Trouble finding a bolt: M10 1.5 thread 35mm partial thread

[EricP]

Like the title says. BUT key point: it can’t have more than 15mm threaded. I need about 20mm unthreaded.

Hex head. This is to bolt a Pinto to the oil tank. The bolts I removed were fully threaded.

I’ve looked online at Fastenal, Aircraft Spruce, McMaster, Grainger and others. Some say “partially threaded” but don’t say how much and after buying some with that description from McMaster and they only head about 5mm unthreaded, I’m not doing that again.

I’m using my phone to search which is kinda hard so I may have just missed something but I don’t think so.
Any ideas?

[EricP]

Doesn’t have to be hex head...

[DanW]

Perhaps check with Primus?

[BeerBudgetRacing]

I looked at ARP. 35mm or less is fully threaded. 40mm and up are partially threaded with the threaded section being 26mm.

Reading your post these are the 4 bolts that capture the block ears into the tank, correct.

Yeah, I don't think anyone uses anything special there. I don't think the threads against the inside of the iron ears will cause any problems. I had to put in inserts on my tank. And someone converted to SAE somewhere along the way.

I believe the stress on those is much lower than the street car application in my 94 vd. Yous might be dfferent.

[Thomas Wirtz]

Try here

https://www.boltdepot.com

https://www.boltdepot.com/Product-Details.aspx?product=6749

https://www.boltdepot.com/Product-De...x?product=6467

[TimH]

I suppose you could cut a little off the threaded end:

https://www.mcmaster.com/metric-bolt...oulder-screws/

[ExKartracer]

Get a longer bolt and cut off the excess threads. I sand a chamfer on the end of the thread by holding the bolt in line with the belt rather than at 90 degrees to the belt. This allows the bolt to start easily.

[tlracer]

The difficulty with so many metric bolts is that they are produced to ISO4762/DIN912. The specification sets the threaded length, which means they are fully threaded up to 30mm length. Only at 35mm is there any plain shank, but only 3mm.

As has been suggested a longer bolt will have more plain shank, eg. 50mm length has 18mm plain, which is the nearest to your needs.

If I need to shorten a bolt I always fit a plain nut before starting. Then having shortened it and tidied the end, unscrew the nut to raise any burrs, so they can be removed.

[EricP]

Looks like I’ll be cutting a bolt (but I’ll wait to hear back from emailing Brad).

The bolt goes through the upper ears of the aluminum tank into the iron block so I’m not comfortable with the possibility of threads against the aluminum ears. If it were the lower tabs in which the bolt goes through the iron block and bolts into the tank, I’d worry less.

tlracer - yeah, after years I’ve finally learned to thread a nut before cutting. Very good idea.

As always: thanks! I’m going to check out some of the links you guys provided.

[Garey Guzman]

The difficulty with so many metric bolts is that they are produced to ISO4762/DIN912. The specification sets the threaded length, which means they are fully threaded up to 30mm length. Only at 35mm is there any plain shank, but only 3mm.

As has been suggested a longer bolt will have more plain shank, eg. 50mm length has 18mm plain, which is the nearest to your needs.

If I need to shorten a bolt I always fit a plain nut before starting. Then having shortened it and tidied the end, unscrew the nut to raise any burrs, so they can be removed.

I used to do it that way, then I decided to just spin on a die from my tap&die set! I chamfer the end after cutting it to size, then spin off the die.