I drive a 90 DA which handles worse than my mums camry. Turn-in is poor, and there is lots of understeer. The front never feels 'right', the slower the turn, the worse the car feels.

Setup is stock DA other than:
400f/500r Koni/GC A few inches lower all round
15x6" with toyo t1-r tyres, 37psi/33psi
No chassis reinforcement
23mm rear swaybar with rear tie bar
Energy suspension bushes everywhere except RTA which is fubared stock
290,000km on the chassis.

Got an alignment today:
Front (L/R)
Camber: -3'07' / -1'33'
Castor: 1'03' / 2'11'
Toe: 0.4mm / 0.4mm

Rear (L/R)
Camber: -2'58' / -2'51'
Toe: -1.9mm / -1.8mm

So there's some bent business going on somewhere, and there's a bit too much camber on the rear that i'll fix up with some washers.

From those specs, you'd think it'd turn right pretty good from the big static camber but it doesn't. It seems like it takes a long time to respond to my turning inputs, never really settling, especially at low speeds.

Taking 90 degree turns at low speeds feels very understeery and not that smooth rolling feel that i'm after.

Is my alignment enough to cause disappointing handling under all conditions? (havnt tested anything more than about 100kph (60mph) around mild corners but it definately felt on the limit of the front, never the rear)

My ex-gf had an early 90's little mazda 323 sedan which when you turned it felt like it would keep on turning. I think I would have rolled that before it understeered. My mum's old camry is similar (but not as good), it just feels so balanced and solid. Understeers like a beast when you push it too far (which isn't all that far) but it feels right! My car just feels wrong. Even with a big rear swaybar and rear biased spring rates, it still plows like my worst nightmare.

What other factors are there that could be causing this? Is my old frame too sloppy and bending? Could a bent component that is causing my off alignment, cause such bad handling?

If you need me to clarify anything just say so as i'm incredibly disappointed in the car and will do whatever it takes to get it right. Thanks.

 

why is your tire pressure so high? and is that 37psi in the front or rear? your tires arent the best either...

 

Something is bent in the right front. You're going to have to get the car on a frame machine, or take some measurements yourself and compare to the frame measurements provided in Honda documentation to figure out what exactly is going on up there.

Looks like you're also too low for the spring rates, and probably running into the bump stops pretty early up front. The front definitely needs to be either sprung much stiffer, or raised higher.

Messing around with the rear alignment is a bit pointless if the trailing arm bushings are broken. Replace the TA bushings and then re-set the toe. I'd actually set the toe to 0 in the rear instead of toed-out, and I'd toe-out the front a bit to help turn-in.

A lot of static camber doesn't necessarily make for a good-handling car.

Your description is rather vague, so without driving the car personally it is difficult to determine what exactly is going on or how to go about fixing it. When is the car understeering? Corner entry, mid-corner, exit? Are you sure it isn't being caused by hacktastic driver inputs? Entering a turn too fast and opening the throttle too far too soon are the main causes of understeer.

 

I'd start with replacing any "fubared" bushes.

How stiff are the Konis set? If you have them set soft then this won't help steering / handling response. Softly set rear dampers won't help reduce transient understeer.

Good quality (i.e. rigid) front and rear tower braces will sharpen up steering / handling responsiveness, and may assist in decreasing understeer if the rear end of the chassis is particularly felxible (more likely with hatch and wagon type bodies than sedans, though many sedans need help here too). Tower bars that are less than very rigid are a waste of time (which rules out typical Ebay type items).

I'd set rear toe to zero, and front toe to zero or very slight toe-out. You need more caster angle, especially the left caster is way too little (and caster should be equal side to side of course). Even the right side caster is less than you want for better steering response, it can be increased but it may be a fair amount of work and you need to know what you're doing (I think you want more like 4° to 5° if you can get it).

Left front camber is quite high (I'll bet your car pulls to the right?). You need to get the front camber more equal, personally I'd try to reduce left camber to match right camber, which IMO is about right for a road car. I think I'd take about 2° out of the rear camber. What does your tyre wear look like? I wouldn't expect you'd need a lot of camber anywhere as the car doesn't sound like it's going to roll all that much.

