound. I did not experience this handling until I did my post coilover alignment and switch from KDW2s to the Eagle GTs.

 

The alignment was set with ride height (arch to center) at 13.75" front and back. I lowered the front to 13.5" and it helped a little but did not eliminate the issue. My alignment guy thought it could be the tires but I'm skeptical that they could have such an extreme dead zone in the front when the rears feel like anchors. He also thought more negative camber could help (like -1.5deg. He didn't think the toe was an issue. He was unable to get more negative camber out of the front. I'm thinking:

 

-flip the caster plates into camber plates and dial in around -1.5

-more rear toe out

 

Anyone else experience a similar issue? Any thoughts on how to solve? Before getting it aligned again, I'd like a better sense of where to head with it. Thanks.

[BAC5.2]

Why in the world do you have so much toe-in up front!? That is your problem.

 

A few minor points. It's nearly impossible that you can ONLY get -.75 degrees of front camber. With plates flipped left-to-right and kicked all the way back to the firewally, PLUS the stock front camber bolts, you should be able to, at minimum, get at least -1 degree. Mine is an outback, but my hub-to-fender height was 2" higher than yours with my Enduratech's and I could max camber out at -1.6 degrees.

 

I'd go to zero toe in the front, +0.01 in the rear. Get as much negative front camber as you can, and don't exceed that amount of camber in the rear.

 

I'd also invest in rack bushings.

 

It is, almost assuredly, NOT the tires.

[AZP Installs]

Also have you done your LCA Bushings?

 

I second the steering rack busings as well.

 

have you done a roll center kit?

 

Remember all those soft bushings with stiff coilovers will yield wierd results.

 

-mike

[notthesnail]

I could kind of be the tires, in that many tires geared toward motorsport use have been tested to find the optimum range of camber adjustment. If you're outside of the range, you won't be taking full advantage of the available traction.

 

I once found the numbers for a couple Toyo tires (R888 and R1R), but couldn't find them again on a quick search. I (think I) remember that the R888 requires more -ve camber than the R1R, enough so that I'd need plates and bolts and bushings to get that much with the stock struts.

[BAC5.2]

The EagleGT isn't a tire geared towards motorsport. It's simply a "better than decent" all-season. It's a staple tire shops recommend to nearly everyone coming through the door as a "high performance all season". A friend has them on her Mazda Millenia, and another on his New Beetle.

[LRegvall]

Thanks for the feedback so far. A few additional thoughts/questions:

 

1. the front has negative toe (-.01 and -.02 = -.03 total) which I understand to be toe out. This is what the alignment guy intended to enhance turn in response. Before my alignment, when I didn't have this weird behavior, I had -.08 front toe. The car does have a quick initial response before it hits the understeer dead zone. I was actually wondering whether more toe out would be helpful. The rear has slight positive toe in (.01 total), which may explain why the back end feels so anchored.

 

2. I agree about the front camber. My alignment guy said he couldn't get any more with the camber plates set as caster plates but it sounds strange. I'm going to pull the wheels off this weekend and see if I can see what is going on with the camber bolts. I've never used them before so it will take some exploring to see what I can do with them. If I have the time, I may reverse the plates into their camber adjustment position. My gut suspicion is that camber may be the culprit.

 

3. I have the eccentric LCA bushings on my shopping list, especially if I end up dialing out some of the caster I now have by reorienting the camber plates. I'm not familiar with rack bushings and what they will improve. I will do some research.

 

4. I've looked at the roll center kit but the feedback on it I've read has been mixed. Other than to correct the roll center after lowering, I'm not sure what effect that has on handling and feel. Can you elaborate on your experience with it as effects the handling?

 

5. The Eagle GTs actually handle pretty well once I get the car rotated properly. They tested pretty well on Tire Rack relative to the rest of the all-season competition. They don't have the ultimate grip that the KDWs had but they feel pretty good and progressive in their behavior. Except for this understeering dead zone. They may contribute to the problem (Tire Rack did say they could use better on center feel, though I think that's a different issue) but my guess is it's a 10% contribution. It could be more, but the non-linear way that this quirck happens leads me to think it is something more mechanical or alignment related.

 

Thanks again for the helpful insights. It helps me map out a solution. Any other feedback is appreciated.

