Why did the factory use fine thread bolts in so many locations?

Was helping a friend with his Tacoma (changing fuel filter, oil filter/oil, transmission filter) and noticed that many of the threads on the skid plate and the one holding the fuel filter are stripped. Luckily his oil pan bolt was still Ok.

I plan to use 1/4 inch drive with these bolts in the future, as I am afraid of stripping them myself.

Q; Why did the factory use fine thread bolts in many locations? They must know from experience that they will ultimately be stripped if taken on and off often (like the skid plate).

Would coarse thread be weaker? or maybe has less surface area on the nut to grab?

Any insights will be appreciated.

Alex

 

Fine threads are more resistant to backing out during vibration, so they don't need to be torqued as much to prevent coming free or they could be used to eliminate the need for a locking feature or loctite which would be required with coarse threads. Coarse threads are stronger but will work free faster due to the steeper pitch

 

^ what he said.

 

Thanks guys

That makes sense

I told him to go and get longer bolts and nuts (where applicable) and we will fasten them and use a little loctite and 1/4" drive.

He will buy the Fumoto oil drain valve so one less stripped location that needs repair. I am going to guess that given the long life of Toyotas and the frequency of oil change, sooner or later many oil drain plugs are going to be stripped.

Alex

 

The oil drain plugs should never get stripped if the proper gasket and torque is being used. The threads will always be bathed in oil, so there's to corrosion there either.

 

^ ^

Correct if one is patient and does it the right way. he goes to quick lube places for oil change the probability that some hack is going to strip in is high. So I just want to eliminate that.

 

I must admit that I certainly miss the fancy rust prevention coating that Toyota,s manufactured in Japan use to have on all their bolts and am sure they still use overseas .
Someone correct me if I am wrong but anodizing bolts was a smart idea .
I was expecting to see anodized bolts on my 2005 matrix and 2010 Tacoma . Nope , American built , crappy hardware lol

 

You are not wrong. I certainly enjoy that fact when working on my cruisers(Toyota won't take the risk of having a manufacturing plant outside of Japan build their flagship vehicle the Land Cruiser).

 

Something else that crossed my mind is that the mechanical parts (engine, trans, drive-train) are so well built at Toyota that they outlast the body parts, chassis, nuts, bolts etc. Hopefully one day they will use aluminum chassis so it will outlast the mechanical parts.

GM, F and C do not have to worry about this as their products self destruct at 60K miles or so. Well, to be fair F is making better trucks but they are no Toyota by far. And someone is going to correct me re this comment, but we are talking ON AVERAGE and not the few that have lasted.

 

My 2016 4Runner is made in Japan.

My 2004 Tacoma has stripped skid plate bolts, but I think the nuts welded on are still good

 

Yeah, the Land Cruiser, the 4Runner, and I believe most of the Lexus line is built in Japan. There are also a couple other Toyota vehicles built there, I don't remember off the top of my head. The Cruisers are built at the Araco plant in the Yoshiwara district. Oh chit, I'm going on and on.... I'm out, peace all

Edit: what I wouldn't give to take a tour of that Araco plant...

 

Just about every Toyota That I ever changed oil got a new drain plug .

Most people are brutal .

Are removing all the rounded bolts and nuts and replacing with New I have no problem with the fine thread bolts 1.25

People in a hurry can cross thread even the easy hardware to get at.

Then the fun use of Winter Chemicals does not help

 

Curious to know.

Is the bolt softer material than the nuts?

I rather replace the bolt than a welded nut.

I am thinking Toyota engineers would let the bolt strip before the nut.

Anyone knows?

PS: In my drag racing days, we sleeved aluminum cylinder heads with brass or metal sleeves so they do not strip. Worked OK.

 

My skid plate bolts look stripped to me, very hard to thread back in, just wanted to spin. I assume the nuts are good as eventually the bolts did thread in.

 

Good to know, thanks

 

Whats wrong with fine thread? Its strong and toyota uses damn near the same thread pitch for each size bolt. Go work on a jeep with torx bolts on just about evreything and 3 different size bolts on the same part, and you will come back to toyota with that much higher appreciation for their build quality.

 

You need to think assembly line.

Do you really think any Engineer gives any thought to working on a vehicle once it rolls out the door

Bolts being removed hundreds of times

That is why flange bolts are used head goes in the socket in any position hit the trigger done

Hard to tell which is really stronger male threads or female threads but I bet someone got a Grant to to test this very thing

 

I stripped one of those

$13 M12x1.25 mm Self-Locking Nylon Insert Hex Lock Nuts, Pack of 6

M12x1.25 thread nuts inside the front crossmember that holds my skid plate. Bolt is just pushed in with locktite and ducktape for now. Eventually I'll do a helicoil or something but it's got 5 other good bolts in it still.

 

We are just talking about different possibilities and reasons why? No one suggested anything otherwise. You should refrain from posting when angry Mr. Slander. And i do know about Toyota quality, that is why i own one.

Good day

 

Cant tell if this is a joke or not?