# BMW Genuine underseal



## lion_yo (May 10, 2009)

Is the above underseal part number 83420428348 used for places open to exposed elements or for box sections and 'hidden corners'?

Want to use it on the underside of my car!

Many thanks!


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## -Kev- (Oct 30, 2007)

the whole underneath i'd of thought - nowt 'genuine BMW' about it though lol
probably same as Waxoyl...


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## Lars Z (Jul 20, 2011)

In Danish it says "hulrumskonservering" that would to me mean box sections and 'hidden corners'

I would not use it underneath the car.


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## Goodfella36 (Jul 21, 2009)

i would take a look at Bilt Hamber Dynax-UC


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## lion_yo (May 10, 2009)

I didn't want to use waxoil because it stays damp attracting dirt thought the BMW underseal is polyurethane and dries rock solid but if it is the same as waxoil then its not what I'm after.

I am after a underseal that dries rock solid and protects the underneath! Which one would be upto the job

Edit -

Just found out that the one above is a cavity wax Bmw also do a urethane type underseal

Here is a link http://www.estore-central.com/bmw-accesories-and-lifestyle-catalog/underfloor-protection/


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## lion_yo (May 10, 2009)

No one to assist?

Is Bilt hamber UB good for the underside how does it dry?? i.e. rock solid or stay damp?


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## lowejackson (Feb 23, 2006)

Seems to be lots of positive threads about Dynax UB yet, I have not used it but have been very happy with their other products. I would give Bilt Hamber a call or maybe ask in the Manufactures Section


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## steveo3002 (Jan 30, 2006)

says cavitys on the tin


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## lion_yo (May 10, 2009)

Ordered Bilt hamber dynax UB - 5 litre jerry can format so I can put it on the compressor and apply it.

And Dynax S50 to inject into the chassis and also is it good to use on the arches or would it be too messy and oil up when it rains?

Also chucked in Surfex HD to degrease the underneath of the car and then go over with G101, snow foam to make sure the underneath is throughly cleaned before Bilt hamber UB is applied.


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## OldskoolRS (May 5, 2011)

I took off my sill cover and wheel arch liners today so I can clean behind them and then treat with BH UC. I only bought spray cans (not a huge area) but I'll post back photos tomorrow if the weather is kind to me. My Z3 is metallic blue, so I didn't want anything that would plaster the blue with thick black 'underseal.'


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## lion_yo (May 10, 2009)

OldskoolRS said:


> I took off my sill cover and wheel arch liners today so I can clean behind them and then treat with BH UC. I only bought spray cans (not a huge area) but I'll post back photos tomorrow if the weather is kind to me. My Z3 is metallic blue, so I didn't want anything that would plaster the blue with thick black 'underseal.'


Thanks mate looking forward to that :thumb:


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## OldskoolRS (May 5, 2011)

Hear you go:










I just cleaned the arches with Surfex HD and used some tar remover before lightly spraying the blue painted parts, which you can see look clear and almost as if they have been clearcoated. The UC is still slightly soft/sticky, so I'm waiting to see if it dries out fully as otherwise it will cause dust and grit to stick to it which I don't want. If this happens, it wasn't hard to remove the UC using some panel wipe I have (white spirit or probably Tardis would do equally well).


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## lion_yo (May 10, 2009)

Thanks for sharing the pictures buddy.

My dynax UB arrived I am going to apply it on the underside of my car.

Hope it dries dry as it is supposed to as I don't want the stuff to stay damp so it collects dust which can cause rust.

I think it needs time to dry?


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## Lars Z (Jul 20, 2011)

lion_yo said:


> so it collects dust which can cause rust.


Dust causing rust? Never heard that before.
You want the underseal to stay flexible so it wont crack or flake causing water to penetrate.

But maybe it´s just me.:tumbleweed:

Lars


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