ThoR294

iTrader: (6)

Is this the only way to adjust a PHB? if I install my double adj PHB on an alignment machine, can I use the alignment machine to center the rear? is there a measurement I can follow or am I boned and have to use the damn string lol

witry

iTrader: (8)

alignment rack is you best bet honestly.... i have done the string method and still was a little off, so we took it to my buddys shop threw it on the rack and it was close but still off.

ThoR294

iTrader: (6)

what is it measuring? Toe?

mitchntx

iTrader: (14)

Assuming you have no wheel spacers and identical off-sets on both the front and rear wheels ....

Spray a small area on the driveway with water, roll the car through it and compare the footprints left by the front and rear tires. Adjust the PHB till they are even.

EchoMirage

iTrader: (3)

spend the $70 for a quality 4 wheel laser alignment and be done with it

ThoR294

iTrader: (6)

I can do it myself. Im just curious to what I'm looking at on the machine. I havent set it up on the machine yet. Is it the total toe of the rear or something?

mitchntx

iTrader: (14)

Lower control arms will set thrust angle.

Toe is how much "bend" there is axle tubes. 0.6* toe/camber (depending upon the plane the bend is on) is considered factory tolerence according to published accounts from GM repair manuals. I'd actually like to see it myself, but ... The "bending" occurs during heating and cooling of the tube when the spring perch and LCAs brackets are welded in place.

PHB stabilizes the rear diff laterally and only adjusts tracking.

ThoR294

iTrader: (6)

ah alright. so to adjust the PHB I am just going to have to use that nut and string thing. haha nuts...

Racin'Z28

iTrader: (7)

When I did mine, I used a long straight edge off the body from the rocker panels and measured the distance from the axle centerline out to the straight edge. I then measured both sides. Found it to be off center by 3/8". Moved it over until both sides measured exactly the same from the axle center line to the straight edge off the body.
There may be other ways, but it worked well for me. I then took it in for a front end alignment, since I also did front end work, and it was dead on center based on the rack with this method. Seems a little more accurate than a string and nut that can move around I think.
As they say, they're more than one way to skin a cat. I'm sure others will have ideas too. I like Mitchntx's idea. I would have never thought of that.

Nimitz87

iTrader: (17)

lol your fancy nut and string is called a plumb bob....if it was good enough for the Egyptians it'll work for you

I did mine this way...dead straight.

Chad

UMI Sales

iTrader: (1)

I never thought of that...Mitch that's a great idea and allows you to see where exactly your tires are positioned. I always relied on the plum ball option. And I can spray anything outside due to the snow.... If you have any other questions feel free to ask.
Thanks
Brad

mitchntx

iTrader: (14)

Well, that's what you get for living in PA ...

I never liked the plum-bob method because I never had a warm, fuzzy feeling that the body panels have that close of a tolerence to be measuring wheel track off of.

When you are measuring to a 1/16" and the factory tolerence for body panels is +/- 1/4", what have you gained?

ThoR294

iTrader: (6)

guess Ill go to a nice big empty parking lot with a few gallons of water and get to adjusting.... hahaha (i have a stone driveway)

JDM74

The manufacturing tolerance for stamped body panels is on the order of .010". I don't think you are going to see a 1/4" tolerance on anything like a automobile. Center the axle to the body side to side and be done with it. It may not track perfect to the front but it will be asthetically pleasing. Thrust angle of the rear axle is more important.

mitchntx

iTrader: (14)

Interesting ... I'm sure GM's requirement for individual panels are closer than 1/4" ... 10 thousands ... that's awefully close.

But you start putting together 6, 7 or 8 of the panels together and the tolerences begin stacking. And remember, we're talking about cars built in a plant with early 90's technology.

I do take issue with not worrying about tracking straight, though. Crabbing going down the hiway will cause excessive wear on the tires.

ThoR294

iTrader: (6)

I gotta get adjustable LCAs and relocation brackets... I just have non adj ones. I did not think ahead. I had no plans on lowering the car till i saw our cars on strano springs lol