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Author Topic: Suspension "settles" re-aginment issues
jensen Verified Driver Made Donation to Website
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First time out this weekend @ GIR in a new-built '99. I used the J.D. guide as a baseline set up. After running @ GIR the car had "settled" and lost a considerable amount of ride height. Started with 4 5/8 @ all four, ended with 4.25 LF, 4.375 RF, 4.5 LR, 4.5 RR. I started to raise the front but now lost a ton of camber in the RF, was @ -2.5, now at -1.8. I also am running the shock spacers in the hats. Possible bent LCA? Need new adjusters? I have aftermarket(new) ball joints, possible differences? Any suggestions would be great.

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Matt Jensen
SCCA SM Cen-Div
MC NASA 68

disquek Verified Driver Made Donation to Website
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Did you torque the CA bushing bolts when the car was at full droop?

-Kyle

jensen Verified Driver Made Donation to Website
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Kyle,
I did torque the bolts when the suspension was loaded. I marked all settings and re-checked after practice sessions. No bolts/paint marks moved, but ride height and RF camber did.

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Matt Jensen
SCCA SM Cen-Div
MC NASA 68

CP Verified Driver
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How much should I expect the SM springs to settle, and how long before they stop shrinking? I need to know when I should schedule my next alignment with my shop (they have a 4 week backlog).

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-Cy
Supported by LTD Racing & Speed Shack - New England's Premier Auto Accessory Store
Rt1 AutoMile - Norwood, MA
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jensen Verified Driver Made Donation to Website
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I ordered a new LCA for the right corner. I will see if this cures the problem. while I am at it I will be replacing all of the eccentric bolts. I'll keep you guys posted.

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Matt Jensen
SCCA SM Cen-Div
MC NASA 68

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quote:
Originally posted by CP:
I need to know when I should schedule my next alignment with my shop (they have a 4 week backlog).

You should start thinking about doing your own setup in your garage. It really is not that hard. You can take care of caster, camber and toe with nothing more than some string, jackstands, wood planks for leveling, and lots of patience. Upgrading to a digital level, the Iron Canyon Miata Alignment System (freaking love this thing) and toe plates will help get it done at least twice as fast.

Grab Boemler's setup spreadsheet here:
Boemler Setup Worksheet and start wrenching. Use JD's setup guide (linked on the SpecMiata.com homepage) as a baseline and go from there. I also put together a simpler guide that addresses some of my quibbles with JD's guide (sorry Jim) here Simplified Setup Guide and Track Tuning

Make sure to level your floor using the water method, using a length of clear tubing attached to each wheel. Insert pieces of wood or whatever under each wheel until the water in the tube settles at the same place on the wheel on all 4 corners.

Make a plumb level out of string and a weight, hang it off the fender and measure how far the top of the rim and bottom of the rim are from the plumb. These are your camber numbers. Insert them in the spreadsheet and it will tell you what degree of camber you have.

Assemble a string box according to JD's guide around your car to check toe on all 4 corners, keeping in mind that you want all 4 wheels pointed straight ahead, not just parallel to each other. Measure from the front of the rim and the back of the rim to the string. The numbers should be the same. Follow my guide for the proper adjustment order so you don't wind up chasing your tail more than necessary.

You can use the string box for relative toe (how parallel 2 wheels are from each other) but it is a good idea to have toe plates to double check your measurements. You can make some cheap toe plates out of aluminum stock, but spending a bill and a half on some off the shelf pieces is well worth it, especially if you were planning on spending big $$ on a pro alignment.

Crossweight is more difficult with garage tools. Actually, it is impossible to do without scales. Does the pro shop you use do crossweight? If so, maybe it is easier for you just to go there unless you invest in scales.

The problem with not having the car on scales when doing a full setup is cross changes as soon as you breath on the car. If you are really serious about racing, you will want to invest in your own setup equipment. PM me for a retailer recommendation.

If you really want to see if your setup is ideal for a particular track, you also need a good tire pyrometer (probe type) and tire pressure gauge. Analyzing your tire temperature profile (inside, middle, outside) is the only way to know much rubber is actually getting to the road. Of course you need someone in the pits to take these measurements also.

That covers just about everything. Let me know if I left anything out (besides the omitted ride height. Check my guide for that.)

   

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