Seeking advice on 3-pc wheels

[Paul_D]

Howdy.

At the POC PDS event at Fontana 2 weeks ago, I suddenly lost pressure in my left rear, causing a spin and the tire bead to unseat. No harm done other than a chewed up rim. The post mortem revealed that of the grade 12.9 4 bolts that hold the Graku (Holland made knockoffs of BBS, Compomotive) component wheels together had sheared.









The wheels are of unknown age, but not in bad shape other than some corrosion on the 20 screws that hold each wheel together. I want to replace all the screws, and clean, polish and reseal all the wheels.

Here's the problem and question... As far as I can tell Graku wheels are not sold any more - at least not in the U.S. And thus there are no parts available. There is a seal between the center and each of the rim halves. I assume they are the original seals.



One side of the molded seal is flat, the other has a rounded bead that fits in the groove of the wheel center. The wheel centers have a groove in them, the rim flanges are flat...




Because of the flat lips on the seals the surfaces of the wheel center and the rim halves are not bolted tight together. They are somewhat "cushioned" by the rubber seals. Since I'm probably never going to find replacement seals, I'm thinking I can use O-rings of the right diameter and cross section (315mm X 3.0) , along with some silicone on the mating surfaces, and bolt them up tight. However, I'm worried that maybe these component wheels are supposed to have some flexible material inside the joints, and not be rigidly clamped. Does anyone know how are the parts joined with BBS or other similar wheels? What would be the potential problem if I use O-rings and clamp them tight?

After bolting up the wheels, I imagine it would be a good idea to run a bead of silicone around the joints on the inside, and let it cure before mounting tires.






Thanks for any ideas or suggestions.

-Paul

'71 911T
'74 914 2.0 race car (aka "Culligan") with wheel trouble

[skinnerd]

If you can find the correct size O-ring....great.
If not, don't sweat it.
For sure the previous O-ring was compressed such that there was metal-to-metal contact once the bolts have been torqued up.

Think about it....it makes no sense that there is some cushion between the two wheels halves.
They must be ridgedly bolted together.

I would not put any silicon between the wheels halves.
Instead put a good bead of RTV silicon sealant around the joint where the wheel halves meet on the inside....just as you mentioned, and let it dry overnight before mounting up your tires.

This is how Fikse does their 3 pc wheels.
You should be good to go.
One thing you experienced is how the fasteners can corrode and fail.
Worth inspecting those guys every season I'd say.
Good luck.

[rsrfan]

If you are unable to find the correct o-ring. Grab a tube of "the Right stuff" and lay down a thick bead. It is an amazing product...

[Paul_D]

Doug,

Thanks. I know what you're saying. It makes sense that the wheels should be bolted up as solid as possible, with metal against metal. That's why I posted this question. The seal that came out had flat lips that prevented the wheel rim flanges from pulling tight up against the center. Now I'm starting to think that someone in the past had used an O-ring that was too large (in cross section) for the groove in the wheel center, and that it got squeezed out into the flange area when the bolts were snugged up. I assumed that the seal was molded in the shape it was in, but it could just be extreme distortion of a regular O-ring.

And, yes - a good lesson in the importance of replacing old hardware on key components at the first sign of corrosion. The incident could have had a much worse outcome.

-Paul

[slow&rusty]

Having refinished over 30sets of wheels including complete dismantling them, I agree with Skinnerd. Not. having the rubber O-ring is no biggie

[Paul_D]

Thanks, all. You birds are a big help as usual!

-Paul

[Jeff Alton]

We use a Dow silicone Adhesive Sealant. The best stuff out there is DOW 832.

Even if you could find the seal, I would not bother, I would just use the Dow and be done. This is the same sealant we have used for years and the same one that Fikse now uses...

Cheers

[TimT]

DOW 832

Yes use this, Fikse sent it to us, and the cat was out of the bag....

Omit the o-ring, you want nothing to interfere with the clamping of the wheel halves/center..

Clean the wheel halves well, use scotch-brite to give the surface of the wheel halves a bit of tooth, assemble and torque the wheels, apply the caulk, and let cure..

mount tires...

[jcge]

Dare I say your 12.9 fasteners failed because they were under virtually zero tension due to the very presence of the rubber between the halves. The fasteners themselves would have been subject to very ugly cyclic loading - someting they are not designed to handle. A metal to metal joint is mandatory.

John

[jax911]

I have a set of three of these Graku wheels, if you are looking for spares or parts shoot me a pm.

[Paul_D]

With such solid endorsements, Dow 832 it shall be. Ordering some this morning. Thanks again.

Jax911 - I sent you PM

-Paul

[Noah930]

I had to reseal a leaking wheel this spring. As mentioned above, the manufacturer recommended Dow Corning 832 RTV Sealant Gray. Their second choice was 3M Super Silicone Sealant 08664 Black. I couldn't find either in any of my local hardware stores, so I used some silicone made/sold by GE. It was Silicone II for aluminum and metal, gray in color. Big tube, for use in a caulking gun. That's held up fine, so far.

[wildcat077]

The reason they recommend the gray 832 silicone sealant is because it's non corrosive when in contact with aluminium parts,it's widely used in the aeronautics industry ...

Cheers !
Phil

[saddest6day66]

If you decide you want to sell of the Graku's let me know, they are pretty neat wheels!

Regards,

-Matt

[IROC]

During re-assembly, what fasteners are you going to use (specifically) and what are you going to torque them to? Both choices are critical. I am considering a "refresh" of some HRE 3-piece wheels I have never sat down and figured this part out.