Help with Cross Threaded Seatbelt Bolts

Hi all!

While installing some sick new gear on my 2009 Tacoma I had to remove some of the seatbelt bolts. One bolt is on the driver seatbelt down low. The second is in the backseat where the center buckles bolt on. When I went to put them back in they didn’t go in correctly and I cross threaded them. (an impact drill is the best and worst tool I have ever purchased) Would anyone be able to help me determine what to do next? I figured I could use a tap and die set (haven’t ever used one before) to try to correct the threads on the bolts and bolt holes but I’m not sure what size I need. I took it to the d(st)ealership and they quoted me $750. Any information or tips/tricks you could provide would be a super huge help.

ps. Post to follow soon on the mod. It’s a project I have been working on for over a year now. It’s basically a cheap alternative to an S-POD system.

 

Sorry, can’t help you with that. But rule is to always start bolts by hand, then use driver. Good luck.

 

That’s the funny thing. I did start them by hand and they were going in just fine but as soon as I got the impact out they stopped and wouldn’t go any further and now the threads look a little chewed up.

 

First time playing with taps, it is best to practice first on a piece of scrap metal. Make sure to drill the hole with the correct size bit for the tap you are using. Use plenty of oil. Go slow and only go in a little bit at a time and then back out to clear the shavings. Plenty of oil, back in, back out, repeat.

1. Get that bolt out and check the threads. If that bolt is bad, then throw it away and get a new bolt. Try to chase the hole from the back side. Stop if the threads show excessive resistance
2. If you meet any significant resistance threading from the backside, then try tapping it from the backside first if you can.
3. as a last resort tap from the front side , but make sure you go slow and keep the tap straight when going in.


If that don't work, could you drill through it, get a longer high strength bolt and throw a nut and lock washer on the backside ??


Good Luck!!!

 

Thanks for the advice! Unfortunately being on the b pillar I don’t believe I will be able to get behind the hole to tap from the other side but that’s a brilliant idea! I ordered what I believe is the correct bolt to replace the chewed up one on the drivers side but I’m not sure how to go about choosing a tap size. Any recommendations on that? I can’t find any information online about the size of the bolts anywhere! The only thing I was able to find was a diagram showing the part number for the bolt from another thread here on TW.

The Part Number is: 90109-A0033

 

Is the truck on the road ? Take it to a machine shop and they can tap it for you .

 

Thank you all for the help! Does anyone have any advice on finding the correct tap size for this bolt? I cant find anything anywhere on the size of it. I called a local auto shop but they still quoted $350 to re-tap the two holes.

 

For $350, are they chasing the threads or doing a helicoil repair?

 

Measure the bolt thread diameter with a caliper or other suitable tool, and measure the threads with a thread gauge. Once you learn this skill, you can measure very fastener on your truck.

 

I honestly didn't think to ask. It beats the heck out of the dealerships quote of $750 though. I figured I would give it a shot myself first and maybe learn something new. I dont feel like I could make it much worse tbh.

 

Once you do what @Hobbs said you can double check the tap by holding the bolt one way and the tap the opposite way and insert the threads together and make every high goes in every low . If the hole you are tapping has a bottom in it you will need a flat bottom tap but if it has no bottom get a regular tap .

 

I'll add that start turning them as if you're loosening and feel for the threads to drop. When you feel it, you'll understand what I mean, and that drop is the indication that the ends of the threads are lined up to start tightening.

 

Impact wrenches are great for some things. Driving fine thread structural bolts is not one of those things. Wheel lugs (removal), suspension pivots and such, etc. An impact wrench on something like seatbelt bolts saves you about 30 seconds of time, probably over torques the fastener and chews up the head faster.

Getting a tap to start straight is going to be tough and it will end up removing some material by design. Probably not an issue for a seatbelt anchor bolt since it's in shear, but still not ideal. There are thread restoration tools that work kind of like a tap but are designed to straighten and clean deformed threads without cutting. I would recommend those and a brand new bolt.

