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New flares, what offset do I need?


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I really suck at this stuff, so I'm hoping you guys can help me out. I'm hoping someone out there knows this right off the top of their head.

 

Working with 3" flares front and rear. Old wheels were 15x8 with 5" backspacing. That amount of backspacing should be about right as far as keeping the tire close to the coilover. What I want is I would like the rear tires about 1" INSIDE of the flares. On the front I want the tires to fill the flare. I will use 1" wheel spacers up front so that I can have the same rims on all 4 corners.

 

I have coilovers and 10" springs, and I'm running a 23.5" tall tire.

 

Anyone know what I should be looking for?

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The way I did this was to measure from the center line of the hubs up to a mark on some tape laid on the fender. Jack the car up and level it on the stands. Then jack the hubs up to where the measurement on the tape matches the on ground spec.

 

Then I used a plum-bob and a regular framing square and to measure from the hub faces to the string and then hub faces to the spring or perch. Whichever you hit first on the inside.

 

This should give you an idea of how much total room you have. Leave 1/4"-1/2" from the perch or spring and about the same to the flare. You can take the spring off and measure full compression specs for fender rub.

 

Hope this helps.

 

Alan

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I'd wait until the car is back on it's wheels fully loaded, then you can get the exact backspace you need to maximize track, and keep the tire just inside the flare. You might be able to use your old wheels and some washers to figure it out.

 

If you keep the same 5" backspace (which is just about perfect with coil overs), you 10" wheels should stick out another 2" from where they were before the flares. It might be just about right with the 3" flare, but I would wait and order your wheels when you know for sure.

 

Not to hyjack the thread, but what cage did you end up going with, custom?

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Jon,

I'll second what Pete says and recommend waiting until you are on the ground to make your final decision... That said, I have the 3" flares and I am running 16x10" wheels with 5" back space and have run the bigger 23.5x11.5x16 Hoosier slicks with no problems. I had about 1/4" clearance between the tire and the springs, and after running numerous events I did find a small black smudge on one rear spring from a minor rub. I couldn't find a mark on the tire, so it was a very minor kiss or two during extreme conditions (like when I would get on 2 wheels at mid turn over a nasty bump). I never saw any sign that the tires touched the flares, however my flares have a bit of extra clearance ground into them at about 2 o'clock (on the right side, 10 o'clock on the left side) as you face the wheel. The fit of the tires in the fenders looked great, very full muscular look... I've attached a couple of pics that show how it fit with those big tires.

 

You don't say what size wheels you are going to. Pete mentioned 10" wide... If you are planning on 15" wheels, you may need to keep your section width smaller than the Hoosiers I mentioned, to maintain clearance from the spring. If you go with 16's I don't think you can fit anymore rubber under the car than those Hoosiers. If you go bigger in diameter on the wheel, you may be able to get away with a little more sidewall buldge on the inside, but you might have to give up a little overall width on the outside to avoid the flare.

 

Hope that helps a little!

 

Tom

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EDIT--Sorry guys. 15x10 is the wheel I'm planning on.

 

I think that's the info I needed Pete. I was able to space the wheel out about an inch and 9/16, and I was thinking that I needed a bit more. I just haven't had any luck with backspacing so far, so I was a bit worried...

 

I bought a HF 16 ton tubing bender and didn't have any luck with it, so the cage is getting set aside for the moment. I'm trying to get all the bottomside stuff done and painted so that I can move without exposing all my work from the last 3 years to 1000 miles of road grime and rain and whatever else there happens to be along the way.

 

When I get back to it I think I'm going to buy a real tubing bender (should have listened to dr hunt on that one) and then I'll do it up. I have the 4 point roll bar basically done. The thread on that is here: http://forums.hybridz.org/showthread.php?t=102715. I think I know what I want to do though. The cage I've got in mind is going to be pretty extensive with a 6 point in 1.75 x .120 and then all the ancillary stuff with thinner walled tube, probably 1.625 x .065.

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Jon, You might check out art morrison next time you head down to Tacoma (they're in Fife actually). I know they have the equipment to make cages, but I don't know if they still do semi custom work.

 

I think I called them a couple years ago to see about a roll bar for my 240z, if I remember correctly, they had plans on file for most cars.

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Well I cut the fenders and bolted up a wheel and pulled the suspension up and the tire hit the inside of the fenderwell before the strut bottomed. I did have the camber plates all the way in, so I put them in the middle, roughly in the same area where I ran them before. Tried again and the tire hit the outside. So now I am going to recut the fender another inch farther up.

 

I have to wonder if there aren't a lot of guys running around with setups that are screwed up so that the tire hits the fenders. I was really pretty surprised, seeing as how my current 5" BS wheels are somewhat "normal". I guess this means that I should go to a 4.75" BS when I order new wheels...

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That's the number one online question I get about my car. I wish I knew the answer. They were on the car when I bought it. I want to say they look like the ones Arizona Z car sold, but they got out of the fiberglas business. I think Motorsport Auto used to sell something very close also, but I don't see them anymore... So bottom line... I don't know.

 

Sorry...

Tom

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  • 1 year later...

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