[LRegvall]

So I flipped the "caster plates" into the camber plates they were intended to be. I got around -1.75' of negative camber rather than the -.75' I had. This was measured using a fairly crude protractor and level to measure with. There is an immediate change in the handling. The front grips far better, the front and rear seem much more connected. Also, as an additional benefit, the front seems more resilient and forgiving of bumps than it was before. There is less tendency of the camber/caster plates (with their metal to metal connection to the chassis) to crash or bang over bumps. Overall, a very good change as far as I can tell so far.

 

On another note, I haven't been able to drive the car too much because when I had the wheels off the car I found an "open tread splice" on one of my tires. I've never seen one of these and Tire Rack said it is more common on racing tires. I've been reluctant to drive the car much until I get the tire replaced.

[LRegvall]

To close the loop on the problem I was having. After replacing my defective tire, I had a chance to drive my car more with the reset camber plates. I took a trip with plates canted all the way to the negative side. My initial measure showed this to be 1.75' negative. After the trip a more careful measure showed the negative camber to be more like -3'.

 

On my trip, the car drove really well and the steering dead spot was gone. The front and rear were much better connected. The front felt like it was biting really well, almost too well. It appeared that the very inside of the tread was wearing. That is when I did a more careful measurement of the camber and found it to be closer to -3'. I reset the front camber plates to around -1.5'. The camber plate adjustment is divided into four. -1.5' was at the 1/4 position.

 

The car actually is perfect at this setting. No more front/rear disconnect. No steering dead zone. No understeer, instead very neutral handling. The steering feel is actually better than at the previous -3'. It turns in and unwinds better. I think at -3', there was too much friction for the the steering to center itself easily after a turn.

 

I'm not sure where my caster ended up after flipping the plates (I haven't figured out a way to measure caster as easily as camber). And the reset camber plates have improved the resilience of the BC Racing coilovers. They actually are feeling pretty civilized. If only I could get rid of the bang from hitting sharp road ridges.

[robinlsb]

camber plates set as caster plates but it sounds strange.

 

This is at least the third time I have heard of this. The BC/BR plates are for camber only. If you put in BC/BRs, you MUST put in a roll center kit. Some guys think that the plates are for both.

 

Even at the highest setting, the suspension geometry is changed in BC/BRs

by the fact the car is lowered. The roll center kit ensures that the arms are straight as opposed to an angle.

 

If you add in the caster kit, the front is pretty much fixed.

 

Let's move to the rear. Same problem. The lowered suspension overcomes the stock adjustable capability of camber and toe in. Fix the toe in and camber is wrong, fix the camber and toe in is wrong.

 

Whiteline makes a kit that is outrageously priced to allow real adjustment of toe in and camber. Or you can just go to adjustable rear camber (LCAs) and live with "odd" toe in in the rear.

 

The net result is oversteer. But then, since I am used to over steer:lol:

[LRegvall]

This is at least the third time I have heard of this. The BC/BR plates are for camber only. If you put in BC/BRs, you MUST put in a roll center kit. Some guys think that the plates are for both.

 

Even at the highest setting, the suspension geometry is changed in BC/BRs

by the fact the car is lowered. The roll center kit ensures that the arms are straight as opposed to an angle.

 

If you add in the caster kit, the front is pretty much fixed.

 

Let's move to the rear. Same problem. The lowered suspension overcomes the stock adjustable capability of camber and toe in. Fix the toe in and camber is wrong, fix the camber and toe in is wrong.

 

Whiteline makes a kit that is outrageously priced to allow real adjustment of toe in and camber. Or you can just go to adjustable rear camber (LCAs) and live with "odd" toe in in the rear.

 

The net result is oversteer. But then, since I am used to over steer:lol:

 

When used as caster plates, they are flipped to a north-south orientation rather than east-west when used as camber plates. Do your comments about the effects of lowering apply to springs (e.g. Eibachs, Ralliteks) as well? I have my BC BRs lowering the car about the same amount as springs at about 1" rear and 1.5" front.

 

With respect to the roll center kit, what's the difference between the arms (which arms?) being straight or at an angle? What is the effect of this on alignment and handling feel? Sorry if I'm being anal, but I appreciate being able to pick your brain on this to learn more about it.

 

On the rear suspension, are you talking about eccentric LCA bushings? What kind of toe setting does that give you? I like my cars to be on the "loose" side so that there is lift throttle rotation.

 

Thanks a bunch for your insights!

[robinlsb]

When used as caster plates, they are flipped to a north-south orientation rather than east-west when used as camber plates. Do your comments about the effects of lowering apply to springs (e.g. Eibachs, Ralliteks) as well? I have my BC BRs lowering the car about the same amount as springs at about 1" rear and 1.5" front.

