Corner Balance Results

[blender]

I had the car corner balanced and realigned this week. Results were illuminating.

This was done after putting about 400mi on a new set of KW V3s to allow the springs to settle in.

Darin at West End Alignment in LA is part scientist, part artist and he practices what we preaches by frequently autocrossing his own cars. He runs a very clean professional shop. Total time ~2 hours for corner balancing, another hour for 4-wheel alignment. Cost was ~$250.

We discovered my car was significantly unbalanced towards the left rear tire once I was in the driver seat. This was probably a result of where we set the coilover ride heights at time of install [ both rears same, both fronts same based on a ground clearance I wanted.]

Additionally I carry 'trunk bag' of stuff in the car [ toolset, compact compressor, torque wrench, saftey reflectors, firstaid kit, manuals, funnel, code reader, detailing junk, etc etc]. The bag and its contents are ~40Lb. I pull the bag for autocrossing, but on weekend drives I want all this stuff handy.

So with the bag and me , 3/4 tank of gas, and other minimal junk in the car, the over-the-road weight was 3527 lb.

Process involved initial weighing, then multiple trips between the rack and a set of 4 scales to check the progress.

With some minute height adjustments we were able to move the car to a very nearly perfect front-to-rear and side-to-side weight distribution with me in the driver's seat. Even the diagonals are with one pound of identical. Darin is a master of his craft.

The car was initially about 10% heavy to the left, which we reduced to ~2%. If I shove the bag in the right rear corner of the trunk if goes to ~1%

See below/attached for Corner Balance results.

The car handles better than ever and turn-in is crisper thanks to the balancing and the final alignment:

Front: -2.6 Camber, caster 6.0L/6.2R, toe-in 3/32"
Rear: -1.6 Camber, 1/32" toe-in

Darin highly recommends a corner-balancing after installing coilovers, to take advantage of their ride height adjustability to truly (re) balance the car. I have to agree based on my own experience. If you have coilovers or are pondering them, do yourself a favor, spend the money for a cornerbalance and alignment. It's the best way to really get your money's worth from the car and upgraded suspension.

Attachment 387852

[Blind32]

Awesome. Thanks for posting this information. Just to be clear, did you install the suspension then wait 400 miles and do the corner balance & alignment or did you install suspension, corner balance and then wait 400 miles to align? As far as price, he charged 3 hours of work at the normal indy shop rate?

[inTgr8r]

^WHS+1
Thanks for the write up

(subscribed for future reference)

[blender]

Originally Posted by Blind32

Awesome. Thanks for posting this information. Just to be clear, did you install the suspension then wait 400 miles and do the corner balance & alignment or did you install suspension, corner balance and then wait 400 miles to align? As far as price, he charged 3 hours of work at the normal indy shop rate?

I did the KW install, did an initial alignment, and drove around 400mi to allow everything to settle in before the corner balance and final alignment.

cost for ~3 hours labor was $250.

[blender]

Update: got a good long canyon session this afternoon after the alignment & corner balancing. The handling has gone up another level !! over stock or H&Rs. The squirrelly pendulum feeling from the rear end is gone, and the car turns and sticks sooo good. Much more confidence at the limits of handling because it's much more predictable; Really superb.

It's like dating a nymphomaniac gymnast: it can (and will) do nearly anything you can imagine, all day long...

[shitbrownMcoupe]

thanks for sharing. i had the car alignment done and had the rears camber adjusted and fronts toe in as well.... totally different when turning.... i'll definitely do the balance as you did later on.

cheers

[Master Apex]

Can you post the static (no person in the car) height on each corner of the car ?
Say from the fender line to the bottom of the rim (to reduce error in tire deflection due to surface)....

Thanks.

[blender]

Originally Posted by Master Apex

Can you post the static (no person in the car) height on each corner of the car ?
Say from the fender line to the bottom of the rim (to reduce error in tire deflection due to surface)....

Thanks.

Sure....

Attachment 395032

I also confirmed :
factory Front ride height should be 608mm (+40 or -20 acceptable) 608mm = 23.93 inches
factory Rear ride height should be 595mm (+40 or -20 acceptable) 595mm = 23.42 inches

According to the BMW TIS method, "ride height is measured from the bottom of the rim to the wheel well", which is E to C in pic above. Pardon my camber...

Anyway, E to C measurements, no occupants:

Front Left / Right: 592 mm, 590 mm
Rear Left/Right: 594.5mm, 587mm

This had the effect 'tipping' the CG away from the overloaded left-rear towards the sweet spot right behind the gear shift lever. It absolutely improved the handling.

