Undertray screws

[macky17]

I've just removed one with a view to treating the rear subframe and want to replace them all in the process. Obviously I can measure it but wondered if anyone knows the exact spec screw in case I order incorrectly. Thanks.

[Jcerb]

Hi there, size 8 5/8 as link below. Flanged are the best, POR15 paint seems to be the best.

http://www.ebay.co.uk/itm/361063732473?_trksid=p20...

[macky17]

Thanks mate. Much appreciated

[Jcerb]

No problem, when you take the diffuser out remember to unbolt the 2x L shape brackets by thr clam pivot points. Previous owner of mine looks like they broke the diffuser this way, now it's in for repair and paint along with front splitter!

[TrickyDickyChappers]

Jcerb said:

Hi there, size 8 5/8 as link below. Flanged are the best, POR15 paint seems to be the best.

http://www.ebay.co.uk/itm/361063732473?_trksid=p20...

Thanks from me for that link too, have ordered myself a load. Cheers.

[Driven]

Do yourself a favor and replace the screws with rivnuts and M6 bolts.
After seeing these screws fall out, lose tension, strip out, etc. I removed nearly all of the screws on the belly pan, and replaced half of them with rivnuts, as well as sectioning the belly pan so I can remove smaller sections if needed. I work on my car myself, so I wanted an easier method of removing/reinstalling the pan.

[macky17]

Great advice. Thanks to you both.

[Jcerb]

No problem, personally I would leave the self tappers, though I see your point on the M6's though this makes a lot of work when you're talking 200 plus screws to change behind the bulkhead floor section alone. Size 10 self tappers would be fine for the lose fitting screws, then if these ever become lose I'd go for the M6 method, which should have been factory standard! If only more thought had gone into a lot of the design on these cars.

[Driven]

Jcerb said:

No problem, personally I would leave the self tappers, though I see your point on the M6's though this makes a lot of work when you're talking 200 plus screws to change behind the bulkhead floor section alone.

Oh... I know haha


That's JUST the belly pan/undertray alone.

It took some effort installing the 50 some odd rivnuts, but, very happy I did.

[Jcerb]

Good effort for that

[Midlifecrisis71]

Rivnuts - I like those.
Can I ask, with the rivnuts, why use the washer as well ? it looks in your picture like the rivnut rim is sticking proud/lower than the undertray and therefore holding the washer off the aluminium and leaving a gap.
Maybe a perfect gap for water to sit in, then road grime ?

I am no mechanic, but i just wondered if it was just the one image like that or if they all have gaps between the floor and the washer ?

[Driven]

Midlifecrisis71 said:

Rivnuts - I like those.
Can I ask, with the rivnuts, why use the washer as well ? it looks in your picture like the rivnut rim is sticking proud/lower than the undertray and therefore holding the washer off the aluminium and leaving a gap.
Maybe a perfect gap for water to sit in, then road grime ?

I am no mechanic, but i just wondered if it was just the one image like that or if they all have gaps between the floor and the washer ?

The rivnut does have a flange that keeps the tray from being completely flush mounted to the chassis. The gap is very minor though.
However, I've had this fitted for about 4 months now, haven't noticed anything different from when I didn't have them installed.

I only did this for the undertray for the engine bay and the tunnel access panels

[Libs]

C/sunk Rivnuts available in Stainless or Aluminium if a flush finish is needed.

But the amount of effort to replace all those screws.......!