Wheel Alignment Perfect; car still does not go straight

[eastla]

anyway, what sasso is getting at, is that it;d be worth checking that the shocks are set to the same amount of "clicks" at each wheel. this is easy to check with the little allen ket tool they would have supplied you.

I do have the tools that came with the coilovers.
Could someone please point me to some instructions on how to do it.
I have been searching for the last half hour with no luck as yet.
Also, can this all be done by jacking up the car; or do I need to pull the trim out to do this?
I have no idea how to remove the trim.

[JBT]

I still think the problem is being caused by zero front toe. There may also be a setback condition exacerbating it.

[eastla]

I still think the problem is being caused by zero front toe. There may also be a setback condition exacerbating it.

Um excuse my ignorance; but what does setback mean?

[JBT]

Alignment terms.

[eastla]

Alignment terms.

Thanks ;)

[eastla]

Had my NC wheel alignment done as car was pulling left; still does the same thing after alignment.

I am finding that it tracks slightly left particularly as I come off power.
Under full accerleration it goes pretty straight, same when just coasting.
The main problem is as I come off minimal power.
Over all though it seems to always pull very slightly to the left.
I read in another thread that it may have something to do with large amounts of camber and zero toe combination.

I have Tein Super Streets on and also Whiteline adjustable sway bars.

Any advice or guidance would be much appreciated.


Alignment Settings:

Front:
toe 0mm both sides
Camber L-2.26 r-2.25
Caster L 7.46 r 7.56


Rear
toe L 1.1mm r 1.2mm
Camber L -2.04 r -2.02

Looking at those specs, 0.1mm on the rear toe and that small difference in caster would do it.

I would throw it back on the same machine and see what it says. I have had similar problems. Due to the crowning on our roads (at least, here i Sydney on alot of them) the cars i align generally get similar caster specs but reversed so that it will naturally go against the slight crown. Keeps the wheel straight. Essentially, those specs (especially the rear) are steering it left. At the moment, the rear is steering the car.

Just reading over what has been said, and MxJadeMonkey has already mentioned it, but i guess that confirms it.

So just to clarify.

I currently have the following caster settings:
Caster L 7.46 R 7.56

You suggest I go to the aligner and ask them for the following caster setting?
Caster L 7.56 R 7.46

And I should leave all camber and toe settings as they currently are?

[eastla]

As for the caster, that is correct. I would run the left hand side with more caster.

Camber front and rear is ok. You'll get some camber thrust (where it will pull a little bit over bumps if the bump is on one side and not the other) but that's it. It's the price you pay for more camber.

I would get them to re-do the rear toe though. They should be the same. If they can get it that close, they can get them exactly the same. Anything else is being lazy. Trust me, i should know because i do wheel alignments When i'm feeling lazy or it needs to be gone 20 minutes ago, 0.1mm difference would be fine. If i was paying for it to be done, i'd expect it to be the same.

Thank you VERY much for the advice.

Im gonna get this done, hopefully this week and Ill let you know how it goes.

Cheers

[JBT]

By the sounds of it you have two completely different problems. One is the tracking the road camber, the other is inconsistent tracking from off to on power.
........... too little toe in front or rear will cause straight line instability....

That's my thoughts. Static zero toe at the front will be toe out when the car is moving and can cause the instability problems.

The normal measurement for toe is shown in mm. About 2mm total toe in (i.e. 1mm per side) both ends will work fine. 0.1mm difference in toe from side to side will be undetectable.

[eastla]

Your other and more concerning problem is that it tracks differently when you accelerate and brake.

I may have not explained this properly.
Under acceleration it goes pretty straight; eventually it starts to pull a little to the left though.
Under braking the car is dead straight.
When I come off light throttle the weight transfers forward and it can send me a little left.
It is not a dramatic thing; just seems to speed up the rate it veers to the left.

[eastla]

JBT, So where is the MM of toe measured from? I thought it was the difference between the front of the wheel and the back measured from a line parallel to the car. If you have bigger wheels, the same number translates to less angle, and angle is not ambiguous in this case, you don't measure camber in mm.
If its combined toe then I have 3mm on each side making 6mm total, but on a 14"wheel, may be a bit much but its so hard to do by yourself, , would have liked 4mm total, but the car handles well so I'll leave it.

