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01-01-2010, 01:21 AM | #1 |
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Everything You Ever Wanted To Know About Spacers
A great article by TMS... copied from http://www.turnermotorsport.com/html...cer_tech.shtml
This is a thread that we've been thinking of for a long time. We also created a page on our website with the same information (more to come!). It consists of everything Turner Motorsport has learned about wheel spacers for BMWs. A lot of this info also applies to other makes as well. It's a very long and comprehensive collection of data, tips, and technical info and it's a bit Turner-centric but should prove useful to everyone. If you should have any further questions, please call or e-mail us. Why Use Wheel Spacers?
Once you know WHY you need spacers, you can figure out what size to use... |
01-01-2010, 01:21 AM | #2 |
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What Size Should I Use?
Knowing why you need spacers leads you to the question of what size to use. The best way of figuring this out is to measure the gap between your tire and the inside lip of your fender. This will tell you how much space you have before the tire will make contact with the fender. Too big of a spacer will obviously give you rubbing issues. So the answer is - How much space do you have to work with? Measuring your wheel gap is very easy and we have provided some examples below. Turner Motorsport may be the biggest BMW wheel spacer dealer in the world. As such we have learned not to make assumptions on spacer size. Every situation is different and the best advice we can give is to measure your car. It's tempting to listen to what everyone else is running but unless they have your exact wheel, exact tire, exact suspension, and exact suspension settings, no one can tell you what spacer size to use. They can only guess... Please keep in mind that spacers that have been installed and tested cannot be returned. This is to be fair to the next customer who expects new, top quality parts from us. Which is all the more reason to be precise about what size you can install. Here are some easy ways to measure your wheel gap -- Old-Fashioned Tape Measure With the car on the ground, hang a piece of masking tape from your fender. Stick a quarter or a nickel on the end so that it hangs straight down. Next measure in from the masking tape to the outside edge of your tire. This will tell you how much space you have until the tire would contact the lip of the fender. Pick a spacer that is slightly less than this measurement. This will ensure the tire does not rub on the fender lip. Even More Old-Fashioned Rulers Same as the method above but if you don't have masking tape to hang from the fender, you can use a straight-edge or ruler and another ruler or tape measure. Gently hold the straight-edge from the bottom of the fender lip. Measure in to the outiside of the tire. The gap between the straight-edge and the tire is your available clearance. Choose a spacer size slightly less than this dimension. Wheel Studs and Washers For this method, you would purchase at least two wheel studs to thread into the hub and corresponding nuts to lock the wheel down (link to TMS 90mm studs). Remove your wheel and bolts. Thread the studs into the hub. Place washers down the stud to the hub. Slide the wheel over the studs. If it makes contact with the caliper or suspension, add more washers. Once the clearances are set, lock the wheel down with the nuts. Lower the car to the ground and roll - don't drive! - the car back and forth so the suspension will settle. Check your clearances again and also for tire-fender contact. Adjust if necessary. The end thickness of your washers will be your minimum spacer size. If you have space left over before the tire hits the fender, consider going with an even bigger spacer for improved looks. Remember to remove your studs or install them the proper way before driving. Studs and washers installed in the hub. Pictured is a BBS 90mm stud and 5 washers (roughly 15mm). Studs and washers installed with the wheel. BMW Wheel Pin and Washers If wheel studs are not available to you, you can use the factory BMW wheel pin tool in your tool kit. More than one pin is recommended. This method does not allow you to set the car on the ground as the wheel pin will not support the weight of the car and there is no way to fasten the wheel to the hub. Don't even try it! Remove your wheel from the car. Insert the pins into the hub. Slide M12 sized washers onto the pin down to the hub. Slide your wheel onto the pins until it contacts the caliper, suspension, etc.. Add washers until the wheel sufficiently clears. The thickness of your stack of washers is the size of your spacer. Factory BMW wheel pin tool installed with washers. OK, so now you know what will likely fit. Choose a spacer slightly less than the maximum gap. Remember to order longer wheel bolts too! Of course, that's not the whole story so read on for a more in-depth look at spacers in general, as well as some helpful tech info on fitments. |
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01-01-2010, 01:22 AM | #3 |
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Wheel Bolts
Remember that every wheel spacer needs a longer wheel bolt or stud. It's amazing how many bolts we sell without spacers so this fact is getting lost on a lot of people (or their supplier is leaving out critical information). The correct length wheel bolt is your stock bolt + the thickness of your spacer. As a general rule, we consider the stock BMW length bolt to be 25mm as measured from the base of the cone seat to the tip, including all threads and shank. So a 10mm spacer will require a 35mm wheel bolt. However, we have seen a range of stock BMW bolt sizes from 25 to 28mm. A bolt that is too long will interfere with other parts inside the hub (ABS sensors, parking brake mechanism, etc). Existing wheel bolt offerings may vary by 2-3mm but you can trust us that we have extensively researched, sold, used, and tested the fitments on all of the spacers and bolts that we sell. If a situation comes up where an unusual application is needed, we have many sizes to offer. |
