Cavity Wax

[Lennym1984]

I know that established logic tells us that Boxsters and Caymans never rust but the reality is that they do and will. Spot welds are a good example of a vulnerable area as the galvanizing will have been removed/burnt off during manufacturing processes. Now that I have got that out of the way...

 

Given that my car is currently in pretty good nick, I was thinking about trying to keep it that way by cavity waxing the sills and rear quarters. I can access these through the plugs in the sill (a few of mine had dry rotted so whilst replacing I had a little look) and/or the side vents. I routinely wax the front arches/strut towers but I'm wondering whether waxing the sills makes sense. At present it's all pretty tidy up there so they have obviously survived the last 14 years unscathed.

 

What's the general consensus? Leave them be or wax them up?

 

My Cayman doesn't owe me much but given that prevention is cheap whereas cure is expensive, it kind of feels like a job worth considering.

 

[Hunter]

I'm struggling to picture what you mean by sills and rear quarters—I imagine you don't mean the panel outers. Perhaps you could include a picture?

 

Generally speaking, wax will be worn away by a consistent spray of road debris, so I wouldn't bother in wheel wells or under the car unless it is something you can reapply regularly. Furthermore I would avoid waxing any surface that gets truly hot (e.g. anything on or near the exhaust system). A thicker all-purpose grease might be a better solution for unseen vulnerable areas such as the spot welds you mention, since it provides a thicker layer of protection that may come away less quickly.

 

Another option is an actual undercoat (or any paint coat, I suppose). AMMO NYC did an interesting video on undercoating, but admittedly this isn't something I've ever considered.

[Lennym1984]

Cavity wax typically goes inside panels - so in my example, inside the sill (the panel below the doors) and behind the rear quarter (the panel behind the door and above the rear wheels). It is typically used to protect metal from rust as it creeps and covers all the internal surfaces which you won't reach with paint. Many manufacturers will do this in the factory (VW as an example).

 

The wax used in wheel arches is slightly different (and is not like the wax you would use for painted bodywork), it is underbody wax (similar to Dynax UC) that covers the underbody to protect from salt and moisture. It dries quite hard and if you get it on bodywork it is a pain to remove.

 

My question is really whether it is worth cavity waxing these inner panels

[Aaron]

There is no such thing as too much rustproofing.  That is all I have to add to this thread.

 

Go as nuts as you feel the need to.  Whether you were over zealous of not, the result is the same: it doesn't rust.

[Hunter]

7 hours ago, Lennym1984 said:

Cavity wax typically goes inside panels - so in my example, inside the sill (the panel below the doors) and behind the rear quarter (the panel behind the door and above the rear wheels). It is typically used to protect metal from rust as it creeps and covers all the internal surfaces which you won't reach with paint. Many manufacturers will do this in the factory (VW as an example).

 

The wax used in wheel arches is slightly different (and is not like the wax you would use for painted bodywork), it is underbody wax (similar to Dynax UC) that covers the underbody to protect from salt and moisture. It dries quite hard and if you get it on bodywork it is a pain to remove.

 

My question is really whether it is worth cavity waxing these inner panels

 

Ah, funny I've never come across the stuff. I'll agree with Aaron, then; go mad if it makes no difference to you!

[GlosRich]

Certainly when I had the underfloor panels off my 2009 Gen2, it was rust free apart from the jacking points, they were all very rusty, surface rust only.

 

The front ones especially are in the line of fire from the front wheels, so all the underseal and paint had been blasted off.

 

I rubbed them down, treated, primed and hammerite'd.

 

I could see if left, these will rot out the floor of many a Cayman.

 

Generally not overly impressed with the quality of the Finnish paint. Seems very thin, also thin in the strut towers.

 

But TBF it had lasted 11 years without serious corrosion.

[Lennym1984]

11 hours ago, GlosRich said:

Certainly when I had the underfloor panels off my 2009 Gen2, it was rust free apart from the jacking points, they were all very rusty, surface rust only.

 

The front ones especially are in the line of fire from the front wheels, so all the underseal and paint had been blasted off.

 

I rubbed them down, treated, primed and hammerite'd.

 

I could see if left, these will rot out the floor of many a Cayman.

 

Generally not overly impressed with the quality of the Finnish paint. Seems very thin, also thin in the strut towers.

 

But TBF it had lasted 11 years without serious corrosion.

 

I had the front wheel arch liners off this weekend and as you say it was surprisingly rust free behind there. I have epoxy masticed the strut towers but even they were fine (the only rust I found was on the spot welds and that was more like a patina than actual rust).

 

As such, I think I'll leave the cavity wax for now and just get all the covers off annually to inspect thing.

 

Edited February 22, 2021 by Lennym1984

[zcacogp]

On 19/02/2021 at 17:37, Aaron said:

There is no such thing as too much rustproofing.  That is all I have to add to this thread.

 

Go as nuts as you feel the need to.  Whether you were over zealous of not, the result is the same: it doesn't rust.

Wot Aaron Sed. And 987's of all varieties certainly do rust, alarmingly so. Whenever I've had the covers off my 987.1 Cayman I have been disappointed by how much rust there is there. 

 

And before you start asking about brands, I'd STRONGLY recommend Bilt Hamber stuff. 

 

https://www.bilthamber.com/corrosion-protection-and-rust-treatments

Edited February 25, 2021 by zcacogp

[Lennym1984]

14 hours ago, zcacogp said:

Wot Aaron Sed. And 987's of all varieties certainly do rust, alarmingly so. Whenever I've had the covers off my 987.1 Cayman I have been disappointed by how much rust there is there. 

 

And before you start asking about brands, I'd STRONGLY recommend Bilt Hamber stuff. 

 

https://www.bilthamber.com/corrosion-protection-and-rust-treatments

Out of interest, where are you finding rust? I've had all the covers off at one stage or another and have never found anything worse than a lightly rusted spot weld. Mine is no garage queen so I assume it would be at least as bad as any other

[zcacogp]

When I removed the front bumper there was a LOT of surface rust around generally. Also, taking the covers off underneath has revealed some bits which are browner than I'd like. Noticable were the long bolt-on braces that attach to the front subframe and go along the length of the car. Those were really quite rusty; bad enough to need rubbing down and a good coating of Dynax S50. 

[Lennym1984]

2 hours ago, zcacogp said:

When I removed the front bumper there was a LOT of surface rust around generally. Also, taking the covers off underneath has revealed some bits which are browner than I'd like. Noticable were the long bolt-on braces that attach to the front subframe and go along the length of the car. Those were really quite rusty; bad enough to need rubbing down and a good coating of Dynax S50. 

 

Ah I don't count "bolt on" fittings in my assessment of rustiness. If I did then I would agree with your assessment - a lot of the brackets and braces do indeed look a bit manky. I tend to either douse stuff in Comma Waxseal or - if I can get to it to rub it down - Epoxy Mastic (I love that stuff and it dries rock hard)