Looking for a source for Metric Carriage Bolts

[John2004]

Hi Everyone,

I am having trouble finding what I would call a carriage bolt, it looks just like a carriage bolt except that it has a spline round shape under the head instead of a square shape that is usually under the head of a carriage bolt. The round shoulder under the head is a fine spline that looks about 8 mm long.

The bolts are used to secure a steel gas tank support arm to the frame of a truck.

I need a source of supply I can order from here in the USA but I'm having trouble finding this item.

Thread specs = 10 mm OD X 1.5 mm pitch
Length under head = Need at least 40 mm long but can cut down a longer bolt if needed.
Head diameter = Approximately 20 mm OD, but can use a little larger if needed.
Grade = Prefer a 10.9 class or whatever the strongest grade available is.
The round spline shape or shoulder that is directly under the head has an 11 mm OD.

I have tried local hardware and autoparts stores along with

http://www.mcmaster.com.

I also looked through the

http://www.auveco.com/

catalog but have not found anything yet.

Does anyone have an idea of where I might find something like this ?

Thanks
John

 

[SincoTC]

Have you tried searching for "Rib Neck" carriage/coach bolts rather than splined? I think that's what they're called.

Good luck

Trevor Clarke. (R & D) Scientific Instruments.Somerset. UK

SW2007x64 SP3.0 Pentium P4 3.6Ghz, 4Gb Ram ATI FireGL V7100 Driver: 8.323.0.0
SW2007x32 SP4.0 Pentium P4 3.6Ghz, 2Gb Ram NVIDIA Quadro FX 500 Driver: 6.14.10.7756

 

[CoryPad]

The longitudinal pattern on the shank is referred to as splines or serrations. These are common on wheel studs. Does your part look something like this?

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[SincoTC]

Here's a starting point for your search, second image, second line looks like what you're after.

http://www.fastenersplusinc.com/bolts/bolts.html

Trevor Clarke. (R & D) Scientific Instruments.Somerset. UK

SW2007x64 SP3.0 Pentium P4 3.6Ghz, 4Gb Ram ATI FireGL V7100 Driver: 8.323.0.0
SW2007x32 SP4.0 Pentium P4 3.6Ghz, 2Gb Ram NVIDIA Quadro FX 500 Driver: 6.14.10.7756

 

[MintJulep]

IFI-544 defines "metric round head ribbed neck bolts".

Google turns up some Chinese suppliers.

 

[John2004]

Thanks for your replies guys,

Cory, yes, it looks just like your picture of a common wheel stud, except with a bigger head that looks like a standard round carriage bolt head.

It does not look like the picture shown at the fastener- plus link given by Trevor because the "ribs" or splines are too course and too long. The spline on what I need is like the fine splines on the wheel studs.

What I need is just what is shown in the picture Cory posted, except with a standard carriage bolt round head.

I tried a local store that specializes in fasteners and they said metric carriage bolts are hard to find.

Since the spline portion of the bolt is 11 mm in diameter, I might try to use a standard hex head bolt that has an equal diameter. I don't think metric bolts come with an 11 mm thread OD, (I think they generally go from 10 to 12 mm) but I could try to use a 7/16" OD grade 8 standard hex head bolt with a washer under the head.

Normally I would not give it much thought but since this is a gas tank I wanted to stick with the stock fastener. I guess there could be all sorts of reasons why they used a carriage bolt instead of a regular hex head bolt, and perhaps it has to do more with cost or assembly than function. It looks like a standard hex head would work OK.

Are carriage bolts even used for a high strength joint ? I don't think I have ever seen a carriage bolt above a grade 5.

Thanks again,
John

 

[MiketheEngineer]

Call the truck manufacturer or OEM who installed the tanks??

 

[SincoTC]

I guess the splines are too big/long because carriage bolts are usually intended to be fitted into wood and need the extra bite, but yours go into metal, so unless you can track down a supplier (or cut a shaped hole to fit the available types), then MiketheEngineer has the answer if they're still around

Trevor Clarke. (R & D) Scientific Instruments.Somerset. UK

SW2007x64 SP3.0 Pentium P4 3.6Ghz, 4Gb Ram ATI FireGL V7100 Driver: 8.323.0.0
SW2007x32 SP4.0 Pentium P4 3.6Ghz, 2Gb Ram NVIDIA Quadro FX 500 Driver: 6.14.10.7756

 

[John2004]

I think this type of fine spline carriage bolt is probably a custom made bolt that was used to speed assembly at the factory. After you insert the bolt into the hole, you don't need two wrenches to torque it down since the splines keep the bolt from turning as you torque the nut down.

I just went with a 7/16" thread OD, grade 8 hex / flange head bolt and a grade 8 flanged nut.

 

[ischgl99]

I have had good luck finding whatever I needed in metric fasteners from Maryland Metric.

http://www.mdmetric.com

Their website is also an excellent source of information.