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2" lug conversion spacers bad idea?


turbogrill
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Hi, 

 

To be able to fit some fancy Miata wheels we currently have ~1" 4x100 -> 4x113 conversion spacers on our 280zx. It seems to work fine so far, no wheels has been falling of.

However we are now getting even fancier wheels, problem is that the lug nuts barely goes on there. So we need either thicker spacers or longer studs.

 

Have you guys had any issues with wide spacers? 

 

(I don't mind changing wheel bearings once every year)

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I don't understand the "thicker spacers or longer studs".  I am sure you know what you are doing but wouldn't a thicker spacer cover even more threads?  Longer studs is the obvious answer but I shy away from thick spacers as well.

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Nobody would run wheel adapters by choice but sometimes it is the best option available to you. I expect to see more of these with the new wide 15 inch tires, by far the best source of wide 15 inch wheels is to use Miata wheels which have a real deep offset. This is handy since it allows you to use adapters and still have the center of the tires in basically the same place. 

 

We are not talking about sandwich spacers where the studs are installed in the hubs and the spacers fit between the hubs and wheels. With these you don't really need long studs since the wheel mounts directly to the adapter. 

 

Chump rules on these adapters have evolved but are still kind of silly. For one thing there is a limit to how thick they can be, which is understandable for sandwich spacers but bolt pattern adapters actually get stronger as they get thicker. You are also limited to a single spacer or adapter per wheel, so if you need different thickness front and rear you can't just use the thinner adapter and a spacer at the other end. 

 

rhs1_zpsw4hnahml.jpg

 

On my car since I started with the weird 4X110 stock rx7 pattern and needed different thickness front and rear I made my own. Since I was making my own I made them from 7075 instead of the common 6061, 7075 is nearly twice as strong.

 

Very important point if you use adapters is that you can't retorque the bolts holding the adapters to the hubs during a pit stop like we do regular lug nuts. I torqued the adapters down and used red loctite to make sure they will never come loose. The downside is that I will have to deal with the loctite every time I need to change rotors. 

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  • Technical Advisory Committee

   2 in spacers ,adapters on my race car neva ..    what carries All the stress during cornering, braking ,bouncing., off tracking .over curbing ..  I am sure someone makes something that can take it but I am really sure most don't ..  the force that is put on  A frames spindles hubs and bearings is multiplied when you move the centerline of the wheel outward ..   my suggestion  find the correct  wheels and leave the adapting to less stressed areas

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7 hours ago, mhr650 said:

Since I was making my own I made them from 7075 instead of the common 6061, 7075 is nearly twice as strong.

 

 

 

Be careful with 7075 (and aluminum in general) in high-temp environments, as it's strength drops off significantly above about ~250F.  At 300F, typical yield strength for 6061-T6 is ~31ksi, vs only 27ksi for 7075-T6.  At 400F, its 12.6ksi for 7075 and 14.9ksi for 6061.  2xxx alloys are generally a bit better, but still not great.  Would probably use a steel adapter over an aluminum spacer (see below for friction explanation justifying the Al) if there was any concern about joint strength.  Wish I could find 7075, 6061, and 2024 all on the same graph from the same source for this, but my google-fu is failing today, so here's 7075 and some 2xxx alloys:

 

Image result for strength vs temperature 2024

 

And here's some text data vs temp for 6061 and 7075, both from the same AL supplier to help with test consistency:

http://www.clintonaluminum.com/wp-content/uploads/2014/08/Grade-7075-Text-data.pdf

http://www.clintonaluminum.com/wp-content/uploads/2014/08/Grade-6061-T6-T651-Text-Data1.pdf

 

And on the topic of wheel spacers - the interface between the wheel and brake rotor is critical to lug stud life.  If that interface slips under braking, the lugs will experience much more stress, and fatigue quite a bit more quickly, than if there was no slip.  The coefficient of friction for steel on steel is ~0.2, and if there's a little bit of oil or grease on there (such a wheel bearing grease, oil leak, or gunk left over from the rotor mfg process, it drops to ~0.13.  Coefficient of friction for steel on aluminum is ~0.6, and aluminum on aluminum is 0.3ish.  So, aluminum wheel bolted to steel rotor is unlikely to slip and fatigue lugs.  Aluminum wheel on aluminum spacer is generally within the OEM's factor of safety for the joint (especially if the car was designed for steel wheels), but twice as likely to slip and break lugs.  Start spending lots of money on lug studs here, and think about lubricating threads to increase clamp load.  Steel spacers (or steel wheels) on steel lugs, are twice as likely to slip again.  Steel wheels with aluminum spacers in between the wheel and rotor are just as good as aluminum wheels from a joint integrity standpoint.

 

Basically, it's not a trivial joint to understand, so be careful and don't cheap out on anything related to it.  Luckily, it's usually over-designed from the factory, but racing abuse, oversize wheels and tires, and high temperatures can quickly take up all of the mfg's margin.  So feel free to play with spacers and adapters, but be very careful and buy the good stuff. 

