PIF2: Adjustable Rear Camber Bolts

[Dropspeed]

PIF: Pay it forward with useful info to help others and save a few dollars.


I see this one come up a lot in threads.....So for those looking for an adjustable rear camber bolt after lowering:

SPC 87430 About $30 from our sponsors here. (You need two boxes as each contains 1 camber bolt and 1 caster bolt)

Double the range of rear camber and toe adjustment on the popular Camaro to increase handling performance and minimize tire wear. Remove and replace the OE cam bolts with our 87430 kit for +/- 1.0 degree camber change and +/- 2.0 degrees toe change. No slotting or grinding needed! Rear Adjustment Range: Camber +/- 1.0 degree Toe +/- 2.0 degrees Installation time: .6 hr/side Required: 1 per wheel

Pedders makes one too......but you would have to search to see who has inventory left at this time.

-Matt

[X25]

Ordered two of these at $27 shipped on Amazon per kit. When I installed Z/28 suspension kit, I was surprised to see that I could not get more than -1 camber at the rears, which will not be enough for Trofeo Rs :(. Considering Z/28 shocks lower the car by 33mm as well, I was actually expecting the other way around.

Here's hoping this is enough. If not, I'll have to go the route of adjustable rear arms, which add quite a bit of weight where you wouldn't want.

[tw78911sc]

Any idea how much camber you pick up after lower the car an 1"? I was barely able to get 1 degree in mine at OEM height, not enough but will be dropping car 1" and wonder if I should order adjustable control arms as well. Thx

[X25]

Originally Posted by tw78911sc

Any idea how much camber you pick up after lower the car an 1"? I was barely able to get 1 degree in mine at OEM height, not enough but will be dropping car 1" and wonder if I should order adjustable control arms as well. Thx

Mine did stay at -1 max after Z/28 suspension. Perhaps GM somehow compensates for the height drop in suspension design, so you don't get high negative camber. All good, except I wanted high negative camber

[Norm Peterson]

Originally Posted by X25

Mine did stay at -1 max after Z/28 suspension. Perhaps GM somehow compensates for the height drop in suspension design, so you don't get high negative camber. All good, except I wanted high negative camber

You need good coordinates for all of the pivot points and a decent suspension program or spreadsheet to find out what happens as the suspension moves into bump or the car is lowered.

Crudely, the closer the LCA and UCA are to being the same length, the smaller the camber changes will be for any given amount of suspension travel or lowering. But sometimes, what you want is a little more camber gain.


Norm

[Moreno1]

X25, did you measure a drop when you installed the z/28 parts? I thought the lower ride height of the z/28 was because of its 26.2" OD tires vs the SS's 28.7"

[X25]

Originally Posted by Nathan Moreno

X25, did you measure a drop when you installed the z/28 parts? I thought the lower ride height of the z/28 was because of its 26.2" OD tires vs the SS's 28.7"

GM lists Z/28 as 33mm lower, which is about 1.3"? The tire diameter difference only explains 0.8" of it.

[X25]

Originally Posted by Norm Peterson

You need good coordinates for all of the pivot points and a decent suspension program or spreadsheet to find out what happens as the suspension moves into bump or the car is lowered.

Crudely, the closer the LCA and UCA are to being the same length, the smaller the camber changes will be for any given amount of suspension travel or lowering. But sometimes, what you want is a little more camber gain.


Norm

It is no secret: Camaros gain negative camber, especially at the rears, when the car is dropped in height using springs. When I replaced the 1LE suspension with Z/28 shocks/struts, by max negative rear camber did not increase at all, suggesting GM might have offset the gain I'd get with change in the length of control arms (kit comes with Z/28 spec control arms, too) or the design of the shocks themselves.

Now that I have the Trofeo R tires as well, it is crucial that I hit my camber targets. I'm thinking about -1.5R / -2.5F. As is, I cannot go more than -1 rear, so did not go more than -1.8F not to upset the balance : (

[Norm Peterson]

Originally Posted by X25

It is no secret: Camaros gain negative camber, especially at the rears, when the car is dropped in height using springs. When I replaced the 1LE suspension with Z/28 shocks/struts, by max negative rear camber did not increase at all, suggesting GM might have offset the gain I'd get with change in the length of control arms (kit comes with Z/28 spec control arms, too) or the design of the shocks themselves.

In the one picture of the Camaro's rear suspension I happened to see yesterday, it appears that there isn't a whole lot of difference in the LCA and UCA lengths nor do they sharply converge toward the Front View Instant Center. So while camber will change with ride height, it'll be at a rather slow rate and minimal suspension lowering won't result in very much change. Of course, any lowering via shorter tires will not cause any camber change at all, and if you aren't consciously keeping that in mind you might be subconsciously expecting too much camber change.

