I know how to set up toe in and camber, but not caster.

Questions:

How do you measure it and then reset it.

Also what is the stock caster setting and how will adding caster impact the amount of force needed to turn the wheel?

Also understand that adding caster will impact toe in and camber. At what setting does this impact begin.

All help appreciated.

Caster is the angle off vertical in the side view that the strut sits. ...leaned back on top. On a 914 it is set about 5.5 deg or more.
Caster does effect camber when the wheel is truned......the outside tire goes negative & the inside positive. Since camber, toe, & camber are all set with strut movement, they is all set at once....juggled, if you will, to what you want within the limits of adjustment. I like all the caster you can get on a 914....close to 6 deg.
This puts a good hunk of negative camber into the outside front durring conering.

Here's an old pic that shows the effect pretty well. Note the left front wheeel.

So what do you measure the 5.5 degrees against. The strut or ?

Get the car level & use plumb. If no inclinometer use a small hand level on the strut & do the trig.....it's run vs rise then tangent.

Or, you can download an angle app on yer iPhone and slap it on the strut to measure the degrees.. Pick yer poison.

I have some good angle measurement tools and my iphone app, so will try both. If the factory setup is 5.5 degrees (towards the driver) then what do racers typically run?

Most folks max it out but that makes it heavy on the hands. I'm using a bit less. It makes for a light steering car with all that rubber I have up front. If I switch to a narrower front tire I may go back to maxed out.

Mine is maxed out.

Just did this today. Mine was way off from left to right which made for some funny driving.

Maxed it out which is about 6 degrees with the stock strut tops.

Ya'll got an app for my cracked & bleedin' ass?
Kids these days......

Will this help?

https://play.google.com/store/apps/details?...cButt&hl=en

So that was the weird handling "thing" we were talking about. Glad you found it.

Is this the correct way:

I put a straight edge across the cup that holds the shock bolt. My iphone app was flipping back between 9 and 10 degrees(*). So given that the floor is 2 degrees my caster is 8 degrees?

Not sure if this is the way to measure it, but isn’t that a bit high and a cause for my hard steering?

(*) The reading on the picture looks like 19 degrees, but the camera caught the app switching from 9 to 10 degrees.

Click to view attachment

Most of it it seems. There's still a bit of a "mushy" feeling and the alignment is not yet dead on, but the bouncing in corners is almost gone.

I know i still have a bit bump steer due to my current ride height (way up) and once that is dialed out and the alignment is spot on the car should drive *much* better.

The caster was off by several degrees between left and right. No idea how that happened.

Considering how I have done this for years...I never thought to look for an app.

How very cool..
Gotta get me one for my android.

Rich

You want to measure on the strut, not the cap. Caster is the measurement of the kingpin angle viewed from the side of the car. For MacPherson front ends, it's the angle of the strut. Google "alignment caster" and you'll see what you are supposed to be measuring.

Edit: Read the other scale - it looks like you have about 3 degrees (90-87). I would still say you should measure off the strut itself.

Thanks for the advice!

OK so measure against the strut as per the picture, i.e., the red arrow?

Click to view attachment

I would measure below the dust cover on the actual strut itself. My car is maxed out at 5.5 degrees.

Don't use the dust cover (if you still have one), use the strut itself. Now would also be a good time to see if there's a difference in angle between the strut and the shaft.

Measure front face of strut tube....or insert (piston rod) in same, that is more uinform.
Keep the instrument parallell to the tube in X & Y.
App that with the machined surface of your cell phone.

Old QA guy...can't slip anything pass you.

OK I'll remove the cover.



Results measuring the strut, not dust cover.

Left (drivers) side is 10 degrees
Right side is 11 degrees.

No wonder this thing is hard to steer.

When I get back from Cascade Lakes will have to realign the front, getting the caster angle back to 6 degrees. We've never even checked caster (duh!) when aligning the front. We always been busy boys getting the camber, toe-in and weight balance correct..... Live and learn.

Hard to squeeze your head into that tiny space to read the angle.

OK, so what's the best sequence for doing the alignment?

This has worked well for me:

- Disconnect any sway bars you may have
- Roughly set ride height to where you want it to be
- Brake tie rods lose
- Make sure your scales are level, don't forget to check cross levels
- Roll car onto your scales
- Lock steering wheel down in center position (do *not* use the key lock, if you still have one)
- Make sure your tank is about 1/2 of what you would start with at the beginning of a race/AX
- Corner balance the car with your weight in the drivers seat (don't forget gear!)
- Adjust camber and caster
- Adjust toe
- Tighten tie rods and rear bolts
- Reconnect sway bars, make sure you do not introduce any preload
- Double check camber/caster/toe
- Drive!

Randal those caster readings are suspect. I don't see how you could possibly have that much. I would suggest you get it professionally aligned to set a base line.

You could just buy one of these https://www.pegasusautoracing.com/productde...s.asp?RecID=883 and read the bubble and be done.

As a side note, you would be surprised how many NASCAR teams still use these for alignments.

+1

I had to turn the tire/wheel full lock to the outside so I could get underneath the car and take the measurement and see the angle. Would that screw up the caster measurement?

No. the location at the top mount & ball joint don't change position.

