Alignment Spec Questions, another alignment thread Options

[John]

I have a few questions that some of you smart people out there might be kind enough to answer for me.

I am wondering how you convert angular toe-in (per factory specs) to inches of toe-in.

I could convert angles to inches if I knew where to measure. Is the toe-in measured at the rim, at the tread, at the sidewall?

Or am I reading the chart from the factory manuals incorrectly?

What are the "factory" settings for:

Front Caster
Front Camber
Front Toe

Rear Camber
Rear Toe


On another note, RIDE HEIGHT.........

The front ride height is measured as the DIFFERENCE between the center of the torsion bar and the center of the wheel rim.

How is the rear ride height supposed to be measured, and what is the 'spec'?????

Thanks for replying.

[Joe Ricard]

I guess it depends which car are you going to align.
Are you going to do this yourself? Refer to the other thread for the tools to use. and the procedures others are using.
Street alignment is different than autocross or even race track (high speed stuff).
Street gets toe in 1/16" difference from front of 15" rim to back edge of rim. do the same for the rear it will be fine.
Camber.... Hmm most cars with stock rubber center camber plates could stand all the negative camber you can get keeping both side equal. Well maybe 1/2 degree negative if you drive it like your granny.

[Dave_Darling]

Stock camber is 0 degrees front, -1/2 degree rear. I think those were both +- 1/4 of a degree, or was it 1/2 degree?
Stock caster is 6 degrees, I believe.

Unsure of where the "inches" of toe is typically measured. But toe adjustments should be very small numbers...

Note that you can get a lot more traction in the curves with more negative camber than the stock settings.

--DD

[John]

Thank you Joe and Dave for replying.

I was hoping for a little more info, but it is a start.

I may have not been clear enough. I was looking through my workshop manual, because I thought it had "stock" information. The ride height procedure for the front seems straight forward (WAY HIGH, but straight forward).

There are 60 minutes in a degree.

I found the stock settings of:

Front wheel camber ---> 0 +/- 20' -----> 0 +/- .333 degrees
Max difference 20' ----> .333 degrees

Front Caster -----> 6 +/- 30' -------> 6 +/- .500 degrees

Total Front wheel Toe (in) -----> +20' +/- 10' ------ 0.333 +/- 0.166 degrees

I did not find individual front toe dimensions, but knowing that total toe is equal between each front wheel, then for each wheel they should be:

Front toe (in) --------> +10' +/- 5' ----- 0.166 +/- 0.083 degrees (Is this correct?, and how does this relate to inches toe?)


Joe, If the 1/16" toe is measured as the difference between the front of the 15" rim and the back of the 15" rim, isn't that really 1/32" toe-in? (.03") This is what I use.


I also asked about Rear Ride Height and how it is determined. I couldn't find that in the Workshop manuals.


BTW,

I am doing my own alignments on my alignment machine to my specs and am just trying to corelate what the stock settings were(are) to what I am using. I would like to come up with a set of "SPECS" to input into my alignment machine so I don't have to keep all these scraps of paper laying about.

Yes toys are cool!

[John]

My questions started this weekend when I aligned the track car. I started out by lowering it to where my dad wanted it, and then corner balanced it and finally aligned it.

The car seems to be tail heavy. It is a 3.2 with a 915 trans. 9x16" wheels on all four corners Kuhmo Victoracers (245/45).

23mm torsion bars
21mm Front Sway bar
400# Rear Springs

My percentages ended up as follows:

LF = 20.4% RF = 17.7%

LR = 32.6% RR = 29.2%

As expected, the driver side is heavier (it included the driver), but the diagonals worked out fairly well.

I aligned it with as much negative camber as possible and keeping both sides even.