Unless the hub carriers are different, with the control arm pivot points on it relocated, the rate of camber change can't vary from what it was before by very much. The ratio of the arm lengths and their inclinations would change only minutely if the link lengths are the only changes.

Now that I have the Trofeo R tires as well, it is crucial that I hit my camber targets. I'm thinking about -1.5R / -2.5F. As is, I cannot go more than -1 rear, so did not go more than -1.8F not to upset the balance : (

I see some test-n-tune in your future to go with - or more usefully after - getting a little feel for the stickier rubber.


FWIW: Most SLA and multilink independent suspensions gain negative camber as they move in the 'bump' direction. But it is possible to arrange the links such that the camber gain in the bump direction goes positive (aka "the wrong way") instead, while the geo roll center goes underground. In 1969, Buick's "accu-drive" was one example.


Norm

[X25]

Originally Posted by 130R

28.70" (OEM SS P-Zero) - 26.14" (Z/28 Trofeo R) = 2.56" / 2 = 1.28" or 32.50mm

Your 0.8" is based on the 27.9" diameter of the OEM 1LE tire.


In other-words, the Z/28 is 33mm lower than the SS, & 22mm lower than an SS 1LE.

There should be no difference in available static camber with the Z/28 suspension, as the difference in ride height is entirely due to the smaller diameter of the 305/30/19.

Good point, I base my measurements over stock 1LE, but there is indeed drop in suspension height by about 1" besides the tires based on my measurements I took at my build thread:
http://www.camaro5.com/forums/showth...90#post8057990

1" drop usually adds at least -0.5 camber based on others' experience. Not in my experience.

[X25]

I went ahead and checked it out. Watch this video:

• The GM engineer explicitly states that the ride height difference between Z/28 and 1LE is 33mm.
• Check out the pictures of the shocks/struts in my thread and you'll see that they're considerably shorter than 1LE counterparts. Some of that height difference will be offset by the stiffer springs, but not all.
• In order to measure suspension height, you don't measure suspension height from the wheel lips, but rather from the hub center to the fender. Hence, wheel diameter does not change anything. There is a drop in suspension height.

I hope the numbers are adding up better now

[X25]

Originally Posted by 130R

I didn't watch the video, but if Mark did say the Z/28 is 33mm lower than a 1LE, I'm inclined to dismiss it as a slip of the tongue. The numbers obviously support the Z/28 being 33mm lower than an SS, as does GM's literature. If it were true, that would make the Z/28 ~2.3 inches lower than an SS, and with that splitter, pretty tough to make it out of driveways.

You're probably one of the only people on the board that measures from the center of the hub, so the measurements are interesting. The obvious assumption was you just forgot to compensate for the smaller wheel... I'm not entirely sure why you would measure from the hub though, it would seem much more difficult to get an accurate measurement.

As for the front dampers, that's interesting. What did the rears look like? Do they come with hats? Is there a different part number for the Z/28 hats?


I'm nursing a pretty good hangover, so I don't feel like running the numbers, but it would be pretty easy to compare where the cars would sit using the weight differences and the spring rates. Somethings seems wonky though. I just can't wrap my head around how that strut could be that much shorter without losing the same amount travel. The spring perch and the mounts appear to be in the same place...

Hmmm...

Interesting...

Learn something new every day...

I honestly don't care much for what the official number is, but GM's statements are definitely inconsistent; it is more likely based on the base SS. Mine dropped by about 1", and 1LE is actually almost identical to Z28 in weight (especially considering my weight loss in terms of front BBK, exhaust, etc.).

Measuring from the hub is definitely harder (depending on wheel surface), but is consistent regardless of wheel and tire choice, which is why that's the only way I see being used, at least in other cars' enthusiast sites (S2000, BRZ, Miata, EvoX, etc.). I did not take my time to get very accurate measurements after the Z/28 install, but the drop in height is obvious.

Both fronts and rears come complete from the kit, with the hats already installed. Actually, the installation could not be easier. All I torqued was the top and bottom connections for the struts and shocks. The kit comes with the Z/28-spec suspension control arms, too. One thing I have in mind is that I installed all the components when the car was on the lift, with tires/hubs sagging inwards (with as positive camber as they can get). Since I tightened these suspension components without load, perhaps all the little tolerances it has in bolt holes, etc. might have favored positive camber. FYI, I don't think I'd have any clocking/binding issue since Z/28 control arms all have metal sleeves for the bolt holes, etc., which would prevent any such binding, unlike aftermarket bushings. I actually don't like aftermarket bushings anymore; the OEM designs look a lot more durable.