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Thread: To space or not to space......?

  1. #1
    Team Z8 riverflyer's Avatar
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    To space or not to space......?

    I have a beautiful new set of HRE 447r's sitting in my garage. Made for e46M3 and never mounted.
    I have been told I can use them on the Z8 with the use of 15mm fr and 8mm rear spacers (need brembo clearance).

    I usually avoid spacers but in this case I believe the spacers will adjust the wheels to about factory specs relative to original intention.

    BUT, with the susp/frame issues on these cars, it makes me hesitant. Anyone on board with experience using hub centric spacers? Long term?

    thanks, John

  2. #2
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    If you use high quality wheel spacers coupled with the correct length lug bolts (very important), there will be no stability or safety issues. The Z8 has hub-centric flanges which insure proper alignment of the wheel when mounted on the hub. Properly designed wheel spacers will use those flanges to insure their own alignment and then provide their own hub-centric flange to insure proper wheel alignment. Unfortunately, this only applies to spacers 10mm or thicker. Less than that and there isn't enough material to provide a proper hub-centric flange. Having said that, I have used 5mm spacers on my Z8 with no problems. You do have to pay more attention when mounting the wheels to insure proper alignment but some of the original flange will protrude through the thin spacers to help with this. I use studs instead of lugs which makes the whole process much simpler. Most wheel spacers are made from an aluminum alloy to keep their weight down but that means they are subject to electrolysis when mounted on a steel hub. To avoid them becoming "welded" onto your hub, be sure to coat them with a thin layer of anti-seize compound when first installed. Also, make sure you clean your hubs with a wire brush to insure the spacers seat flat against the mounting surface. Also, count the number of OE lug threads extending beyond the wheel's mounting surface and make sure your new lugs are long enough to provide an equal number of threads when spacers are included. Particularly in the rear, be careful not to use lugs that are too long since they will interfere with the hub's ability to rotate by protruding into the parking brake mechanism which is inside the hub. It should be pointed out that the use of wheel spacers does put more strain on the wheel bearings but unless you are going above 50mm, this really isn't an issue. The same is true for wheels whose negative offset moves the outer edge of the wheel outboard of the OE position. While wheel spacers may seem like a compromise on a high performance automobile, keep in mind that Porsche uses wheel spacers on a regular basis to allow fitment of their various wheel on different models. You might want to try a little more offset in the rear to fill in the wheel wells. If 8mm equals stock offset, I'd try 15mm in the rear. I have used wheels spacers on my Z8 for years with no issues.

  3. #3
    Team Z8 riverflyer's Avatar
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    GM, I was so hoping you would throw down one of your very informative posts here! Thanks, I have been asking around and getting lots of different answers but your response, as usual, is complete and logical. I think I will go 15mm fr and rear. Do you have a source you would recommend for the hubcentric spacers? thanks, John

    Oh yeah, if I test fit the wheels, how much space should there be between spokes and brake calipers to insure no issues under high speed cornering? HRE tech said the brembos would require 8mm rear and 15mm fr to clear the brakes.
    The wheels are 19" and made for e46m3 with 19x9 with 38mm offset and rear are 19x10 with 28mm offset.

  4. #4
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    BMP Design is my source for wheel spacers. 800-648-7278 www.bmpdesign.com. They have their own billet spacers and they sell spacers by H&R, which are the ones I use. They are available in 5mm,12mm,15mm,20mm, and 25mm sizes. The fitment you are undertaking is unusual so I don't have any experience with it. It wouldn't surprise me if you end up needing some other size spacers so be prepared to exchange some of them if you only order 15mm. Brake caliper clearance should be at least 2-3mm although it really depends on how much flex your wheels will experience under extreme side loading. Just remember, just because you can use spacers to provide brake clearance doesn't mean the wheels will fit well on your Z8. You must pay close attention to inner clearance of the wheels and tires (tires are usually where the problem comes in) from the suspension components, particularly up front, and then see if the tires are fully enclosed by the fender lips and that you don't encounter rubbing of the tires on those lips while cornering. The front fender has a joint on the inside of the fender lip which can be problematic so pay particular attention to it. Spacing in the rear is much less critical and the primary reason for moving the wheel out a bit in back is cosmetic, i.e., to fully fill up the rear wheel well visually. After installation, don't judge their fitment when the car is first lowered onto the ground; roll the car a few feet to allow the suspension to settle. Hope this helps and good luck with the project. P.S. Don't force them to fit. If you have to make significant compromises, I'd go with different wheels.

  5. #5
    Team Z8 riverflyer's Avatar
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    Yes, you are very right in that the wheels may not fit. I don't think there is anyway to know for sure until I fit them and try it out. I really like the style and feel it will compliment the car, so its worth a try. thanks again for your kind help.