LF Camber -1.766 deg RF Camber -1.733 deg
LF Caster 5.38 deg RF Caster 5.23 deg
LF Toe 0.03 inches RF Toe 0.03 inches

LF Inc Angle 13.26 deg RF Inc Angle 13.36 deg

LF SAI 15.03 deg RF SAI 15.10 deg

Total Toe 0.06 inches

LR Camber -0.88 deg RR Camber -0.93 deg
LR Toe 0.03 inches RR Toe 0.03 inches

Total Toe 0.06 inches

Thrust Angle 0.00 degrees

I thought this information might help explain what i'm attempting to figure out.

[J P Stein]

Angular to Lineal must be calculated over a known length ...leg of the triangle.

So, 10' is: 10/60=.1666 deg. Tangent of .166666deg is .00290889 X known length..say 15 inches= .043633 inches. 10 min of angle over 15 inches equals .043 inches....per wheel.

[John]

Thanks J P

But is it 15" or is it 7.5"???

[J P Stein]

QUOTE (JOHNMAN @ Mar 15 2005, 10:40 PM)

Thanks J P But is it 15" or is it 7.5"???

Neither actually, it's the angle. I could have used any dimension. Your multiplier is tangent of the angle.....which is why they give it to you in degrees. Slope per inch.... the lineal dimension is the offset for a given length. I used 15 inches cause a 15 inch wheel has a flat plane 15 inches wide (the outer rim) to measure on.

If you want 1/16 toe in (total), your alignment guy converts that to degrees...or his machine does.

Camber works the same way.
If you want -2 deg for instance and you're presently at 0, the top mount needs to move inboard. Approx length, ball joint to top mount (WAG) is 18 inches X tangent of 2 deg is .0349=.628.....which is why it's tough to get-2 in front.
Over a 15 inch span on the wheel, it's .52 ....the top of the wheel is inboard that much more than the bottom....slope.
1 deg is .017 slope per inch. Once ya got that, you can get close in working it out in your haid (IMG:http://www.914world.com/bbs2/html/emoticons/screwy.gif)

Assuming 0 at the rear, the swing arm tube is about 12 inches wide.
Take out .41 inches of shims....if ya got em'.....slope perpendicular to the wheel and the wheel goes with it. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

Lowering the car as much as feasible gives negative camber
for free....at both ends...at the cost of suspension travel...so then ya need stiffer springs to keep it off the bump stops (or raised spindles.... or both), non pliable bushings to hold what you've worked to get.....yada, yada.
We're having fun now, by gawd.

[John]

I suppose that I have not been clear.

The camber (measured in degrees or degrees and minutes) is straight forward. Easy to measure and understand.

Toe-in is what I would like to focus on.

When a wheel (single) is said to have 1/16" toe in, is this a difference between the front edge and the rear edge of the wheel rim and the theoretical centerline of the vehicle? Or is it the difference between the front edge of the rim and the theoretical center of the rim and the theoretical centerline of the vehicle.

I guess that is clear as mud.

I could always just put my car back on my machine and set the machine to measure toe as degrees instead of inches.

[Joe Ricard]

Yada Yada Yada. Holy crap you make my head hurt.
By the way JP My offset camber plate should be done Thursday. (IMG:http://www.914world.com/bbs2/html/emoticons/boldblue.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/boldblue.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/boldblue.gif) Cost 2X more to fix this one that I bought the pair from you for. (IMG:http://www.914world.com/bbs2/html/emoticons/blink.gif)
But it is being done by a real welder and machinist with a QA inspection by a real NDT guy. Should be GUD NUFF.

[J P Stein]

OK, If you measure from a line parallel to the centerline of the car to the wheel rim in 2 places 15 inches apart, the difference in measurements for a 10 minute angle is .044"...total toe in would be 20 minutes. If you wanted .062 , the angle would be about 14 minutes.....total toe in would be 28 minutes....if ya got both sides the same.

[John]

Thanks again JP.

I did some searching and came to the conclusion that Toe is indeed based upon the difference between the front and rear of the rim and the theoretical centerline of the vehicle (per side) and Total Toe is the difference in measurement between the rear of both wheels and the front of both wheels.