I can't really comment on your tyres, but the relatively large pressure difference front / rear seems excessive to me. I'd try a more equal setting, then play with pressure to find what works best with those tyres, then play with front / rear differences to fine tune the handling balance.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Targa250R &raquo;</TD></TR><TR><TD CLASS="quote">A lot of static camber doesn't necessarily make for a good-handling car.
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I didn't say that it did. What I did imply is that I should be getting far less understeer than I am given my static camber and rear biased rol resistance (hence front grip).

What makes you say my spring rates are too soft? Front is near tripple and rear is nearly 4x the standard rates. I am yet to hit the front bump stop, tested with the cable tie method. I forgot to mention that I have extended top hats up front.

Car pulls to the left very slightly if you start straight, but will pull right if you start right a little bit.

Now the real question i'm asking is, where is my front grip going and why?

My spring rates and swaybars are unarguably giving me plenty of load over the front so i've come up with a few scenarios, I am asking which of them is possible or likely to be a significant problem:

a) Dynamic front alignment due to a bent front component causing a loss in grip. This could give me non linear total toe changes with steering angle.
b) Losing grip from alignment going out of spec with chassis flex. (I can visually see the chassis bend inline with the firewall if I jack off the front x-member, also, my doors don't line up at all when one side is on stands and the other is still on the tyre).
c) Poor front castor. Turn in is (relatively)excellent when the corner is on a rise.

Understeer is apparent on corner entry, and then whatever understeer I encountered on turn-in, I keep mid-corner, only easing up if I let off the throttle or start winding back on steering . There is some on-power understeer but it's a different beast and expected from my open diff.

Am I correct in saying that any loss of alignment in the rear will give me less understeer not more, due to giving up grip in the rear?

Thanks again.

 

Any reason for such a massive spring rate increase over stock? It certainly seems much too much for a road car application. Too much spring will cause problems with the contact patch being unable to faithfully follow undulations in the road surface (so the contact patch excessively loads up then excessively unloads over undulations, i.e. grip , grip loss, grip, grip loss etc etc...). Not such a problem on the track but won't help on the road.

If the springs are too stiff for the surfaces on which the car is driven then you can’t really fix it by altering the damper rates, though you might be able to make it less bad by backing the dampers off (at the possible danger of making the suspension ‘floaty’, which causes it’s own problems).

Any pull will I think be related to unequal side to side geometry (though unequal corner weighting could have a very slight affect, as could tyre ‘conicity’). Worn bushes may cause an alignment setting(s) to change on the move ( change moment to moment, or more of a consistent change from that measured statically), and this may also cause a pull (that may change in different conditions), even if the alignment change is on the rear. This may also cause erratic handling.

How low is the tyre aspect ratio? With a lot of camber and low aspect ratio with stiff sidewalls and high pressure (especially with a wider tyre), you may in effect have a small contact patch, i.e. most of the chassis weight is being carried on the inner part of the tread and little on the outer part of the tread. In effect you may have less 'rubber on the road' due to static camber (and obviously more so on one side of your car than the other).

If so then when you turn in you may not have enough front grip for a sharp response, and then (with such massive rate springs and thick rear ARB) you don't get enough body roll to counteract the large static camber angle on the outside front wheel, so you're still cornering on a small contact patch. Considering your very unequal front camber angles I'd expect the handling to be somewhat different in left vs right hand corners?

If this analysis is correct I'd expect turn in to be somewhat better in one direction than the other, possibly better to the right because a lot of turn in front grip comes from the inside front wheel (largely because caster angle causes the steered inside wheel to lower relative to the chassis, pressing harder against the road surface, and the outside wheel to rise…), which in your case has better camber on the right wheel (and better caster, which reduces camber on the inside wheel as you steer, but increases it on the outside wheel), which is the inside wheel in right hand corners.

Either way, both front wheels are important for sharp turn in. It's important that they both have good grip when you turn the wheels, and very high static camber works against this because it effectively reduces contact patch size, i.e. even if all the tread width is in actual contact with the ground the contact patch will be heavily loaded on one side and lightly loaded on the other, whereas the ideal is for the whole contact patch to be evenly loaded.

Rubber grip decreases with lesser loading and increases with greater loading, but grip doesn't increase at the same rate as the loading increases, so with a heavily cambered wheel you don't lose X grip at the lightly loaded part of the contact patch and pick up X grip at the heavily loaded part, you pick up X- at the more loaded part of the contact patch, i.e. you lose grip with an unequally loaded contact patch.

