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Thread: Making my own e46 roof rack

  1. #1
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    Making my own e46 roof rack

    Hi all,

    I have been wanting a roof rack ever since I got my e46 so that I could move all of my junk to and from college and to internships by myself. I have been on the search for quite a while to find a used OEM or Thule roof rack for a decent price but I haven't had any luck. So I decided, why not make my own. It sounds like a fun project and I could use another 3D printing project to stay on my toes. Plus, I don't really like the looks of the OEM racks, especially how the mounting points are exposed. And I've heard that they are quite noisy. So I figured I could do a better job and eliminated those issue in the process too.

    Goal:
    • Make roof rack for under $100 (I'm the stereotypical broke college student)
    • Have it be noise free and decent looking
    • Easy and quick to remove
    • Make it a fun project


    To start, I did a lot of searching on eBay for some cheap extruded rails, and guess what, the best deals were to buy other rack bars. So that's what I did. I purchased these:
    https://www.ebay.com/itm/For-2011-20...72.m2749.l2649

    IMG_20190329_132717849.jpgIMG_20190329_132740738.jpg

    They have an air foil shape and are quite stong. They say they can support 165 lb, and I wouldn't be surprised if they could hold that. they are quite nice for the price. I like the wider look as opposed to the square chanel that the OEM ones have. Plus they are powdercoated black and not bare aluminum.

    This is what they look like set in place on my car (don't mind the dirt. Sunday is wash day). The only thing I was a little consered with was their length. They were the shortest length rails I could find, and I figured if they looked too long, I could just cut them down. What do you guys think?
    IMG_20190329_133659885_HDR.jpgIMG_20190329_133719402_HDR.jpgIMG_20190329_133754480_HDR.jpg

    The mounting hardware for the purchased bars actually came with the same size bolts I needed for the mounting points! Already more than half way done!

    Next up will be desiging and modeling the mount portion. I'm considering making each corner two parts. A base piece that attaches to the roof, seals the entire area, and distributes the wigth evenly. And then a piece that attaches/bolts to the base piece and of course the bars.

    I'll keep posting on my progress.

  2. #2
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    I'll be surprised if you will be able to build up Jeep roof rails to fit your BMW for significantly less than the $300 I spent on my Yakima rails and Q-feet.
    Quote Originally Posted by B4SH View Post
    If anyone knows, it's this guy who knows literally nothing about everything.
    Quote Originally Posted by fcvapor05 View Post
    Do you even OT? The mean 401k around here is probably about $6, what with all the shiny cars and $1,000 watches and donations to get other members' Volvos running.


  3. #3
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    @Critter7r, a spool of filament is about the only thing left to purchase ($20), well and a pad of EVA foam ($0.50). I don't see what else I'd spend money on. If you're talking man-hours, then yes. But that's not the point of a custom project.

    Just completed a model of the roof mounting section for dimensioning.
    Mounting point.jpg
    Here is a very rough model (not accounting for curvature or anything) of the first idea that came to mind for the supports. Let me know what you guys think.
    with BMW symbol.jpg

  4. #4
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    Looks solid, here's my rack if you need inspiration but you got a solid design and plan.

    Sent from my Pixel 2 XL using Tapatalk
    05 330i Alpine White
    Past:
    02 330i Titanium Silver
    R56 MCS
    00 540i6

  5. #5
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    Quote Originally Posted by MasterBuilder View Post
    @Critter7r, a spool of filament is about the only thing left to purchase ($20), well and a pad of EVA foam ($0.50). I don't see what else I'd spend money on. If you're talking man-hours, then yes. But that's not the point of a custom project.
    Agreed. I spend countless hours working on my own house to avoid paying someone else to do it.

    Just completed a model of the roof mounting section for dimensioning.
    Mounting point.jpg
    Here is a very rough model (not accounting for curvature or anything) of the first idea that came to mind for the supports. Let me know what you guys think.
    with BMW symbol.jpg
    Don't forget to allow space for the hinged covers on the roof rail, unless you just plan to remove them altogether.
    Quote Originally Posted by B4SH View Post
    If anyone knows, it's this guy who knows literally nothing about everything.
    Quote Originally Posted by fcvapor05 View Post
    Do you even OT? The mean 401k around here is probably about $6, what with all the shiny cars and $1,000 watches and donations to get other members' Volvos running.


