Prepping Centers for 3 piece conversion, question about milling the shelf on centers

[bmw m3 s50]

Prepping Centers for 3 piece conversion, question about milling the shelf on centers

Question most wheel centers have a shelf where the lip and barrels flanges sit on then bolts hold them together.

The centers I am using are from a 2 -piece wheel. It is a BMW style 42 or BBS rs740 centers. I believe the centers have a 5mm shelf at the top where the barrel was placed on then bolted together. I was told that the flanges on barrels and lips are about 5mm thick. The centers are top mounted so lips and barrels would be mounted behind the centers. So I assume the lip flange will rest on the shelf but the barrel will not be able to rest on the shelf since the shelf is not deep enough.

Is there any issues? I assume both lip and barrel flanges have to sit on the shelf to handle the forces and loads on the wheel? How would I mount the Lips and Barrel flanges?

[zoo]

It is best if the center is in contact with all of the surface on both the inner and outer flange, or at least all of the one and some of the other.
You should not rely on solely the bolts to support the center.

That is in theory. In practice - not so much.

How it should look:

CCW


HRE


How it sometimes looks:

Luxury wheel brand 1
(note the absence of load spreading hardware)





Luxury wheel brand 2. Gap all around.






Example of a properly sized register:


If you cut a wider register you will lose some of the bolt flange thickness. In my experience you should not go below 7mm. 12-13mm would be ideal.

[bmw m3 s50]

It is best if the center is in contact with all of the surface on both the inner and outer flange, or at least all of the one and some of the other.
You should not rely on solely the bolts to support the center.

That is in theory. In practice - not so much.

How it should look:

CCW


HRE


How it sometimes looks:

Luxury wheel brand 1
(note the absence of load spreading hardware)





Luxury wheel brand 2. Gap all around.






Example of a properly sized register:


If you cut a wider register you will lose some of the bolt flange thickness. In my experience you should not go below 7mm. 12-13mm would be ideal.

ZOO thank you for responding

I am not quite sure I understand in regards to the cutting a wider register?

My project is that I am converting a set of BBS rs-gt wheels to 3 -piece to get them wider. The BBS RS-GT only has a 3.5mm shelf on the the face to support the lips and the barrels.

My understanding is that this is not enough. I will have to weld the lips and barrels together since it is only a 16 hole face and 3.5mm shelf.

I want to build the safest wheel possible as the wheels are going on a high hp track car. I want the wheels to be able to handle all the stress and loads on it.

[zoo]

Then yes, definetely weld the lip/barrel together.
The RSGT does not have any extra meat on it to cut a wider register.
Wre you going from 18" to 19"? Unrelated question.

[OrangeBlue]

A big part of this is how the face is mounted, front, sandwish or rear...

On the RS GT the face is front-mounted.., if you plan on welding the lip and barrel together
you shoudn't have any issues. Even with a low register and only 16 bolts.
If there is enough material, take some of, and listen to ZOO.

A lot of multi piece wheels for high stress applications are welded, making them either one or 2pc.

[bmw m3 s50]

Then yes, definetely weld the lip/barrel together.
The RSGT does not have any extra meat on it to cut a wider register.
Wre you going from 18" to 19"? Unrelated question.

Yes the RS-GT is forged lightweight wheel and not much of any room to do anything. So anything or mill anything on the face.

When welding the lip and barrel should it be welded where the lip and barrel meet be welded at the top and the bottom, then sanded and cleaned up?

I am staying at 18" with a reverse lip setup or not I may build a 19" step in the future.

I will be building 18x12.5 rear and 18x10 in the front.

If I weld the lip and barrel, do you see any safety or strength concerns or issues?

[bmw m3 s50]

A big part of this is how the face is mounted, front, sandwish or rear...

On the RS GT the face is front-mounted.., if you plan on welding the lip and barrel together
you shoudn't have any issues. Even with a low register and only 16 bolts.
If there is enough material, take some of, and listen to ZOO.

A lot of multi piece wheels for high stress applications are welded, making them either one or 2pc.

Take material off from where?

Do you see any safety or strength concerns or issues with the proposed setup?

Definitely taking as much feedback as I can from everyone to build the strongest wheels.

[zoo]

Weld the lips/barrels where the sealant would be normally. Then run sealant over the weld to prevent any air leaks.
Note, the welding should be done once everything is machined and ready for assembly. Bolt the face in, get a few tack welds in, remove the face and finish the weld.

[bmw m3 s50]

Weld the lips/barrels where the sealant would be normally. Then run sealant over the weld to prevent any air leaks.
Note, the welding should be done once everything is machined and ready for assembly. Bolt the face in, get a few tack welds in, remove the face and finish the weld.

Any type of hardware that you can recommend that is strong enough to hold the wheel with the forces and loads ?

Also would these wheels ( when built ) be safe to run on the track on a road course?

[zoo]

Any type of hardware that you can recommend that is strong enough to hold the wheel with the forces and loads ?

Also would these wheels ( when built ) be safe to run on the track on a road course?

Honestly, the bolts virtually never fail unless improperly torqued or fatigued/stretched.

Not sure if the holes are large enough for 8mm threads. ARP does not make a 7mm, not much is available in that size other than regular plated 7mm.
However, if 8mm fits or barely fits, consider using 5/16-24 grade 8. Can be safely torqued to 25 - 27ft/lbs.

Provided that everything is machined true and properly assembled, the wheels will be fine. The RSGT face is die forged, and should withstand the abuse.

I sent you a PM.

[The_Sauce]

RSGTs need m7 bolt head size or smaller head M8 cap screws. I always convert them to 31 bolt(15 hidden bolts and the valve stem) when I build them to 3 piece. They mating of the lip and barrel without a full register is fine structurally as the lip or barrel will bend before the hardware fails and shifts if everything is properly torqued.

Last set of RSGT's I did for an e90 M3.





To give you an idea of what the backside looks like. These were some 32 bolt converted RS2's.

[Eurofreak90]

Hey can i get some more info on this build from you

RSGTs need m7 bolt head size or smaller head M8 cap screws. I always convert them to 31 bolt(15 hidden bolts and the valve stem) when I build them to 3 piece. They mating of the lip and barrel without a full register is fine structurally as the lip or barrel will bend before the hardware fails and shifts if everything is properly torqued.

Last set of RSGT's I did for an e90 M3.





To give you an idea of what the backside looks like. These were some 32 bolt converted RS2's.

Hey can i get some more info on this build from you