Camber will provide some increased steering response and cornering grip due to an affect called 'camber thrust', but not if the camber is so great that it's seriously affecting the effective contact patch size. You need 'rubber on the road' before anything else, you may then be able to tilt the wheel somewhat to gain some camber thrust, but if you go too far you’ll lose more grip from uneven contact patch loading than you’ll pick up from camber thrust.

I'd also expect (well, wouldn’t be surprised if ) mid corner understeer to be worse in right hand corners (as weight transfers to the outside wheel), if you're not getting the left front wheel to near vertical when the body rolls (or doesn't roll!). I would think your car has very high roll stiffness and doubt it rolls much at all, the stiff rear ARB will limit roll of the whole chassis both front and rear (not just at the rear), as will the high spring rates front and rear.

Despite weight transfer making the dynamic camber angle of the inside wheel less important than the dynamic camber angle of the outside wheel, inside wheel camber still has importance at lesser amounts of lateral weight transfer before the inside wheel is substantially unloaded. If you have excessive static camber then as weight transfer unloads the inside wheel it's dynamic camber angle (and thus grip) will be even worse than it otherwise would be, meaning that at even modest amounts of weight transfer you'll be relying excessively on outside wheel grip.

This will affect front / rear grip balance leading up to max lateral weight transfer (at which point very little weight will remain on the inside wheel, so it's camber is then fairly unimportant), but before you reach this point you'll have less front grip relative to rear grip than you need to prevent understeer.

So, I can se at least two theoretical camber related reasons why you may be getting understeer in either direction, though I’d expect the exact nature of the understeer to be somewhat different in left vs right hand corners??

What you want is for more of the total weight transfer to occur at the rear than at the front, causing the front wheels to be more equally loaded in corners than the rear wheels (this moves grip balance toward the front and away from the rear). Your set up (with a very stiff rear ARB and stiffer rear than front springs) should do this in spades. This is why I mostly suspect your camber angles (and to a lesser degree your unequal caster) are more likely to be the problem, though I could be wrong.

Of course your spring rates may just be so high that the car is having trouble maintaining grip on anything less than a perfectly smooth road, and this is showing up first as severe understeer, if you attempted to push hard through the understeer you may get a snap oversteer…?

I don’t think that dynamic front toe change is likely to be caused by a bent component, or that dynamic front toe change is likely to be the problem (unless perhaps an alignment change caused by a worn ball joint?). Dynamic rear toe changes due to worn bushes might be more likely (?), especially as we know there is a rear bush problem.

If you can actually see the chassis twist when you jack the chassis then you have a significant problem. You need a good tower brace to lessen this. Braces do make a significant difference, but only if very rigid, and this includes the attachment brackets (the bar itself should also be free of any bends if possible, but if bends are needed to clear other components then the bar itself needs to be very substantial to cope with bending forces).

I’d be surprised if the front of the chassis being ‘soft’ would increase understeer, but it will affect steering and handling response.

I’m sure it won’t be helping, but not sure exactly what it might be doing. You do want caster to be equal (or near), and more is better for steering response and feel (associated with the increase in ‘trail’ created by increase in caster). Higher caster is also beneficial for steered camber change at both the inside and outside front wheels (inside / outside relative to corner direction), but if you have excessive static camber on the outside wheel then higher caster will make this particular problem worse when that wheel is steered (i.e. increase steered camber even further). Higher caster generally allows lesser static camber angle to be used because it increases desirable steered camber changes (caused by caster), making higher static camber unnecessary, which is a ‘good thing’.

High camber angles are a compromise to account for less than perfect suspension geometry (‘double wishbone’ suspensions typically need less static camber than Mac struts due to having a better ‘camber curve’ with suspension motion, which also manifests in roll), you want to use as little as you actually need to have. Keep in mind that the more camber you have the more unevenly loaded the contact patches will tend to be, and this will also affect braking performance (especially if the nose dives substantially under hard braking, gaining even more camber).

You can’t make a blanket assumption, it depends on exactly what the worn bush does to the momentary dynamic alignment. A worn bush could increase understeer or oversteer, but I would think it most likely to be associatred with what the bush does to momentary dynamic toe more than any other factor (could be wrong).

