front wheelalignment - shortcuts ? / CASTER espec.

[geert]

Hello, I know front -wheelalignment is a serious thing and the handbooks recommend ' go to the next dealer ' ;
but : are there possibilities to do that at home ( even if it takes a long time ) ?

In earlier topics different figures have been given, according to personal choices.

but how to align ?

- first CASTER : - seems difficult to measure ?
- would like to know what is the difference between front and back shims on your cars (on the lower controlarm): is that +- 1mm, or a lot more, 3mm ?

- CAMBER : possible to measure line top-bottom of the wheel -angle versus vertical and using sinus-formula to get the angle ?

-T in/out : difference middle of the tire front/back of the wheel, ( rolling over sheet of paper, mm versus line front to back of the car )


might all be a bit hazy ; but I would love to have your settings ( diff in shims) concerning CASTER because that would give me something to start with.

Thanks in advance,
groeten, Geert.

[azruss]

the last time i rebuilt my suspension, i did the caster, camber and alignment myself. Very doable and knowing how to use trig calcs is a big help. If you dont know, I can help with some very simple formulas and a calculator.
First, your shims adjust both camber and caster. For setting camber, i used a framing square on a flat concrete floor. measure from the square to the top and bottom of the wheel and did the trig to find the angle. you can also use the math to figure out how thick your shims need to be. caster is very difficult because there is no concrete point to measure from. again, i used a framing square to measure the distance between the center of the top ball joint and the bottom ball joint. doing the math gives me the caster angle. if the caster is too little, you add shims to the front lower a-arm bolt. If the caster is too much, add shims to the back bolt. Do your caster first. Once the caster is set, you add identical shims to both the front and back bolts for camber.
The hard part and time consuming part is the suspension has to be loaded and the car had so be loaded to weight specs. sand bags, hay bales, chunks of metal work to get an operating weight. You can also give your wife a tall cold drink and ask her to sit patiently in the car for hours while you do all this work. (never found this solution to work for me). I also built blocks the exact height of the tires and wheels for the suspension to rest on. this must be accurate. after each shim adjustment is made, put the tire back on the car and roll it back and forth a distance of about 10' (3 meters), then take your measurements again. once caster and camber are set, then do alignment. I actually made an alignment tool that was a couple of pointers on a stick. I have also used a pair of tape measures for the front and back of the tire. biggest issue is to find the exact spot on the front and back of the tire to measure from.
Before i did mine, i was wearing out tires in 15k miles and had a constant pull. When i finished, the pull was gone and i got 65k miles out of my next set of tires.

[geert]

thanks azruss,
gives some confidence.

and ( a bit ignoring your detailled answer ) could you say how much mm shims you have put front/back for the caster ( to start with)?

groeten, Geert.

[azruss]

When i did my car, I replaced the shims in the same way they came out and then made the adjustments. If you are starting from scratch, you may want to do initial measurments with maybe 1mm shims on both the front and back. this gives the opportunity to subtract from either end if needed. tried not to get too detailed.

[So Cal Mark]

setting your alignment based on another cars' shim pack would be like making your budget based on your neighbors' income.

[kmead]

There are a number of ways to do this, the Spider is a tough car to align this way due to having to change shims but it can be done.

Try the "string alignment method", this will work for toe, camber can be done with an accurate level and a set of calipers if you don't own the tool for measuring it.

http://www.network54.com/Forum/12159/me ... ING+METHOD

http://www.c-speedracing.com/howto/alig ... gnment.php

When setting the toe, be sure to have the steering wheel exactly horizontal (this will ensure it is centered) and then align the wheels accordingly.

Some camber gauges:
http://www.amazon.com/Digi-Pas-DWL-80G- ... sbs_auto_7
http://www.amazon.com/iGaging-35-222-Di ... sbs_auto_6

http://www.tomhoppe.com/index.php/2009/ ... ber-gauge/
http://www.instructables.com/id/Hands-f ... ber-Gauge/
http://www.jdmuniverse.com/forums/sus-t ... gauge.html



http://www.speedwaymotors.com/ECONOMY-C ... GoogleBase

[geert]

Thanks everybody for answering.
I spend an interesting Sunday aligning the front wheels.
Great stuff for explaining measuring camber at different angles to find caster, thanks kmead

Tried to get my 16 year old daughter Marjolein, Chinese volunteer to sit in the car as part of the operating weight, interested in mathematics by demonstrating the use of sinus en tangens to find camber. Not sure I succeeded in getting her interested

Thanks,
groeten, Geert.

[v6spider]

Get you a protractor level... they have them at sears and they are fairly accurate. Measuring caster isn't too difficult best way I found is cranking the wheel all the way to the right and taking an angle measurement with the protractor level. Then turn the wheel to the left and take another angle measurment. Once you have both sets of measurements for both wheels then it is just a matter of finding the average or middle point between the two measurements for each wheel. There is a book I highly recommend that shows you exactly how to do this. "Chassis engineering" by herb adams ...shows you how to do it with just a protractor level... A tape measure...two coffee cans. And a length of square tubing for a straight edge...

[kensmith]

To be honest, I'd rather spend the $59.99 at my local tire store for a laser alignment and know everything is right on. Then I can work on other stuff and not worry about tires, driving, handling, etc. Just my 2 cents.

[v6spider]

Those alignments are only as good as the setup and calibration of the machine... I have had two alignments that were not within specs because the machine was out of calibration. It is really easy to do yourself and get the results you want. I had to learn how to do this because I built my own steering components to accommodate my 4.3 v6 modfication. There are no mysteries. To alignment.

Cheers!
Rob