CTS-V Suspension Tuning
10-11-2013, 04:00 AM
#41
Garrett, putting aside the fact that I despise your application of the CTS-V (you really should buy a SUV), your understanding of how springs work and how wheel rates can affect ride comfort needs an overhaul. If I have time this weekend, I'll try to explain why I think you're doing exactly the opposite of what is necessary to help you achieve what you want.
10-11-2013, 08:33 AM
#43
While I agree with you Fuzzy that the V is no tow vehicle (can't believe I contemplated getting a hitch), you are thinking the trailer he is towing is overly heavy and has alot of tongue weight. The trailer he, and others are towing to auto cross events are tiny and have very minimal tongue weight, when the trailer is loaded properly allowing it's axel to bear the load. Having two adults and two youths in the car would equal the same load on the V's suspension as the trailer would. It may add 50-80 pounds max. These trailers you unhook, lift, and push around by hand in the pits. Even if you had a motorcycle on there it is still easy enough to move it around by hand. Plus, when you think about it they are going to have just as much weight in the trunk or back seat, if not more, with all the gear they take to the track i.e. tents, coolers, tools etc. So it would be wiser to put it on a trailer and take a set of R-comps with you as well, all while really being easier on the V's suspension. Only thing is the added weight of the hitch, which hopefully was adjusted for when they setup their suspension. Then there is the fact that no one is putting their suspension under a race type scenario while towing a trailer. Just my two cents.
10-11-2013, 09:18 AM
#44
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Well said^. Proper weight distribution on a trailer is what makes the difference, the hitch class you can run on a V which is less than a class III hitch has a max tongue weight of less than 500lbs. Class III which is a light duty truck has a tongue weight of 600lbs/ (1000 weight distributed). 2 adults and some groceries in the back will put more strain on the rear suspension than a small track trailer as long as the trailer is loaded correctly. That said, I can't imagine ever towing with the V as it must be miserable; maybe I've been hauling with an 8000lb 2500 HD for two long ( I like being able to pull 10K and pass people with ease going 75-80mph.
10-11-2013, 11:15 AM
#45
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Towing 500-1000 pounds behind the V is really not a big deal. I used a trailer less than 10 times, I have since sold my bike. Mostly to take 1 or 2 sport bikes to the track or some other destination. It is also very common for people to trailer track wheels/tires. I have seen a Boxster S tow in track wheels for example.
10-15-2013, 12:11 PM
#46
Fuzz, I just ran into a guy that has some KWs with very used shocks/struts and he wants to get rid of them.
Before I ran into him I was looking at replacing everything with stock and getting her riding more stock again and then using this thread as a guideline.
With that said, I am probably not going to race my car any, unless it is at a Texas Mile event. I would not mind less body roll and a more stable ride, but definitely not going to be tracking her solely.
I DD her, mostly on rough highways, so the ride is important.
Thoughts?
Before I ran into him I was looking at replacing everything with stock and getting her riding more stock again and then using this thread as a guideline.
With that said, I am probably not going to race my car any, unless it is at a Texas Mile event. I would not mind less body roll and a more stable ride, but definitely not going to be tracking her solely.
I DD her, mostly on rough highways, so the ride is important.
Thoughts?
10-15-2013, 12:42 PM
#47
Fuzz, I just ran into a guy that has some KWs with very used shocks/struts and he wants to get rid of them.
Before I ran into him I was looking at replacing everything with stock and getting her riding more stock again and then using this thread as a guideline.
With that said, I am probably not going to race my car any, unless it is at a Texas Mile event. I would not mind less body roll and a more stable ride, but definitely not going to be tracking her solely.
I DD her, mostly on rough highways, so the ride is important.
Thoughts?
Before I ran into him I was looking at replacing everything with stock and getting her riding more stock again and then using this thread as a guideline.
With that said, I am probably not going to race my car any, unless it is at a Texas Mile event. I would not mind less body roll and a more stable ride, but definitely not going to be tracking her solely.
I DD her, mostly on rough highways, so the ride is important.
Thoughts?