 

Edited by Hi_Im_Will
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I agree that you need to take care and think about what you are doing. In my case and the original poster we are not moving the tire center line out any further than stock, we are using wheels that have a lot of offset and the adapters just space the wheels out where they started, in my case the rears are even tucked in from stock... 

 

Any extra load is from using wider grippier tires and that is the same problem no matter how you get there, just ask MR2 racers. Also remember that hubs, and are not infinitly strong, again ask MR2 racers... Wheels are certainly not infinitly strong ask any number of racers that have lost wheels due to contact... My analysis showed that the wheel would always fall before the adapter. 

 

Hi_Im_Will helped me validate my adapters at VIR, took a hit hard enough to bend the stub axle on the strut far enough to give me 3/4 inch of toe in and the adapter survived just fine ☺️

Edited by mhr650
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11 minutes ago, mhr650 said:

Hi_Im_Will helped me validate my adapters at VIR, took a hit hard enough to bend the stub axle on the strut far enough to give me 3/4 inch of toe in and the adapter survived just fine ☺️

 

Just adding for some info for people who don't design turbochargers all day - your hub adapters demonstrated their exceptional strength several times at that race IIRC.  If you start selling kits, I'll write you a testimonial :)

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  • 2 weeks later...

As a couple others here have said, there is no issue if it is done correctly. A properly executed bolted joint would give me no concern.  Will and mhr650 gave good advice.

  • Pay attention to your materials
  • Pay attention to pilots/hubs/fits
  • Longer bolts are more forgiving under load and temp
  • Loctite on the hub isn't a bad suggestion
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On January 22, 2017 at 10:21 AM, mhr650 said:

Nobody would run wheel adapters by choice but sometimes it is the best option available to you. I expect to see more of these with the new wide 15 inch tires, by far the best source of wide 15 inch wheels is to use Miata wheels which have a real deep offset. This is handy since it allows you to use adapters and still have the center of the tires in basically the same place. 

 

We are not talking about sandwich spacers where the studs are installed in the hubs and the spacers fit between the hubs and wheels. With these you don't really need long studs since the wheel mounts directly to the adapter. 

 

Chump rules on these adapters have evolved but are still kind of silly. For one thing there is a limit to how thick they can be, which is understandable for sandwich spacers but bolt pattern adapters actually get stronger as they get thicker. You are also limited to a single spacer or adapter per wheel, so if you need different thickness front and rear you can't just use the thinner adapter and a spacer at the other end. 

 

rhs1_zpsw4hnahml.jpg

 

On my car since I started with the weird 4X110 stock rx7 pattern and needed different thickness front and rear I made my own. Since I was making my own I made them from 7075 instead of the common 6061, 7075 is nearly twice as strong.

 

Very important point if you use adapters is that you can't retorque the bolts holding the adapters to the hubs during a pit stop like we do regular lug nuts. I torqued the adapters down and used red loctite to make sure they will never come loose. The downside is that I will have to deal with the loctite every time I need to change rotors. 

How much for a set? 

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It’s very unlikely that my spacer thickness would work out for your car. I very carefully set it up exactly for the combination I have with second gen rotors over turned down first gen hubs in the front and second gen rear brakes adapted to fit on a drum brake rear end housing, my 15X9 wheels have 36mm offset.  In the end I was able to get the front tires tucked in with only about 5mm clearance between the tires and struts.

 

I am not really in a positon to make any more for someone else, but I do have a detailed drawing of my spacers I would be happy to share. If you can get me some measurements of your setup I can model it up and find out what thickness spacers you need for your car and supply drawings for the correct thickness adapters.
 

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I use adapters from www.adaptitusa.com.  The quality is very good and I really like the use of extended shank lugnuts to hold the adapter to the hub.  It seems much more solid than standard cone seat lugnuts.  YMMV.

 

You do need to coordinate wheel backspacing with adapter thickness (minimum 1") and tire size.  I have 1" adapters and can use 205's (but not Hoosiers) with ET38 to ET30 15x7 wheels.

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we use adapters/spacers on our car. It allows us to run Corvette 17x9.5 rims they have a bunch of backspace. I think ours are 1.5 or 1.75",  No problems, make sure they are hub-centric You don't want all the stress on your lug nuts.

13245322_266918533658243_4494268310572837739_n.jpg

 

I have a set of hub centric adapters (for another set of wheels) I have been planning to experiment with... would you mind elaborating on how may hours you have on your vette wheels + adapters?  

 

Related question - ours have pressed in studs (into the adapter) to hold the wheels on, this seemed to be a weak point, and I was wondering if someone got too aggressive with lug nut torque, if that stud spun in the adapter (i.e. you couldn't loosen the lug nut), what the heck would you do then?

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