How to assemble composite wheels?

[billtebbutt]

All,

What is the best "goo" to use between the rubber o-rings and the wheels halves? I've used silicone, Hylomar, and nothing at all over the years (which is my preference). The set I am working on now has a little waviness between bolts holes on the rear half (over tightening from the previous owner I suspect) - I have straightened this as best as I can, and it is pretty good. But I'm wondering if I shouldn't use a little sealer of some description as well.

Thoughts?

bt

[Steve Demeter]

Ask Dave W.

[tlracer]

My preference is to bolt together with no sealant between the joints, then run a generous bead of silicone and smooth into a fillet. Building this way allows the seal to be cut and the wheel disassembled if needed without having to pry apart and risking damaging the spun parts.

[BeerBudgetRacing]

What TL said.

The only thing I've been told to do a little differently is to not torque the wheel halves at first.
Hand tighten, apply the bead of silcone, and wait for it to cure. Then Torque the wheel halves.
Adds just a little more 'seal'.

[DaveW]

What TL said.

The only thing I've been told to do a little differently is to not torque the wheel halves at first.
Hand tighten, apply the bead of silcone, and wait for it to cure. Then Torque the wheel halves.
Adds just a little more 'seal'.

I always torque before sealing. Anything between the wheel sections before torqueing will relax over time, similar to o-ring issues, and cause the fasteners to loosen. And the sealant in the joint between the sections is too thin to resist flexing of the relatively thin rim sections, so, IMO, does no long-term good. Sealant between surfaces only works if both sides are stiff and rigid (relative to their loading) like the cast transmission sections.

Obviously, the above applies to stressed parts such as wheel rims. A location such as a non-stressed oil pan is a candidate for sealant between the parts since the likelihood of enough stress to cause the joint to leak is much lower and normal sealant stress relaxation would not cause issues.

Links to several related threads:
http://www.apexspeed.com/forums/show...t=sealing+rims
https://www.apexspeed.com/forums/sho...=wheel+sealing
https://www.apexspeed.com/forums/sho...=wheel+sealing
https://www.apexspeed.com/forums/sho...=wheel+sealing

[BeerBudgetRacing]

I always torque before sealing. Anything between the wheel sections before torqueing will relax over time, similar to o-ring issues, and cause the fasteners to loosen.

I agree. I didn't mean to suggest putting sealant between the mating surfaces. I never did.

[DaveW]

I agree. I didn't mean to suggest putting sealant between the mating surfaces. I never did.

What you said before does put a tiny amount of sealant between the halves - it's just a matter of degree - is that small amount enough to matter? Why take any chances?

It's like the old joke - a guy sees a sexy girl on the elevator and asks if she'd go to bed with him for $100. Of course she says no. So he says would you sleep with me for $1 million. She says yes. He then says how about $500? She says of course not! He says we already established your profession, now we're discussing the cost.

[EYERACE]

When the long ago assembled 3 piece wheels used for the rain tires had new rains mounted.....at many of the bolts/boltholes air leaked rather obviously with water application. So.........
Dismount tires.........check torque of all bolts (finding quite a few that took half / one full / more than one turn) and tighten accordingly.
Rubber gloves and a couple tubes of Permatex RTV to apply a lot around the inner bead of the mating surfaces.
Let sit to cure many hours
Remount tires - balance (duh)........air up a little higher than desired 'working' pressure.......wait......
Recheck with water
Smile

[jkeller]

Got this a few years ago from Mike Barnby at MB racing wheels in England
Note the the torque spec is for his wheels, check with whomever made your wheels for the correct spec.

"Torque is 18Nm (13lbft)

We assemble dry fully torque and then put the sealant on and smooth with finger to get the
thickest fillet you can."

JK

[tlracer]

Got this a few years ago from Mike Barnby at MB racing wheels in England
Note the the torque spec is for his wheels, check with whomever made your wheels for the correct spec.

"Torque is 18Nm (13lbft)

JK

Compomotive suggested torque is 17Nm, so same ballpark.

As an aside on building up aluminium wheels, avoid stainless bolts and use carbon steel ones. Whilst the torque values don't require especially high-tensile grades to be used, stainless is a real no-no with aluminium as it increases corrosion of the latter. This is due to galvanic corrosion as the two metals are quite far apart on the reactivity scale, much more so than aluminium and carbon steel:

https://bssa.org.uk/bssa_articles/bi...nic-corrosion/

[DaveW]

Got this a few years ago from Mike Barnby at MB racing wheels in England
Note the the torque spec is for his wheels, check with whomever made your wheels for the correct spec.

