Disco rear Ladder install hardware - what is it?

surfchimp

Member
Dec 28, 2019
14
1
RI
Got my hands on an OEM rear ladder for my new to me 04 D2. No mounting hardware though. I know I need rivnuts and bolts. Does anyone know the size originally used and the type of rivnut? I am guessing M6 bolts? Aluminum (or steel?) rivnuts? Any help much appreciated.
 

Tugela

Well-known member
May 21, 2007
4,287
156
Seattle
I installed my ladder with M6 aluminum rivnuts. Wide flange, I think. Might have smeared some kind of sealant around the holes during installation, it was years ago and the setup has shown no sign of wear. I use my ladder all the time as a handle for opening and closing the door. Once or twice a month I'll climb up on it.
 

surfchimp

Member
Dec 28, 2019
14
1
RI
Thanks - I discovered (!) that the rear outer door skin is aluminum but the inner is steel? At least a magnet indicated that. So top rivnuts are going into steel, bottom ones in Al. SO ideally I guess you would use steel rivnuts up top and Al below to avoid galvanic issues. Like Defenders - I think if you hooked up wires in the right spot on a Defender body it would generate voltage.
 

ERover82

Well-known member
Nov 26, 2011
3,440
192
Darien Gap
Use rubber rivnuts if you're really that concerned about galvanic corrosion. In a dry climate, I wouldn't worry at all though.
 

surfchimp

Member
Dec 28, 2019
14
1
RI
Not very dry in RI - salty too. Wonder if rubber ones will hold - I know door takes most of load but still
 

ERover82

Well-known member
Nov 26, 2011
3,440
192
Darien Gap
1/4 well-nuts/insulated rivnuts use a 1/2 hole. They'll hold fine, but at a price. Another option would be using nylon shoulder-bushings creatively to insulate at some point in the conductive path.
 

luckyjoe

Well-known member
Oct 10, 2004
311
30
New Jersey USA
Just use steel rivnuts. It doesn't really matter. I drove my D1 for 16 years, with a genuine ladder with steel rivnuts, and when I adjusted the rear door latch before selling it there wasn't any corrosion. And this was in NJ. If your really going to freak out about it, spray some fluid film in there 2x per year...
 

surfchimp

Member
Dec 28, 2019
14
1
RI
Here's how I ended up installing the rear door OEM ladder: I used M6 aluminum ribbed rivnuts and 22mm M6 stainless button head bolts. The rivnuts required a 10mm drill (you could also use 1/4-20 rivnuts - very similar in size). I already had a rivnut tool (believe it or not) so I just needed a 6mm mandrel for it. All these parts were purchased from Mcmaster Carr. Slid ladder on door from the side, made sure it looked centered and leveled, then marked the holes with a silver paint marker (truck is black). Used a punch and hammer to tap some starter dents for the drill, and used a 1/8" drill for two initial pilot holes on top of door first. Then drilled them out to 10mm. Painted the edges of holes with touchup paint, let it dry. Coated rivnuts in clear silicone sealant, and set them with the rivnut tool. Silicone oughta prevent any tendency for water to leak around the rivnuts. Put ladder back on door, loosely screwed it down, and rechecked my marks for the bottom holes - looked good so repeated the drilling/painting rivnut process for these two holes. I greased the Stainless bolts (to prevent galvanic corrosion, leaking water, etc before inserting into rivnuts and tightening down. Worked great!
 

ERover82

Well-known member
Nov 26, 2011
3,440
192
Darien Gap
FYI, aluminum and stainless will present more galvanic corrosion potential than just using aluminum with standard zinc hardware. Also, thread sealer will keep out moisture and contains anti-corrosion additives.
 
Last edited:

Harv

Well-known member
I agree with ERover's caution about using stainless. There's a tendency for people to use stainless hardware thinking they are preventing corrosion. (In my world of aircraft maintenance anyway), the cheaper easier to replace parts, eg bolts washers and nuts, are often designed to be sacrificial (like cadmium plated steel), so they will take the corrosion rather than the base metal they are fastening.
 

surfchimp

Member
Dec 28, 2019
14
1
RI
Thanks - I work with/build racing/triathlon bicycles and they are constantly exposed to sweat, salt water and sports drink and also frequently have stainless aluminum and Ti mixed, with carbon composite thrown in for good measure (carbon and aluminum in contact make a great battery) - hence the use of Ti on 787 wings). The rule there is lots of grease on all threaded parts, especially if two unlike materials. Copper grease on all Ti, and on some stainless. Hasn't failed me yet. Hence the grease on the stainless bolts.