My wheel weights keep melting off!

[Brad B]

Here is an interesting challenge for you. I drive my Cayman S at track events throughout the year. I run upgraded brake fluid (ATE Super Blue) and brake pads (Pagid Yellow) to aid in stopping. I also run titanium shims between the calipers and the brake pads to help stop heat transfer from the pads to the brake fluid. This reduces the chances of fluid boiling and brake fade. In addition, I run upgraded Porsche GT3 brake ducts for better cooling. My rotors are in good condition. All good things.

My problem is that so much heat gets into the wheel itself that it melts the adhesive on my wheel weights. Sometimes they just slide and move, more often they just fly off and disappear, or cause damage somewhere in flight.



For the last couple events I purchased metal foil tape and covered the wheel weights. This has helped, but only because there is just more adhesive that has to melt. You can see by the one picture how one has migrated from the heat and inertia.

Any ideas on how I can get these things to stick? There isn't a practical solution, besides driving style changes, to furher reduce the heat issues.

 

[C. Charles Hahn]

The question is, is the heat transfer due to proximity to the braking system, or is the transfer happening through conduction between the mating surface of the rotor hat and the wheel flange?



If it's due to contact conduction then the solution would be to find something to place between the wheel and rotor that dissipates the heat, kind of like the shims you have between the brake pads and calipers. If it's a proximity issue, maybe there's an additional cooling vent mod you can do? That, or pick up some wheels specifically for use at the track which can accept clamp-on weights....

 

[wascallyrabbit]

is adding additional cooling vents an option? air scoop in the front bumper ducted to the brake/wheel area.

 

[Brad B]

The question is, is the heat transfer due to proximity to the braking system, or is the transfer happening through conduction between the mating surface of the rotor hat and the wheel flange?

Good question. I would be inclined to think that conduction is the main issue. It's kind of a chicken and egg thing in reality, but ultimately I think the heating of the wheel must be the culprit.



I haven't see or heard of anything to insulate the wheel from the rotor hat. Never thought of that but will look into it.



As far as additional cooling I need to look at several areas that promote heat build up. My rotors are in above average condition regarding wear. In other words they have reduced thickness from new but are still servicable. Brand new rotors would be a bit thicker and thus have more heat sync capability. Same thing for my pads themselves. They are under 1/2 thickness from new so I think more heat is getting through those.



I really need to see if I can route some additional cooling ducts to the brakes from the nose of the car. Trouble is there is not much space and no undercarriage clearance to deal with. Not sure I can pull this one off.



The wheels I use are 18" x 8" and 18"x10" oem Cayman S wheels which are fully roadtested and approved as being the ideal size, weight and strength for track/competition events. Very common for this. (I use 19' wheels on the street) Not sure you can clamp weights on them or not.



I'm just frustrated because even though the calipers and rotors are stock, they should suffice for what I do. At least they work for most everyone else.

 

[Accumulator]

Brad B.- Huh, interesting dilemma :think: I wonder if some heat-indicator paint might tell you anything (a dab on the wheel, perhaps).



Isn't gold a good heat insulator? Heh heh, a thin gold foil between the hat and the wheel hub if it *is* conduction...just thinking out loud.

 

[C. Charles Hahn]

Brad B.- Huh, interesting dilemma :think: I wonder if some heat-indicator paint might tell you anything (a dab on the wheel, perhaps).



Isn't gold a good heat insulator? Heh heh, a thin gold foil between the hat and the wheel hub if it *is* conduction...just thinking out loud.

That's kinda what I was thinking too, either a thin shim, or maybe even just a thin film of anti-seize might do wonders to cut down the heat transfer....

At least they work for most everyone else.

Yes, but as I think most of us know by now, you are most decidedly not "most everyone else." :der:



:nana:

 

[TedFred]

1. Don't try to insulate the wheel from the rotor. The wheel is a large heat sink and is needed for proper brake function and cooling. PLEASE DO NOT INSULATE THE WHEEL CONNECTION.



2. Encapsulate the weight in RTV. RTV (silicone) can handle 500 degrees and will not melt under you circumstances. I have done this to vehicles subhect to high braking loads and never had one fall off after that.



By the way I have designed numerous brake systems for industrial equipment as well as vehicles.

 

[Brad B]

. Encapsulate the weight in RTV. RTV (silicone) can handle 500 degrees and will not melt under you circumstances.

Let me get this straight, do you mean to add RTV around and over the stick-on weight -or- use the RTV as the actual adhesive for the weight as well as all around it? Thanks for the input.

 

[Brad B]

Yes, but as I think most of us know by now, you are most decidedly not "most everyone else." :der:

I resemble that remark! Yuk yuk yuk!

 

[TedFred]

Let me get this straight, do you mean to add RTV around and over the stick-on weight -or- use the RTV as the actual adhesive for the weight as well as all around it? Thanks for the input.

Around and over the weight

 

[Accumulator]

TedFred- That makes sense about not isolating.



Brad B.- It'd be interesting see if the RTV helps. Not heavy enough to affect the balance I presume :think:



Actually, I find this whole thing interesting as my wheels never got all that hot during track days, sure not hot enough to mess with the wheel weights!

 

[Brad B]

I've been doing this a long time and this is the first year this had happened. It's only at Autobahn Country Club Track, a 3.5 mile 20+ turn track where each lap has multiple sections of 100mph sections followed by turns as slow as 45-50. So brakes get worked pretty hard. We'll see what happens next time out.

 

[Accumulator]

Brad B.- That sounds like a great course, especially for that car.

 

[aviography]

I'd speak to local professional racers or shops known to prep race cars for their advice.



As well, have you cosidered a separate set of lapping day rims/tires that you don't mind using the traditional clip-on weights?

 

[Brad B]

These are track only wheels, but I haven't tried clamp on weights yet because of the looks. But now function is more important so will look into it.



Many other pros use stick on weights with tape so I am not sure what gives. Could be the place I have my wheels balanced uses cheap adhesive weights.

 

[Accumulator]

Brad B.- Wouldn't surprise me if you'd already thought of this, so I hope you don't think I'm insulting your intelligence or anything, but if you do go with the clip/crimp-on weights, the ones that re commonly used on Benzes are very gentle on the wheels and pretty easy to clean around. Much better than the ones that really bite into the wheel.



I do wonder about the current adhesive being an unusual issue; my Audi dealer had a batch of adhesive weights that started coming loose for me, actually lost one little one, but it was just some anomaly; never happened before or since.

 

[SpoolinNoMore]

I had a weight fall off my MDX wheel from the heat of being outside in the sun this past summer. It may be a combination of wheel cleaners reacting with the wheel weight adhesives, or my weights were put on with bad adhesive. :shrug:

 

[Brad B]

I had a weight fall off my MDX wheel from the heat of being outside in the sun this past summer. It may be a combination of wheel cleaners reacting with the wheel weight adhesives, or my weights were put on with bad adhesive. :shrug:

Good thinking about the wheel cleaner affecting the adhesive. But in this case I don't think so since the wheels are for track only and don't get cleaned very much. Good to keep in mind, though.

 

[Darkstar752]

Do you know what adhesive was used? I.E. did you apply the adhesive yourself or take it to a shop? I'd imagine some shops would use cheaper adhesive since most people don't track their car.



At any rate, let us know if you find a solution!

 

[Brad B]

Do you know what adhesive was used? I.E. did you apply the adhesive yourself or take it to a shop? I'd imagine some shops would use cheaper adhesive since most people don't track their car.

No, I don't. The weights were applied at the shop. I'll let you know results after the next event.