what grade bolts to use for tow loops, anybody with OEMs on?

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e9999

e9999

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I was wondering if somebody would know what grade/class the OEM bolts for the tow loops are.
My rig has had both a bull bar and a hitch put on, so I don't know if the bolts are original or not.
Would somebody with original bolts be kind enough to have a look at the bolthead for markings?
Alternatively, somebody who has pulled the snot out of the loops and it's still there?

(The bolts are 12x1.25 IIRC, but it seems like the normal places don't have better than 8.8, which I have already.)

TIA
 
What Eric is looking for is the number of hash-marks on the original bolt-heads that attach the loops to the frame. I can translate from there.

D-
 
on the front there are 4 lines, 3 of them 120* apart, the fourth is between two of them, kinda like a peace sighn, they look OEM

the rears on mine are marked 8 8. those probably went on with the hitch

I have not used mine yet, doubt the Soccer mom PO did either.
 
IIRC the 8.8 rating is approx grade 5 SAE rating, which is usually plenty strong for about anything you have on a vehicle. I think the next higher metric rating is 10.9, which I have seen at places, but I think all bolts I have ever bought have been 8.8.

Good Luck...
 
Looked in the FSM, the 4 lines correlate to class 8T, the FSM does not give the second # but I would assume it is an 8.8 ?
 
As a further note: The allowable tensile strength on a threaded fastener is typically taken as 0.33 x Fu (the specified minimum tensile strength of the fastener material) and the allowable shear strength as 0.17 x Fu if the threads are included in the shear plane, and 0.22 x Fu uf the threads are not included in the shear. If both tension and shear are acting on the bolt at the same time, then you need to combine the affect of the stresses and make sure the combined affect doesn't exceed the allowable. Dynamic and cyclic loading (fatique) are a different animal too. You need to use the appropriate bolts for these applications, typically A325 or A490 high strength bolts.

:beer:
Rookie2
 
WOW R2!


Ya lost me right after tensile...............:D


You mean a bolt is not a bolt?..................:eek:



I thought tensiles was what you had removed when you were a kid....:D




Oh, wait......You work on airplanes..........That explains your fastener fetish...:D
 
Rookie2 said:
...and 0.22 x Fu uf the threads...
Click to expand...

Heh. He said F U. :flipoff2:

Long week.
 
When in doubt, always go 10.9.
 
Dirk Diggler said:
When in doubt, always go 10.9.
Click to expand...

well, that's part of what I'm wondering, whether it's always a good thing to go with grade 8 or 10.9 . May be better to have a bolt deform in some cases than shear off suddenly. So the material is critical. And the snatch operation may be pretty stressful for the poor things. Which is why I'd rather go with something close to OEM.

In any case, a cursory look did not reveal any 12x1.25 in 10.9 at McMasters etc. That seems to be an oddball. From what I gather normal practice is to have 12x1.75 for class 10.9 IIRC.

Even C-Dan the omnipotent doesn't stock these suckers, apparently.

RT, thanks for checking, now to translate this 8T in ISO...

Anybody else has 8Ts as well on there?
 
Mine are stock, but the wife has it so I can't tell you what the marking is, but.......we winched my 80 up out of a big ditch sideways using the stock loops and merely bent the rear loop. Later that day in a tug of war with a willys, my loop didn't budge and two grade 5 bolts on the bumper of the willys sheared off and the other two deformed so bad we couldn't get them loose. The single loop also held when we finally did get the 80 unstuck by getting yanked on by a one ton chevy with a 454 and 44 inch boggers. I'd say its plenty strong the way it is
Good luck
Dan
 
cruiserdan said:
Oh, wait......You work on airplanes..........That explains your fastener fetish...:D
Click to expand...


nope, that sounds more like engineering, to work on them you just have to follow the directions.
 
I used to install gooseneck hitchs on 1 ton trucks that were rated to tow 30,000lbs. Of the four different manufactures of the hitches, all of them used grade 5 bolts, simply because they wouldn't shear so much as stretch. Granted, there were plenty of bolts, most half inch. These things weren't built cheaply either; for them to use the wrong kind of bolt would be a liability if it fails.

I am not saying that by any means am I an expert (as Rookie2 might be!), but if it was mine, I'd use grade five for anything that gets constantly pulled, and I'd make sure it wasn't any kind of common chinese junk bolt either.
 
I've never seen one deform under recovery stress, so OEM must be OK. Just order some up from CDan, they should work fine. The best recovery point of all is the shackle tab on the back of a Slee bumper-consider that option. To get someone out of the mud, I snached someone with multiple hard snatch pulls, so I know the Slee bumper can take the heat.
 
Is there a location where you can get these bolts?
 
interesting to read in the 80s cool site that one guy had his bolts come out with the tread from the nut attached.... yikes!

Might just pay off to have the bolt go on up through the whole rail and put a nut up there too...

and one of these guys sounded like he had an 8T as well....
 
I remember reading awhile ago about the debate over grade-5 and grade-8, some say grade-8 is too brittle so will snap, whereas grade-5 would stretch or 'give' enough to not break. After several tests the consensus was to just use grade-8 wherever you can. Most auto makers don't use it because it adds dramatically to the cost of a vehicle. Instead of using a grade-8 7/16" bolt, it'd be cheaper usually for them to use a grade-5 1/2" bolt, so bigger, but lower quality. My brother does structural analysis/design for steel buildings, they always use the absolute cheapest steel they can, always 36,000 psi, which is far less strength than like 50K or 80K (Christo's front bumper is made from 80K psi steel), but it's cheaper to use weaker steel and a thicker beam...and to reassure all you out there, every building is always built the cheapest it can be built.. :D

So, even though you are referring to metric not SAE, if you can get the 10.9 rated metric bolts, then I'd get them, if not, don't sweat it, the shear that 2 of those bolts can handle is quite a bit!
 
well, I did a bunch of searches, and I can't find anything about the bolt head markings shown in the FSM and about these class 8T etc. All I've seen are references to the property class being stamped as a number ("8.8" etc) on the bolt head, nothing about line marks...
Surely, these can't be Toyota specific. Maybe a Japanese standard?
 
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