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flip rims for negative offset???


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i have a set of rare dynalite 3 piece meshes similar to the ssr reverse mesh style. the rims are 16x8 suposebly, but looks to be like 16x7s to me. anyways, the outter lip is about 2 1/4 inches and about 4 1/2 or 5" on the inside. i was thinking would it be safe to flip it so the 4 1/2 is on the outside and run only 2 1/4 inch of lip on the inside! i ask around and alot of guys says itll be safe. i know the previouse owner ran them that way for a while cause it has curve marks on the inside and the old marking on the inside towards the brakes. it has valve stems on both sides also. im not too sure whats the offsets on these but its about 1 inch away from the shock/spring the way it is right now. let me know what you guys think. im running a 95 lt1 330hp/ t56 on a 75 280z. thanks.

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Can you post a picture? I've never heard of a reversable wheel...If they were designed to be mounted both ways, I suppose as long as you don't have directional tires? I asked one of the techs at my dealership if it was safe to mount the face of my wheels inside out to use the lip as the inside, and they said that they couldn't get the balancing machine to balance one when they mounted it backwards. I would guess that's just because the part that would normally be flat wasn't making full contact, but I would still be very hesitant to do something like that. Just my $.02.

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its a 3 piece like the ssr reverse meshes. i dont know how to work the pics yet so i can only explain. the center piece comes off after removing all the nuts and bolts and it can can be fliped around to mount on either side. the question is, i just want to know is it safe to run a 2 inch lip on the inside?

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I always heard (and this is totally hearsay, but I'm going to put it out there for what it's worth) that not having enough backspace -whether it be from having too much spacer or whatever- would cause excessive wear on your wheel bearings. Can anybody out there either confirm or bust this urban legend?

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Guest 280ZForce
I always heard (and this is totally hearsay, but I'm going to put it out there for what it's worth) that not having enough backspace -whether it be from having too much spacer or whatever- would cause excessive wear on your wheel bearings. Can anybody out there either confirm or bust this urban legend?

yeah, submit this one to the mythbusters. lol j/k...but it does sound like it would be harsh on something w/ only a 2" backspace.

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I always heard (and this is totally hearsay, but I'm going to put it out there for what it's worth) that not having enough backspace -whether it be from having too much spacer or whatever- would cause excessive wear on your wheel bearings. Can anybody out there either confirm or bust this urban legend?

 

True - sort of.

 

Actually, it's not the backspacing per se, but the amount that the backspacing differs from stock. Generally speaking, the inner and outer bearings are designed and sized to handle loads resulting from a given center of force from the contact patch. If you change the offset (offset is a better way to talk about this) appreciably, you can dramatically change the forces that the bearings see.

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posted by TimZ: If you change the offset (offset is a better way to talk about this) appreciably, you can dramatically change the forces that the bearings see.

Offset really doesn't tell you anything about a wheel unless you know the width as well. Would that mean an extra wide wheel with enough offset to fit correctly would add extra load to a wheel bearing as well? If so, is this load caused by the mass of the larger wheel, or the distribution of mass from where the wheel center meets the rim? What if the wheel hub was spaced far forward or back, but the spokes curved back to attach to the lip in the center (like the momo quasar-the old one, not the quasar 2)Does a high offset wheel with an adapter put more load on a wheel bearing than a normally sized wheel would, or does it cancel out? I'm curious, because that's how I'm running the wheels on my personal Z. I haven't had problems so far, but I haven't driven it especially hard either...I hope these questions don't seem combative, they are all real questions if anybody knows the answer.

 

Also, Johnc, it took a few posts to figure that one out (he confused me when he was talking about having two valve stems). I think he's just talking about taking the center section out and flipping it around, not disassembling the rim section too. Those are glued together with some kind of adhesive usually (that's what they told me at www.kodiakracingwheels.com when I called to find out about having my Impul's resized).

 

*edit* here is a pic of one of my MOMO quasar wheels from my gallery for reference:

datsunstuff_004.jpg

this particular wheel is +34 offset 15X7

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Offset really doesn't tell you anything about a wheel unless you know the width as well. Would that mean an extra wide wheel with enough offset to fit correctly would add extra load to a wheel bearing as well? If so, is this load caused by the mass of the larger wheel, or the distribution of mass from where the wheel center meets the rim? What if the wheel hub was spaced far forward or back, but the spokes curved back to attach to the lip in the center (like the momo quasar-the old one, not the quasar 2)Does a high offset wheel with an adapter put more load on a wheel bearing than a normally sized wheel would, or does it cancel out? I'm curious, because that's how I'm running the wheels on my personal Z. I haven't had problems so far, but I haven't driven it especially hard either...I hope these questions don't seem combative, they are all real questions if anybody knows the answer.

 

I think you misunderstood. Offset doesn't tell you anything about fitment on a particular vehicle without width, but it tells you exactly where the center of force from the contact patch (and hence the resulting bearing loads) is. You don't need to know the width for this - in fact, it doesn't really matter. All that stuff about whether the spokes are curved, etc are red herrings. That stuff can effect the caliper clearance, but the offset is the offset, and that is just the distance from the wheel centerline to the mounting face.

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My understanding of offset is that it is the distance from the centerline of the wheel to the mounting flange of the hub. Exactly how this is going to affect the fitment on a particular vehicle is going to depend on the width of the wheel. A zero offset wheel that is 6 inches wide will not fit the same as a 0 offset wheel that is 8 inches wide, because you just picked up another inch of backspace (one inch in the back, one on the lip). Once you get past a certain wheel width, you would need a negative offset to make the wheel fit the same way that a factory wheel fit in relation to the suspension components (the strut tube as it relates to S30 z-cars). Using my Impul RS-III's as an example, I have a 17X7" wheel with a +38mm offset. At 0 offset, this wheel would have 4" of backspace, but since it's +38mm, I needed a 1.5" adapter to correct the offset back to 0. If this wheel were a different width, the offset would need to be different to compensate for the new backspace. Without knowing the width of the wheel, offset is a useless number, because it tells you nothing about the backspace or the lip without it. Offset is a descriptor of a given wheel, and in combination with the backspacing of that wheel, will allow you to make a judgement on how that wheel will fit within the known parameters of a given vehicle.

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Is there a way to calculate that change, and then to determine the point of bearing/hub failure? I imagine there must be, but whether anyone has tested it to the point of "X change in offset will result in Y bearing life under Z conditions" I have no idea...

 

*edit* Also, wouldn't a wheel with a flat face that had a +offset and a bolt on adapter distribute the bearing load in the same way as a wheel with the correct offset but outward curving spokes that met the wheel at the face? here are some examples:

datsunstuff_002.jpg is an example of the spaced flat wheel, and datsunstuff_003.jpg is an example of a correct offset wheel with outward curving spokes

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