Rear Bumper Holes' Thread Size?

[Old smart]

K8PJ,

Be wary of mixing metric and SAE if you want a proper fit. The smart, being German-designed and French-built, is obviously metric, and the tow eye is ISO metric Acme - M16x4 (alternately called "Tr16x4" for its trapizoidal tooth profile). Sixteen is the major diameter of the male thread in millimeters, and four is the pitch - 4mm between teeth. The closest standard SAE Acme size is 5/8"-8 (5/8" diameter and 8 teeth per inch). Five/eights is very close to 16mm (15.9mm), but 8TPI is not close to 4mm - 8TPI is over 6mm. If a 5/8" thread is inserted into a 16mm socket, it will eventually bind solidly, not because it is a good fit but because it is a bad fit, and all of the strain and holding power is concentrated on the two sets of teeth that finally made solid contact. It would be best to do a combination of ISO metric for the socket insertion, and a standard SAE fastener thread for a lock nut and final mounting stud. Unless you have a specialty fastener retailer handy, there isn't much selection in ISO metric, but SAE is very common. Probably some machine shop work involved to do it right.

The standard mounting thread for the whip antennas I am familiar with is SAE 1"-14TPI.

[Toolman]

I know this is an old thread, but in case other folks search for information about bumper bolts, I want them to find this. Having last had a Ford Focus, where aftermarket parts are plentiful and reasonably priced, I've been amazed at how much some companies are charging for smart accessories. I guess it's just because they can. If I could afford $189 for pedal covers, I wouldn't be driving a smart, if everyone will please forgive me for saying. I love my smart, but part of the reason I have it is because I could afford it.

Now that I'm past that - I also think $50 for a bolt and a piece of metal to mount your front license plate on is also TOO TOO much. I would have ordered this in a heartbeat for $20, maybe even $25. But not $50. I'm going to buy a piece of sheet metal from Home Depot to fashion the mounting plate from, and will paint it black for aesthetic reasons. And once I found the right terminology to search for - I found bumper bolts at a couple of different locations. Of course the first place I found sold them in pairs and wanted $40 plus shipping - that's no good, I won't even provide that link.

Okay, nevermind 4wheelonline.com - I ordered my part from them 13 days ago, had to wait 5 days before I could even inquire about tracking info, and when I did request tracking, I got nothing. (The site says if you request tracking in less than 5 days they'll simply ignore it.) I called them and while holding for about 15 minutes, I googled the site and the word 'reviews' and I see nothing but people complaining about them. I gave up holding - the automatic voice saying thank you for holding stopped saying that after about 5 minutes. So I hope nobody else ordered this part from them based on my post that I'm now changing. I guess I just lost $13. (This update was done on 8-28-10.)

It can also be purchased individually from this site, if you'd prefer to pay the same price AND an additional $3.99 in shipping:
http://www.smartmadness.com/servlet/the-745/smart-car-bumper-bolt/Detail