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01-01-2010, 01:22 AM | #4 |
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Wheel Spacers With Wheel Studs
Wheel studs protrude from the hub and help to locate the wheel to the hub. A wheel nut (lugnut) would then be used to fasten the wheel to the hub. The issue with using them with spacers is that it can actually push the wheel out too far, leaving you without enough threads to securely fasten the wheel nut. Here are some things to keep in mind when choosing studs and spacers -
For instance, a TMS 75mm wheel stud usually has enough room left over to use a 10mm spacer. However, a big brake kit may have a thicker rotor hat than stock which would reduce your available space on the stud. As well, the thickness inside the bolt bore can vary a lot as well. A thicker wheel will reduce your available threads. The solution here is to use a longer wheel stud. TMS Wheel Spacer and Stud Design in SolidWorks (click the image below for a super-sized version) This image was created by the TMS engineers in SolidWorks - a CAD program. All components are scaled correctly in relation to one another. Here you can see the relationship between wheel spacers, wheels, and the hub (wheel bearing). You can also see how brake rotor hats and wheels also play into spacer fitment. This particular drawing is of a E36 M3 with a TMS 12.5mm spacer, a stock BMW brake rotor, a TMS 75mm wheel stud and TMS wheel nut, and a generic wheel design. There's a lot to look at on this drawing but things to pay particular attention to are -
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01-01-2010, 01:23 AM | #5 |
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The 10mm Spacer Dilemma
10mm wheel spacers are one of the most common spacer sizes out there. However, what a lot of people don't realize is that a 10mm size is not a true fitment on any BMW. It's considered a "tuner" fitment, meaning some extra thought is usually required to correctly install them. Only with the right combination of parts will a 10mm spacer fit without a vibration or other fitment issues. Factory Hub Lips Are Greater Than 10mm The depth of the lip on the car where the spacer will rest will vary. The available lip space may be 11mm and a 10mm spacer with its own hubcentric lip cannot physically fit. The spacer will bottom out on the lip instead of on the brake hat, leaving a gap between the spacer and the rotor hat. The biggest reason for this is the thickness of the rotor hat. The thickness varies by manufacturer and design. A thinner hat (such as used with aluminum Euro Floating rotors) will leave more lip protruding and make the problem worse. Most spacer manufacturers add an extra chamfer, or shoulder, to push the hubcentric lip further out. The extra chamfer clears any extra part of the stock lip. The other way to get the spacer to fit is to shave the stock lip with a metal file. While not the most elegant solution, it works. Wheels With Incorrect Beveled Edge Some wheels (Kosei in particular) have a beveled mounting surface that is at a different angle than on the spacer. Think of really precise puzzle pieces fitting together - if the pieces are not precisely machined to match, the parts don't fit together very well. The wheel will vibrate since enough of the wheel bore is not resting on the spacer lip. Note that all of this only occurs when using a 10mm spacer with its own hubcentric lip. Any spacer over 10mm is not affected by this. The TMS 10mm spacers with Hub Extender is also exempt from this as the spacer has a flush outer face and will not interfere with the mounting surface of the wheel. What's the solution? You could shave the stock lip on the car so its depth is under 10mm... Or you could just use a 12mm spacer and be done with it. The difference between a 10mm spacer and a 12mm spacer is the thickness of a nickel! The 2mm difference is smaller than the thickness of a CF memory card or your typical cardboard box. Trust us - 12mm is the way to go. The TMS Hub Extender/10mm Spacer set also works well and allows you to swap spacers in and out for different setups. |
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01-01-2010, 01:23 AM | #6 |
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Spacers for Wheel Offset Issues
A lot of the calls we get are to correct a wheel offset when using a wheel not intended for the chassis. Examples - E36 M3 wheels on an E30 M3 or E46 wheels on an E34. The 3-series cars generally have a higher offset than the 5-series. This results in the wheel being tucked in too far and making contact with brakes, suspension components, or the inner wheel well. The differences in offset are usually around 15-20mm but that's not the whole story... Not only is the offset different but the width of the wheel is usually different as well. An E30 M3 had a 7.0" stock wheel. Most E36 wheels are 7.5" or 8.0" and a higher offset. So not only are you fighting the higher offset but the wheel is physically wider. If the wheels were the same width, your spacer would simply be the differences in the offsets. But add the extra width and you now have another dimension to figure out. The mathematical formula is very intricate but you can find offset calculators online. Call us if you need further assistance. E39 owners need to be careful because their wheels use a different center bore than most other BMWs. This limits their wheel choices. The E39 center bore is 74.0mm. Just about all