Wheel Leaking

[Jim Garry]

OK, so I'll admit up front that I really showed my air headed thinking when I put these old Mad'In wheels together. Sheesh, how dumb can I get?

They are 25 or more years old but in very good condition. I emailed the manufacturer and was told to throw away the rubber/aluminum seal that was under the bolt head area all around the rim.

I dutifully did so but then like the idiot I am I failed to seal the area with something else. Of course I added Dow Sil 832 to the opposite side of the wheel at the rim halves. So obviously the wheels leak about the same as if they weren't assembled.

I'm about to disassemble the wheels and start again but of course the thought of cleaning up the sealant on four wheels makes me wonder if there's another way to seal these wheels.

So here's the shortcut kid idea ... can the DOW Sil 832 be applied to the edges where the wheel center and rim half come together? It's only holding back 14 to 18 psi. Or is this just dumb?

[R. Pare]

It will blow right out - sealant on tires needs to be pushed down INTO a dead end so that the strength of the bond ans the strength of the sealant itself does not matter. If sealant is at a place like where you pointed out, it will just get blown out, and almost immediately.

Best place to put the sealant is at the joints where the 2 spun rims meet the center section, INSIDE the tire area.

[DaveW]

What do you mean "opposite side" ? As Richard said you seal them on the tire side at both rim-center joints. The seal shown below looks massive, but it is thin and just sealing the 2 grooves. It was evenly spread with 1 finger in a rubber glove.

[EYERACE]

Last weekend at Sebring and non-hurricane Alex blowing through..........and old rains on 3 piece Compomotives for the rains....one wheel already leaked but would hold air long enough for a session.......suddenly now two of 'em leaked badly at the bolts after mounting new tires. So..........unmount. Go tighten all bolts.....found a few that could be tightened over a full revolution, some near a half a turn. Hmmmmmmm..............never thought before to check/tighten the wheel bolts as part of a nut&bolt of the car itself. Optimisticly remount tires.....and now even more bolts leak.
Conclusion #1 .....never tighten wheel bolts on wheels that don't leak.
So unmount tires and attack wheels with copious amounts of Permatex RTV (black and/or red....when the other tube ran out) in a thick slopping amount all around the inner seam covering from one half wheel to the other half wheel. Let set up for about three hours so it won't be as likely to gum up the Hoosier machines as the tires get mounted again. Mount 'em....again. Run pressures up to about 22 and let 'em sit for a half hour......pressure still right around 22!! Decide to take 'em that way and think to make sure pressures set to about 19 right before I'd go out as nearly the last item before going out on a wet track.
And it worked.

[Jim Garry]

Ok, thanks Richard and Dave.

From Dave's photo I see I didn't seal wide enough there. Is it OK to add new sealant over the existing bead?

[R. Pare]

You only really need the sealant to be right at the seam. As to why Dave put it across the whole area, I'd guess that was easier to do than to spend a lot of time getting fussy making it look pretty.

[DaveW]

Ok, thanks Richard and Dave.

From Dave's photo I see I didn't seal wide enough there. Is it OK to add new sealant over the existing bead?

You just need the sealant at the 2 grooves formed by the 2 rims and center section. Part of the reason it looks wide is that a larger bead is able to stay sealed even if there is a little lateral stretching of the bead. The sealant is ~1/8" thick spanning each joint - it's very thin in the middle of the center section. A very small bead will not stand much if any widening of the sealed gap. Strain is deflection divided by length, and the larger bead has more length to accommodate flexing at the joint. Some flexing is unavoidable no matter how tight the bolts are, so the wider bead is less likely to fail and leak.

That is why O-rings between the sections always develop leaks when the o-rings take a set - there is not enough springiness left to accommodate the flexing. And sealant between the flat surfaces of the sections will leak for the same reason, plus sealant between the sections will creep and the bolts will loosen.

I never seal over the existing bead (unless it's an emergency) because adhesion of cured 832 to fresh 832 is not as good as to the bare aluminum, and curing a whole new bead takes no longer than curing a small section. In an emergency, you could try "Seal-All" for a pinhole leak, and fix it right later when you have time.

[EYERACE]

I know a guy who needed the last race weekend of the year to renew his License....and the slick developed a leak. He ended up squirting a can of Fix-A-Flat into the tire/wheel and went out.....and finished. I would not want to be the person who next had to change out the tire (and clean up the wheel). Desperate men do desperate things

[BeerBudgetRacing]

Best place to put the sealant is at the joints where the 2 spun rims meet the center section, INSIDE the tire area.

