Alignment & Corner Weights - First Pass...

4348 Views 23 Replies 11 Participants Last post by Ara, Oct 12, 2004

Stan

Discussion Starter · Sep 27, 2004 (Edited)

(Dunno if this should be in this forum, the auto-x forum or whatever...)

I had my car checked for alignment with and without me in the driver's seat and also noted the corner weights.

* The toe is way off up front with one aboard

* The camber goes positive with me aboard...not good.

* Caster was okay.

* Rear Toe is too high, Rear camber a bit too high.

* Corner weights show the expected left side bias and some potential to get things right since they are not too far off. The car weight came out higher than expected but that can also be scale related and the main thing there (as with dynos) is that things repeat so that when you get the corner weights set you know you are "there".

Now that I see the alignment numbers I can see a number of obvious areas for improvement. Lotus Elise camber/caster is set via shims. I will guess at how many shims to change/remove before getting the alignment rechecked. That way I can see how much things changed via the shimming and will know for example that camber changes about x degrees per shim of Y thickness. My uprights have about 5 shims apiece presently. So I can further fine tune as required and can gain much more negative camber. I want to wind up with the same camber on each side with me aboard and with a favorable amount that is still streetable. Caster is about right up front so only the front and rear camber need to be tweaked, especially the front. Then the toe can be set. I'd like to have zero up front and a bit less toe in out back. Then toe can be set at an event if desired since I will have the car measured to see how much, say, a half turn of a front tie rod changes the toe. For auto-x maybe an 1/8 or so toe out might be a nice setup but this has not yet been tested.

On the chart below, note that the "Before" figures are for the car alone. And the "Actual" figures are for the car plus me sitting in it.

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008

· #2 · Sep 27, 2004

Do you have LSS? Are you going to corner balance it before you align?

Stan

Discussion Starter · #3 · Sep 27, 2004 (Edited)

>>>Do you have LSS? Are you going to corner balance it before you align?<<

This is the baseline result for my 3,000 mile old LTS suspension. I'll be converting to an SCCA type "LSS" in the future. Lotus springs, lotus sized wheels, Non-Lotus dampers, Lotus rack shim. Yes the car will be corner balanced and aligned as much as possible and optimized for the driver alone in the car. Some of this stuff is iterative. This is just where things stand now, a baseline or a starting point.

_JD_

· #4 · Sep 27, 2004

008 said:
Do you have LSS? Are you going to corner balance it before you align?

Just to note, you can adjust the height of the std. suspension as well as the sport pack.

Stan

Discussion Starter · #5 · Sep 27, 2004

>>Just to note, you can adjust the height of the std. suspension as well as the sport pack.<<<

Yes this is the case. But only in about 5 mm increments on the body of the damper. This is not the same as 5 mm at the contact patch. If the service manual says you can shim, then you will be able to get perfect corner weights for SCCA stock class purposes. Of if that is not an issue for someone this can be done right now. Factory specs DO call out specific ride heights and where they are measured.

JonOrangeElise

· #6 · Sep 27, 2004

Stan: What kind of driving have you done (i.e., how spirited?), and over what kind of road conditions?

To anyone who cares to answer: Is this going to be a car that consistently gets knocked out of alignment?

My M3 could never keep an alignment with worn bushings, but after a full-car bushings replacement about 25,000 miles ago, the car now keeps its alignment surprisingly well.

adamant

· #7 · Sep 27, 2004 (Edited)

Thanks Stan. Wow, the front Camber changes a huge amount with/without driver!
I'm not sure what you mean by "LTS"
If I have it right your Elise weighs ~2060lbs. Is this with touring or the hardtop?

Surferjer

· #8 · Sep 27, 2004

ADAMANT-LTs is the same as "base" non-LSS suspension. Stan-who did your measuring? Did you take it to the dealer or someone else?

Great information, thanks. I'm converting mine in less than a month to LSS. I'm creating another thread on pricing...

Stan

Discussion Starter · #9 · Sep 27, 2004

My Elise has been driven normally, sedately most of the time on the road. And it's been in a few autocrosses. LTS is the normal, non LSS suspension.

It appears that Lotus aligns the car using either no weight or equal weights per side. Knowing that, we can adjust things to our intended use, one aboard in my case. The suspension is pretty adjustable. Only the toe is super easy to adjust for an event.