Your other and more concerning problem is that it tracks differently when you accelerate and brake.

I may have not explained this properly.
Under acceleration it goes pretty straight; eventually it starts to pull a little to the left though.
Under braking the car is dead straight.
When I come off light throttle the weight transfers forward and it can send me a little left.
It is not a dramatic thing; just seems to speed up the rate it veers to the left.

Ok rule out the brakes then. The fact that weight transfer makes the car pull says that something is not even left and right, could be alignment or shocks or springs even. Your alignment is pretty damn close left and right but you could always try, not forgetting that once you sit in the car you completely change the numbers. Too little rear toe in is still my suggestion.

A friend of mine DavidM who has quite a bit of experience drove my car and seems to think it is pretty close to perfect.
He thinks I am crazy to try to change things.

Im off to Winton on Sunday; I think Ill see how things go and consider this problem afterwards if it still is bugging me.

Thanks to all of you again for all the pointers.

[JBT]

JBT, So where is the MM of toe measured from? I thought it was the difference between the front of the wheel and the back measured from a line parallel to the car. If you have bigger wheels, the same number translates to less angle, and angle is not ambiguous in this case, you don't measure camber in mm.

It can be given in degrees, mm or inches. Yes, degrees is a constant but what is a typical setting in degrees? 0.15 degree? 0.25 degree? The wheel size doesn't matter (for lineal measurement) as long as you don't change the rolling diameter for a particular vehicle.

Most wheel aligners show the toe result in mm or (in the past) inches. I don't think I've ever seen one in degrees.

If its combined toe then I have 3mm on each side making 6mm total....

It is combined. 6mm is far too much IMHO. You'll be chewing out tyres.

[JBT]

From the Whiteline website:

Toe is the difference in distance between the front and rear of the tyres. Historically front toe was the only thing that could be modified as rear wheel drive vehicles using a rigid axle had fixed rear toe, usually neutral. Many modern front wheel drives have rear toe adjustment as standard which is critical to their handling.

[JBT]

The measuring instruments attach to the wheels but the measurement is given in mm. Maybe the computer calculates a rolling diameter. The NC wheel/tyre size is 205/45 17\" which is much bigger than NA.

[JBT]

No, I think the rear toe is fine. I think it is a problem with his front setting. It is set to zero which will be toe out (undesirable) when moving.

Mine is running:

Front

2.5 mm total toe in
0.5 - 0.75 degrees negative camber
5.5 degrees castor

Rear

2.1 mm total toe in
1.25 - 1.5 degrees negative camber

It runs dead straight with no instability and handles very well indeed.

[eastla]

No, I think the rear toe is fine. I think it is a problem with his front setting. It is set to zero which will be toe out (undesirable) when moving.

Mine is running:

Front

2.5 mm total toe in
0.5 - 0.75 degrees negative camber
5.5 degrees castor

Rear

2.1 mm total toe in
1.25 - 1.5 degrees negative camber

It runs dead straight with no instability and handles very well indeed.

Looking at your front alignment I would have expected it to have more understeer than I like.
With toe in and such little neg camber etc.

I had a similar alignment to that when I first got the Tein's installed.
It handled excellent!
But I could not get the back out no matter what I tried.
Also, it did not turn into corners as quickly as I wanted.
I never took notice if it went straighter or not though?

The current setup I have is MUCH closer to my perfect setup as far as handling goes.
Turns into corners much faster than before with less steering input.
Still very stable under brakes.
Still pushes its nose under extreme cornering mid corner which I like; does not feel snappy.
My tires now have approx 6000km on them which could also explain a bit of the difference in characteristics.
But when pushing very hard on power early I can slide the back out slightly mid corner now. That is what it should do IMO.

I am presuming that your car is pretty stock?
Your alignment from memory is pretty much to Mazda spec so I am sure it is going to handle brilliantly. After all its an MX5

Its just that the handling characteristics can be changed and in my opinion improved with the right alignment.

Obviously I still have a slight problem; the slight veer to the left. But this does not negatively impact on the handling around corners.
Seems to steer brilliantly left and right and is AWESOME fun to punt around slow and fast corners.