Mazdarotaryparts
11th January 2010, 01:20 PM
In answer to a couple of questions raised on another site I thought it would be an idea to put this up in here as well FYI,
As many of you already know a lot of the experience I offer through MRP is due to personal experience gained via 20 years of racing and automotive industry engineering back round and whilst none of us know it all in many cases I have learnt much of what you read below the hard way, through hands on experience.
Onto wheels and wheel spacers, agreed Losing wheels is not fun, indeed I lost a wheel coming off Clearway's at Brands and watched with horror as it accelerated faster than the car and I thought it going into the crowd, however it bounced back up in the air onto the track,
This was due to a wheel center tearing out though rather than a wheel spacer, point being I understand more than most what happens when a wheel detaches itself !!!
Also due to further experience gained with larger vehicles where keeping wheels on heavy vehicles is even more paramount due to the weights and implications involved, McGard the people who make the locking wheel nut for all RX-8 used my knowledge in this field for a year to enable the development and manufacture of a locking wheel nut for Lorries, Busses and Coaches
As for wheel spacers I used these to great effect over the years and like most things providing you use properly engineered parts that are correctly fitted then this IS a safe route to take,
First of all many people do not actually understand how a road wheel is held on so this is a good place to start explaining about how wheel spacers can be safe.
The common misconception is that wheels are held on purely by the torque setting that is exerted when the wheel nut is tightened when it is actually the clamping force that is exerted between the wheel and the hub face that really holds the wheel on and prevents not only the wheel falling off but also the nuts coming loose.
Think of the wheel studs as acting like elastic springs, indeed it is this elasticity that clamps the surfaces together because once the wheel nuts are torqued up to their recommended settings they are stretched and therefore under tension, thus acting the same way as a spring under tension, this elasticity then exerts far far more pressure onto the surfaces than mearly doing up the wheel nuts imply.
Another misconception is to tighten the nuts more than the manufactures setting to ensure the wheels don’t come off, this is actually dangerous because by doing this you can then stretch the stud and loose the elasticity explained above, leading to loose wheel nuts and the studs shearing off due to the loss of clamping effect between the wheel and the hub!.
Also always tighten wheels as diagonal as possible is also crucial achieving to this clamping effect correctly.
On understanding exactly what this clamping effect achieves it then becomes possible to understand why wheel spacers are safe providing the following is ascertained.
The presence of clean flat surfaces is crucial to achieve the correct clamping effect, also that the spacers locate properly over the raised boss in the middle of the hub to ensure the spacer is properly centralised and lastly that this boss is then duplicated onto the spacer itself, taking the shape of a raised lip,
These spacers are known as “hub centric” spacers and here at MRP we sell the Eibach spacers pictured below and as some of you know, Eibach is such a respected company that Mazda themselves used Eibach in the development of the RX-8 PZ and this in itself should help to dispel the misconception that “spacers are unsafe”.
As for thickness of the spacer once the clamping effect becomes fully understood then you will realise that no matter if the thickness is 6mm or 60mm and made of good quality alloy such as the alloy used to make your wheels then you will realize that using the correct spacers for the vehicle the spacers were made for is perfectly safe.
As for me, I have run the 20mm Ebach spacers pictured below all round on my RX-8 for the last 2 years and 55mm for the last 5 years on my 2 ton Ford Explorer !,
Lastly to show you that spacers can be used safely on the track as well a friend of mine in Japan went to a meeting and sent me close up pictures of the Pan Speed RX-7 complete with big wide spacers both front and rear.
Hope this helps
As many of you already know a lot of the experience I offer through MRP is due to personal experience gained via 20 years of racing and automotive industry engineering back round and whilst none of us know it all in many cases I have learnt much of what you read below the hard way, through hands on experience.
Onto wheels and wheel spacers, agreed Losing wheels is not fun, indeed I lost a wheel coming off Clearway's at Brands and watched with horror as it accelerated faster than the car and I thought it going into the crowd, however it bounced back up in the air onto the track,
This was due to a wheel center tearing out though rather than a wheel spacer, point being I understand more than most what happens when a wheel detaches itself !!!
Also due to further experience gained with larger vehicles where keeping wheels on heavy vehicles is even more paramount due to the weights and implications involved, McGard the people who make the locking wheel nut for all RX-8 used my knowledge in this field for a year to enable the development and manufacture of a locking wheel nut for Lorries, Busses and Coaches
As for wheel spacers I used these to great effect over the years and like most things providing you use properly engineered parts that are correctly fitted then this IS a safe route to take,
First of all many people do not actually understand how a road wheel is held on so this is a good place to start explaining about how wheel spacers can be safe.
The common misconception is that wheels are held on purely by the torque setting that is exerted when the wheel nut is tightened when it is actually the clamping force that is exerted between the wheel and the hub face that really holds the wheel on and prevents not only the wheel falling off but also the nuts coming loose.
Think of the wheel studs as acting like elastic springs, indeed it is this elasticity that clamps the surfaces together because once the wheel nuts are torqued up to their recommended settings they are stretched and therefore under tension, thus acting the same way as a spring under tension, this elasticity then exerts far far more pressure onto the surfaces than mearly doing up the wheel nuts imply.
Another misconception is to tighten the nuts more than the manufactures setting to ensure the wheels don’t come off, this is actually dangerous because by doing this you can then stretch the stud and loose the elasticity explained above, leading to loose wheel nuts and the studs shearing off due to the loss of clamping effect between the wheel and the hub!.
Also always tighten wheels as diagonal as possible is also crucial achieving to this clamping effect correctly.
On understanding exactly what this clamping effect achieves it then becomes possible to understand why wheel spacers are safe providing the following is ascertained.
The presence of clean flat surfaces is crucial to achieve the correct clamping effect, also that the spacers locate properly over the raised boss in the middle of the hub to ensure the spacer is properly centralised and lastly that this boss is then duplicated onto the spacer itself, taking the shape of a raised lip,
These spacers are known as “hub centric” spacers and here at MRP we sell the Eibach spacers pictured below and as some of you know, Eibach is such a respected company that Mazda themselves used Eibach in the development of the RX-8 PZ and this in itself should help to dispel the misconception that “spacers are unsafe”.
As for thickness of the spacer once the clamping effect becomes fully understood then you will realise that no matter if the thickness is 6mm or 60mm and made of good quality alloy such as the alloy used to make your wheels then you will realize that using the correct spacers for the vehicle the spacers were made for is perfectly safe.
As for me, I have run the 20mm Ebach spacers pictured below all round on my RX-8 for the last 2 years and 55mm for the last 5 years on my 2 ton Ford Explorer !,
Lastly to show you that spacers can be used safely on the track as well a friend of mine in Japan went to a meeting and sent me close up pictures of the Pan Speed RX-7 complete with big wide spacers both front and rear.
Hope this helps