The front camber is set at the out end of the upper a-arm. There are shims between the ball joint plate and the actual suspension upright. Caster is set via washers at the inner ends of the upper arm. Neither are easy to do at an event.

The alignment was checked at a local shop.

Stan

Discussion Starter · #10 · Sep 28, 2004

I've been looking at autocross PICs of Surferjer's BRP car as well as my SY Elise. Both are LTS cars. When you see the body roll in a picture, you can adjust the angle back to zero in photoshop. This gives you an idea of the chassis roll the car is experiencing. I'm finding that around a 3 degree change brings the chassis back to horizontal...so this means that that is roughly the amount of roll that we were experiencing. If a car rolled three degrees and the suspension added some negative camber as the outside tire moved the suspension up this would help improve the tire footprint on the ground. Combine with static negative camber and that is how we try to keep the tire on the ground. Tires like to be slightly negative cambered to the road, so add maybe and extra 1/4 to 1/2 degree if you can get it.. So if a chassis rolled 3 degrees in the unfavorable direction, we would need about that much and maybe a bit more to get the best footprint for grip. This is assuming that various side effects don't mess us up. For example negative camber can steer the car a bit, and hurts the footprint for braking and acceleration efforts.

Suppose the Elise chassis rolled about 3 degrees in a steady turn and we could not stiffen the springs / swaybars. Then if the camber gain from compressing the outside suspension gave us about 1.5 degrees negative camber and the car was set to about 1.5 degrees negative camber that would be roughly enough.

I'm suspecting that the Elise may like tires that can tolerate less than ideal camber..rounded shoulders perhaps...

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ConeFusion

· #11 · Sep 28, 2004

Interesting, thanks for posting this. Unfortunately it doesn't seem unusual that new cars (of any brand) get delivered with questionable alignments. Some comments/questions:

The biggest problem seems to be the camber on the left front. It's slightly positive unloaded, and goes substantially positive with you in the car. That can't be good!

If I converted the units correctly, that's about 1/16" of total toe-in in the front? Not a large amount, but should be worth correcting.

You got some wild values for the front toe with the driver, but they have opposite signs. I guess something went wrong with the measurement there? The total toe actually improved.

The rear values look much better, even though it also has more toe-in than recommended.

Very surprised at the weight: 2070 lbs without driver? :huh: That doesn't look consistent with the officially specified weight.

The front/rear weight distribution is different from what I seem to remember from previous discussions, even trying to account for the driver. Under the assumption that 2/3 of your weight are on the front (is that reasonable?), it's a 40/60 weight distribution for the empty car. I thought it was supposed to be more rear heavy than that? Not too far off from some numbers I found with a search, though, one article suggested 38/62.

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Arno

· #12 · Sep 28, 2004

Stan said:
Only the toe is super easy to adjust for an event.

Umm.. As the toe is super-super sensitive I would not share that opinion.

Adjustment on the steering arms you're talking about fractions of turns and not even full turns.

When I adjust the alignment on my car using a Hunter rig I always have to be very careful to allow some margin before tightening the locknuts. Just the locknut tightening will change the toe by 2 minutes or so, which in the Elise's case is significant.

I'd stay away from touching the toe settings when not on an alignment rig.. But that's just me..

Changing the camber is actually a piece of p*ss and can be done in about 10 minutes. Just jack up one side, remove wheel, undo 2 bolts, add or remove shims (discrete 'steps', so once you know your baseline you can simply do the math), put new loctite on bolts, put bolts back and re-install wheel. Done..

Changing the front camber does not have an effect on the toe settings on the Elise (or very, very minor) as the camber shims are between the steering arm and the hub carrier.

Caster adjustment is not easy and does take a long time as you have to undo the wishbones. But that's hardly ever required to be changed.

Bye, Arno.

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Stan

Discussion Starter · #13 · Sep 28, 2004

Yeah front caster appears to be acceptable so I will leave it alone. Do you know the negative camber change per shim? I'll likely guess and then remeasure so I can get side to side camber more even and discover the increment per shim for future changes. Front toe actually got worse with me in it if I'm reading the chart corrently...contrary to someone's comment. The total toe improved, but side to side got worse. It's possible that something moved when I got into the car. I'll have to watch for that next time and makes sure that the car hits the empty figures again when I get out. Toe gets set last in an alignment anyway.

Toe is changed at autocrosses all the time. You just have to be able to get back to your street nor normal setting. So paint marks or other means can be used. Some front toe out / reduced rear toe-in really helps out some cars.