"Torque is 18Nm (13lbft)

We assemble dry fully torque and then put the sealant on and smooth with finger to get the
thickest fillet you can."

JK

Compomotive suggested torque is 17Nm, so same ballpark.

As an aside on building up aluminium wheels, avoid stainless bolts and use carbon steel ones. Whilst the torque values don't require especially high-tensile grades to be used, stainless is a real no-no with aluminium as it increases corrosion of the latter. This is due to galvanic corrosion as the two metals are quite far apart on the reactivity scale, much more so than aluminium and carbon steel:

https://bssa.org.uk/bssa_articles/bi...nic-corrosion/

What bolt size are these? The torque seems a bit high to me for 1/4" grade 5 cap-screws.

[Marty Nygard]

I somehow missed this thread but what class of car are we discussing? If FF or FC, the rules specifically state:
"B.21. The use of carbon fiber and/or Kevlar reinforcement, titanium, beryllium, metal matrix composites, ceramics, high strength composites and similar materials is prohibited unless the listed material is specifically permitted."

Also, wheel "material must be metal".

I have seen carbon rims on some cars but never at SCCA.

M

[problemchild]

I have seen carbon rims on some cars but never at SCCA.

M

.
Composite Definition
noun

• 1.
  a thing made up of several parts or elements.

[Mike B]

I somehow missed this thread but what class of car are we discussing? If FF or FC, the rules specifically state:
"B.21. The use of carbon fiber and/or Kevlar reinforcement, titanium, beryllium, metal matrix composites, ceramics, high strength composites and similar materials is prohibited unless the listed material is specifically permitted."

Also, wheel "material must be metal".

I have seen carbon rims on some cars but never at SCCA.

M

com·pos·ite-
adjective

1. made up of various parts or elements.

noun

1. a thing made up of several parts or elements.

I'm 100% certain that this thread is about 3 piece wheels. At no point did anybody mention carbon fiber.

[tlracer]

What bolt size are these? The torque seems a bit high to me for 1/4" grade 5 cap-screws.

Compomotive use M6 which, in 10.9 grade, has suggested maximum torque of 17ftlb.

I should perhaps have been clearer when I mentioned high-tensile bolts, as I had 12.9 grade in mind when I wrote it.

Going deeper into it, the torque values are questionable in a way as nyloc or other stiffnuts are required...and we could be here all day if we go down that particular rabbit-hole!!

[DaveW]

Compomotive use M6 which, in 10.9 grade, has suggested maximum torque of 17ftlb.

I should perhaps have been clearer when I mentioned high-tensile bolts, as I had 12.9 grade in mind when I wrote it.

Going deeper into it, the torque values are questionable in a way as nyloc or other stiffnuts are required...and we could be here all day if we go down that particular rabbit-hole!!

The bold, italic, underlined part of your post is why I use 14 lb-ft on my 1/4-20 black-oxide flanged Allen screws with grade C locknuts. The grade C locknuts are worth a few lb-ft by themselves, and I'm assembling dry to avoid contamination where the sealant goes. I calculated the required torque for this exact situation, and was surprised that it came out as high as it did. It's worked well for many years now, so they're not over-torqued.

[billtebbutt]

I realized long after my initial post that my use of the word "composite" could be interpreted incorrectly.

bt

[Marty Nygard]

Reading more of the dictionary:
composite

2 of 3

noun


: a solid material which is composed of two or more substances having different physical characteristics and in which each substance retains its identity while contributing desirable properties to the wholeespecially : a structural material made of plastic within which a fibrous material (such as silicon carbide) is embedded

[tlracer]

The bold, italic, underlined part of your post is why I use 14 lb-ft on my 1/4-20 black-oxide flanged Allen screws with grade C locknuts. The grade C locknuts are worth a few lb-ft by themselves, and I'm assembling dry to avoid contamination where the sealant goes. I calculated the required torque for this exact situation, and was surprised that it came out as high as it did. It's worked well for many years now, so they're not over-torqued.

Sounds like broadly in agreement - assemble dry with no sealant in the joints, torque to 13-14ftlb with new stiffnuts, working on opposing pairs to minimise deformation and finish off with a healthy fillet of silicone.

[DaveW]

Reading more of the dictionary:
composite

2 of 3

noun


: a solid material which is composed of two or more substances having different physical characteristics and in which each substance retains its identity while contributing desirable properties to the wholeespecially : a structural material made of plastic within which a fibrous material (such as silicon carbide) is embedded

When I first read the initial post, I thought it was an unusual use of the word "composite", but then reading more of it the context made it clear that it was not referring to a composite in the sense of CF or fiberglass.