10-15-2013, 08:25 PM
#48
Update: I cut another slice off the Supra end link rod.
This tweak shortened the end link to the point where both nuts would *almost* be in contact with the arms of the end link, but still free to twist to follow the movement of the bar. The reason why I felt this was necessary was that my previous settings were too long to activate the sway bar when I wanted them to. I may shorten the end link further in the future, but I'll need a week or so to test.
If you decide you want to do this, just ensure that you cut the threaded rod to a length equal to or less than 54mm.
This tweak shortened the end link to the point where both nuts would *almost* be in contact with the arms of the end link, but still free to twist to follow the movement of the bar. The reason why I felt this was necessary was that my previous settings were too long to activate the sway bar when I wanted them to. I may shorten the end link further in the future, but I'll need a week or so to test.
If you decide you want to do this, just ensure that you cut the threaded rod to a length equal to or less than 54mm.
Last edited by FuzzyLog1c; 10-15-2013 at 08:30 PM.
10-16-2013, 08:54 AM
#49
I was under the impression that adjustable end links were used to dial out preload in the sway bar when corner balancing the suspension. I suppose if adjusted in extreme amounts in tandem, the pair could change the bars effective stiffness through geometry, but I'm missing how they would affect when the sway bar activates.
10-16-2013, 02:35 PM
#50
Depends on the price. When you said, "very used," that worries me. Many shops can rebuild KW Variant 3's ... might be something to keep in mind. There's no question in my mind that your car will ride better than it did with the FG2s. Highly recommend you pick up a set of 784 or 896 in-lb Swift springs for the rear.
I have some coilover springs laying around; eibach.
What is the best way to test the spring rate?
10-16-2013, 03:26 PM
#53
Here is your multi-language documentation:
http://www.kw-store.com/extras/docs/...ah68663001.pdf
http://www.kw-store.com/extras/docs/...ea68577080.pdf
Last edited by FuzzyLog1c; 10-16-2013 at 03:32 PM.
10-16-2013, 10:11 PM
#54
I was under the impression that adjustable end links were used to dial out preload in the sway bar when corner balancing the suspension. I suppose if adjusted in extreme amounts in tandem, the pair could change the bars effective stiffness through geometry, but I'm missing how they would affect when the sway bar activates.
The lesser-known fact (which, ironically, I consider more important) is that end link geometry determines how effective your sway bar is at canceling out body lean. Depending on your background, it might be hard to picture this without drawing force body diagrams. If you're willing to take my word for it, the nominal end link and sway bar geometry is pictured below:
Under nominal conditions, any differential compression or expansion of the vehicle's suspension (e.g. imagine the LCA in the picture above moving up or down) will transfer that force to the other side of the car through the sway bar. Notice how this is force is actually torque (T = r x F), as it is applied perpendicular to the axis of rotation of the sway bar.
The force transfer is not 1:1--the sway bar twists under the torsion, acting like a massive straight spring, and reduces the degree to which load is shared between the sides of the vehicle. If the end links are too long or too short, the resultant, non-ideal geometry reduces the amount of the force that directly translates to torsion on the sway bar. What's left is not perpendicular to the axis of rotation of the sway bar, and essentially tries to rip the sway bar out of the car.
Unfortunately, this nominal geometry is very hard to achieve in modified vehicles--usually because the suspension geometry has changed due to lowering the vehicle. However, this can also happen to vehicles at stock height, because some aftermarket suspension parts do not match the OEM suspension geometry.
Last edited by FuzzyLog1c; 10-16-2013 at 10:22 PM.
10-17-2013, 12:24 AM
#55
After correcting for the slope of my parking spot, I measured 88 degrees, fore-aft, using . Since my setup is far from ideal (despite my attempts to correct for it), I'd give my measurement a generous ±5 degree margin of error. Still, that's pretty good. No picture, unfortunately--I couldn't get my camera, head, and gauge into a good position.
Athwartships angle with the wheels off the ground. This angle is set by the length of the sway bar. No possibility of improvement.