[jdl1pt]

Originally Posted by rclem05

It's like dating a kinky nymphomaniac gymnast: it can (and will) do nearly anything you can imagine, all day long...

Uhhh, I'm sold!

[Master Apex]

Originally Posted by rclem05

Sure....

Attachment 395032

I also confirmed :
factory Front ride height should be 608mm (+40 or -20 acceptable) 608mm = 23.93 inches
factory Rear ride height should be 595mm (+40 or -20 acceptable) 595mm = 23.42 inches

According to the BMW TIS method, "ride height is measured from the bottom of the rim to the wheel well", which is E to C in pic above. Pardon my camber...

Anyway, E to C measurements, no occupants:

Front Left / Right: 592 mm, 590 mm
Rear Left/Right: 594.5mm, 587mm

This had the effect 'tipping' the CG away from the overloaded left-rear towards the sweet spot right behind the gear shift lever. It absolutely improved the handling.

Thank You very much.
I will be installing KW Clubsport in the two weeks and will try to adopt your setup.
Were you sitting in the car during the corner balance? Wondering if that will be more effective?

[blender]

Originally Posted by Master Apex

Thank You very much.
I will be installing KW Clubsport in the two weeks and will try to adopt your setup.
Were you sitting in the car during the corner balance? Wondering if that will be more effective?

Yes, definitely sit in the car during the CB, or have similar weights in the drivers seat [sandbags maybe]. The driver's mass is the single biggest off-center mass in the car; it's both left and back of the CG. You'll want approximately half a tank of gas, plus any other items in the car which you'll keep with you while driving. My application is canyon carving so I have a sport bag in the trunk with a few must-haves - tire patch, compressor, a handful of tools etc. Depending on the car you may have a spare tire, etc. For a track setup I'd empty the car except for me and a helmet.

good luck.

RC

[Master Apex]

Originally Posted by rclem05

Sure....

Attachment 395032

Anyway, E to C measurements, no occupants:

Front Left / Right: 592 mm, 590 mm
Rear Left/Right: 594.5mm, 587mm

This had the effect 'tipping' the CG away from the overloaded left-rear towards the sweet spot right behind the gear shift lever. It absolutely improved the handling.

After further experiment and reading, I think raising the Rear Left is actually adding weight to Rear Left so you may need to re-adjust your corner balance.

Your setup:
FL 592mm - 892 lb
FR 590mm - 854 lb
RL 594.5mm - 910lb
RR 587mm - 870lb

Lowering (ride height) RL will reduce the weight on RL
Increasing (ride height) RR will add weight on RR

Check this reference:
http://www.scottgood.com/jsg/blog.ns...ks/SGOD-6B9PFW
http://www.bimmerfest.com/forums/sho...059&highlight=

http://www.lotustalk.com/forums/f91/...ustment-77759/
Lotus perch in on the opposite side so "upward" means "downward" for KW.

[Punko]

Great technical thread

[MIKe86]

So does your M have four noticeably different size fender gaps over each wheel now?

[The HACK]

Originally Posted by MIKe86

So does your M have four noticeably different size fender gaps over each wheel now?

Why would it be noticeable?

[blender]

Originally Posted by MIKe86

So does your M have four noticeably different size fender gaps over each wheel now?

"Noticeably different?" Different than stock, yes. Different from left side to right side, no.

[blender]

Originally Posted by Master Apex

After further experiment and reading, I think raising the Rear Left is actually adding weight to Rear Left so you may need to re-adjust your corner balance.

Your setup:
FL 592mm - 892 lb
FR 590mm - 854 lb
RL 594.5mm - 910lb
RR 587mm - 870lb

Lowering (ride height) RL will reduce the weight on RL
Increasing (ride height) RR will add weight on RR

Check this reference:
http://www.scottgood.com/jsg/blog.ns...ks/SGOD-6B9PFW
http://www.bimmerfest.com/forums/sho...059&highlight=

http://www.lotustalk.com/forums/f91/...ustment-77759/
Lotus perch in on the opposite side so "upward" means "downward" for KW.

Great links!

And yes raising the left rear (to set ride height with driver) added weight bias to the Left rear, which we then compensated for by raising the other corners to achieve the final result documented above. I can live with a 51/49 L/R balance.

[Caddyshk]

Great write up! I'm sold on the need to corner balance the car after the GC's are installed