8 replies to this topic

[Don Brown]

Before I had tools to measure my own alignment setup, I had a local alignment shop get me an aggressive and balanced (I asked for max neg camber, most caster, same left to right) setup on my '95 Miata - I got -2 camber front and -1.5 camber rear, and zero toe in the front and rear; +4.5 caster.

After my first race weekend (on new tires), I had significant wear on the outside half of my RF tire, and to a lesser degree on the others. Experienced pilots in the paddock said "you need more (negative) camber"...

I'm trying to get setup according to Jim Daniel's revised guide (http://www.specmiata...up_guide_v2.pdf). The ride height has been set to 4 5/8" as measured from the pinch welds, and with the eccentric bolts adjusted to their "full negative camber" position (I wanna see how much I can get; no concern yet given to caster), I measure -2.8 on the LF and -1.9 on the RF. That supports the shop's assessment that -2 was the best (balanced) camber they could get up front.

I was hoping for a far greater max neg to work from...

The bushing are of unknown history (the car's odometer reads 138K); could they be a factor? Bent components? Visual inspection shows nothing obvious, and other than the tire wear, I was pretty happy with the car's handling (gotta work on the driver, of course )

How can I get more negative camber out of the car? I don't want to have to replace tires every other weekend due to inadequate setup. And of course I want to be faster.

Thanks in advance for your thoughts...

[davew]

My guess would be something is bent. Most likely would be lower control arm, lower ball joint and or subframe.

Inspect the lower arm very carefully for a bend, even a slight bend will make a difference. I made a set of jigs for measuring all the control arms, but you are too far away.

Remove the boot from the lower ball joint, it nis very common for the studs to bend.

Measure the distance between the allignment horseshoes. This is a little tricky and you may need a couple of plumb bobs. The distance from the left horseshoe, to the coresponding right horseshoe should be tha same at all 4 pairs

Dave

[Bruce Wilson]

RF is likely bent lower control arm. max 1.5 negative in the rear, both sides?

-bw

[dstevens]

Measure the distance between the allignment horseshoes. This is a little tricky and you may need a couple of plumb bobs. The distance from the left horseshoe, to the coresponding right horseshoe should be tha same at all 4 pairs

Good tip, thanks. I'm there right now. Right upper bent for certain plus both lower ball joints. Hoping the front sub frame isn't bent. Those control arm jigs are something a guy like me would buy or even buy plans to. I keep meaning to pick up a rear sub frame checker.

[Don Brown]

My guess would be something is bent. Most likely would be lower control arm, lower ball joint and or subframe.

Inspect the lower arm very carefully for a bend, even a slight bend will make a difference. I made a set of jigs for measuring all the control arms, but you are too far away.

Remove the boot from the lower ball joint, it nis very common for the studs to bend.

Measure the distance between the allignment horseshoes. This is a little tricky and you may need a couple of plumb bobs. The distance from the left horseshoe, to the coresponding right horseshoe should be tha same at all 4 pairs

Dave

Dave, thanks for the reply; I'll give your measurement method a try for sure. By the way, I'm getting good use out of your "Constructors Manual"; thanks for producing that!

[Don Brown]

RF is likely bent lower control arm. max 1.5 negative in the rear, both sides?

-bw

Thanks for the reply, Bruce. I've not yet checked max in the back; I'll post back here with my measurements. I'll be measuring horseshoe-to-horseshoe distances per DaveW's suggestion; have you tricks for measuring/assessing a control arm bend? Some have said most bends aren't naked-eye visible...

[Don Brown]

Folks,

Thanks again for your input. Bruce, I can get -4 degrees on both sides in the rear. Dave, measuring the front lower control arms relative to each other as you suggested produced a 3/8" diff between the fore and aft attachments to the subframe. Hope that is more inaccuracy of my measurement than subframe issue...

The thoughts that the LCA and/or lower ball joint might be bent has had me source an LCA and LBJ which I'll install.

We'll see how my max camber changes as a result; I'll post my findings...

Again, thanks.

[davew]

If you have 3/8" difference between the horseshoes, your subframe is bent.

Dave

[Don Brown]

Folks,

Thanks again for your thoughts and suggestions. Upon replacing the right front LCA and ball joint, I was able to get to -2.75 degrees camber. Seems that was one source of my alignment issue. I'll continue to look at the subframe, but for now I'm not at as great a risk of scrubbing through tires every weekend!