Phil_Hendrie_is_back

I've read more than 10 threads on alignments, including the big one in which people jot down their alignment specs. Virtually every set of specs is for modified cars used for autocrossing or tracking or some combination of both with daily driving. One person asked for specs for totally OEM car used for daily driving but no one responded.

I have a GT package, manual, OEM equipped (wheels, shocks, sway bars, and tire specs). Last week I got a set of 4 Kumho SPT's 225/45/18 mounted (these are my 2nd set of SPT's), and now I need alignment done.

I drive mostly fwys (NO autocrossing or racing) and was able to get over 50,000 miles on my OEM Bridgestone RE040's. The OEM's wore out PERFECTLY EVENLY. Then I got my 1st set of SPT's, which were aligned at a local shop. These SPT's lasted 45,000 miles but the inside edges of all 4 wore out first (probably could have gone another 10,000 to 15,000 miles otherwise), suggesting the negative camber was set too aggressively for my conservative driving style. This shop only charged me $65 but they do not have computerized alignment so I did not get before and after specs. I do not want to go back to that shop.

I would love to get back to my original factory settings but it's too late now. By that I mean the exact specs as they were on MY CAR from the factory. I don't mean the spec sheet for sport suspension with all the ranges, which seems ridiculous. Is it just that I'm confused or is that spec sheet virtually useless?

In the "Do I need an alignment?" thread in this same forum, RX8maine listed what he said were the factory settings. I'm assuming he means for HIS car. He wrote that there was negative camber for both the front (~ -0.3) and back (-1.0). He also said there was toe-in all the way around but does not state exact figures.

Can I get some input from people with experience, specifically those with totally OEM equipped RX8's who drive only city roads and fwys (no autocrossing or tracking)? What are your alignment specs? What were they coming from the factory? And what are they now? What are your suggestions?

Here's what I've learned from this forum (read it and weep, Swoope!). I learned that the front camber should be adjusted before the caster because camber affects how much caster will be possible. I'm thinking minimal negative front camber, about -0.5 both left and right, and back camber about -1.0 both left and right. Then positive caster between 5.0 and 6.0. Possibly 0 toe for the front left and right, and a little toe-in for the back left and right (but how much?). Thrust at 0.00. Are these settings reasonable?

Regarding caster, should the left and right be the same for someone who drives only city roads and fwys? I ask because a "reputable" local guy who was recommended by a forum member told me on the phone today that he will set the left and right sides differently to compensate for road crown so my car won't pull to one side. Is this "expert" right or wrong? I told him that I do not autocross or track my car, so he answered with that info in mind. Also, he supposedly does a lot of performance miatas and exotic cars. In one of the other alignment threads, a forum member wrote that the caster for left and right should be set the same for road driving because the crown will be different depending on the lane. Who is correct?

Thanks in advance.

auzoom

Well in Australia, if you look at the "Target Data" column or this image, this is the factory specs. Note that it has a tolerance and a recommended setting.



Personally I think the idea if setting left and right is silly. How many roads have you seen the lean to one side! If you look at the results of most alignments they are never exactly identical left to right or front to back. This is because you are talking < mm of turn to adjust 1' of camber or toe, etc. Maybe he is trying to sound smart and using this as an "excuse"???

As for whats "best" it depends on what you like. For street use I will hazzard that a higher castor setting will be beneficial as it helps with straight line stability. I would go with as little toe as possible and compensate with more castor. It means the car wont turn in as well but I would think this the best compromise.

RX8Maine

If you are NOT looking for a performance set-up, just use the factory specs.

You'll get longer tire life if you reduce the amount of toe-in, but that will make the car feel less stable at highway speeds, especially when the road surface isn't perfect.

Phil_Hendrie_is_back

auzoom

I'm confused by the table. Why would there be a range for the camber under the column Target Data and then the bold value down the middle is outside that range?

Phil_Hendrie_is_back

What do you mean by factory specs? Do you mean the factory spec sheet for sport suspension that has the table with the RANGES? What numbers do I pick inside those ranges?