  6. #6
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    Looks solid, here's my rack if you need inspiration but you got a solid design and plan.
    Thanks for the picture. Are your mounting points completely covered with your setup, or are the doors still showing?

    Don't forget to allow space for the hinged covers on the roof rail, unless you just plan to remove them altogether.
    My plan is just to remove the doors and put a thin foam pad between the body and my printed mounts.

    Quick update after some measuring to get all of the mounting points at the right angles and positions for accurate modeling. I went with the same kind of idea with the BWM symbol as before. I ordered a spool of ASA (excellent chemical and UV resistances) filament for printing the mounts. I'm going to print a front and back test mount first to ensure correct fitment.

    After playing around with the bar models, I think they will look a lot better if an inch or two were cut off on all ends. I'll have to do that when I head home and have access to the appropriate tools.

    RackUpdate 2.jpgRackUpdate.jpg
    Last edited by MasterBuilder; 03-30-2019 at 10:35 PM.

  7. #7
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    I got a front and backtest piece printed up.
    IMG_20190331_142542914.jpgIMG_20190331_142559998.jpg

    I set them up to see how they fit and they great! no adjustments needed!
    IMG_20190331_141636396_HDR.jpgIMG_20190331_141644638_HDR.jpgIMG_20190331_141659569_HDR.jpg

    The second role of the cylindrical cutouts is to allow access to bolt the mounts to the car and have access to press in a nut for the rail bolt. My concern as of now is the strength of the bottom hole. With how large I left the BMW symbol, there wasn't much material left to make a flush mounting hole and have a decent thickness of material for the rest of the bolt portion. I don't want to scale down the BMW symbol, so I'll have to come up with a reenforcement.

    I have also been thinking that given how the roof bars are bent up in the middle, when they are loaded they are going to push out on both ends. I don't want the stress to levered into the bolt holes so I'll probably add a slight taper/round to the top and bottom of the mounts so they can roll a little to compensate for the ends kicking out.

  8. #8
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    Quote Originally Posted by MasterBuilder View Post
    I got a front and backtest piece printed up.
    IMG_20190331_142542914.jpgIMG_20190331_142559998.jpg

    I set them up to see how they fit and they great! no adjustments needed!
    IMG_20190331_141636396_HDR.jpgIMG_20190331_141644638_HDR.jpgIMG_20190331_141659569_HDR.jpg

    The second role of the cylindrical cutouts is to allow access to bolt the mounts to the car and have access to press in a nut for the rail bolt. My concern as of now is the strength of the bottom hole.
    That is a pretty thin flange for a bolt head to hang on to, considering the forces involved, and that it's plastic. Maybe you could create a 3-hole curved steel bracket to put inside the hole in the mount. One bolt would go thru the center hole to the roof, and the other 2 holes would be to hold the steel to the plastic.


    With how large I left the BMW symbol, there wasn't much material left to make a flush mounting hole and have a decent thickness of material for the rest of the bolt portion. I don't want to scale down the BMW symbol, so I'll have to come up with a reenforcement.

    I have also been thinking that given how the roof bars are bent up in the middle, when they are loaded they are going to push out on both ends. I don't want the stress to levered into the bolt holes so I'll probably add a slight taper/round to the top and bottom of the mounts so they can roll a little to compensate for the ends kicking out.
    If you are planning on only loading up a couple of bikes on the roof, I wouldn't be too concerned with the bars flexing.
    Quote Originally Posted by B4SH View Post
    If anyone knows, it's this guy who knows literally nothing about everything.
    Quote Originally Posted by fcvapor05 View Post
    Do you even OT? The mean 401k around here is probably about $6, what with all the shiny cars and $1,000 watches and donations to get other members' Volvos running.


  9. #9
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    Update:

    Changed a couple small things with the model. Incorporated a steel plate on the bottom to deal with the strength concern of the mounting hole. Also shrunk down the BMW inner circle so the bolt would have more grab on the plastic. To make it look like I didn't shrink it down, I added another circling profile to make it look bigger.

    I was also concerned with the chose of material to print with since a lot of polymers degrade outdoors, especially the most commonly used filaments for FDM printing, ABS and PLA. So I did some research and sourcing and came up with ASA which is the superior to ABS. ASA was designed to solve ABS's problems with weather and UV resistance and is used primarily in the automotive industry. So I shouldn't have to worry about the mounts degrading over time (this is actually a good experiment in itself. I haven't printed anything that would stay outside and in the sun 100% of the time yet).