I was confused and making it harder than it really is.

One question down, one (three-part) question to go.



What is the "factory" rear ride height? How do you measure it? How low can you go? (Until the rear axles are horizontal?)

[Joe Ricard]

QUOTE (JOHNMAN @ Mar 17 2005, 11:12 PM)

Thanks again JP. I did some searching and came to the conclusion that Toe is indeed based upon the difference between the front and rear of the rim and the theoretical centerline of the vehicle (per side) and Total Toe is the difference in measurement between the rear of both wheels and the front of both wheels. I was confused and making it harder than it really is. One question down, one (three-part) question to go. What is the "factory" rear ride height? How do you measure it? How low can you go? (Until the rear axles are horizontal?)

LOW !!!!! If you look at my Avatar you can see that the top of the rim in back is up under the lip of the fender.

I'm running 150 lb rear coil overs on Koni red externally adjustable. AX tires are Kumho V700 in the 205/50-15. Lots of camber slight toe in 1/32 and a 1/4" wheel spacer to keep it off the inner fender well. Probably too low for the street but I NEVER listen to me. (IMG:http://www.914world.com/bbs2/html/emoticons/lol2.gif)

JP the camber plates are in and I got 1 full degree more (IMG:http://www.914world.com/bbs2/html/emoticons/mueba.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/mueba.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/mueba.gif)
the Welder / machinist did such a good job you almost can't tell what was done.

[Dave_Darling]

QUOTE (JOHNMAN @ Mar 17 2005, 11:12 PM)

What is the "factory" rear ride height? How do you measure it? How low can you go? (Until the rear axles are horizontal?)

The factory setup is in the manual. It has to do with the difference between the centerline of the wheel (I think) and the centerline of the torsion bar. It's a convoluted way of measuring it, to be sure...

You can go as low as you like, until you start scraping... It's very unnerving, BTW, to drive out of a parking lot through the spring-loaded "Severe Tire Damage" spikes and have them scrape their way along the bottom of the car's floor pan. Ask Birgit, she heard mine do that at Parade in Ft. Worth!

The general consensus seems to be that you shouldn't go any lower than having the A-arms parallel to the ground. Ditto the trailing arms. I would prefer a little higher than that, even.

--DD

[J P Stein]

How low is tougher and is another double edged sword.

Much depends on your tire size so giving a specific answer is real difficult.
The lower you go the more difficult it is to keep the suspension off the bump stops. I run about a 22.5 dia tire. Clearance from the ground to the doughnuts is about 4.75 inches.This keeps the A arms angled down a bit to the outside and bump steer to a minimum(with rack spacers). I could go a bit lower if it was a track racer as tracks are smooth.....unless you like to jump curbs. As it is, our AX venue is rough as a cob and I do get on the stops fairly regularly in front.....where it's easy to tell. This is with 21 mm T bars & 225 lb springs.

I have recently bought a set of raised spindle struts and am going to 275 or 300 lb springs in back. The ride height in front won't change, but I'll get another .75 suspension travel.

Good luck. Hitting the proper combo of springs/dampening/travel/oversteer/understeer/alignment has been an on going battle for me. I'm still learning how to get the most out of the car with my driving....not even close yet. As I go faster I find "things" change.....I'm back to lifting the inside rear wheel, for instance. Thought I had that whipped... then I went to stickier tiars. (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif)

[John]

Um, Dave,

This is a 914. I don't have torsion bars in the REAR. I have COIL SPRINGS.

I can't find it in the manual anywhere!



JP we are a bit lower than that on the track car. The A-arms are damn near horizontal, and the center of the rear wheels is slightly lower than the center of the trailing arm pivot.

My GUESS is that I shouldn't go any lower than the center of the trailing arm pivot equal to the center of the rear wheels. (as long as I can get enough toe-in and negative camber)

I am really surprised that NOBODY knows what the rear ride height is.

Kind of perplexing.