In the other thread in which you posted factory settings, were those numbers directly from your car? If so, I'm more inclined to go with what was on owners' actual cars.

If I keep the front toe at 0, how much toe-in would you recommend I do for the back? Also, would you advise I do toe-in for the front? If so, how much?

auzoom

As I mentioned above (mispelt toe) you can compensate (to some degree) for straight line stability with less toe, with more positive castor. Have a read of this http://www.familycar.com/Alignment.htm and this http://www.ozebiz.com.au/racetech/theory/align.html

Cheers

Andrew

Phil_Hendrie_is_back

auzoom,

I actually read the first link before. But you still haven't answered why, for camber, the BOLD number down the middle is outside the factory range. First of all, in general, for the Target Data column, what do all the BOLD numbers down the middle of the entire table represent? Are they the factory recommended settings? If so, why would the factory recommend numbers that are outside their own range?

auzoom

OK in the target data you have a left, centre and right value. The centre data is the actual "target". The left and right are the acceptable tolerances. So for example you can see the front axle camber. The target is to have it at -0".45' but its acceptable to have it up to 1" + or - this value, so in fact, acceptable is considered -1".45' to +1".45'.

Personally, any rear toe is useless on the street if you are just getting from A to B. Front toe in will help with straight line stability and toe out will be the opposite but help with turning. Any toe setting other than zero in theory is a detriment to tire life as you are scrubbing your tyres.

Hoep this helps.

Phil_Hendrie_is_back

Thanks! I finally got it.

From your last post, I finally figured it out, haha. The outside numbers are just plus and minus adjustments FROM the center target number. I had been reading the table from a sort of reverse way of thinking.

Based on what you say, I'll probably go 0 toe all around. Increase positive castor to 6.0.

What do you think about negative camber of -0.5 for the fronts and -1.0 for the backs? Are these camber settings close to how the factory originally set up our cars?

dannobre

iTrader: (3)

You will want a bit of toe in on the front...and probably the rear as well. Zero toe will be twitchy on a street only driven car.

auzoom

I agree with dannobre, I would probably go a small amount of toe in on the front...you can see from the settings above that I run only .1mm.

As for camber, factory settings for "sports suspension" here in Aus is -.45 front and -1.44 in the rear. I think for street that -.5 all around is fine.

One final thing too. I would aim for around +6.5 of castor, but beware that your steering maybe a little heavier than you expect. if it is, then just back it off to around 6.

Cheers

Andrew

Phil_Hendrie_is_back

Great, thanks for all the advice.



I'll go -0.50 camber all around then. Slight toe in, about -0.1 all around. Positive caster of 6.5.

BTW, auzoom, what is your reason for going with so much toe out in the back?

swoope

iTrader: (5)

| Winton: 1:42.86 | Sandown: 1:32.42 | Broadford: 1:12.46 | Wakefield: 1:15.94

btw, great thread phil!!! i want to know how the crown thing works out.. if you do it...

it has been a while since i have driven on crowned roads.

and this is a straight up honest post. it was a great ?

beers

auzoom

haha very true swoope. What he is getting at phil is that those readings were in the middle of going from a track setup to a street setup. The particular track is a very tight windy track and so toe out in the rear allows for oversteer bias, meaning the rear end comes out instead of just plowing straight ahead.

I would also be interested in seeing the setting this guy does for your car if he insists/convinces you to go with the different left/right settings. My suggestion if he pushes for it is to get him to agree that you will do it but if you dont like it he will go with your settings.

Cheers

Andrew

auzoom

Hey Phil, how did you go with this?

Cheers

Andrew

swoope

iTrader: (5)

phil is gone.

beers

auzoom

Gone where?

swoope

iTrader: (5)

did not play well with others..

might search some of his posts..

this was his shining star... it was a great ?.


beers

auzoom

Yeah bummer...guessed I missed the big "banned" under his name :p

tangoshark

why does the specs say negative toe in the front and positive toe in the rear? positive means toe "out", right?

auzoom

Rear toe out allows for the rear end to come around a corner easier. Toe in in the front helps to keep the car in a straight line when not turning. Its a compromise for street driving.