 

Tapping a hole for the first time in something that has to be correct is not a good idea for you. The worst sound in the world is when a tap snaps. But chasing the treads is not near as bad. But i would suggest find a friend that has some experience to help you. As far as what tap you will need, buy a new bolt run down to home depot and use there tread matching templates or take it to a bolt store they will be able to tell you.

 

Great news! I was able to fix the threads!

I started by purchasing a brand new bolt (part# 90109-A0033) as that would be the easiest way to ensure I get it 100% right.
I then used a set of calipers to measure the bolt diameter which was 11mm.
I then used a

$9 OriGlam Screw Thread Pitch Cutting Gauge Tool, Stainless Steel Metric Screw Pitc

thread gauge to determine the thread pitch which was 1.25.
After that I ordered an

$19 Drill America - DWTSMT11X1.25 m11 x 1.25 High Speed Steel Plug Tap, (Pack of 1)

11mmx1.25 tap and

$14 uxcell Tap Wrench Handle, for Metric M4-M12 8/16"-1/2" (UNC/UNF) Thread Taps, Screw Tap Holder Hand Tapping Threading Tool for Machinist Repair

tap handle (I didn't end up using the tap handle as it was too large) and

$5 Tap Magic 30004P ProTap Cutting Fluid, 4 oz. Size

cutting fluid.
I was just barely able to get the tap inside the B pillar to chase the threads from the back.
I started chasing the threads by turning the tap by hand at first to make sure the tap was going in straight, then I used a pair of needle nose pliers to turn the tap as the tap handle wouldn't fit inside the B pillar.
I went very slowly using lots of cutting oil and backing the tap out and restarting occasionally.
After about 30 minutes I had run the tap mostly through and then test fitted the bolt which went all the way in by hand easily.

In all I spent around $80 (there were lots of tools I didn't have previously), fixed my truck myself, and learned a little along the way. Thank you all for your help and my wallet is forever grateful! I still have one more seat belt bolt to fix for the back seat but that can wait until another day.

I hope this is helpful for the next sorry fellow that makes my same mistake!

 

Glad you were able to sort it out on your own, save a ton of money , learn a new skill and end up with some new toys. You may have done this but since it isn’t mentioned, I will check out the internet and YouTube to help me often. I am a visual learner so seeing it done often helps.

 

If the seat belt bolt screwed in easily by hand, I sure wouldn’t want to rely on it holding should the belt be needed in an accident.

 

You made a very very small mistake. Sometime back, a TW member posted that the rear seat, seat belt bolts are 7/16” NF. I thought this odd on a truck where everything else is metric. When your situation arose, I didn’t post any size suggestion, since I didn’t know the accuracy of the previous information and also considered that the front seat belt retractor bolt could be different.

Well, I just did research and it turns out that the NHTSA has very strict requirements for seat belt bolts.

Currently, FMVSS No. 209 "Seat Belt Assemblies," requires the safety belt anchorage bolt to be

"7/16-20 UNF-2A or 1/2-13 UNC-2A attachment bolts or equivalent hardware" (S4.1.(f)).

So, I did some math to figure out just how close 11mm-1.25 is to 7/16”-20tpi. It turns out it’s really really close. 11mm is .443”. 7/16” is .4375”. That’s a difference of .0045”. A human hair is .004”. So, your 11mm tap is a RCH too small. Better undersize than oversize.

Now, the thread pitch. By doing the math, it turns out that 1.25 metric thread pitch works out to 20.3 tpi. A little more than the previously mentioned RCH, but still really really close.

In summary, not the right tap, but close enough that It shouldn’t be a concern as long as you didn’t cut out too much metal as a result of your previous crossthreading.

 

The bolt is in shear, if it doesn't fall out it's going to be fine in an accident. Medium Loctite should guarantee it stays put.

 

I don't know what size the bolt is, but the part from your post I bolded sure seems to leave plenty of room for metric parts.