thrust angle and alignment issues

sooty
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thrust angle and alignment issues

Postby sooty » Mon Aug 26, 2013 12:19 pm

Seeking some answers concerning my alignment.

Just a quick background history, I've had my Corolla hatch a little over two years and have noticed wear patterns on my tires.
It takes at least 4-6 months (4-7k miles) to really notice the wear, but It is constant with time. I've already had to get new tires for the front once because of bad positive camber wear, and the rear tires had some inner wear closer to the diff, not as bad.
I just put a full set of tires on about 6 months ago and I'm noticing wear on the fronts again, after I took them to a shop twice
to get them aligned. After seeing some of the alignment specs, I noticed rear end was slightly cocked (thrust angle), so I purchased adjustable 4 links to "solve' the problem. It helped with the rear thrust angle but didn't really cure the issue, plus the heim joints were too aggressive and noisy (since it's my daily).

Here are some specs after my trip to the alignment shop (w/ stock links):

Front Drivers camber : Before: -0.8 , Now: -0.2
Front passenger camber : Before: -0.4 , Now: -0.2

Front drivers caster : Before: 2.2 , Now: 2.3
Front passenger caster : Before: 3.6 , Now: 2.8

Front drivers toe :Before: 0.50 , Now: 0.03
Front passenger toe :Before: 0.59 , Now: 0.03

Now here's the prick in my side :x

Rear drivers side toe :Before: 0.55 , Now: 0.54
Rear passenger toe :Before: -0.62 , Now: -0.61

Thrust angle 0.58

The set of specs above is with the stock 4 links. Obviously no adjustment for the rear, so just the front specs were dialed in.
After installing the aftermarket 4 links, rear toe specs were 0.40 and -0.54 , drivers and passenger prospectively. Only a .1 to .15 difference in toe from the stock. The shop didn't mess with the rear even after I installed the adjustable links... (???)

Thrust angle 0.47 (with adjustable 4 links) after a little DIY adjustment

Here is a pic from underneath

Image

Sorry this pic is a little blurry, had a hard time holding the phone, but this is an idea of how far off the links align with the mounting points.
I've taken them off probably 3 or 4 times and each time getting them back on it takes a lot of prying, sweating, crying and cussing to get them
to align for the bolt to be put through. The holes for each link are slightly off, top and bottom.

Image

And lastly, just an outside shot of the wheel well. This can't be a super accurate representation because of the body panel shape and so forth, but it still gives
you an idea

Image

I've installed the energy suspension full bushing kit prior to all this as well, nothing changed. I've since picked up some Megan springs and AGX shocks, still didn't see any difference. The only thing that caused a different result were the adjustable four links. Previous said there were no wrecks....

Frame tweakage? Old car syndrome? Any ideas would be MUCH appreciated.
Image

Deuce Cam
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Re: thrust angle and alignment issues

Postby Deuce Cam » Mon Aug 26, 2013 12:38 pm

The car is lowered so you will need an adjustable panhard bar at a minimum to center the axle. On my old car I was able to get 0 thrust angle on a hunter alignment rack with adjustable panhard, stock links/prothane bushings with megan springs. ymmv.

To truly get the pinion and thrust angles dialed in you'll need the adjustable links. This type of work generally isn't included in the standard 4 wheel alignment and the average shop tech won't know how to do it. It's probably best to find a hot rod shop, diff. shop, etc. that has experience with performance alignments on live axles.

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idreamofdrifting
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Re: thrust angle and alignment issues

Postby idreamofdrifting » Mon Aug 26, 2013 4:37 pm

sooty wrote:I've taken them off probably 3 or 4 times and each time getting them back on it takes a lot of prying, sweating, crying and cussing to get them
to align for the bolt to be put through. The holes for each link are slightly off, top and bottom.


OMG i FEEL your pain. I dont even wanna think about installing a set of 4 links, and Panhard bar, again. Especially installing them with Traction brackets. Very labor intensive, especially if its the first time.

With that said, boy what a difference it makes though! Youll love your Hachi even more!
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totta crolla
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Re: thrust angle and alignment issues

Postby totta crolla » Tue Aug 27, 2013 1:48 am

idreamofdrifting wrote:
sooty wrote:I've taken them off probably 3 or 4 times and each time getting them back on it takes a lot of prying, sweating, crying and cussing to get them
to align for the bolt to be put through. The holes for each link are slightly off, top and bottom.


OMG i FEEL your pain. I dont even wanna think about installing a set of 4 links, and Panhard bar, again. Especially installing them with Traction brackets. Very labor intensive, especially if its the first time.

With that said, boy what a difference it makes though! Youll love your Hachi even more!


TOP TIP !!
Use a ratchet strap around the axle and hook the end of the strap onto a strong place on the underside of the car. Ratchet the axle into place.
That job is so easy then !

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gotzoom?
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Re: thrust angle and alignment issues

Postby gotzoom? » Tue Aug 27, 2013 9:19 am

I'd say all of that is normal on the rear. The chassis isn't that rigid to begin with, and nearly 30 years later, you have to expect some chassis distortion to occur. It's just as likely that the thrust angle existed from the factory when it originally left. Factory alignments have a really wide range of spec too. The only way to correct that is with adjustable rear links.

If you're driving relatively hard, you will need a lot more camber than that to get even tire wear. These cars have a high center of gravity and therefore roll a lot. In the case of the rear, you have next to no camber, so you will always have high outside wear on the rears and there isn't anything you can do about it. I figured out how much camber I need up front for my usage and rotate tires often to get as much life as possible out of the tires. That's just the way it goes with a live axle car.