stupid fwd alignment question

So im finally doing some suspension rehab on the daily. 02 mazda protege5 If it matters.

Want to align it when I'm done, as it is needed for work Monday morning, and next week is lookinglike a 2k week.

Im planning on using the mazdaspeed specs, as im dropping it a little and anticipating sway bar upgrades in the near future.

The problem lies in the specs. Toe is all measured in degrees. My tools measure in inches. And fractions. At least for toe.

So what the hell is the conversion?

If there isn't one, whats a good setting for tire wear balanced with handling?

Thanks. Y'all are the only people i trust to steer me right.

One is half of the other, and I can never remember which is which. I usually try to find specs of something called out in both formats to refresh my memory.

Use trig and convert degrees to radians?

Tire is say...27 inches tall. If I turned it 360 degrees the leading edge would go around pi*d or about 85 inches. Divide that by 360 and you get a smidge under a quarter inch per degree. This is about right and my go to baseline setting. 1/4 toe in.
Now someone prove me wrong.

Noooooooo 1/4" is huge for pavement.

In is for RWD.

FWD is usually 0 or a touch out, because when you apply power it pulls them in (rear steer).

That said there is no substitute for a Laser 4 wheel alignment by a competent technician.

Find someone who cares and is not just flagging hours and knows what they are doing (Real Racer).

1/4 inch of toe in? I'd call that about 3/16" too much on anything built after about 1940. I'd say, if you are doing the adjustment with a tape measure, string or other handheld device, get it as close to zero as you can, because you'll probably be off 1/8" anyway.

1/16 to 1/8" of total toe in is good for street use. If you want to get a little racy, try to get toe close to 0...

Zero the toe by tape measure. Drive car to work, and take in for pro alignment when time allows. Giving yourself +/- 1/8" on the toe will give you a car that's drivable, especially given that it's a FWD car.

At worst it's an 1/8 in, which will give you a slightly sluggish but perfectly controllable steering feel, or an 1/8 out, which should be sharp on a FWD but not twitchy.

I definitely second the opinion(s) of those advising you to shop around for an alignment shop (and especially an alignment tech) that understands performance alignments and cares.

For street cars, I like a wee bit of toe-in - like 1/16 or 1/8. Helps most cars track straight.

Some simple soh-cah-toa trig will get you the conversion.

per the googles … ( conversion for toe alignment )

http://robrobinette.com/ConvertToeInchesToDegrees.htm

http://bulletproofsteering.com/alignment_conversion_chart/

Just do the conversion once and write the #s on your toe plates. Remember to use the distance between the measurements... not the size of the tire.

Yes, 1/4 is too much for performance FWD. It's on the high side of safe for normal street cars driven by normal people.
I was just laying out the procedure for figuring out how to covert degrees to inches when doing it at home. What are the MS specs for the car?

me and math don't mix too good. I actually almost didn't graduate high school because of that....

so heres the specs that I have.

FRONT / SPEC / TOL. +/-

Left camber / -0.97Deg. / 1.00Deg. Right camber / -0.97Deg. / 1.00Deg. cross camber / 1.50Deg. left caster / 2.02Deg. / 1.00Deg. right caster / 2.02Deg. / 1.00Deg. cross caster / 1.00Deg. Total Toe / -0.10Deg. / 0.10Deg. left SAI / 12.98Deg. right SAI / 12.98Deg. cross SAI / (this one is missing info)

REAR / SPEC. / TOL.

left camber / -0.80Deg. / 1.00Deg. right camber / -0.80Deg. / 1.00Deg. cross camber / 1.50Deg. total toe / -0.10Deg. / 0.10Deg. Thrust Angle / 0.80Deg.

The factory specs are actually not too far off an ideal performance setup. You'll want more front negative camber - like -2~-2.5, and maybe more rear negative camber, but the factory -0.8 is not a bad setting.

As for toe, I'd recommend zero all-around, unless you have slow steering - then you can use a hint of front toe-out to make the car leap into the corners a little faster, at the expense of greater tire wear.

kylini wrote: Use trig and convert degrees to radians?

For toe, I measure off the rim in line with the center of the axle. Measuring off the tire introduces too much variation. I use a steel rule in millimeters and measure between my string and the front of the rim and the and back of rim, then take the difference.

For camber, you can use Excel to create spreadsheet to convert to degrees. Think of columns A, B, C, D on a spreadsheet. Just copy down the spreadsheet and change B for different measurements.

To figure angle for camber:

A: (rim diameter x 25.4mm) or use just use inches

B: actual measurement from rule (whatever units your instruments measure)

C: =TAN( B / A )

D: =Degrees ( C )

Now you can measure the difference in between the top and bottom of your rim (B) and relate it directly to degrees for camber (D).

Front toe should be close to zero for tire wear. Add slight toe-out for better turn-in response. No more than 1/8 total toe. 1/16 total would be better for a street car. The more toe out, the car will become less stable and will tend to drift around on the road. This requires constant attention to keep you going in the right direction.

Just set the toe at "0" and be happy. That is what I ran on my ZX2SR.

Look at it this way. Accelerating tends to toe in, decelerating tends to toe out.

so compromise.