Crank Bolt Woes (1 Viewer)

[Riad]

I am little worried about the crank bolt I reinstalled after replacing the oil pump seal. I got a chain from home depot that was rated for 450 LB. I used the bolt and chain method to hold the pulley in place while I cranked my torque wrench. The torque wrench I have goes upto 350 ft LB. I did this from the bottom so I could get more leverage by lying under the truck while using the DS tire as added leverage using my legs. I decided to crank the bolt in steps; meaning I tried 250 ft LB then higher until I get upto 304. So after cranking the bolt upto 280 ft LB I just could not crank it any more with my hands and legs. Hey I am little guy, can't do much beyond 300 anyway . So this is what I did: I set up the wrench from the top instead of the bottom. Then I got my come along winch, hooked it up to my wife's 4Runner's (parked beside my truck in the garage) rear tow receiver recovery point . Then I Got my 30K recovery strap and attach that to the end point of the wrench handle that was sticking out (at 11 o'clock) through the top of the engine bay. The distance between the end point of the wrench handle and the 4Runner's recovery point would be 5 ft (+/-) . The chain was still holding the pulley in place at this moment. After that I started to crank the winch. The more I cranked the winch, the tension got really hard on the strap and the cable of the winch and the DS of the 80 was nose diving to the ground (I think this is a result of not having sway bar up front but I could be wrong). Then BANG! The frigging chain shattered. I did not hear the click from the torque wrench. So the bottom line is: I know I got upto 280 ft lb for sure. And I shattered the chain that was rated for 450 ft LB. Did I tighten the crank bolt too much or not enough? The truck is running great. Oil pressure looks better than it used to be and the steering feel better than before.

Sorry for the long description; hope I explained it right.

 

[a.mus.ed]

Next time get a fat friend to help.

 

[scottm]

Amazing that you didn't do expensive damage with that setup. That reminds me, I made a sweet aluminum pulley holder for the 80, should get that to Doug, it's kind of big to ship with the big box of 80 stuff I'll be sending. There are a few more homemade holders in this thread: https://forum.ih8mud.com/80-series-tech/113591-1fz-crankshaft-bolt-help.html

 

[Riad]

I wasn't expecting any expensive damage. Had a large board protecting the fins of the radiator. It just didn't look like some thing could go wrong other than the chain it self. I went back to home depot and got a 1000 LB rated chain. I think I'm gonna wrap the chains around both side of the frame next time (instead of just the PS frame) with two bolts. I saw those home made tools, they are pretty sweet. I'm need to get into making one soon.

Thanks

 

[nicholas]

I used the brass drift in the flex plate/fly wheel?? method through the window under the transmission. The torque wrench I used had about a 4ft handle on it and I weigh about 200lbs, so I didn't have any trouble cranking it down. Hopefully the Harbor freight wrench I used was close enough to spec (it was brand new). I cranked it up to about 312ft-lbs to make sure.

 

[anderaa13]

I might try and find out what weight the chain you used will break at. I could be wrong but I believe that the ratings on chains are pretty conservative and you might be able to find an actual breaking strength. From there you could figure out if you overtightened the bolt. If the bolt was compromised and breaks later that would be bad.

 

[Riad]

I might try and find out what weight the chain you used will break at. I could be wrong but I believe that the ratings on chains are pretty conservative and you might be able to find an actual breaking strength. From there you could figure out if you overtightened the bolt. If the bolt was compromised and breaks later that would be bad.

I see. That sounds really scary now . I broke this chain.

Crown Bolt LLC #2/0 x 1 Ft. Chain Passing Link Zinc Plated

 

[alia176]

Riad,

You can undo the bolt and then retighten it using a Non-Darwinian method. When I did mine, I found out that I was easily able to overtighten the bolt using a 3/4" breaker (20") bar Plus a 20" cheater bar. This was verified by borrowing a proper mondo torque wrench.

I bet you over tightened it in any case.

 

[Riad]

Thanks Ali. Yeah I remember reading about you getting Dan's mondo wrench + the Gorilla method to get the bolt tightened. I am guessing you are tagging my method as the "Darwinian" method . Hey, I didn't have much of a choice. I was also laughing at myself and thinking I should put this out on youtube . Anyway, I was thinking of doing the same thing this coming weekend: basically undo the bolt and go at it using a Non-Darwinian method . What are the common implications of over tightening the bolt? The truck has been running fine although I am not mentally comfortable driving it since I don't exactly know how tight that bolt is.

Thanks

 

[SBFJ60FIG]

Forget the torque wrench I say...you just tighten that thing as far as you can make it and you'll be fine....the last one I did sans torque wrench has been fine for 25k miles so far.

 

[Rookie2]

Did I tighten the crank bolt too much or not enough?