other BMWs use a 72.5mm center bore. Depending on what the wheel was originally designed for (E36, E46, etc) there may be an offset difference to deal with as well. In the case of fitting one of these wheels to an E39, H&R has developed a wheel spacer adapter that is 72.5CB on the wheel side and 74.0CB on the hub side. The adapters come in 15mm and 20mm sizes to take up the offset difference. See these adapters on our website here - 15mm adatpers, 20mm adapters. Here are some not-uncommon situations: E36 M3 wheels on an E30 M3. The stock wheel is a 15x7.0 ET20. The new wheel will be a 17x8.0 ET40. If we just installed the wheel with no spacers, it would be 33mm futher inward than stock but will stick out 7mm more than stock. The stock E30 M3 has a lot of wheel clearance before the stock wheel will hit the fender (20mm using the measuring methods above). So right away we know that a big spacer can be used without worrying about it rubbing on the outside fender. Let's say we put just a 7mm spacer on - it will bring the new wheel to the same position as the stock wheel on the outside, but will still be 26mm tucked in towards the strut (and rub on the strut). But we know that we can safely go another 20mm more and still not touch the fender. If we put a 25mm spacer on the new wheel, it will rest 18mm further out than stock and only 8mm further in. We now have a wheel that is spaced out enough to sit flush with the fender and not rub on the inside! Winter Wheel Package for E92 335 coupe. Many people are finding themselves without a true winter wheel package on the E9X models. These cars come with a stock wheel with an offset quite a bit lower than the E36 and E46 predecessors. When trying to fit these E36/E46 wheels to the 335, they sit too far inward because of their higher offsets and narrower width. The best solution would be to buy wheels with the correct offset. Aside from that, spacers can be used to make up the difference. First measure your stock wheel clearance as outlined above. We'll use a 17x8.0 ET40 as the winter wheel. The stock 335 wheel is a 18x8.0 ET34. In this case, you only need a 6mm spacer to get it back to the original stance. However, the back wheel is a 18x8.5 ET37 and to use the winter wheel you will need a 9mm spacer to get it back to stock stance. Because you measured beforehand, you know how much more room you have to space the stock wheels out. This is critical because 6mm and 9mm spacers don't exist; you will need something larger and you need to make sure there is adequate clearance for it. E46 M3 19" ZCP wheels on an E92 335 coupe. The stock sport package wheel is a 18x8.0 ET34 and 18x8.5 ET37. The E46 M3 uses a 19x8.0 ET47 in front and a 19x9.5 ET27 in the rear. Using our calculations, the front will sit further in by 13mm. A 15mm spacer will bring it back to the factory wheel stance. Measuring the stock wheel beforehand we know that it will take a 12mm spacer before the stock wheel contacts the fender. Therefore, adding 15 and 12 gets us to 27mm. So the E46 M3 front wheel will take a 20-25mm spacer in order to sit flush with the E92 fender. The M3 rear wheel will sit only 3mm in but an additional 23mm further out. Measuring beforehand, we found that the stock wheel only has 15mm of clearance before it hits the fender. The M3 wheel will most likely rub on the fender, requiring the fender to be rolled or negative camber added for more clearance. |
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01-01-2010, 01:24 AM | #7 |
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Miscellaneous Notes and Details on Spacers
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01-01-2010, 12:58 PM | #9 |
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Moderators, please make this thread a sticky...
rzm3, thanks for posting this detailed information about wheel spacers. This will help many current (and new) m3post members for years to to come.
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Last edited by Lemans_Blue_M; 01-01-2010 at 04:04 PM.. |
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01-01-2010, 02:59 PM | #10 |
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01-01-2010, 08:47 PM | #13 |
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So I guess the 10mm spacers I was about to get are a no-no.
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01-02-2010, 07:28 AM | #14 | |
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01-03-2010, 01:01 AM | #16 |
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01-24-2010, 01:01 PM | #17 |
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How can I find out that 10mm would be okay to use in the rear? I don't want to find out the hard while driving over 100mph
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02-05-2010, 07:59 PM | #18 |
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A word of caution. I ordered H&R spacers for my E90 M3 with OEM 18" wheels. Was advised to get 12mm in front and 15mm in back. Looks great, but getting some tire rub in rear, so swapping 15mm for 12.5mm.
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02-12-2010, 11:54 AM | #19 |
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thanks for posting that info! that really did help! I love it when you guys post stuff like this thanks a lot!
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02-26-2010, 04:55 PM | #20 |
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I almost had a heart attack when I saw the part about wheel studs and washers...until I realised that it was for measuring purposes only, not as an actual spacing method. I have seen people do this as a spacing method when they have studs in all 5, and it is a horrible idea.
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02-27-2010, 10:06 PM | #21 | |
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