Bolt Survey

Tom’s Hex Head Bolt (marking) Survey

Years ago, Roy Harris at Atlantic Automotive in the UK said to me that doing an MB right is harder than a GPW, because of the bolts. Now, some might think I am a little nuts….(pun) but, I would like to get the bolts right on the Feb 1942 slatgrill I am doing, and I know others would like this information too…

I know for example that TR20 marked bolts are used on the headlight hinges and hood and windshield catches on slatgrills. But when did EC marked bolts come into use? and where? I have found a mixture of EC and TR marked bolts on body handles that looked to be original on MBs from the first half of 1942 for example. If there were more people who found EC marked bolts on early 1942 MBs for example, then one might be able to say that ECs came into use at that time. Or, if 1945 MBs has all EC marked bolts, that would be interesting too…

There is some method to my madness in this survey. For example, I ask for data on each individual bolt, and for bolts in a few funny places, like windshield pivot brackets (on the side of the cowl). These brackets were hardly ever removed, and almost all of them have their original bolts still in place (except on restorations). If there were a sudden and consistent change from TR to EC bolts at this bracket, that would be meaningful I think.

If you have an MB that you think has a fair number of original hex head bolts on it, please take the time to fill out the form below and send it to me. I will compile all the results, and post it to G503 when I have something interesting.

You are also welcome to add a few lines at the bottom should you want. For example, it might be useful to see how many people think TR marked head bolts are a good idea for early MBs, and what was used on later MB engines.

I have included two forms of my survey. The best would be if you are familiar with Excel, to download both the xls and pdf versions. Print out the pdf, go out to your MB(s) and mark it up, and return to your computer and edit the xls file with your results. Then email the file to me as an enclosure.

If you are not familiar with Excel or xls files, just print out the pdf and send it back by regular post to me, and I will enter the data.

If you have any trouble contacting me such as spam problems, take a look at: and send me an email from there.

Thanks much!

Excel xls version of the survey for data entry

PDF version of the survey for printing or just to take a look