I have a brand new 2018 Ford Transit cargo van that came without a passenger seat; the van was ordered as a fleet vehicle for some purpose that didn't require a front passenger seat. I'm now installing a factory seat.

What I have are four holes in the floor of the van into which I will bolt my seat base. However, there are no threads in those holes. I assume the hardware here is higher that average in terms of strength, but I've ordered the bolts from Ford so I;m not concerned about choosing the wrong grade/type of bolt.

I'm trying to understand all the parameters of doing the tapping correctly. One thing I'm struggling with is the tap selection. I've read that the different metals that the taps themselves are made from determines the hardness of materials they can perform their function against.

So, how can I determine the correct tap to purchase? Again, I'm not looking for sizing or anything like that ... more quality or functional match to the thing I'm tapping, the floor of my van.


  • Welcome to Motor Vehicle Maintenance & Repair! I don't know that it actually makes a difference in this case, but could you confirm that your van's model year is 2018?
    – Cullub
    Aug 24, 2018 at 23:21

1 Answer 1


Any decent quality tap of the correct size and thread pitch made for HSS "High Speed Steel" will be fine for the material used in your van. The metal is nothing exotic. Stay away from carbide, as these are hard yet fragile, and not designed to be used by hand.

Get a "long lead" or "starter" type tap. Standard is also fine, but avoid "bottoming" style as these have a very short lead-in and tap very abruptly.

Make certain you start square and perpendicular. Again, a longer lead "starter" tap will help with this.

Take it slow, back off often to clear the chips, and use plenty of lubricant. PB blaster or kerosene works fine, motor oil will work as well. I like sprays because they lubricate as well as blow much of the swarf (That's really a word for the little chips, I swear...) out the hole.

  • 1
    As SteveRacer suggests, back off often to clear the chips. I use a half turn forward and a quarter turn back to ensure the chips break and clear the hole. For steel, a dedicated tapping lubricant is a superior choice. You very much want to avoid breaking a tap off in the hole! Ideally, you'll discover the hole is drilled to the correct diameter for the tap.
    – fred_dot_u
    Aug 25, 2018 at 1:28
  • Yes - As @fred_dot_u mentions, it might be worth running the proper tap drill through the hole first, to remove any paint/rust and to make certain these holes start out being the correct size. It is possible the OEM uses a so-called "tapdrill" on a robot to first drill the hole to the correct size, and then feed the tap through in one pass. If the hole is too small, you risk breaking the tap - and that's a really very extra bad mess.
    – SteveRacer
    Aug 27, 2018 at 4:36
  • @SteveRacer Just re-reading your answer ... you say "made for HSS 'High Speed Steel' will be fine" ... does this main the tap is made of HSS or that it's made to be used to tap materials themsevles made of HSS?
    – chad
    Sep 5, 2018 at 22:58
  • There is no such material as "high speed steel" - it just means it can be used in a machine (high speed) for steel, which means it will be tougher than a "hand" tap. Really, any decent quality tap will work fine. It's more important you get a tap with a long lead (slow gradual cutting flutes). If you specify the thread pitch and diameter of the fastener, I can find some internet references to what you need.
    – SteveRacer
    Sep 6, 2018 at 1:08
  • @SteveRacer Gotcha. I went with an Irwin Performance Threading System ... a smaller set because of $$$, but it has the sizes I need and boasts a feature called "self aligning" which I understand to be an innovation on the long lead or starting taps.
    – chad
    Sep 6, 2018 at 19:40

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