Your understeer sounds to me more like a lack of front grip that you need to address by increasing front grip, not by decreasing rear grip. Sometimes (often) an understeer can be caused by ‘too much’ rear lateral grip that needs to addressed by decreasing rear grip, but only if front grip can’t be further increased to match rear grip (or be greater than rear grip if you want oversteer).

It’s often possible to deduct rear grip and effectively add that grip to the front, which is typically more or less what happens if you increase rear roll stiffness to reduce understeer (increasing rear weight transfer and thus decreasing front weight transfer), but in your case you already have a very stiff rear end that will have heaps of roll stiffness already, making it even stiffer is I suspect not a good idea.

 

Thanks for your reply.

Tyres are 195/55 with not so stiff sidewalls. It definately doesn't feel like I am skidding across the road, the corners I usually travel on are very smooth. I chose heavy front rates so counter diving under braking, then just chose a rear to give me some front grip.

I played with damper settings yesterday and managed to get it feeling a fair bit better - front is about half-way, rear is full stiff.

Turn-in feels much more solid, and the car a little more enjoyable.

I can easy get some understeer by turning in more during a changing radius corner - what I am after is instead for that steering input to induce a little versteer instead, which I can then counter with throttle. At the moment it feels like there just isn't enough grip on the front to do that, instead it understeers.

Now, I have 2mm of toe-in on the rear each side. Guy at the alignment shop put it on there to 'reduce camber tyre wear' on the rear - I wasn't in the mood to argue, i'll be getting a good alignment when everything is sorted anyway. So i've got a compressed outer rear gaining even more toe-in, and a worn trailing arm bushing doing god knows what. My logic tells me that the more toe-in on the rear, the more the rear axel will oppose rotation (as the rear is trying to rotate the car the opposite way of the steering).

So I think my list is:
Find front bent parts, and adjust height until around 1.5-2 degrees of front negative camber.
Rethread radius rods to get around 4 degrees of castor.
Fix rear trailing arm bushing.
Zero toe all round.

Hopefully this will give me more front grip with some castor, and reduce understeer by fixing rear alignment issues.

I hope i'm making sense!

 

That's OK. Don't consider any of my responses to be definitive, I'm just jotting down all the things I can think of that might have some bearing.

I still think you have too much spring for a road set up, and maybe a lot even for a race set up. I don’t know how stiff a typical racing sedan’s springs would be, but from what I gather the tendency these days for racing sedans etc is toward lower rates than were commonly used some years ago, with more emphasis on ARB rates and damper settings. This will tend to make the car a bit less responsive, but improve grip over undulations etc. ‘V8 Supercars’ seem a case in point, just watching them you can see the springs aren’t all that stiff, they move up and down on the springs quite a bit, but on the other hand BTCC, DTM and some similar cars seem to do so a lot less…?

I didn’t mean to suggest you were “skidding” in any extreme sense, just that front grip might not be what it could be because of camber, and this may be affecting your turn in and front / rear grip balance. Your tyre size seems a good choice for a road car, but I think my comments on higher pressures and high camber angle still apply to some degree.

So you had your Konis on a softer setting? With those springs I think you're going to have to max them out (and they still might not be stiff enough to properly control the springs). My CB7 has stock springs, and I have the Konis at max stiff front and rear. The harder they are the better I like the handling, but it's not ideal, to some degree I'm using the dampers to make up for the springs being to soft, but having said that the handling is quite good and very predictable even over bumpy surfaces (if a little on the harsh side!). Konis are great dampers!

Increasing the front dampers to max stiffness as well as the rears ought to sharpen the turn in even further, as should fitting a (good) front tower brace. I’d also suggest stiffer front and rear upper damping mount rubbers (maybe replace with poly items or pre-load the existing rubber ones).

The first thing the chassis ‘sees’ as far as roll stiffness is concerned (or bump and rebound stiffness for that matter) are the dampers, and if the dampers are attached with soft bushes this affects the initial transient roll stiffness, dulling response. This may be more problematic with stiffer set ups than softer set ups(?), as the dampers will have less control over the springs, roll motion and weight transfer until the rubbers load up (in both bump and rebound motion).

Still sounds like a grip problem generated (or failing to be generated) at the actual individual front contact patches rather than a distribution of weight transfer problem (i.e. front / rear roll stiffness). With a very stiff set up the transition between understeer or neutral to oversteer may be very abrupt, so you might not want it too biased toward oversteer.