Buy yourself a 6 inch dumpy hand level and a measuring tape. Taint rocket science.
At 6 deg, a 6 inch run comes to .630" rise.

I tend to disagree. The caster will change, along with the other measurements when you turn the wheel. The ball joint isn't necessarily in line with the strut tube. This is where ackerman angle comes from and how the camber changes as well. On an actual alignment machine caster is measured by steering the wheels back and forth, this is called a caster sweep and I believe is averaged to show caster while steering ahead.

That is correct. The problem with the averaging is that you can be out side to side.

In my opinion it is better to measure both struts independently to make sure the caster is set equal left/right.

That is a nice unit, thanks.

It's not averaging left and right together, it's averaging right side turned 30* left and 30* right. Setting left and right equal is still up to you.

There is no such thing (that I know of) as average caster for a car. It's not like toe.

Thanks Matt, thats what I meant. If it averaged it side to side the car would never show a pull, which can primarily be caused by caster.

Couldn't understand why my caster measurement was so off.

Sure looks like the iphone app is a bunch off.

Click to view attachment

So assuming the bubble measurement tool is correct and taking in the correction for the floor my caster is about 6-7 degrees.

You forgot to hit the cal button before using it to measure, lol.

Looks to me like the iphone is just not working properly. If the bubble at the bottom indicates 12 degrees from horizontal then the corresponding measurement from vertical should read 78 degrees (90-12). iphones are wonderful

Right, like 3+ degrees off which would explain my earlier measurement of 10-12degrees of caster when measured off the strut.

So if the range for caster is 0-6+ what impact would either end of that scale have on camber?

I would suggest you mentally go back to the solution you are seeking.

At zero caster, perfectly plumb, your steering wheel would be the easiest to turn.

At maximum caster (which you are at currently, in a stock tub) you are now dealing with the hardest steering wheel to turn.
It will also try to get back to center...at every bump.

Rich

You didn't understand what I was saying. If we assume that the 12 degree reading from the horizontal is correct, the the other reading from the vertical is off by 10 degrees!! So the iphone doesn't even agree with itself. There is no reason to believe either number is correct. I never even measure caster, how are you reaching around the wheel/tire with the car on the ground to read the gauge anyway? I've never been able to do it.

It wasn't easy. Had to crank the wheel all the way to left or right, then get behind or in front of it, depending upon which side, to see the phone. BTW I tried it with the e manual gauge and there was 3 degrees difference from the phone.

So how do you measure caster Bill?

Guess putting the car up on some big blocks would work.

Like I said I've never been able to do it. I always just maxed it out and made sure the car didn't pull one way or another when I drove it.

I have found that you can setup one side more than the other for both caster and camber.
No idea, but the tubs are different from side to side.

I would push them both back, wheel straight.
Measure both sides and move one side forward to match the smaller measurement....whichever side that is.

Then you are the same on both sides.
Same thing with camber.

Then corner balance it.
then align it.

rich

Randal,

I would personally recommend you NOT use that dial faced angle finder in the photo.They are NOT accurate. I know you see a lot of guys using them, but I've checked these against a precision digital angle finder and they're always off (as much as 2*). As for the phone app, I can't say I've checked it, so I just don't know......but the engineer in me would be skeptical. In leu of my $300 SPI digital angle finder, I think the plumb line would yeild a better result; the more span, the greater the accuracy; One degree = .0175"/inch. Also, the Longacre caster/camber gauge that Matt suggested is a great tool. It mounts in plain sight, very easy to use, and quite accurate.

Andys

Randal-I"ve always liked to set my caster to 5 degrees.
Back in the early-stock class days- we would set the caster and then get all of the camber we could evenly get to that caster-usually 2 to 2.5 degrees negative camber at that caster setting -those were radial days-
On the bias ply slicks -we still run 5 degrees of caster

J Jackson

Clue......
I just rough set caster Then have it completed on a machine.....usually within 1/4 deg when it goes on the machine.

A pic with the tire on & the suspension fully compressed.....the tire don't have to be there.

I used a pic with the wheels turned & the T-bar disconnected to show the jacking set up. In this pic the work was done for tire/bodywork clearance. Basicly there's a block under the balljoint to jack on.

Ayup, lotta caster makes the wheel snap bact to straight way faster than you can countersteer. There's an advanced AX proceedure for catching a tank slapper on the first slap. If ya don't know it, that's your problem......it does take some practice .

LOL JP! hands off method!

Just don't forget the "hands on" part.

So Bill and I aligned the car yesterday. The caster was indeed set at 6 degrees.

On the other hand did find that the passenger side strut bolts had loosened and the right side was like a degree and one half. Fixed the camber and got the bolts really tight, so should be good to go.

Also discovered that the rear toe in was off. So spent a bunch of time fixing that and making sure the three bolt sets were tight. Got to find the torque specification for both the front strut bolts and the rear camber plate bolts before this weekend.

And Bill emailed me this morning to say to remember to put the sway bar back on. AHHHH, almost another "Shootout" experience which I sure don't want to do again!

"222" should really be handling good now, especially with the camber set properly for both front struts and the toe corrected in the back.

Corner balance was right on, i.e., within two pounds of perfect for each corner.