Does anyone know the bolt size to mount stock GM running boards to the frame of the H3?

My new-to-me H3 has them removed and I have them sitting in my garage waiting to put them back on. The local Chubby service center said they could get the "mounting package" but would be like $70 for the kit.

Thanks!

 

M12 sound right? 1.5-3" in length?

 

theres as looooong post with pics of 5/16 and m10,1.5 i think. i posted the pics and now dont remember!!

well find it but IT IS METRIC like the rest of the h3 ,,dont listen to any bs!!

ez way is go to ace hdwe and get 2-3 and turn in with yoour fingers only. caution, its metric and us 5/16 will go in loose and then may bind.




try 10,1.5 pitch,,,or search!!
found;

Rockers/Nerfbar Bolt Size (Multi-page thread 1 2)
MetcalfeH3 MetcalfeH3

0-04-2010 10:40 AM
by drtom Go to last post

i found it but dont know how to link it,,,this shud do it

https://www.hummerforums.com/forum/s...t=metric+bolts

go to the end

 

I still have the instructions for the set I just put on my new 2010 H3 and they are M10 x 30 mm and you need 8 ea.

Hope this helps..

 

Forgot to mention you need a 15 mm socket to mount them to 36 ft lbs or 50 nm torque..

 

Perfect, thanks!

 

10MM 1.5 pitch 30MM in length (or a bit longer like 40MM if you think you got to) requires a 17MM wrench.

I suggest you squirt the bolt holes with a dose of liquid wrench or PB Blaster the day before, and just before you start the install. Run a bolt in each hole before you start trying to mount the boards. The bolts don't turn in all by themselves, it takes some serious elbow grease. Turn in the bolt a few turns, back it out and squirt the hole again and repeat, until you get the bolt to seat all the way in. If you bust off the bolt head, plan on finding a stud extractor.

I just took my rock rails off to avoid the winter road salt, I can pull the six bolts out and then back in with an air socket wrench after prepping the bolt holes as above. The first time is a beech, after that it get better.

 

My truck never had anything mounted so it had 2 years of rust and crud in those holes when I bought it. I tried running a bolt into the first hole and it felt like it was going to snap.
I ended up running a tap into each hole. Then the bolts went in easier when I mounted my rock rails.
Make sure you get the right pitch. 10 mm bolts come in fine and coarse pitch.
Like Doc stated, 10 x 1.5 is the right thread.

 

Hhmm. These boards must not be stock then. They only take 4 bolts each.

 

I have rock rails, they use six. If I find time before spring, I'll be adding another bracket with a horizontal gusset, and they will use all 8 frame holes.





Oh, and I deleated your duplicate post.... every once in a while they can get away on ya.