    Total cost:
    $50 for bars
    $38 for ASA filament (I only used just over half the spool)
    $2 for EVA foam, screws, etc.

    So about $75 total which is right on pare with what I was originally thinking it would be.
    PSX_20190415_235231.jpgPSX_20190415_234954.jpg

  10. #10
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    I still think you need some sort of metal strip on the inside of the circle for the bolt head to hold, which would transfer the forces over a larger area of the mount. I wouldn't be comfortable with having only the amount of plastic that fits under the head of the bolt being responsible for containing all that force. You could use a full circle metal insert with a hole drilled in it, and a half-moon-shaped washer for the bolt to rest on. It seems to me that having a plate inside the circle would make the mount stronger than the plate on the bottom. In fact, you could just probably just shorten and roll the bottom plates into a circle and use those.
    Last edited by Critter7r; 04-16-2019 at 09:03 AM.
    Quote Originally Posted by B4SH View Post
    If anyone knows, it's this guy who knows literally nothing about everything.
    Quote Originally Posted by fcvapor05 View Post
    Do you even OT? The mean 401k around here is probably about $6, what with all the shiny cars and $1,000 watches and donations to get other members' Volvos running.


  11. #11
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    I get what your saying and I suppose I could have incorporated a washer or something for the bolt head. I'm not worried about it though with the plate on the bottom. My concern was that the plastic would rip/pull out the bottom with the tin flange from before, but with the plate added that can't happen. The bolt head is effectively compressing the plastic flange against the plate which is intern pulling on the rest of the mount to hold it in place. It's not like the plastic is going to "squeeze" out somewhere. The flange part is solid and I made the tolerances very tight so there is not free space between the plastic and bolt. It might get compressed a little at first and I might have to go back and re tighten things once. But we'll see.

    I got everything put together and it seems very secure. I'll post pictures shortly.

  12. #12
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    It looks like it'll work fine, I'm just not familiar with the plastic, so I was thinking that I would be more comfortable (if it were my bike on the roof, lol) compressing the plastic between the bolt head and the roof with a metal ring inside the circle, instead of holding it down with that plate under the base. It's just the small amount and type of material being retained by the bolt head that concerns me. Being able to feel the material and know its strength (as you do) might put my mind more at ease.
    Quote Originally Posted by B4SH View Post
    If anyone knows, it's this guy who knows literally nothing about everything.
    Quote Originally Posted by fcvapor05 View Post
    Do you even OT? The mean 401k around here is probably about $6, what with all the shiny cars and $1,000 watches and donations to get other members' Volvos running.


  13. #13
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    It would be most idea to have a plate of some sort like you're thinking, and I was considering a bunch of different options but they all required me to source something I didn't already have or to change the model drastically and get rid of the partial/half solid bimmer logo, which I kind of like.

    Here's the finished product:
    IMG_20190416_195044588_HDR.jpgIMG_20190416_195058581_HDR.jpgIMG_20190416_195137040_HDR.jpgIMG_20190416_195205761_HDR.jpgIMG_20190416_195154424_HDR.jpg

    Everything is quite sturdy. I can put my full weight (which isn't much) into trying to wiggle it and it wont budge a bit.

    Now I am just considering cutting the ends of the rails down by an inch or so on either end to make them look better. What do you guys think?

  14. #14
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    Looks great and solid. I dig the logo.

  15. #15
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    They look spectacular. And I thought you were going to use the flat space between the larger outer circle and the empty center to adhere a BMW roundel. I didn't realize you were putting something inside that smaller circle like that. They really look perfect.
    Quote Originally Posted by B4SH View Post
    If anyone knows, it's this guy who knows literally nothing about everything.
    Quote Originally Posted by fcvapor05 View Post
    Do you even OT? The mean 401k around here is probably about $6, what with all the shiny cars and $1,000 watches and donations to get other members' Volvos running.


  16. #16
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    Thanks! The project turned out just as I hopped it would.

    Now I am just on the search for a good cargo bin. I see a lot of people around here have the half width ones. I think I'd prefer a full size one though. Does anyone have experience with a larger bin on their e46? I don't want to go too oversize.

