Very strange front end shake and wobble....
05-19-08, 07:25 AM
#47
That was quite a detailed response from the Professor character... the bottom line is, when I worked at HRE, we became aware of this problem some time after beginning to sell the reverse-drop center wheels. A customer in Miami called to complain about a vibration in the rain. After some head scratching and testing, we decided the customer was, in fact, right.
The "drop center" region of the wheel is necessary to physically mount the tires on all wheels. The "water retention issue" is only present on so-called "reverse drop center wheels", aka 'flat style lip.'
With a "Conventional" or "standard" profile rim, the drop center is located towards the 'face' or front of the wheel. Due to this configuration, no channel exists for water to accumulate in. N o issue possible here!
For styling reasons, the "reverse" style rims are currently very popular. To achieve this large 'full face' wheel spoke style, the "center" (plate that comprises the wheel spokes) portion is basically the full diameter of the wheel. This necessitates moving the drop center region of the wheel to the rear, or inside of the wheels. Unfortunately, this creates a channel that can collect water or other liquids directly behind the wheel assembly nuts.
With small amounts of liquids, or large amounts at low speed, the vibration does not manifest itself. Since no wheel is PERFECTLY round, larger amounts of water will tend to migrate towards a high spot (actually a depression if you could see it from the liquid's point of view) where it essentially gets stuck as centrifugal force builds. This acts like a giant wheel weight, and throws the wheel/tire assemble out of balance.
HRE's engineer and I did exhaustive testing and brainstorming in attempt to solve this issue. We created spiral 'dams' made of clay in hopes of directing water out of the channel and the wheel- tests proved the water would simply pass right over the dam, and in some cases even exxagerated the problem by trapping the water between the dams.
We toyed with closed-cell foam inserts, but this created other issues. Increasing the size of the drop-center region (to decrease the channels' width) would work well, but makes it all but impossible to assemble the wheels...
OZ has a neat solution to this on their Superlegerra 3 wheels, but it is patented and (frankly) makes the wheels quite heavy (18x10 weighs 26 lbs... my 20x10.5 HREs weigh 27 lbs!). Also, it requires a blind fastener which can strip or create issues if the wheel ever needed to be serviced... as you can see, besides the patent infringement issues, there are valid technical issues with this compromise.
Basically, most (if not all) of the three-piece Japanese and American-made reverse drop center wheels will have this issue if enough water is present. Most people will live with it because they love the 'look' this style of rim provides. So, there is the age-old question- do you warn every single potential customer and put yourself out of business in the process? Or do you simply suggest that the customer move to a more arid climate once an issue occurs?
No easy answers here.... my suggestion: if you have a sweet set of aftermarket wheels, spend $10 on an Absorber, and keep it in the trunk!
Best regards,
Bob Hale
Director of Marketing
Zone Wheels USA
The "drop center" region of the wheel is necessary to physically mount the tires on all wheels. The "water retention issue" is only present on so-called "reverse drop center wheels", aka 'flat style lip.'
With a "Conventional" or "standard" profile rim, the drop center is located towards the 'face' or front of the wheel. Due to this configuration, no channel exists for water to accumulate in. N o issue possible here!
For styling reasons, the "reverse" style rims are currently very popular. To achieve this large 'full face' wheel spoke style, the "center" (plate that comprises the wheel spokes) portion is basically the full diameter of the wheel. This necessitates moving the drop center region of the wheel to the rear, or inside of the wheels. Unfortunately, this creates a channel that can collect water or other liquids directly behind the wheel assembly nuts.
With small amounts of liquids, or large amounts at low speed, the vibration does not manifest itself. Since no wheel is PERFECTLY round, larger amounts of water will tend to migrate towards a high spot (actually a depression if you could see it from the liquid's point of view) where it essentially gets stuck as centrifugal force builds. This acts like a giant wheel weight, and throws the wheel/tire assemble out of balance.
HRE's engineer and I did exhaustive testing and brainstorming in attempt to solve this issue. We created spiral 'dams' made of clay in hopes of directing water out of the channel and the wheel- tests proved the water would simply pass right over the dam, and in some cases even exxagerated the problem by trapping the water between the dams.
We toyed with closed-cell foam inserts, but this created other issues. Increasing the size of the drop-center region (to decrease the channels' width) would work well, but makes it all but impossible to assemble the wheels...
OZ has a neat solution to this on their Superlegerra 3 wheels, but it is patented and (frankly) makes the wheels quite heavy (18x10 weighs 26 lbs... my 20x10.5 HREs weigh 27 lbs!). Also, it requires a blind fastener which can strip or create issues if the wheel ever needed to be serviced... as you can see, besides the patent infringement issues, there are valid technical issues with this compromise.
Basically, most (if not all) of the three-piece Japanese and American-made reverse drop center wheels will have this issue if enough water is present. Most people will live with it because they love the 'look' this style of rim provides. So, there is the age-old question- do you warn every single potential customer and put yourself out of business in the process? Or do you simply suggest that the customer move to a more arid climate once an issue occurs?
No easy answers here.... my suggestion: if you have a sweet set of aftermarket wheels, spend $10 on an Absorber, and keep it in the trunk!
Best regards,
Bob Hale
Director of Marketing
Zone Wheels USA
" So, there is the age-old question- do you warn every single potential customer and put yourself out of business in the process? Or do you simply suggest that the customer move to a more arid climate once an issue occurs?"
If your business has integrity, isn't it your responsibility to advise your customers about this issue? Or, is "buyer beware" the catch phrase of the after-market wheel industry?
If a manufacturer knows about this problem and decides not to disclose information related to vehicle safety, then it should be their responsibility to allow customers (at the customer's option) to return the wheels at the full priice initially paid by the customer. This only seems fair to me.
Thank you, Cecil
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