Angle on the sway bar with the wheels off the ground. Will try to get one with the wheels on the ground later. Whiteline KLL135 and KLL127 link locks are necessary on the Addco bars to maintain the athwartships angle identified in the previous picture. Hotchkis bars come with welded stops that prevent the bar from sliding, so you don't need aftermarket locks.
I almost gagged on a Reese's Peanut Butter cup when I saw this picture in its full, 24 megapixel glory. Proof that both sway bars slid back and forth a lot. Check out the clean-ish areas next to the brackets.
Athwartships angle with the wheels off the ground. This angle is set by the length of the sway bar. No possibility of improvement.
Angle on the sway bar with the wheels off the ground. Will try to get one with the wheels on the ground later. Whiteline KLL135 and KLL127 link locks are necessary on the Addco bars to maintain the athwartships angle identified in the previous picture. Hotchkis bars come with welded stops that prevent the bar from sliding, so you don't need aftermarket locks.
I almost gagged on a Reese's Peanut Butter cup when I saw this picture in its full, 24 megapixel glory. Proof that both sway bars slid back and forth a lot. Check out the clean-ish areas next to the brackets.
10-17-2013, 08:58 AM
#56
According to this thread, KW charges $125 per strut for a rebuild. If you can get those for $200 + $600 for the rebuild (assuming $100 shipping) + $400 for Swift springs (which are better and lighter than the stock KW springs), I'd say that seems like a good price. Make sure you get all of the adjustment and mounting hardware. A set of Banski spherical RSMs for the rear might not be a bad idea either.
Here is your multi-language documentation:
http://www.kw-store.com/extras/docs/...ah68663001.pdf
http://www.kw-store.com/extras/docs/...ea68577080.pdf
Here is your multi-language documentation:
http://www.kw-store.com/extras/docs/...ah68663001.pdf
http://www.kw-store.com/extras/docs/...ea68577080.pdf
10-17-2013, 10:19 AM
#58
Well, that sucks. 
If your'e still in the market, I'd suggest getting a Belltech 21060--the KW Variant 3, packaged by Belltech, the North American branch of KW. Not sure what price they'll accept, but maybe start at $1750 and go up from there:
http://www.ebay.com/itm/Belltech-Coilover-Kit-for-2003-2007-Cadillac-CTS-and-CTS-V-21060-/331045518817?pt=Motors_Car_Truck_Parts_Accessories&hash=item4d13d9bde1&vxp=mtr
It's literally just a different label on the box. The documentation and contents are identical.
If your'e still in the market, I'd suggest getting a Belltech 21060--the KW Variant 3, packaged by Belltech, the North American branch of KW. Not sure what price they'll accept, but maybe start at $1750 and go up from there:
http://www.ebay.com/itm/Belltech-Coilover-Kit-for-2003-2007-Cadillac-CTS-and-CTS-V-21060-/331045518817?pt=Motors_Car_Truck_Parts_Accessories&hash=item4d13d9bde1&vxp=mtr
It's literally just a different label on the box. The documentation and contents are identical.
10-17-2013, 12:28 PM
#59
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Well, that sucks.
If your'e still in the market, I'd suggest getting a Belltech 21060--the KW Variant 3, packaged by Belltech, the North American branch of KW. Not sure what price they'll accept, but maybe start at $1750 and go up from there:
Belltech coilover Kit for 2003 2007 Cadillac cts and cts V 21060 | eBay
It's literally just a different label on the box. The documentation and contents are identical.
If your'e still in the market, I'd suggest getting a Belltech 21060--the KW Variant 3, packaged by Belltech, the North American branch of KW. Not sure what price they'll accept, but maybe start at $1750 and go up from there:
Belltech coilover Kit for 2003 2007 Cadillac cts and cts V 21060 | eBay
It's literally just a different label on the box. The documentation and contents are identical.
10-17-2013, 12:49 PM
#60
Even after KW raised the MSRP on their normal kit to $2799, I got a KW Variant 3 kit for $1950 shipped (including tax). So there are definitely dealers out there that will make a deal. eBay now charges a flat 10% fee on the final value of any auction, so you know they've got that margin built into their price.