 

With respect to the roll center kit, what's the difference between the arms (which arms?) being straight or at an angle? What is the effect of this on alignment and handling feel? Sorry if I'm being anal, but I appreciate being able to pick your brain on this to learn more about it.

 

On the rear suspension, are you talking about eccentric LCA bushings? What kind of toe setting does that give you? I like my cars to be on the "loose" side so that there is lift throttle rotation.

 

Thanks a bunch for your insights!

 

Oh jeepers! Try this for the front suspension issues

 

http://www.circletrack.com/techarticles/camber_change_static_dynamic_tire_traction/index.html.

 

As for the rear,a 1 inch drop will change the camber so much (at least in an 05) that the concentric bolts don't adjust enought to overcome the camber change.

[Stock_Sucks]

you do realize that every time you adjust camber, castor or ride height the toe changes. any time you change camber, caster or ride height you need to to re-do your alignment for toe. Your caster was most likely the cause of the dead zone(think chopper motor bike vs bullet bike, huge difference in caster). Toe would have to be realy far out to cause the dead zone feeling, and the car would still be more darty than anything. Camber that was uneven side to side too much would cause a pull. too much camber will shred tires even with good toe

 

I'm not a race car mechanic, but I align passenger cars pretty much every other day at work. I use a John Bean Lazer/Infrared aligner, and I even align some vehicles with heavier drivers with them in the car, espcialy if they put on a lot of miles. I can even enter info like load wieght, how much fuel and ride hieght if I feel its important.

[LRegvall]

Oh jeepers! Try this for the front suspension issues

 

http://www.circletrack.com/techarticles/camber_change_static_dynamic_tire_traction/index.html.

 

As for the rear,a 1 inch drop will change the camber so much (at least in an 05) that the concentric bolts don't adjust enought to overcome the camber change.

 

Thanks. Some really good technical articles at Circle Track even if you aren't into circle track racing. My sense is that the lowering gave me more rear camber. I stiffened the RSB to compensate for the added stick.

[LRegvall]

you do realize that every time you adjust camber, castor or ride height the toe changes. any time you change camber, caster or ride height you need to to re-do your alignment for toe. Your caster was most likely the cause of the dead zone(think chopper motor bike vs bullet bike, huge difference in caster). Toe would have to be realy far out to cause the dead zone feeling, and the car would still be more darty than anything. Camber that was uneven side to side too much would cause a pull. too much camber will shred tires even with good toe

 

I'm not a race car mechanic, but I align passenger cars pretty much every other day at work. I use a John Bean Lazer/Infrared aligner, and I even align some vehicles with heavier drivers with them in the car, espcialy if they put on a lot of miles. I can even enter info like load wieght, how much fuel and ride hieght if I feel its important.

 

I think you're right that the caster was the culprit. Your analogy of the chopper makes sense. Not sure what a bullet bike is - a road racer? But a chopper is tons of caster and not set up to turn. It makes sense that changing ride height and would change toe somewhat the way bump and rebound can make it change. Does lowering cause toe out or toe in? Not sure I understand why/how camber and caster changes toe though.

 

I'll probably get another alignment though once I settle on my suspension setup. I might even take out the coilovers and replace with springs before that. Even though I've got the coilovers set up to be fairly civilized and handling really nicely, the bangs and thwacks from camber plates are hard to put up with in city driving and on freeways with bunches of expansion joints.

[Drew888]

Lowering causes toe out.

 

Keep an eye out for Whitelines new strut tops...I'm forgetting the name. I'll now have to go look it up. Basically it's a solid rubber (similar stiffness to Group-N) and has an off set mount meaning the neg. camber and pos. caster is molded in. This will be great for street/track and seriously cut down on NVH. When they are available I suspect a fixed -2.0* up front and that suits me fine.

[Stock_Sucks]

Not sure what a bullet bike is - a road racer?

street bike, crotch rocket.

Not sure I understand why/how camber and caster changes toe though.

all the suspension and steering parts are directly connected. Think Triangle, if you change one of the angles the other two will automatically change.

Changing out ball joints, tie rods, bushings, struts/coilovers, control arms etc. all require an alignment unless you dont like your tires!! Haha

 

get the suspension set up the way you like it, then dial in the the alignment at a good shop.(the dealership may not be the best option. find someone that specializes in alignments, hopefully on performance cars)

 

This info is for everyone not just The OP:D