On the total weight...the scale may be wrong but the relative weights should be good. The 38% / 62% figures I have seen might have been done using an empty car with unknown fuel contents. I used about 6 - 6 1/2 gallons of gas.

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del105

· #14 · Sep 28, 2004

I have a very basic question. I have never aligned a car that uses shims. Are shims a removable item? Will I need to buy extra ones or ones of different sizes? Can anyone clue me in on shims in general?

Stan

Discussion Starter · #15 · Sep 28, 2004

Shims...in the PIC below we see an earlier but similar Elise front suspension...caster is set by moving the existing washers surrounding the upper a-arm mounts. The same amount of space is maintained for the "stack" of washers / a-arm bush.

Camber is set by adding/removing shim plates with two holes in them. Most likely you will not need more as you amy wish to leave camber alone or add some negative camber which means you'll pull some shims out. My car has 4 shims plus the plate to hold some of the abs wiring. Two allen bolts retain the suspension upright to the outer ball joint mount.

Toe is set normally via the tie rod. There is also a rear suspension tie rod for toe setting.

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Arno

· #16 · Sep 28, 2004

Stan said:
Do you know the negative camber change per shim?

This is for the S2, but I suspect the 111R/Fed-Elise is the same.

There are 2 shim thickness types used. 1mm and 3mm. A 1mm shim changes the camber by 0.25 degree.

On the 111R/Fed-Elise there ABS sensor bracket is actually a shim too, so if you want to remove that you need to use some cable-ties to attach the connector to the wishbone.

Toe is changed at autocrosses all the time. You just have to be able to get back to your street nor normal setting. So paint marks or other means can be used. Some front toe out / reduced rear toe-in really helps out some cars.

True. I run my Elise with -1 front and -2 degree camber and at 15 minutes total toe OUT at the front and about 30 minutes total toe IN at the rear for both road and track. I like it a lot.

I just question how accurate you can set and re-set the toe by using something as 'coarse' as a paint mark.

I guess you'll just need to try it and later on re-check the car on an alignment rig to see how accurately you canchange and then 'reset' it while on the track of if it ends up off too much.

The Elise is very sensitive to alignment settings and it quickly doesn't 'feel right' if you're only off a little (something you probably would not ntice on other cars at all unless you're off by a huge margin).

Bye, Arno.

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Stan

Discussion Starter · #17 · Sep 28, 2004 (Edited)

2

Federal Elise upper a-arm....note camber shims and abs wire plate. You can also see the tie rod for toe setting...and in the back the caster is set at the upper a-arm mounts.

Arno...for autocross you have to set up for an event / course. It's not a permanent setup. Sometimes an unstable setup is quickest. Many folks reset toe at events. The Elise specs call out zero front toe. This is easy to get back to since this means the distance between the f/r of an axle set of wheels/tires will be the same.

Here's a guy resetting rear toe on an S2000 at an event. It's Perry, who runs the nice site www.autox4u.com serving the NY metro area. He has a nice schedule showing which clubs are running organized by date. For example this weekend there are about 6-7 autocross events in the area.

For autocross, folks sometimes change only one side of the front end which will slightly skew the steering wheel but that is no big deal as it is not a permanent change. These are one minute runs, not hours in a row on track
with no time to stop and change something and then try again. At my last autocross we thought the Elise could use roughly about an 1/8 inch or so total front out but we ran it stock.

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Arno

· #18 · Sep 28, 2004

Ah..

Such a 'string and ruler' setup should work fine if you'll use that. It can be set up with plenty accuracy.

Many of the racers here in europe with Elises use the same method to adjust their cars for each track they run on.

Bye, Arno.

adamant

· #19 · Sep 28, 2004

Arno, Do you still have any shims in place when you are set to -1 deg up front?

I am just trying to determine if -1 is attainable in all cars given manufacturing tolerances. Thanks.

Arno

· #20 · Sep 29, 2004

adamant said:
Arno, Do you still have any shims in place when you are set to -1 deg up front?

No. I removed all shims and I get exactly -1 at the front. The rear still has several shims when at -2

This is normal for the S2. -1 is about the maximum you can reach without having to shave the mounting plinth.

The S1 can usually reach -1.5 to -1.8 when all shims are removed.

I guess for the 111R/FedElise you may also need to remove the ABS bracket/shim to reach the same camber setting at the front.

Bye, Arno.

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