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trunk lid drilling for euro spoiler x-post / bFc

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trunk lid drilling for euro spoiler x-post / bFc

Post by wishbone » Fri Mar 30, 2012 8:25 pm

I bought a euro rubber rear spoiler, and my 84 633 has no holes.

Template construction? Drill bit suggestions? How much of the previous glue needs to be removed? etc

What glue do I need? How should i seal it, so that no rain water/ water can get in to the holes and rust it out

Any info is appreciated
5/1984 633csi 5-speed, delphin metallic, red leather, BBK, style 5s


Post by trailsaw » Fri Mar 30, 2012 8:36 pm

When I installed the M6 spoiler on my 635 I very carefully used the protruding bolts to make a mark in the blue tape I approximated.

Then I verified the positioning about 47 times before drilling. I painted the freshly cut holes, and used windshield sealant all around.

This has worked for about 11 years now! :D

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Post by Jon Ackermann » Sat Mar 31, 2012 3:59 pm

I put a euro trunk spoiler on my car and a friends car.

Take all the trunk lid interior off. you will see the trunk lid structure and there is a spot where the holes will go for the two inside threads. drill a hole in the center of that structure area from the inside out.

I used a drill bit that is a progressive size drill bit. It leaves a very clean hole.

Put the spoiler on the car with the threads taped so you don't scratch the paint.

Line up the outside part of the spoiler with the small pieces that hang down from the spoiler to the trunk lid edge. Mark the place of the thread on the trunk lid and drill those two from the outside inward.

It sounds scary, but as you go along, it will actually be easy.

Paint the holes with auto primer and finally with body color paint. The spoiler should use a double sided tape to help adhere it to the trunk. I bought mine from the dealer.

Keep us posted.

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Michael , Denmark
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rear spoiler

Post by Michael , Denmark » Mon Apr 02, 2012 2:57 pm

This might be something scroll down and find "rear spoiler" and click on e24 :

Michael from Denmark

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Post by Brucey » Mon Apr 02, 2012 7:15 pm

Jon's method sounds pretty good (if you believe the jigging for the inner skin was correct...).

I have a boot (trunk) lid with no spoiler on right now so I can measure if you like.

One comment I would make is that the brackets eventually rust inside the spoiler. The rusting starts where the bracket shows and then eats inwards. I've refurbed several spoilers with stainless steel brackets (a lot of work!). It is worth treating the exposed parts of the brackets with something that will seal them really well, like roofing felt adhesive.

To seal them really well, a rubber washer then a penny washer on the inside is a good idea. If the bore of the rubber washer is snug, when the nut is tightened the threads are sealed.

Edit. From the side edge 193mm, 514mm. From the lower edge, 113mm, 113mm. All measured with a flexible steel tape following the surface. Holes are ~6mm dia so you can be 1mm out.... :shock:


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Post by mauser » Thu Apr 05, 2012 7:41 pm

There is a section about installing mtech spoiler in repair manual I used when I was doing the job ... l#refertoc

Not sure how different it is from rubber spoiler though.
635CSi '79


Post by Big6 » Thu Apr 19, 2012 5:24 am

Listen to Jon. He helped me do my spoiler. Came out perfect.


Post by Big6 » Thu Apr 19, 2012 5:27 am

And to tag onto Bruceys post, my spoiler had exactly the same rusting problem he mentioned. I bought it for the right price but once i got I noticed that since the metal mounts were rusted inside the rubber part it has a slight wave which you cannot get out. Which drives me nuts but once i find another ducktail spoiler I at least know my holes are correct.

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Post by Brucey » Thu Apr 19, 2012 6:57 pm

the 'wave' comes because the rust swells up inside the spoiler; if you 'excavate' the old brackets, (clean out all the rust) and fit new ones, the 'wave ' often just goes away.

I have done this a couple of times now and it worked pretty well.

I have a load of pics and I was going to do a write-up of the process when I get a chance....


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Re: trunk lid drilling for euro spoiler x-post / bFc

Post by jsspagg » Mon Feb 19, 2018 4:22 am

Where do you find new mounting brackets and what do you use to re-attach the to the spoiler?

I am refurbishing one that the existing brackets were torn out when the spoiler was removed. I am trying to figure out new bracket and how to apply/attach.

Thanks- Jeff

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Re: trunk lid drilling for euro spoiler x-post / bFc

Post by Bostn635csi » Mon Mar 05, 2018 11:30 pm

I have struggled with this decision as well. I have a brand new spoiler and have left it off as I did not want to drill the trunk after new paint job. I decided to go with the 3 M auto tape after talking to an auto body technician who has used the tape on newer BMW's and other higher end sport cars. I will post pictures when the install is complete most likely end of April or early May.
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Re: trunk lid drilling for euro spoiler x-post / bFc

Post by Hefeweizen » Tue Mar 06, 2018 12:20 pm

I used the template on ... l#refertoc as well. Sweating like a Twinky in Rosie O'Donnel's purse did I measure over and over again. Making sure that the template is centered on the trunk lid. Make sure to also measure the spoiler and look that the bolts match up with the template. Yes, drilling holes in your trunk lid is a point of no return and you have to make sure it is done right. I used a regular metal drill bit. I read somewhere that regular caulk is corrosive and actually causes the lid to rust.
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Re: trunk lid drilling for euro spoiler x-post / bFc

Post by Restart » Sat Mar 17, 2018 6:25 pm

Totally agree with the tape, I have done two with tape and one with screws. Just be careful when you remove the studs that you don’t distort the rubber by twisting the belt out, better to cut them off flush and seal with paint...damhik.
It is a bit of voodoo putting the piece down , check u tube?

That red backed 3m moulding tape is the shizzel...
A man might be able to dispense with clips at all...
Ymmv :D
Bostn635csi wrote:
Mon Mar 05, 2018 11:30 pm
I have struggled wit>>>snip<<< I decided to go with the 3 M auto tape after talking to an auto body technician <<<<snip>>>

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