MK5 without undertray

[jimojameso]

I just found out mine was missing one so fitted one last week. I go on the motorway everyday and the fuel consumption is exactly the same so doesnt increase drag not having one. I never had any problems without one but i was advised by amd to fit one before the snow, etc, comes as it can knacker the ac pump, etc if you dont have one and crap gets up in it.

My advise would be get one 

[the bruce]

I does increase drag even if you don't recognize it. Otherwise VW would have saved
the money for it.

To me there's not only one point against the (large) undertray, but many points for it.
All GTIs should have come with the ... 237 P from factory.

On the motorway aerodynamic drag is the main factor.

http://www.mk5golfgti.co.uk/forum/index.php/topic,22986.msg307333.html#msg307333

[RedRobin]

^^^^
The one point against the complete frontal undertray is that it will conceal any fluid leaks until they become far worse.

On the floor of my car's batcave (garage without electricity) I keep pristine brown cardboard under the whole area of the engine. Consequently I can immediately spot any drops of fluid. I caught a faulty DSG oil plug seal that way and before it became a serious problem.

In the UK, unfortunately without unrestricted speed autobahns, I don't consider the underfloor aerodynamics of a VW Golf hatchback to be that important.

I think that you are something of an expert on the aerodynamics of the Golf and so I am very interested in your thoughts about the UNIbrace UB regarding underfloor drag etc.



Also whether a Golf which is lower on suspension has any aerodynamic underfloor advantages or disadvantages  (Mine has 95mm overall ground clearance)

[the bruce]

... of my car's batcave (garage without electricity)

  

I think that you are something of an expert on the aerodynamics of the Golf and so I am very interested in your thoughts about the UNIbrace UB regarding underfloor drag etc.

From theory almost any protruding part will increase drag (almost, cos spoilers that prevent
the air hitting other 'draggy' parts do not). The amount of drag won't be significient.

Also whether a Golf which is lower on suspension has any aerodynamic underfloor advantages or disadvantages  (Mine has 95mm overall ground clearance)

Again from theory lowering is a good thing from the view of aerodynamics as less air will
flow underneath the car. This will almost always reduce both drag and lift.

Same with a splitter/air dam (Osir/VWR/Votex): This also reduces the amount of air flow.

[RedRobin]

^^^^
Thanks, Bruce 

Either way, I'm extremely happy with my handling mods but it's nice to understand something about how things work and to know if I'm doing something importantly wrong.

[the bruce]

I'm pretty sure you didn't do anything wrong, mate. 
I strongly believe your GTI is handling great and gives way more driving pleasure than stock.

[jimojameso]

I does increase drag even if you don't recognize it. Otherwise VW would have saved
the money for it.

Yes i know it does affect drag but the point im making is it will not really affect the car on the road. If you were roaring around a track at 150 mph then it would make a lot of difference but for most people who use there golf on the road it wont make the slightest bit of difference. It is mainly needed to protect the engine components from dirt. I actually work in aerodynamics so i know a thing or two about it.

[the bruce]

True, mate. The main advantages are:

- protecting engine bay components from water, dirt, salt, stone chips
- some slight reduction in drag at motorway speeds
- on a TDI: damping the awful Diesel noise

[rdfcpete]

dont know the part number but i was told they are £250 from the dealers

A blue motion (see the improving aerodynamics with oem parts thread) undertray, cost me about 20-30€
A standard (bit smaller / doesn't go as far back) Leon / golf undertray is around £20
Ive seen one on eBay recently for £17

Ancient one I know Mike, but - does the BlueMotion undertray fit all MK5 platform cars i.e. my 8P3 Audi A3 does anyone know?

Cheers.

[betty_swollox]

dont know the part number but i was told they are £250 from the dealers

A blue motion (see the improving aerodynamics with oem parts thread) undertray, cost me about 20-30€
A standard (bit smaller / doesn't go as far back) Leon / golf undertray is around £20
Ive seen one on eBay recently for £17

Ancient one I know Mike, but - does the BlueMotion undertray fit all MK5 platform cars i.e. my 8P3 Audi A3 does anyone know?

Cheers.

http://www.mk5golfgti.co.uk/forum/index.php/topic,85541.0.html


Might help

[rdfcpete]

dont know the part number but i was told they are £250 from the dealers

A blue motion (see the improving aerodynamics with oem parts thread) undertray, cost me about 20-30€
A standard (bit smaller / doesn't go as far back) Leon / golf undertray is around £20
Ive seen one on eBay recently for £17

Ancient one I know Mike, but - does the BlueMotion undertray fit all MK5 platform cars i.e. my 8P3 Audi A3 does anyone know?

Cheers.

http://www.mk5golfgti.co.uk/forum/index.php/topic,85541.0.html


Might help

Cheers fella, it's given me the part number which is as good a start as any. I'll do some general reading up... 

(I did use the search, it didn't retrieve that thread)