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Old 08-28-2007, 11:12 PM   #1
BIGSKYWRX
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Default Trigonometry guys- how much to slot strut to gain 1 degree camber?

somone posted a formula awhile back (can't find it) that calculated how much slotting equated into how much camber change- I want to slot the minimum amount need to gain 1 degree of camber- IIRC it wasn't a heck of a lot.

Mucho Gracious!
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Old 08-28-2007, 11:17 PM   #2
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....well....I researched a doing this one....and I was gonna start with no more than 1mm
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Old 08-28-2007, 11:23 PM   #3
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no idea what that would yield? I'd like to have the slotting done before bringing it to the alignment shop- they probably wouldn't appreciate me experimenting and bringing in my die grinder and borrowing their air

I've got a set of spare struts, so if measurements are needed I can get those
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Old 08-28-2007, 11:38 PM   #4
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edit: my mistake - looks to be a little more than 1mm.

How I quickly figured it - use a base of 100mm and find the distance that would need to change for each degree to find tangent of angle. Thankfully 100mm base makes it easy. To gain a degree it all looks to be about 1.7 to 1.8ish (rounded).

Tangent = opposite / adjacent

Start with 1 degree: tangent = .0174 * adjacent (in this case 100mm) mean opposite side length is 1.74mm
Go to 2 degrees: Tangent = .0349 *100mm = 3.49

3.49-1.74= 1.75mm to get difference between two.

1.75 seems to work fine for each degree wanted to be gained so I'd go close to that to get a degree more camber.

Granted it has been more than a few years since I've done that so please double check my work.

Last edited by Turn in Concepts; 08-28-2007 at 11:51 PM.
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Old 08-28-2007, 11:58 PM   #5
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According to my quick and easy CAD software I have here it's 1.745mm.
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Old 08-29-2007, 04:11 AM   #6
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Where does that 100mm base measurement come from?

It seems to me that it should be based on the distance between the 2 clevis bolts which from memory is 65mm for the 100mm pcd hubs.

For small angles you can use either tangent or sine functions.
So thats about 1.2mm/deg
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Old 08-29-2007, 04:25 AM   #7
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I used 63.5mm between holes when I did my calcs.

1mm should get you just under a degree.

I think when the guy aligned my car he might not have loosened the bottom bolts since I told him they won't rotate and he shouldn't try to turn them.

I'm doing some more suspension work fairly soon so I'll be getting another alignment so I can see if more camber is to be had.
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Old 08-29-2007, 06:47 AM   #8
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Quote:
Originally Posted by duncangrant View Post
Where does that 100mm base measurement come from?

It seems to me that it should be based on the distance between the 2 clevis bolts which from memory is 65mm for the 100mm pcd hubs.

For small angles you can use either tangent or sine functions.
So thats about 1.2mm/deg
Yup I measured 65mm also - this is a sketch I did when trying to estimate the wagon/sedan camber offset:



i.e. 1mm -> 0.88*

or 65mm x tan(1.0*) -> 1.1mm
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Old 08-29-2007, 07:31 AM   #9
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DOH!!! Wasn't even thinking of that!! I have no idea where 100mm came from, and of course I'm too dumb to go out to the garage and measure it.

<- is a big dummy.
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Old 08-29-2007, 09:23 AM   #10
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Very well done gentlemen! I'll shoot for a smidge over 1mm

One other question if I may- as the bottom bolt has to be loose to maximize the camber the upper eccentric bolt can get, how do you deal w/ keeping the lower clevis bolt where it needs to be?

Danke
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Old 08-29-2007, 09:38 AM   #11
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Get someone else to pull/push the hub while you tighten everything up.

