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Old 12-08-2011, 12:01 PM   #121
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Quote:
Originally Posted by cardriverx View Post
I am just guessing here, but no one who calls themselves an automotive engineer would design the cars suspention to transition to positive camber in bump with the stock setup under normal conditions. I am not that well educated on McPherson struts (I have only done some work with our FSAE car - double wishbone F/R), but I do know that it would be ridiculous if the car would transition into positive camber with a stock setup. And I mean they designed this car to be a sports car and to see track time.

Now if you put on 275 wide slicks without changing the suspension settings, that goes out the window.
I was never talking about a stock setup. Of course they are designed to work fine from factory, but who the is going to track this car with stock suspension and ride height and expect to be competitive in TT or something of the sort? (or to post up similar times to miatas/spec miatas). If you read some of the previous questions I raised about MacPherson, I specifically asked how do the subie guys get around the positive bump camber when they are dropped for a track setup.

I am doubtful 275 (or any reasonable sized tire for that matter) slicks will make any difference to the camber curve.

And yes, Scrappy is right. Its cheaper and more compact (horizontally), which in this case is important because unequal A-arms tends to be wider and this car is already using up a lot of that real estate due the horizontal engine.
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Old 12-09-2011, 04:06 AM   #122
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Bunch of armchair and hearsay suspension specialist that have apparently never seen a mcPherson strut up close.

I know that on my AE86 track car, with McPhersons and 2 30$ spacers, there is a linear correlation between bump and negative (yes negative) camber. Not perfect (you'd like a more gain like the miata) but that doesn't stop this car, and every other mcPherson car on the planet, from working just fine on track.

In theory you get positive change when the lower control arms are angled past horizontal. In pratice things don't get that out of shape when you lower the car, or a simple 30$ spacer puts the LCA's back in their original position.
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Old 12-09-2011, 08:44 AM   #123
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I'm actually sitting on a stool....

Do you mad tyte DRIFFFTO your 86? I think I found a pic of your car. I think you have a bit too much toe out. Mighta been why you crashed.

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Old 12-09-2011, 10:13 AM   #124
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I think that's your boyfriends car.
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Old 12-09-2011, 10:15 AM   #125
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Cute comeback.
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Old 12-09-2011, 10:35 AM   #126
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I'll admit that it was hard to match the genius and insightfullness of your original post
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Old 12-09-2011, 10:45 AM   #127
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Quote:
Originally Posted by damir130 View Post
Bunch of armchair and hearsay suspension specialist that have apparently never seen a mcPherson strut up close.

I know that on my AE86 track car, with McPhersons and 2 30$ spacers, there is a linear correlation between bump and negative (yes negative) camber. Not perfect (you'd like a more gain like the miata) but that doesn't stop this car, and every other mcPherson car on the planet, from working just fine on track.

In theory you get positive change when the lower control arms are angled past horizontal. In pratice things don't get that out of shape when you lower the car, or a simple 30$ spacer puts the LCA's back in their original position.
At best you are repeating what someone else told you, without fact checking. Its NOT about the LCA being horizontal, its about the angle created between the LCA and strut. if its more than 90*, then you will get positive camber bump curve. Unless your strut comes down in a straight line (perpendicular to the LCA), horizontal wouldn't be the correct measurement to use.


I don't see how a spacer has anything to do with this, since all it does is move the wheel further out.
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Old 12-09-2011, 11:32 AM   #128
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Granted, but with minimal KPI built into the strut its close enough.

The spacer in my case lowers the attachment point of the LCA. It does this below the hub attachment so ride height is unaffected but control arm angle is reset to something closer to orginal.
The point is that my camber curve, on my McStrut equipped car lowered to race height (yes thats right ladies, no dorifto, I'm gay enough already through the miata), is linear and gives negative camber gain to the tune of -1.5 degrees at 2" inches deflection. That's measured on my POS car, not deducted from the comfort of my armchair.
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Old 12-09-2011, 11:51 AM   #129
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Quote:
Originally Posted by damir130 View Post
Granted, but with minimal KPI built into the strut its close enough.

The spacer in my case lowers the attachment point of the LCA. It does this below the hub attachment so ride height is unaffected but control arm angle is reset to something closer to orginal.
The point is that my camber curve, on my McStrut equipped car lowered to race height (yes thats right ladies, no dorifto, I'm gay enough already through the miata), is linear and gives negative camber gain to the tune of -1.5 degrees at 2" inches deflection. That's measured on my POS car, not deducted from the comfort of my armchair.
There are other problems associated with a low KPI, but thats a discussion for another time.

