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Aftermarket Alloys Discussions

Discussion in 'Tyres & Alloys' started by royj, Apr 12, 2011.

  1. Rituraj

    Rituraj Regolare

    Jorhat, Assam
    Thanks RoyJ, now I can breathe easier :D I have already removed those studs while installing my alloys. I will post pictures in the alloy wheel thread.
  2. M A N U

    M A N U Amatore

    any idea where to buy hub centric RIMs in bangalore?

  3. Manu, it will be tough to source the hub rings from Bangalore shops. Most of them don't have it and doesn't know what a hub ring is and its requirement. The only shop I seen this in Shivsakti tyres in JC road who gives the ring in aluminium. Apart from this shop, I didnt find anyone have this ring.

    Better way is measure the ring size and get it done from a lathe shop.
    Last edited: Aug 13, 2012
    1 person likes this.
  4. royj

    royj Esperto

    PCD Mismatch explained

    Here I will try to explain the PCD and its mismatch a little more in detail with the diagram below.


    The red dotted circle represent the 'imaginary circle' connecting the center of the 4 bolt holes in red and is 98mm in diameter and so we call it 98PCD. Similarly the blue ones represent the 100PCD configuration.
    As you can see the holes will be offset by 1mm with respect to each other and this will result in undue stress on the lug bolt that is driven through these holes. After a while, the thread of the bolts will get worn and it will lose its ability to hold the wheel to the hub.

    Wobbly bolt theory
    This theory "assumes" that the holes in the alloy wheel are larger and can therefore "accommodate" the 1mm offset. See the diagram below.


    The green circles represent the 100 PCD holes of the alloy wheel. So with an eccentric collar on the lug bolt, it can ensure proper seating on the wheel hole and at the same time fit into the 98PCD hole in the hub straight. However as you can see, it make a lot of assumptions starting with the 100PCD holes in the wheel cover the 98PCD holes with proper overlap to allow the bolt to go in straight. Next the collars of the bolts have to be properly aligned to reduce stress on the lug bolts. One will need to check each wheel design and see if it can be properly fitted with wobbly bolts to be sure.

    15 people like this.
  5. Check out this link.
    N1 Racing Equipment
    1 person likes this.
  6. royj

    royj Esperto

    PCD Adapters

    From my previous post it is clear that using Spigot rings or hub-centric rings will not help in correcting wrong PCD.
    For that you need to use PCD Adapters. A 98PCD to 100PCD adapter is a metal disk that will have 4 holes at 98PCD which can be bolted on to the existing hub and 4 holes (or lugs in some cases) at 100PCD that will receive the 100PCD alloy wheel.
    Check these pictures and links for a better understanding.

    Fiat Forum
    Performance Alloys

    If you have to use a 100PCD wheel on your 98PCD hub, this is the way to go. But this too has its share of disadvantages
    1. This adds one more component to the hub and wheel assembly and there by you have more chances of failure.
    2. The disks are approximately 20mm in thickness and so the wheel offset goes for a toss. You need to choose the wheels higher value of positive offset to avoid them sticking out of the wheel well.
    3. They are not cheap.
    Last edited: Aug 17, 2012
    4 people like this.
  7. PatchyBoy

    PatchyBoy Esperto

    I really would not recommend these PCD adapters.

    PCD adapter.png

    The black line shows the thickness and the red line shows the surface area width of the support your wheels will have with the use of these adapters. Unless these are made with high quality materials, I am not sure they can withstand the shear forces of the wheels - specifically when cornering at high speeds and hard braking.

    If one is keen on alloys, there are 3 options:

    1. Buy OEM alloys from FIAT
    2. Buy only 98 PCD Alloys locally available
    3. If you are really serious about getting good quality alloys with 98 pcd, please order online from some UK based vendor. They have a large collection with very nice designs. Please do not fret if they do not ship to India. Enroll with shopandship dot com. Team performance, OZ racing, Borbet have some great designs in 98 PCD all the way from 15" to 18". Check them out.

    IMHO, option 3 is the best, even though it is the most expensive. Hub-centric rings do not bear any major load. Hence I would recommend exploring local machine shops to get them made in aluminium and save some money there.

    2 people like this.
  8. royj

    royj Esperto

    Agree. That precisely is the reason why I mentioned there is more chance of failure.
    Also a set of good quality PCD adapters would cost almost as much as a set of Alloys - upwards of Rs.13K.
    Cheaper ones will be unreliable for reasons mentioned by PatchyBoy.
  9. sunswape

    sunswape Regolare

    Thanks a lot ROYJ for such a detailed report. It really helped me a lot in understanding the vibration issues with aftermarket alloys. Be it 98 or 100 PCD, vibs are 100%ly bound to come. So just ordered hub rings from Hub Rings / Spigot rings for wheels 4,75
    Awaiting delivery :)

    Thanks a lot once again ! :)
  10. sunswape

    sunswape Regolare

    Got the rings today. Installed too. Material is looking quite sturdy and it seems it'll survive the beating well. Shipping was quite fast. Must say
    Iam using 100PCD 15inch aftermarket alloys and like others I was also facing this heavy vibration issue from 80-120kmph speeds, it gets even worse while decelerating or braking.
    Today, got these installed and to be sure if these really work or not, got alignment and balancing done also.
    As I was in city limits so did't exceed 80kmph, so initial experience is quite good, no vibs so far, not even slightest. Now will test it on highway tomorrow.
    IMG_20120828_200646.jpg IMG_20120828_201450.jpg IMG_20120828_201455.jpg

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