Tony
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Old 08-29-2007, 09:51 AM   #12
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this will be on the alignment rack- wheel/tire mounted and under load

short pry bar?
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Old 08-29-2007, 11:04 AM   #13
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Quote:
Originally Posted by BIGSKYWRX View Post
this will be on the alignment rack- wheel/tire mounted and under load

short pry bar?
No pry bar here, just a second set of hands (mine):

Arnie mentioned the pushing to me a while back, and since then I've gone to shops where they let me hang out with the tech during. None of them had a problem with me pushing on the wheel while it was on the rack (them underneath tightening the bolts). Both times this was on a fancy hunter rack with the huge computer readout you can see from all over the car. Tell the tech to loosen both bolts, they turn the top bolt, and you/someone else push the top of the tire..... got me an extra .1-.2deg or so.

FWIW

Last edited by mrpedal; 08-29-2007 at 11:06 AM. Reason: it's 8am and i'm not awake
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Old 08-29-2007, 11:09 AM   #14
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Oh, some questions too: Which hole do you grind out, and how do you keep the bolt from moving? Shim it with something maybe (like what)?
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Old 08-29-2007, 11:18 AM   #15
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Ummm... maybe this is too basic for you guys, but why don't you try measuring the cam on the factory camber bolt & seeing how much camber adjustment you get with that?



(I don't trust calculations as much as I trust reality)
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Old 08-29-2007, 11:24 AM   #16
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Quote:
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Oh, some questions too: Which hole do you grind out, and how do you keep the bolt from moving? Shim it with something maybe (like what)?
Grind the lower hole. I believe the only thing holding it in place is friction.

Is this somehow more effective than just using a camber bolt in the lower hole? I've been autocrossing with the extra bolt for 2 years now without any slipping at all.

-Bryce
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Old 08-29-2007, 12:07 PM   #17
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Regarding slip: Take a cue from the pony car guys... when you've got it ready to be tightened and left alone (i.e. after measuring once to make sure it's right), paint the inside of the nut and the inside of the head of the bolt, then lock it down. Once the paint dries, the sheering force required to make the bolt slip will be HUGE.
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Old 08-29-2007, 02:35 PM   #18
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Quote:
Originally Posted by williaty View Post
Regarding slip: Take a cue from the pony car guys... when you've got it ready to be tightened and left alone (i.e. after measuring once to make sure it's right), paint the inside of the nut and the inside of the head of the bolt, then lock it down. Once the paint dries, the sheering force required to make the bolt slip will be HUGE.
Sorry, do you mean put some paint between the nut face + strut and bolt face + strut?
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Old 08-29-2007, 02:57 PM   #19
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Quote:
Originally Posted by Fred View Post
Ummm... maybe this is too basic for you guys, but why don't you try measuring the cam on the factory camber bolt & seeing how much camber adjustment you get with that?



(I don't trust calculations as much as I trust reality)
good idea- no oe bolt to measure, but the ellipetical hole in the strut is 16mm (x 14mm)- so 2mm elongated over the lower hole. Do you half that amount as it runs from full positive to full negative (+1 to roughly -1.3)?????
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Old 08-29-2007, 03:55 PM   #20
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Quote:
Originally Posted by pinkrobe View Post
Sorry, do you mean put some paint between the nut face + strut and bolt face + strut?
Yup.5
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Old 02-26-2008, 05:58 PM   #21
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has anyone ever tried slotting the lower hole with any success? I'm interested in either slotting it as described above or perhaps trying a second camber bolt, but I'd like to see pictures and/or hear results before I start grinding on my coilover brackets...
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Old 02-26-2008, 06:19 PM   #22
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It looks like I've got enough camber with two bolts now that I've done it myself, so I won't be trying to slot the strut anymore.
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Old 01-23-2009, 01:26 PM   #23
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Quote:
Originally Posted by williaty View Post
It looks like I've got enough camber with two bolts now that I've done it myself, so I won't be trying to slot the strut anymore.
Do you mean:

1) "I've successfully got enough camber on two separate occasions (with one adjuster, one normal bolt"

OR

2) "I've successfully got enough camber on a strut with two adjuster bolts (oem adjuster and a camber bolt)"
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Old 01-23-2009, 03:10 PM   #24
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I'll vote #2
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