  17. #17
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    I have driven well over 1000 miles with about an 80 lb cargo bag on the top and the rack is still rock solid! I've also put my full weight on top of it in addition to a couple of mattresses and it held up fine (~160 lb total).

    I am curious if anyone would be interested in a kit for their own e46. Being that I spent all of the time designing the mounts, I wouldn't mind producing more sets if they would sell and be put to use.

  18. #18
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    What would you charge for it?

  19. #19
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    I was having a rather hard time thinking of a decent price. I would have far more time invested into a kit than materials. I want to say it took me ~18 hours (in 4 settings) to print mine and I had about ~2 hours into sanding, prepping, drilling, and cutting hardware for them. So maybe ~$85 for a base kit, which would be only the printed pieces with the metal reinforcement, and foam. That would require you to buy your own set of roof bars and drill 4 holes to fit them to the base pieces in addition to cutting down the screws that the bars come with. You can buy the roof bars on eBay for $50 with free shipping.
    https://www.ebay.com/itm/For-2011-20...72.m2749.l2649

    The reason I was thinking of that option is that it would save me money in having to ship the bars again after I drill the holes and cut down the screws (which is a rather simple job if you have the tools).

    But I suppose I could offer a complete kit all ready to go for ~$150. I think that would cover shipping costs.

    That probably still doesn't reflect the actual time I'd have invested in a kit. But the whole project started as a cheaper/better looking alternative to OEM bars. So I'd like to be consistent with that.

  20. #20
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    Shipping costs have gotten pretty insane. Especially for large, or oddly-sized packages. You should verify your shipping costs before committing to that price. Box up your kit and see what UPS or USPS charges for shipping it. I wouldn't be surprised if UPS was $40 to ship even locally.
    Quote Originally Posted by B4SH View Post
    If anyone knows, it's this guy who knows literally nothing about everything.
    Quote Originally Posted by fcvapor05 View Post
    Do you even OT? The mean 401k around here is probably about $6, what with all the shiny cars and $1,000 watches and donations to get other members' Volvos running.


  21. #21
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    Hey everyone,

    I made some tweaks to the mount models and I am currently printing up a kit to sell. It'll be $200 with free shipping (cross bars included). Let me know if you're interested. It will be something that you use as your own risk, obviously. Mine are still holding up great! even in the super hot weather here in Alabama. There are zero signs of degradation or loss of sturdiness. I am planing on posting the kit on ebay to see if I get any bits. But if anyone is interested on here, just let me know. I should have the kit done by the end of the week.

    I'll post pictures once it's complete.

  22. #22
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    I made a new thread with the kit available.

    https://www.bimmerforums.com/forum/s...-180-shipping)

  23. #23
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    This looks awesome! It was cool to see the progression of your design through the different iterations.

    I am in the process of making my own version of it and am getting some inspiration from your approach. My plan is to use 25-5010 black anodized 80/20 to allow for versatility with what I can mount to it primarily mountain bike and kayak. And yes, I know this will cause a significant amount of wind noise, but it should be quite easy and not to time consuming to install/remove after each weekend of use.
    https://imgur.com/a/kHjFF94


    I have the bolt going from the top of the 80/20 through the mount into the roof. The thought with this was to compress the plastic between the two rigid bodies. However, one thing I am finding is that the roof mount holes are not vertical at all which makes getting the cross bar level is a bit of a challenge. While you were prototyping did you determine what the angle that the roof mount holes come out at? Or was this not of much concern because your crossbar has some slope to it already?

    Right now the design is pretty blocky, I will add some curvature and a logo once I get the logistics sorted out.
    Last edited by switch10berg; 09-30-2019 at 08:00 PM.

  24. #24
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    Sorry for the late reply.

    I did a lot of creative measuring with cardboard, a straight edge, some math, and such to capture the angles. It took a little time. The screws are normal to the roof AT the mounting points. So if you can measure that you should be good. I didn't get the measurements 100% right the first time but they were pretty darn close. Third time around they were perfect. It took me a set of test blocks to get everything right. Worst case, you could get rough measurements, print a block, and iterate from there. Just note that the back ones are quite different from the front in terms of the angles and height to get a flat setup all the way across.

    Good luck on your design!

    It is really nice to make a car component that looks professional. I've gotten a bunch of comments on mine so far, and it's holding up extremely well.

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