BBS wheels generate thud on acceleration

[Chicane_S54]

I have a like new set of BBS wheels with matching lug/studs that I have tried installing twice (2014 F15). The OEM 19's run perfect, no noise. The new BBS 20's generate a slight thud (almost like hitting a small bump) only on acceleration. Coasting or just holding the gas doesn't generate the thud.

I have some theories but would like to know if anyone else has experienced this or knows what it might be.

[1norseman]

Did the wheels come with hub centric rings, and if so, the correct ones?

I'm guessing hub bore size is your problem.

[Tomcat_F15_STL]

Yeah, what 1norseman said.

Don't drive around on those things until you get it sorted! Digital calipers would help to get reliable answers on how the wheel interfaces with the hub. You can get calipers cheap at Harbor Freight if you do not own one.

[Chicane_S54]

Originally Posted by Tomcat_F15_STL

Yeah, what 1norseman said.

Don't drive around on those things until you get it sorted! Digital calipers would help to get reliable answers on how the wheel interfaces with the hub. You can get calipers cheap at Harbor Freight if you do not own one.

Your not going to be able to fit a digital caliper inside a wheel to measure the hub.

[1norseman]

Originally Posted by Chicane_S54

Your not going to be able to fit a digital caliper inside a wheel to measure the hub.

You can't fit calipers inside the wheel, but you can do your research on the model of the BBS wheels. Find out if they normally require hub centric rings for the F15 (most likely they do require them, like with most BBS wheels)
If you look up the model on tire rack, it might even state that hub centric rings are required.

Anyway, you have not answered if you have hub centric rings or not, so we are still guessing what you have to work with.

[Chicane_S54]

The wheels do have integrated hub-centric rings and C clips. Bought new ones directly from BBS, matched the part number, installed .....no difference.

[Tomcat_F15_STL]

Originally Posted by Chicane_S54

Your not going to be able to fit a digital caliper inside a wheel to measure the hub.

Measurements would be accomplished by using manual calipers and taking digital transfer measurements, in turn.

Something is not a good fit.

[1norseman]

Originally Posted by Chicane_S54

The wheels do have integrated hub-centric rings and C clips. Bought new ones directly from BBS, matched the part number, installed .....no difference.

If that's not it, I can only wildly guess, but not being there seeing the set up... Good luck figuring it out.

[nc.detail]

cone vs ball lugs?

[Clifton]

Originally Posted by nc.detail

cone vs ball lugs?

This is where I'm thinking the culprit is....something to do with the lug bolt's size, shape, or some variation not mating well with the BBS.

[nc.detail]

Originally Posted by Clifton

This is where I'm thinking the culprit is....something to do with the lug bolt's size, shape, or some variation not mating well with the BBS.

At least that's an easy confirmation. I had BBS CI'R's on my audi for a bit and they always vibrated. I spent too much time swapping tires, hub rings, spacers, etc before just replacing w/ bc forged as they're custom fit.

Best of luck

[Qsilver7]

Can we deal with actual specs instead of guessing?

• What is the center bore of the BBS wheels?
• What size hub centric rings are you using?
• What type wheel bolts are you using (flat/ball/conical)?
• What type of bolt hole does the wheels have (float/ball/conical)?

Your F15 has a 74.1mm wheel hub…if your BBS wheels have a center bore that is larger than that…your hubcentric rings needs to reduce the center bore to 74.1mm.

You can see the types of wheel bolts/lug bolts that needs to match the wheel (flat/ball/conical) in the images below:

[Chicane_S54]

Took it to my local Goodyear dealer to check them out (diagnostician with over 20 years experience). Wheels and Tires checked out fine. He hypothesized that after the switch from 19" OEM's to 20" BBS that it is a drive train issue not a wheel/tire issue. That the computer for the drive train still thinks it is running 19's when I am actually running 20" and the diff is not accommodating which makes total sense.

Have you guys had to go into the dealer or use ISTA yourself to make the adjustment when you have upgraded your tire size?

Also: to the post about lug nuts I am using the BBS lug nuts that came with the install package with the BBS wheels.

[///d]

Originally Posted by Chicane_S54

Took it to my local Goodyear dealer to check them out (diagnostician with over 20 years experience). Wheels and Tires checked out fine. He hypothesized that after the switch from 19" OEM's to 20" BBS that it is a drive train issue not a wheel/tire issue. That the computer for the drive train still thinks it is running 19's when I am actually running 20" and the diff is not accommodating which makes total sense.

Have you guys had to go into the dealer or use ISTA yourself to make the adjustment when you have upgraded your tire size?

Also: to the post about lug nuts I am using the BBS lug nuts that came with the install package with the BBS wheels.

What? The car does not care if you have 19s or 20s. Now, if you have incorrect tire sizes, then it will care. The overall diameter of the fronts vs rears need to be within 1% of each other. If you get outside that 1% then you can run into issues with the traction and stability system thinking a wheel is slipping because of differences in rotating speeds.

What are you running for wheel widths and tire sizes? I suspect you're right at the edge of the traction system getting upset. While cruising its happy, but acceleration its right on the edge of thinking you have wheel slip.

[Tomcat_F15_STL]

Originally Posted by Qsilver7

Can we deal with actual specs instead of guessing?

Can't force the horse to drink.

They'll fight you tooth-n-nail every time! lol.

[Chicane_S54]

Originally Posted by ///d

What? The car does not care if you have 19s or 20s. Now, if you have incorrect tire sizes, then it will care. The overall diameter of the fronts vs rears need to be within 1% of each other. If you get outside that 1% then you can run into issues with the traction and stability system thinking a wheel is slipping because of differences in rotating speeds.

What are you running for wheel widths and tire sizes? I suspect you're right at the edge of the traction system getting upset. While cruising its happy, but acceleration its right on the edge of thinking you have wheel slip.

BBS SX's with 275/40R20 Continentals

OEMS 19's 255/50R19 Continentals

[sukhk527]

When I went from 19s to 20s, the tcase was unhappy because of the wear on the tires. Simple recalibration of the tcase should fix your problem.

Your tire sizes are within spec so don't see any issues there.

[Chicane_S54]

Originally Posted by sukhk527

When I went from 19s to 20s, the tcase was unhappy because of the wear on the tires. Simple recalibration of the tcase should fix your problem.

Your tire sizes are within spec so don't see any issues there.

How do you re-calibrate the transfer case? That's basically what i am asking.

[Chicane_S54]

Originally Posted by ///d

What? The car does not care if you have 19s or 20s.

The car clearly cares that I have gone from 19 to 20s

[sukhk527]

Originally Posted by Chicane_S54

How do you re-calibrate the transfer case? That's basically what i am asking.

It'll take ISTA on a pc with an ENET cable, or a Foxwell scan tool for BMW also has the ability to do it.

[crystalworks]

How are there no pictures/specs of everything posted yet? Any hardware, wheels, tires, etc could be influencing this.

We went from 19's to 20's (with used tires) and required no TC calibration. That is until the rears wore down for about 6 months and then we started getting a "tug" or "thud" as you describe. The TC wants <1% difference in rolling diameter from front to back. New tires installed and no more problems from the TC.

As a matter of good maintenance however you could service your TC fluid (we did later) and reset the calibrations using a Foxwell NT530 or ISTA. The fluid that came out @ 85000 miles was not burnt, but it wasn't great either.

[Chicane_S54]

Originally Posted by sukhk527

It'll take ISTA on a pc with an ENET cable, or a Foxwell scan tool for BMW also has the ability to do it.

Right, I need the instructions for ISTA.