Its great you fixed it, but keep in mind here you have had to add a spacer to your LCA (not to your wheel as implied by only saying "spacer"). No one here has really been armchair racing, we are only speculating as to future problems that may come up with the FR-S.

There is no way for any of us to know how the FR-S will handle a "racing" ride height at this time. Perhaps due to the low center of gravity and the fact that this car doesn't have much ground clearance (4.9") already, then a racing drop will only be 1" in which case the LCA may not need any modification and positive camber curves will not be an issue in that case.

We haven't really had real user experience shared on this car. Sure car bloggers and mags. have praised it, but I don't think that transfers over very well to racing/HPDE.
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Old 12-09-2011, 12:06 PM   #130
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It has already been raced during the 24h here at the nurburgring (finished p120) and it was spanked by a S2000 (p116).


Then again..the S2000 was 2nd to a CTR that finished a whopping 48th overal despite its McStrut handicap.

But I guess we're in agreement when you say that guestimating track prowess based on a couple of reviews and the presence of a mcstrut is bench racing at its finest.
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Old 12-09-2011, 02:52 PM   #131
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The race team I work for has won multiple SCCA and NASA national championships in macstrut cars. We have one of the best handling cars in the Grand AM ST class with a macstrut car. We just spent 25 hours running around Thunderhill in cars that handle as well or better than all the NA, NB and NC cars out there in a macstrut car.

Sure it's not ideal, but that doesn't mean it can't be made to work well.
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Old 12-09-2011, 02:59 PM   #132
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Quote:
Originally Posted by Efini~FC3S View Post
The race team I work for has won multiple SCCA and NASA national championships in macstrut cars. We have one of the best handling cars in the Grand AM ST class with a macstrut car. We just spent 25 hours running around Thunderhill in cars that handle as well or better than all the NA, NB and NC cars out there in a macstrut car.

Sure it's not ideal, but that doesn't mean it can't be made to work well.
agreed, bmw and porsche have been making it work for years now, hell even decades.
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Old 12-09-2011, 04:37 PM   #133
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The problem with McStruts isn't that they can't be made to work well for a street car or a purpose built racecar. The problem is for a combo street / track car. A McStrut set up for the track on race rubber will have lots of negative static camber which will eat street tires when driven on the street. Movable tophats that can be adjust camber at the start and end of a track day are a kludge that works, but then the car will understeer on the street. You'd have to also have to disconnect the (right sized) rear bar to get the balance back.

A McStrut stock-suspensioned car that works well on the street will likely understeer on the track when shod with sticky rubber, and eat the tires too.

Miatas are well known to be kind on tires at the track, and the front A-arms are a big reason for this.
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Old 12-09-2011, 06:02 PM   #134
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How much static camber is required to really degrade tire life on the street?

I think it's well proven toe is much more of a tire eater than static camber.
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Old 12-09-2011, 07:25 PM   #135
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Concerned too much static negative camber will degrade tire life on the street?



Corner harder on your way to work?
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Old 12-10-2011, 04:20 PM   #136
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Quote:
Originally Posted by Scrappy Jack View Post
Concerned too much static negative camber will degrade tire life on the street?



Corner harder on your way to work?
I concur.

The macstrut front sus. isn't going to make or break this car for me. Final pricing and actual real world performance/driving will though.
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Old 12-10-2011, 05:01 PM   #137
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Me three, for a mostly-street car whose suspension I keep near-stock.
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Old 12-10-2011, 05:29 PM   #138
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Quote:
Originally Posted by Efini~FC3S View Post
I concur.

The macstrut front sus. isn't going to make or break this car for me. Final pricing and actual real world performance/driving will though.
Agreed, my miata would be the track car anyway.
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Old 12-10-2011, 08:03 PM   #139
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Quote:
Originally Posted by Efini~FC3S View Post
How much static camber is required to really degrade tire life on the street?

I think it's well proven toe is much more of a tire eater than static camber.
Yes the wrong toe will eat tires very quickly, but all else being equal big camber will still eat tires on the street.
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Old 12-10-2011, 08:25 PM   #140
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Quote:
Originally Posted by JasonC SBB View Post
Yes the wrong toe will eat tires very quickly, but all else being equal big camber will still eat tires on the street.
What's big camber?

-1.5?

-2.0?

-3?
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