First Time DIY Alignment, Can someone check my logic? Options

[bbrock]

So first time doing a DIY string alignment. Camber adjustment went well, but I want to make sure I'm doing the toe correctly. FSM shows these specs for front toe:



This should translate to .33 degrees of toe IN which according to a chart I have, is 2.5 - 3.0 mm difference front and rear for a 16" diameter wheel as measured between measurement points. But this is for TOTAL toe so my target is about 1.25-1.5 mm longer distance from string to front of the wheel than at the rear for EACH wheel.

Then at the rear the FSM calls for +15' toe at EACH wheel which is about 1.75mm difference front to rear as measured at the string.

Am I deciphering all this correctly?

[Superhawk996]

@bbrock

As DIY for use to get to real alignment you are shooting for ~ 1/8" of toe in as a general guide. Just make sure it is toe IN. Zero toe or negative toe will be squirrely and you have nothing but highway between you and a real alignment.

You lost me with description " target is about 1.25-1.5 mm longer distance from string to front of the wheel than at the rear for EACH wheel."

Toe IN is shorter distance between the front tire centerline vs. the rear centerline. I usually spray a light coat of white paint on the tire tread, and scribe a very thin line with a machinist gauge like a scribe to establish that cenerline.

You will find this abhorent (painting new tires). There are other home brew gauges and other tools that measure from outside of front tires to outside of rear tires to get the same measurement that make do without paint. I've done the paint thing for so long it is just the way I do it and the light mist of paint quickly wears off with road use and rubber flex.

[bbrock]

You lost me with description " target is about 1.25-1.5 mm longer distance from string to front of the wheel than at the rear for EACH wheel."

Toe IN is shorter distance between the front tire centerline vs. the rear centerline.

Right. So if you have a string parallel to the centerline on the outside of the wheel, the distance between the string and front of the tire should be longer to have toe IN. I'm using the string method to make sure the thrust angle is correct when I'm finished too.

1/8" = 3.175mm so that would be ~1.5mm in toward centerline on each wheel, so that fits the FSM spec.

Is it common to have more toe in at the rear than the front?

[ClayPerrine]

This is what I use to set toe.....


(IMG:http://www.914world.com/bbs2/uploads_offsite/forums.pelicanparts.com-1143-1622050665.1.jpg)

[anderssj]

From my notes (not sure of original source, but somebody here on 914world, I'm sure):

Refer to the chart below to convert to minutes or degrees of toe. There are 60 minutes to one degree. A good rule of thumb is 1/16 inch toe in per wheel front and 1/8 inch toe in per wheel rear for a car doing autocrosses/time trials.

TOE-IN MEASUREMENTS BASED ON 15 INCH WHEELS

Toe measurement 1/16 inch or 0.0625 inch = Toe angle 8.95251minutes
Toe measurement 1/8 inch or 0.125 inch = Toe angle 17.9051 minutes
Toe measurement 3/16 inch or 0.1875 inch = Toe angle 26.8578 minutes
Toe measurement 1/4 inch or 0.25 inch = Toe angle 35.8106 minutes

CAMBER:

NOTE: Camber measurement is performed after measuring/correcting toe-in.

• Use a carpenter's square and place against the wheel with short side of the square on the floor.
• Ensure the long side is vertical (tape long side to fender arch as required).
• Measure the distance between the square and the lower rim edge in 32nds and record.
• Measure the distance between the square and the upper rim edge in 32nds and record.
• Subtract the lower reading from the upper reading and refer to the chart below to get the amount of negative camber.

NOTE: If the lower dimension is smaller than the upper dimension you have negative camber, otherwise it is positive camber. Refer to the chart below to convert to minutes or ° of camber. There are 60 minutes to one degree. Camber settings will depend on what type of tire used and how the car is to be driven, but should probably never be positive!