I could be wrong, but in Jim's original pic and Dave W's picture it looks to me like the halves are attached to the outside of the wheel center.

I had Jongbloeds and it was my understanding you mated the halves and then mounted the center to those halves.
Maybe other manufacturers are different but mating the 2 halves gives you 1 bead to seal. Mating each half to the outside of the center gives you 2.

That said, the method was simple. Assemble with 1/8 of play, bead in 832 and wait to set. Then torque the wheel bolts.
This squeezes the bead in between,

[DaveW]

I could be wrong, but in Jim's original pic and Dave W's picture it looks to me like the halves are attached to the outside of the wheel center.

I had Jongbloeds and it was my understanding you mated the halves and then mounted the center to those halves.
Maybe other manufacturers are different but mating the 2 halves gives you 1 bead to seal. Mating each half to the outside of the center gives you 2.

That said, the method was simple. Assemble with 1/8 of play, bead in 832 and wait to set. Then torque the wheel bolts.
This squeezes the bead in between,

On my Jongbloeds, the rims are attached to the opposite sides of the center. And, as I said, there, IMO, should be NO sealant between the mating surfaces - having sealant there can result in sealant creep and loosening bolts, neither of which I want.

Also, having the rims attach on opposite sides results in a slight weight savings - there is 1/2" less rim width than you get putting them both on the same side.

[Lee Johnson]

On my Jongbloeds, the rims are attached to the opposite sides of the center. And, as I said, there, IMO, should be NO sealant between the mating surfaces - having sealant there can result in sealant creep and loosening bolts, neither of which I want.

Also, having the rims attach on opposite sides results in a slight weight savings - there is 1/2" less rim width than you get putting them both on the same side.

Dave -- you make sound points about weight savings and sealant creep. To say nothing about the challenges in separating silicone bonded wheel sections (don't ask me how I know!).

I have seen some three-piece wheels (don't recall if Jongbloeds do this) that have o-ring grooves on each side of the cast center section. On this style, a silicone bead post-assembly @ the tire-side joints between the wheel pieces is useful thing to do for redundancy.

Lee

[DaveW]

...I have seen some three-piece wheels (don't recall if Jongbloeds do this) that have o-ring grooves on each side of the cast center section. On this style, a silicone bead post-assembly @ the tire-side joints between the wheel pieces is useful thing to do for redundancy.

Lee

Back in the day, I had wheels with o-rings (Speedline?). They always leaked within a year or so due to o-ring stress relaxation (set). Jongbloeds don't have an o-ring setup, so on those sealant is required.

[kea]

I repaired some modular wheels in the past by putting Hylomar on the halves where they joint the center. Let dry before assembly and re-torque hours later after the polyester urethane squeezes into the low tension spot.I still used the O'rings the wheels came with.

[J Leonard]

There may have only been clear and black silicone when this was written in about 1984.

[GAC]

Why not get new proper replacement seals and be done with it?


Sent from my iPhone using Tapatalk

[Jim Garry]

Why not get new proper replacement seals and be done with it?

Sent from my iPhone using Tapatalk

I asked the manufacturer last year and was told the wheels are too old and they no longer make the seals.

[Jim Garry]

OK, I sifted through my old email and here's what the Mad 'In contact told me last year:


o 1/ Put your wheels completely apart and get rid of these o'rings and metal washers. Don't use them anymore.
o 2/ Assemble your wheels without putting any paste between the pieces.
o 3/ Torque the bolts to 18 Nm (13 ft-lb or 159 in-lb)
o 4/ at the very end, you have assembled you wheels complete, just put some paste all around where the 2 rims sections come together.
o Fill with paste then flatten it with your finger and let it dry one day.


o 1/ Put your wheels completely apart and get rid of these o'rings and metal washers. Don't use them anymore.
o 2/ Assemble your wheels without putting any paste between the pieces.
o 3/ Torque the bolts to 18 Nm (13 ft-lb or 159 in-lb)
o 4/ at the very end, you have assembled you wheels complete, just put some paste all around where the 2 rims sections come together.
o Fill with paste then flatten it with your finger and let it dry one day.

[DaveW]

Why not get new proper replacement seals and be done with it?


Sent from my iPhone using Tapatalk

I asked the manufacturer last year and was told the wheels are too old and they no longer make the seals.

On top of which, what I said before - o-rings have a history in this application of taking too much of a set in a year or 2 and developing leaks.