Alignment shops tend to add toe to ‘counteract’ camber wear, but I can’t really see how this can work. It seems to be adding one source of wear on top of another, the affect of one multiplying the other.

Rear toe in ought to increase understeer, but with worn rear bushes you can't know what's really going on back there.

With the rear suspension, because the forward lower control arm is shorter than the rearward lower control arm (outer end of a shorter arm moving in a tighter arc than that on the longer arm), the suspension will increase toe-in with bump, and if the suspension is at stock height (with the control arms more or less parallel with the ground), it will also gain toe-in with rebound motion.

If you lower the suspension so the arms point up toward the hub, then bump will still cause toe-in, but rebound motion will cause initial toe-out, then return to zero, then toe-in with further rebound (though roll would have to be very substantial for toe to go past zero). The toe change on the IR with rebound isn’t exactly linear, but it’s no big deal if rear roll stiffness is significantly increased relative to front roll stiffness because the inside rear should then unload a lot when cornering (reducing it’s grip and influence on the dynamic). Note that if the rear ARB is very stiff the IR needn’t be at full droop to be completely unloaded (the stiff ARB holds it up, even if the main spring isn’t at full droop).

[quote=string]So I think my list is:
Find front bent parts, and adjust height until around 1.5-2 degrees of front negative camber.

If you raise the front you should raise the rear to match. This is for handling reasons as well as cosmetic. I'd be shooting for 1.5° to 2° max on a road car (especially if roll is minimal at most, and doubly especially with a double wishbone suspension). Mine is at about 1.5°. You want less on the rear. You do want camber to be equal side to side, and for this you may need camber adjusters as the damage is likely to be in the chassis itself.

Caster can be adjusted by shortening one of the radius rods to increase caster on that side, but you do need to figure out how much shorter it needs to be. This can be figured out with a schematic of the suspension, but it’s not all that simple.

Yes to all three.

You don't "rethread" the radius rods, you cut the smaller OD section farther along the rod. This can be done on a lathe, but with care can also be done with a grinder and careful filing (make sure the inside corner of the 'shoulder' is slightly radiused, a sharp corner is a stress riser). As I said above, you do need to figure out how much to shorten the radius rod by. Get professional advice if you're unsure, but the average suspension joint may not be able (or willing?) to assist.

Just how much shortening of the RR increases caster by how much very much depends on the geometry of the whole suspension (including some geometries that aren't normally considered to be 'suspension geometry', such as exactly where on the control arm the RR attaches etc). From memory, on my CB7 Accord I gained approximately 1° of caster from shortening the RR by 1cm, but can't recall for certain. I figured it out on the computer (using ‘CorelDraw’) with carefully measured schematics of the suspension layout.

While you're in that neck of the woods, you might want to consider stiffening the front RR bushes by cutting the 'rearward' bush (the one behind the subframe) down to the same length as the forward bush (in front of the SF). This also gives a bit more caster angle. If you do this you also need to shorten the crush tube by an equal amount.

By the way, when you had it aligned did they give you a measurement for side to side wheelbase? I’ll bet it’s shorter on the right side (related to lesser caster on that side).

Also, just so you know, if you increase caster angle significantly you will ‘pull’ the front wheels noticeably forward in the wheelarches (increasing wheelbase), which can look a little strange. My car is like this, but it doesn’t bother me in the least.

You make sense when you use the beer symbol! You can send beer if you want, I'm just up the road from you near Taree.

 

Lower the tire pressures in the front as they will heat up and expand when driving
Raise the tire pressure in the back to a few psi under max recommended to reduce rolling resistance and enhace the thrust angle.

Replace bushings with real oem bushings unless your tracking it or lubing it every month

Wider wheels with a good stiff tire like yokohama avs es100's or s drives will fix the turn in along with some ball joint lube or a new camber kit :SHINSTU grease!

The geometry of the suspension is raped when you lower the car, the mechanical advantage becomes limited and will create a sense of wandering, and bumpster

Atleast compromise and make the RLCA flush with the rear subframe if it already isn't then fix the rake accordingly so it doesnt look 2 stupid

New tires will probably make all the difference since your camber has been fuct, uneven wear can screw everything up real fast