CAMBER MEASUREMENTS BASED ON 15 INCH WHEELS

Camber measurement 1 - 32nds or 0.03125 inches = Camber angle 7.16201 minutes
Camber measurement 2 - 32nds or 0.0625 inches = Camber angle 14.324 minutes
Camber measurement 3 - 32nds or 0.09375 inches = Camber angle 21.4861 minutes
Camber measurement 4 - 32nds or 0.125 inches = Camber angle 28.6483 minutes
Camber measurement 5 - 32nds or 0.15625 inches = Camber angle 35.8106 minutes
Camber measurement 6 - 32nds or 0.1875 inches = Camber angle 42.9731 minutes
Camber measurement 7 - 32nds or 0.21875 inches = Camber angle 50.1358 minutes
Camber measurement 8 - 32nds or 0.25 inches = Camber angle 57.2987 minutes
Camber measurement 9 - 32nds or 0.28125 inches = Camber angle 1.07436°
Camber measurement 10 - 32nds or 0.3125 inches = Camber angle 1.19375°
Camber measurement 11 - 32nds or 0.34375 inches = Camber angle 1.31315°
Camber measurement 12 - 32nds or 0.375 inches = Camber angle 1.43255°
Camber measurement 13 - 32nds or 0.40625 inches = Camber angle 1.55196°
Camber measurement 14 - 32nds or 0.4375 inches = Camber angle 1.67137°
Camber measurement 15 - 32nds or 0.46875 inches = Camber angle 1.79079°
Camber measurement 16 - 32nds or 0.5 inches = Camber angle 1.91022°

[Superhawk996]

So if you have a string parallel to the centerline on the outside of the wheel, the distance between the string and front of the tire should be longer to have toe IN.

Correct.

Is it common to have more toe in at the rear than the front?

Yes. What you don't want is toe out on rear suspension.

In a corner, with lateral load applied, the trailing arm will tend to deform (flex) toward toe out. Toe out on the outside corner wheel will increse yaw moment in a non-linear fashion tending toward instability. Therefore, you start with more static toe in. Semi Trailing Arm arms usually offer toe gain as the suspension is compressed (vertically) helping offset any toe out caused by lateral load deformation.

[Superhawk996]

This is what I use to set toe.....


(IMG:http://www.914world.com/bbs2/uploads_offsite/forums.pelicanparts.com-1143-1622050665.1.jpg)

(IMG:style_emoticons/default/drooley.gif) (IMG:style_emoticons/default/wub.gif)

[Superhawk996]

@bbrock . Go get a real alignment after the DIY. You should only need to get close enough to not chew the heck out of your tires on the trip to town.

[bbrock]

Thanks all. I'm not seeing anything to indicate my calculations were incorrect, so I'll carry on.

BTW, I've found the video that Dan produced and the spreadsheet and online toe angle calculator that are linked from the Youtube page EXTREMELY helpful. (IMG:style_emoticons/default/beerchug.gif)

https://www.youtube.com/watch?v=ILPv_skgtzE

[Mark Henry]

I used a tilt box to set my caster and camber, easy-peasy, but of course it took way longer to set up my 4 corner level than to do the deed.
I made an adjustable slide tool out of wood to set my toe in, again fast and simple.

My tire wear is normal.

[wndsrfr]

Check out the alignment setup here....you can just barely make out the strings they're using for measuring....
http://www.914world.com/bbs2/uploads/post-222-1622163560.jpg

[jmitro]

@bbrock . Go get a real alignment after the DIY. You should only need to get close enough to not chew the heck out of your tires on the trip to town.

sounds like he's using SmartStrings, which is what I use.
with some practice and careful measuring, shouldn't be any reason to get a computerized alignment .

[stownsen914]

I've been aligning my cars at home with strings and a smart camber for years. It's a completely valid and accurate way to align if you are careful. A couple comments:
Make sure your floor space is flat. Even is you're only doing toe, it's still important. A wavy floor can easily have one corner of the car higher or lower by 1/2" or more. Toe does change with ride height.
Flat and level are of course even more important if you are measuring camber.
Agree on the 1/8" of toe in on each rear corner. On the front I might aim more for 1/16" total toe in for a street or dual use car. 1/16" per front corner sounds like too much. On the racecar I go for 1/8" total toe OUT in the front (not good for a street car though).

[bbrock]

Thought I might post the numbers (in degrees) I wound up with. Have taken it out for a couple drives and I really like how she rides. I got lucky on my floor level. My garage has a floor drain in the middle that I thought would cause problems getting the car level. Checking with an eight foot level, I found that by centering the car over the drain, the wheels were dead level with each other.

(IMG:http://www.914world.com/bbs2/uploads/post-20845-1622302344_thumb.jpg)