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Discussion Starter · #1 ·
I've had 45 m offset Shuk W22 17x7.5 wheels for a while. They're light, attractive, strong (two-piece with forged outer rim). As some of you know, I did a ton of reading on offset, scrub radius, etc. to see how low of offset was "reasonable" given that I was interested only in performance, not looks. The main goal was to go with 225/45/17 on a rim 7.5 or 8 inches wide. Needless to say, it's hard to find definitive answers. I can only guess that the suspension engineers of Volvo laugh while I scratch my head.<p>So far, it's pretty fun. But I notice, as did tmtalpey, that as I turn to the right, the car very slightly rotates left (or in other words the right side lifts up slightly). That leftward rotation is the counterbalance to the inner, right tire being pressed down (my guess). That's not necessarily bad. In fact, I might be able to make an argument that 1) it means the inner tire gets initially more weight in a turn, helping to distribute the weight, and 2) it means that both cambers are shifted a bit (negative on left, positive on right), biased so that a hard turn would re-straighten out both wheels. In a sense, perhaps it's better for maximum traction.<p>On the other hand, it is a bit disconcerting that the car has this very slight lift. It seems perhaps not "right" that the car may have some extra tilt / lean, and makes me think that 7.5 mm of offset change from stock really was too much. <p>So today, I turned the wheels with the car staying still. Someone saw that indeed the inner side of the car lifted by about 1 cm.<p>- Does anyone have any experience or technical knowledge about this? There are plenty of people with 42 mm offset wheels, maybe even 40 or 38.<p>Another, perhaps better question is<p>- Can anyone else with stock wheels/tires or aftermarket setups turn their wheels full stop and report whether the inner side of the car lifts up at all? Does the outer side of the car tilt down? This will take two people.<p>- Do people with aftermarket wheels notice car tilting in turns (especially noticeable at low to mid speeds)? Does ANYONE out there notice car tilting?!!! <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/smile.gif" BORDER="0"> <p><br>Bassman<br>
 

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Re: inner lifting, especially with aftermarket wheels? (bassman)

The rise is pretty much built-in, my car rises about 5mm on the inside and close to zero on the outside. This is largely due to the scrub radius, which moves the contact patch in an arc as the wheel turns. [edit - and the Ackerman angle, which turns the inner wheel more than the outer] Combined with the kingpin angle (camber+caster), this makes things move vertically.<p>I notice it a lot more on P2 cars, e.g. our XC90. To see an extreme example, check out a Citroen 2CV.<p><IMG SRC="http://www.citroen.mb.ca/Documents/Motor/jpegs/Leaning.jpg" BORDER="0"><p> <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0"> <p>Tom.
 

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Re: inner lifting, especially with aftermarket wheels? (tmtalpey)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>tmtalpey</b> »</i></TD></TR><TR><TD CLASS="quote">I notice it a lot more on P2 cars, e.g. our XC90. To see an extreme example, check out a Citroen 2CV.<p><IMG SRC="http://www.citroen.mb.ca/Documents/Motor/jpegs/Leaning.jpg" BORDER="0"><p> <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0"> <p>Tom.</TD></TR></TABLE><p>Completely off topic...<p>Wow - that was the first car I ever drove... in France. The complete polar opposite of a Volvo, it had seats made from tubular steel and deck chair fabric that could be unclipped from the car and taken out for a picnic, fishing trip etc. They couldn't have been safe in the event of a crash. Of course, it had a top speed that approached that of a pregnant walrus so crash worthiness was not really an issue <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/smile.gif" BORDER="0"><p>It also had a manual gearbox with what appeared to be an umbrella handle sticking out of the dash board for a shifter.<p>Sorry for the OT... the pic brought back memories.<p>UKMatt
 

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Re: inner lifting, especially with aftermarket wheels? (ukmatt)

Hehe Matt, you are too old, people of your age should not be allowed to drive, at least nothing faster then that motorized chair, like the one that George Costanza once drove <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0"> <br>EDIT: Sorry for the OT too, but I simply could not resist <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/wink.gif" BORDER="0">
 

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Re: inner lifting, especially with aftermarket wheels? (tmtalpey)

So maybe I'm feeling it more now due to the stiffer sidewall tires, or maybe I'm feeling it more now just from being more in tune after having driven this car for 10,000+ miles.<p>
 

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Re: inner lifting, especially with aftermarket wheels? (d_man)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>d_man</b> »</i></TD></TR><TR><TD CLASS="quote">Hehe Matt, you are too old, people of your age should not be allowed to drive, at least nothing faster then that motorized chair, like the one that George Costanza once drove <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0"> <br>EDIT: Sorry for the OT too, but I simply could not resist <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/wink.gif" BORDER="0"></TD></TR></TABLE><p>Ha ha... of course, you have me beat <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/smile.gif" BORDER="0"><p>I was YOUNG when I drove that 2CV and the 2CV was OLD... that's my excuse and I'm sticking to it!<p>UKMatt
 

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Re: inner lifting, especially with aftermarket wheels? (bassman)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>bassman</b> »</i></TD></TR><TR><TD CLASS="quote">So maybe I'm feeling it more now due to the stiffer sidewall tires, or maybe I'm feeling it more now just from being more in tune after having driven this car for 10,000+ miles.</TD></TR></TABLE><br>So first off, sorry for posting the 2CV pic. It was intended to show that some chassis are designed to rise. The page I took it from says the 2CV has 15 degrees of caster.<p>Second, I doubt sidewalls have much to do with the rise. Or are you talking about the cornering? If so, congratulations grasshopper, you have moved to the next level. So, will you be doing coilovers, or springs? <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0"> <p>Tom.
 

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Discussion Starter · #8 ·
Re: inner lifting, especially with aftermarket wheels? (tmtalpey)

I can feel the lift in a few situations<p>Standing still and steering. I can feel the inner side of the car lift a bit. Also, the car moves a wee bit. I suppose there might be moving and perhaps lifting based on non-zero scrub radius even for stock setup, as Tom mentions above. I'm wondering if tmtalpey is the only one that feels this. I'm wondering if I made it a lot worse with the 45 mm offset wheels.<p>In turns at low to medium speed, I can feel the lifting. In some ways it's annoying (now that I'm attuned to it), and in some ways it's kind of cool. I have this horrible feeling, though, thinking about the stress that the inner wheel bearing might be having. <p>At high speeds it's harder to notice the lifting. Quick lane shifts sometimes result in sloshy leaning, but that might be the stock springs/shocks more than a change in wheels. I think the best way to get rid of the sloshy leaning in very quick high speed turns is to get stiffer linear springs and maybe other stiffening elements (I might try poly u bushings).<p>One guy at work was impressed that I could actually detect this lifting. (yay me). So either I'm attuned to the performance aspects of this car (which would be pretty cool), or else I've screwed things up by changing the wheel (which would suck).<p>
 

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Re: inner lifting, especially with aftermarket wheels? (bassman)

1) Don't worry about your wheel bearings!<p>2) No way are you getting lift at speed. You need to cramp the wheel, like, a turn or two.<p>This isn't to say it isn't happening, but it's really not a very big deal. The geometry changes are subtle, and you might even be quicker with them. Unfortunately, that'll be hard to test experimentally.<p>Tom.
 

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Re: inner lifting, especially with aftermarket wheels? (tmtalpey)

if I'm not mistaken the 2CV literally translates into 2 hp? I guess the original had about 2 hp. also had some rubber almost 3 1/2 inches wide. compairable to some HD mountain bikes of now a days, 2 or 3 lug nuts?
 
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