THSCC Forums

I agree Brad. It looks to me like the springs are mixed. Like one front and one rear on each end. That would explain the wildly different spring perch locations.

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Todd Breakey
STS 42 - 1992 Sunburst Miata
Dammit!
"You souldn't play leap frog with a porcupine. You might get hurt." - Eliza

Okay, I set 'er back on stands took pictures of the spring numbers, set all perches at 13 threads from the bottom and set 'er back down.

FR: 11.5" FL 11.5"
RR: 12.5" RL 12.5"

WOW - even all around

Pictures to come later.

Now my theory as to what was screwed up.

fronts may not have been even on the first set down on the ground.
moved too much at a time and didn't keep sides even.
didn't drive after each adjustment to shake out the suspension.
worried about the ride height and didn't think about the perch position until I looked at it once I 'was done'
wanted to be done and probably rushed through the last step

Thanks for the help and I can't tell you how relieved I was tonight when I set all four even and set it down to see all the numbers match.

Final settings before the alignment in the morning

FR: 12.0" FL 12.0"
RR: 12.5" RL 12.5"

with me in da' car.

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Colin O'Connell

'94 BMW NASA SPEC 3
'02 F350 tow vehicle (not bad for a tow vehicle)
'97 Miata STO (autoX and sunny day spoils vehicle)
'97 BMW 328i (loaner to the kids when their cars don't work vehicle)
'05 Toyota Highlander

Both front springs 150-64-66
Both back springs 180-64-44


Looks good now huh?

_________________
Colin O'Connell

'94 BMW NASA SPEC 3
'02 F350 tow vehicle (not bad for a tow vehicle)
'97 Miata STO (autoX and sunny day spoils vehicle)
'97 BMW 328i (loaner to the kids when their cars don't work vehicle)
'05 Toyota Highlander

That looks MUCH better!!

_________________
Todd Breakey
STS 42 - 1992 Sunburst Miata
Dammit!
"You souldn't play leap frog with a porcupine. You might get hurt." - Eliza

Yep. Looks much better.

The perches and the threaded sleeve have machined surfaces. Use these as datum surfaces on initial set-up, rather than counting "Threads". It's the Distance that matters. Use an accurate 3" machinist's scale, and you should be able to get the initial settings within about .010". Then work up or down from there when cross-weighting the car. GC thread pitch is .125", as I remember, so 1/4-turn should yield about .030" (1/32") of perch movement.

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Brad

That might be a little too low, at least if your planning to run a 225 tire. You'll definitely have to do some serious fender rolling in the front.

That's 1/2 " too low in the front. I was highsiding on the exhaust on our gravel driveway with that ride height.

_________________
Has no responsibility whatsoever.

The car is sitting at 12.5 Front (slightly under) and 12.75 rear today.

Seems to be settled in now. Do slight changes to this setting change the alignment? Can I move it to slightly over 12.5 F and 12.8-13" R without redoing the alignment or would I need to recheck that afterwards?

_________________
Colin O'Connell

'94 BMW NASA SPEC 3
'02 F350 tow vehicle (not bad for a tow vehicle)
'97 Miata STO (autoX and sunny day spoils vehicle)
'97 BMW 328i (loaner to the kids when their cars don't work vehicle)
'05 Toyota Highlander

You'd need to have it realigned.

That ride height as is is fine. What alignment specs did you go for?

_________________
Has no responsibility whatsoever.

Ended up with (specified)
Front:
Camber = -2 (-2)
Caster = 5 (max)
Toe = .03 (1/16")

Rear
Camber = -2 (-2)
Toe = .01 (-1/16")

The guy had to redo it and apearently spent all day on it. The first time he did the camber at -.2 and didn't even up the rear's left and right. I was very clear with the service manager, but the tech 'did't think it was right' and didn't ask.

He didn't (said he couldn't) get the rear Toe any farther.

_________________
Colin O'Connell

'94 BMW NASA SPEC 3
'02 F350 tow vehicle (not bad for a tow vehicle)
'97 Miata STO (autoX and sunny day spoils vehicle)
'97 BMW 328i (loaner to the kids when their cars don't work vehicle)
'05 Toyota Highlander

I would submit that you can get a LOT more toe-in, toe-out or toe-jam on the rear. Tell your "mechanik" to re-think the deal.

Hell, there's nearly 3/8" of total eccentricity on the lower cam bolts. If you used all of it, you should be able to get 3 to 3-1/2 deg. of neg. camber and still be able to get your 1/16" of toe-in.

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Brad

I had some pretty good front fender well rubbing at VIR Norht last month. This week, I increased the front spring rate on my SC'd car. While I was at it, I played around with height settings on the adj coil overs.

The car was on jack stands. I would jack up the lower control arm of the corner I was working on until it lifted off the jack stand. Then I'd take my measurements, lower the car to remove the load and adjust accordingly. It wasn't that bad of an affair, but I was a little pushed for time.


Settings are as follows:

Front Rear
Spring Rate 440 250
Height 13" 13 3/8" (Wheel center to fender)
Swaybar 7/8" stock

I like to use the following alignment:

Front
Camber: -1.5
Caster: 4 - 5
Toe: straight, error towards toe in (Track setting, 1/16" Toe out for autocross)

Rear
Camber: -2
Toe: -1/16"

_________________
“I feel safer on a racetrack than I do on Houston's freeways.” - A.J. Foyt

Kevin Butler
Mobetta Autosport Spec E30 #612
2003 C5 Z06 Corvette
AFR Miata, SM2 61, '93 w/200 SC'd RWHP - soon to be resurrected
Waaaay too many other projects....