- Joined
- Feb 18, 2016
- Points
- 231
- Model of Z
- Z3M Imola and Z4 (e89)
I've been doing some long overdue maintenance on the Titan over the past week in as much I have had the sills and wings off a job I have been putting off for the past two years, firstly to check out the condition and secondly to give everything underneath a darn good clean and several coats of Waxoyl. (other brands of anti-rust products are available 
) And luckily, no rust on the inner sills and just some surface rust on the inside of the outer, these were replaced with new ones as I had them ready, the old ones will get re-sprayed and go on another members Zed.
The Waxoyl was put on by brush (3 coats drying in between) then a liberal spaying of rattle can Waxoyl.
The arches front & back were also done.
Here's a few pics
OK this isn't a thread about that and I'm not going into any detail about sill removal as there are very informative and helpful threads already posted that can be better utilised. This is about what happened after.
So I'd spent money and time getting this job done, and I would (as I'm sure all other owners who have treated their sills would too) strongly advise all that haven't to get the sills off and treat the underside, it's not a difficult job it just takes a bit of time. It's pretty scary how much muck gets in and sits there rotting your sills from the inside out ..... UNSEEN. So I was saying I had spent time and money doing this but then got to thinking, it's going to happen again, OK I have treated everything but surely there is a way to improve this poor design that BMW has left us all with.
So I thought I'd make some covers that stop the crud getting into the sill via the poor fit of the wheel arch liners, as are two of them on my Zed.
And here's what I came up with.
I used;
1 plastic seed tray (strong but flexible plastic)
16 self tappers with washers (same as found on the Z3)
A dremel (but a junior hacksaw will do)
Sandpaper
A marker pen
Auto black silicon sealant
All the parts (excluding the dremel) came to under £20
Here's the seed tray, cost £4.75
First job (once the car is up off the ground and the wheels are off is to cut the flat base out of the tray.
As you can see the plastic is flexible, not solid and brittle I am assuming brittle plastic wouldn't last long against stone damage.
Once I had my sheet I cut a square piece, bigger that I needed for the first panel. I put it in place and then drew the outline of the sill on it and marked any other cuts I needed, then set to work with the Dremel (btw if you do this and use a Dremel beware the hot molten plastic bits flying off the cutting wheel, they burn
So I ended up with this.
I then spent a few minutes fettling it with sandpaper to get the best fit I could
Now the beauty of spending extra time on the first one is, the opposite side is identical, just reversed so once you are happy just trace around the first on the plastic sheet before you fit it to create the second.
Clean up the edges with sandpaper and fit.
First job here is to place on the car and drill the holes for the self tappers before putting any sealant on.
I decided to use some sealant on the edges of the cover not touching the sills and to put extra waxoyl on the leading edge of the sill and the cover where it touches the sill.
Next job, screw it on, and I added a little more sealant to the covers edges, again only where plastic touches plastic.
For the rears its the same process just a different shape.
I have absolutely no idea if this will work, but this is how I view it.
The muck gets in there anyway and cant get out, anything that helps to stop this must be an improvement in my book, plus these covers will also protect the leading edges of the sills from stone chips and grit blasting from the wheels, again helping to keep the rust at bay, also its totally reversible if you need / want to remove it.
I haven't blocked any waterways so water that does get in can still drain out.
And though its not the prettiest solution, once the wheels are back on, and all the new shiny plastic has got as scarred and dirty as the rest of the liner you cant really see it.
Hope this is of some use and I have explained the process successfully.
) And luckily, no rust on the inner sills and just some surface rust on the inside of the outer, these were replaced with new ones as I had them ready, the old ones will get re-sprayed and go on another members Zed.The Waxoyl was put on by brush (3 coats drying in between) then a liberal spaying of rattle can Waxoyl.
The arches front & back were also done.
Here's a few pics
OK this isn't a thread about that and I'm not going into any detail about sill removal as there are very informative and helpful threads already posted that can be better utilised. This is about what happened after.
So I'd spent money and time getting this job done, and I would (as I'm sure all other owners who have treated their sills would too) strongly advise all that haven't to get the sills off and treat the underside, it's not a difficult job it just takes a bit of time. It's pretty scary how much muck gets in and sits there rotting your sills from the inside out ..... UNSEEN. So I was saying I had spent time and money doing this but then got to thinking, it's going to happen again, OK I have treated everything but surely there is a way to improve this poor design that BMW has left us all with.
So I thought I'd make some covers that stop the crud getting into the sill via the poor fit of the wheel arch liners, as are two of them on my Zed.
And here's what I came up with.
I used;
1 plastic seed tray (strong but flexible plastic)
16 self tappers with washers (same as found on the Z3)
A dremel (but a junior hacksaw will do)
Sandpaper
A marker pen
Auto black silicon sealant
All the parts (excluding the dremel) came to under £20
Here's the seed tray, cost £4.75
First job (once the car is up off the ground and the wheels are off is to cut the flat base out of the tray.
As you can see the plastic is flexible, not solid and brittle I am assuming brittle plastic wouldn't last long against stone damage.
Once I had my sheet I cut a square piece, bigger that I needed for the first panel. I put it in place and then drew the outline of the sill on it and marked any other cuts I needed, then set to work with the Dremel (btw if you do this and use a Dremel beware the hot molten plastic bits flying off the cutting wheel, they burn
So I ended up with this.
I then spent a few minutes fettling it with sandpaper to get the best fit I could
Now the beauty of spending extra time on the first one is, the opposite side is identical, just reversed so once you are happy just trace around the first on the plastic sheet before you fit it to create the second.
Clean up the edges with sandpaper and fit.
First job here is to place on the car and drill the holes for the self tappers before putting any sealant on.
I decided to use some sealant on the edges of the cover not touching the sills and to put extra waxoyl on the leading edge of the sill and the cover where it touches the sill.
Next job, screw it on, and I added a little more sealant to the covers edges, again only where plastic touches plastic.
For the rears its the same process just a different shape.
I have absolutely no idea if this will work, but this is how I view it.
The muck gets in there anyway and cant get out, anything that helps to stop this must be an improvement in my book, plus these covers will also protect the leading edges of the sills from stone chips and grit blasting from the wheels, again helping to keep the rust at bay, also its totally reversible if you need / want to remove it.
I haven't blocked any waterways so water that does get in can still drain out.
And though its not the prettiest solution, once the wheels are back on, and all the new shiny plastic has got as scarred and dirty as the rest of the liner you cant really see it.
Hope this is of some use and I have explained the process successfully.
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