froggy47

Froggy messing around with caster on his C5Z

mrr23

you say 20* and only turn the wheel a half. in my camber change in turns thread, i posted an update yesterday. to get 20* i had to turn the wheel in the c6 z06 almost 7/8 of a turn. using that as a baseline, then at half a turn you are only getting to 10*.

froggy47

It's based on David Farmers calculations for c5 steering box & ratio's. I did not verify, however I will when I get a chance since you brought it up.

dhowdy

You should be able to turn the wheel with the key in run without the engine on. I still have the column lock, but it worked for me on the studs I just did.

Joshboody

I think Froggy is right at 10deg based on 2.62 multiplier. It comes from below formula
Caster (deg) = (180 / 3.1415) * [(camber1 - camber2) / (turnangle1 - turnangle2)]
sourced from http://quadesl.com/miata_alignment.html

by this math though the multipler is slightly off using 16.1 steering ratio
1/2 turn would be 2.56

Nice vid, I need a camber tool... I use straight edge and level which is a little tedious.

froggy47

Correct, I just set toe now & left the key in, just kept going back to check it centered each time I adjusted. Actually I thought the toe would have changed more with the .2 deg neg I took away but It did not change much 2 to 4/32nds.

Bill Dearborn

I looked at that tool and then purchased this:FASTRAX CAMB/CAS GAUGE 91010. It works well but uses a bubble gauge which I was having a hard time reading the gauge due to not enough contrast (it is PIA to get old). I replaced it with the Longacre Digital Caster/Camber gauge witht AccuLevel. It is really easy to use. It magnetically attaches to the hub and there is a large enough hole in the center it will fit over the end of the rear axle shaft. Just pop off the hub cap, turn on the level and let it zero then pop it on the hub, adjust the sideways tilt using a small bubble level on top of the unit and read the camber on the read out. The digital level unit can be removed from the magnetic holder and used to measure angles like the C7 Corvette requires when setting rear caster.

http://www.longacreracing.com/produc...Level%E2%84%A2


If anybody wants to make an offer plus shipping for the Fatrax unit with the no lip adapters it is available. It has only been used three times and if you have young eyes should do a good job. If you want to look up info on the tool here is a link: http://www.spcalignment.com/componen...tion&pid=91010

Bill

mrr23

when measuring caster using my hunter alignment machine, i only turn 10* left/right. when i tried the formula with the numbers i got doing 20*, it did not come close.

https://www.corvetteforum.com/forums...-in-turns.html

mrr23

10* would be correct. in the video he says 20*.

froggy47

I am not sure where I got the 20 deg, so if you are sure I will make an annotation on the video to call it 10 deg.

You sure?

Joshboody

The multiplier depends on the wheel angle... so 10 (which is diff total 20) is 2.87. 20* each way is 1.43.
Using the steering wheel if 1/2 turn = 180*/16.1 = multiplier 2.56.

I tried your thread alignment readings and was almost dead on +\-0.1*

mrr23

which is why 20* as froggy said would be incorrect.

c6 z06 20* readings
2.16 - (-2.98)= 5.14 * 2.62 = 13.49

now using the 10* turns from the wrx
0.69- (-1.98)= 2.67 * 2.62 = 6.99 then it's correct.

mrr23

in my 14 years of doing alignments from cars to semis, 1/2 turn is the 10* mark. some a little more of a turn due to steering ratio.

mrr23

i know where the 20* comes from. it's called measuring toe-out-in-turns. when turning 20*, the opposite tire should have less angle. it's called the ackerman principle. because the tire on the outside of the curve has to travel a greater distance, it needs less turning radius. depending on track width of vehicle, this difference will vary.

you can se eit here from the c6 z06 i checked

mrr23

something to consider when taking measurements. may want to take into account you being in car.

https://www.corvetteforum.com/forums...post1588906001

froggy47

Yes I agree.