Keep in mind, there's a difference between what rated capacity is and what ultimate (failure) capacity is. When a company rates a product for a certain safe working load, there is a factor of safety that has to be applied and the product has to test out above the safe working load times that factor of safety, which depending on the product can be as high as 4. That means your chain had much more than 450 pounds on it when it broke. Surprized your bolt didn't shear or bend first.

Using the bolt and chain method, the distance (moment arm) between the chain bolt and application of load (crank bolt) is very small... around 2" if I recall. So applying a moment (torque) of 304 ft-lbs, you generate about 1800 pounds of force in the chain.

Bottom line, it's going to be impossible to determine with any level of certainty, that you've got the proper amount of torque, just based on the fact that a chain rated for 450 pound, broke.

I would suggest renting a 600 ft-lb torque wrench. They're about 4 foot long, so you only need to be able to apply about 75 pounds of force to reach the 304 ft-lb torque. You still need a better chain that can handle 1800 pounds or so though.


Rookie2

 

[Riad]

Forget the torque wrench I say...you just tighten that thing as far as you can make it and you'll be fine....the last one I did sans torque wrench has been fine for 25k miles so far.

mmmmm... I don't know man. If the torque is less than the spec then AFAIK you will eventually develop some issues that would be long term effects and result into a dead engine. As you may already know that your PS and oil pump are driven off of the crank (gear driven) and the pressure comes from the torque on the pulley created by the bolt. So if there is inadequate pressure than the gears will slip causing oil pressure drop and other domino effects. Bottom line is: it's good to know that at least 304 ft LB is achieved. But what I don't know is what happens if the torque is more then that.

 

[alia176]

Riad,

When you say "chain", are you referring to a "chain wrench"?

But yeah, undo the bolt and then tighten it gorilla style using a cheater bar and a breaker bar. Just a little correction: I didn't use a cheater bar with the mondo torque wrench. I found out that I overtightened the bolt by using Gorrilla method. The mondo torque wrench just confirmed it for me.

Picture of my setup:

Good luck.

ps is your will up to date?

 

[Rookie2]

When you say "chain", are you referring to a "chain wrench"?

By "bolt and chain method" I think he's referring to where you thread a bolt into one of the holes in the chankshaft pulley, then run a chain off the bolt, to one of the frame rails.

So the chain wrench held good... no slip?? Did you break the bolt loose the same way, or bump the motor?

 

[Riad]

Yep, as Rookie says. I did exactly like the picture below. Except I also used another bolt under the PS frame. Basically bolted a link of the chain to the frame to prevent it from slipping.

I ended up bumping the motor to get it loose. I first tried unbolting the bolt from the bottom (hands+legs+PS tire leverage) but just couldn't budge it. The whole engine plus the truck would rock like a boat. I was pretty surprise how easily the bolt came loose just after one bump. I was bracing for a bang noise and expecting neighbor's dogs to start barking .

 

[Rookie2]

Basically bolted a link of the chain to the frame to prevent it from slipping.

Good idea.

Was the chain you used comperable size wise to the one in the picture?

 

[Grench]

I/we did mine a bit differently when I put the SC on.

5 layers of 1/4" steel plate cut into donuts with holes for bolts. 3 layers used to remove the stock pulley.

On top of the 5 layers we used a 2.5' chunk of 1/4" plate cut to a U on the end to the frame rail.

The whole assembly/set weighs about 40 lbs. I could take some pictures this weekend of the tool we made if anyone wants.

To reach the torque spec I rented a 600lb torque wrench.

 

[Riad]

Was the chain you used comperable size wise to the one in the picture?

Can't tell much from the picture but the one that I used seems to have less fat on the links:

I'd love to rent a 600 ft LB wrench but can't find one. Not sure if I wanna spend $300 to buy one.

 

[nicholas]

I'd love to rent a 600 ft LB wrench but can't find one. Not sure if I wanna spend $300 to buy one.

X2 I called around to about every local place and most just laughed and thought anything over 250ft-lbs was something out of a fairy tale story book.


I know harbor freight can be pretty ghetto and there have been numerous threads on the "quality" of their torque wrenches.

They sell a high torque wrench for around 60$. The crank bolt has held in place so far. I'll keep knocking on wood.

 

[alia176]

X2 I called around to about every local place and most just laughed and thought anything over 250ft-lbs was something out of a fairy tale story book.


I know harbor freight can be pretty ghetto and there have been numerous threads on the "quality" of their torque wrenches.

They sell a high torque wrench for around 60$. The crank bolt has held in place so far. I'll keep knocking on wood.

If you're really staying up at nights worrying about this, get a chain wrench (like the one in my pic) from Harbor Freight and retighten it gorrilla style. I'd be more worried about your "chain" method and its effects on the crank pulley rather than the over tightening that bolt.