Securing Zerk'ed driveshafts while torqueing bolts

This thread applies specifically and only to Tacos with greasable U joints on the front driveshaft.
(I.e. Zerk fittings in the center of the U-joint.)

When installing or just re-torqueing front driveshaft bolts as part of routine maintenance, the main options for securing the driveshaft seem to be either crawling between truck underbody and cab for 8 round-trips to switch in & out of 4WD. (Yeah, you could get away with only 4 trips but not if you want to cross-pattern re-torque.) Or, jam a long stout lever arm (screwdriver, etc.) through the center of the U-joint to bind the shaft in place.

I tried this second method once and it worked for the first bolt, but on the next one the lever-arm bound up in such a way that it ended up snapping off the head of the Zerk fitting that sits in the center-top of the U-joint spider.


Here's what I've worked out as an alternative tool & method to secure the front driveshaft for bolt tightening/torqueing. I clamp it carefully on the weld between the yoke and the tube -- not on the tube alone. I'm thinking the weld is strong enough to bear the repeated clamping force. There is obvious surface damage to the anti-rust coating, and some teeth marks in the weld metal. I don't know if there is a risk of introducing fatigue cracking into the weld by repeatedly clamping there?

Appreciate any comments, analysis, or suggestions for alternative/better underbody clamping methods that do not involve repeated trips to the cab and that don't risk snapping off zerks in the center of U-joint yokes.

Tool is an Irwin® tools model 12L3, Large Jaw Locking Pliers. Easy & fast to reposition & works equally well for both rotational directions needed to secure bolts on both ends of the driveshaft.

 

Do what every mechanic does, use an impact and ugga dugga them.

 

For loosening, sure. For (final) tightening to 65 ft-lbs spec -- no.

 

Do you want the truth or do you want the book specs?

 

"The truth" as interpreted by your average paid mechanic is why I do whatever maintance I'm able to do, myself.

Most impact wrenches, esp. anything in the 1/2" class, will tend to WAY overtighten nuts unless used with a lot of caution. (As-advertised and as-designed, i.e. they can easily put out 500 ft-lbs of torque without breaking a sweat.)

Here's my truth:

 

With that extension, your torque values will be off. Drives me nuts when they just HAVE to put something blocking the use of a socket/wrench or a box end wrench, extensions are the devil sometimes.

Honestly, I have just always tightened the heck down on driveshaft bolts and have never had an issue for, oh, about 45 years. First vehicle I bought at 16 was a 1972 FJ40. Had 5, last year of the solid axle pickups, FJC, Taco. I was always more worried about them loosening up myself.

I don't tend to use full power when tightening bolts anyways, probably the most oomph I use is on my mower blade bolts and those have close to two inches of thread engagement alone. Always use torque wrenches on aluminum and wheel nuts.

 

Not shown in that photo (for sake of clarity,) but I use my free hand/arm to secure the top end of the extension shaft to minimize any off-angle torqueing. As far as the shaft throwing off values (due to torsional flex within the extension shaft itself) -- I think this is minimized by it being an impact-rated extension, not only thicker than normal but also made from what feels to me (subjectively, I admit) like a stiffer alloy.

It's probably fine to just use an impact to carefully snug down the bolts. But I like to do it by the book when I have the time & oppty to do so. I'd hate to strip the threads on one of the press-fit studs on the transfer case front output flange.

 

Are you saying that you check/tighten the bolts as part of the routine maintenance, if so how often? More importantly how often do you find them to be loose?
As for using a impact, I just use my milwaukee midtorque 1/2inch to tighten them when I pull a driveshaft.

 

The extensions still flexes and you loose some of the torque through it. AS A MECHANIC I have a slide rule that takes the calculations out of adding up what torque is lost through extensions and different sockets. Also as a mechanic we learn how our tools work and their strengths and when to stop, it's a feel that takes years to aquire. Lastly the advertised ftlbs of those impacts is in reverse and NOT scientifically tested nor a standard for testing, it's advertising and marketing jargon, real world none of them put out what the manufacturers say they do. Impact sockets and extensions are actually a softer material and not heat treated, they are designed to give and deform under the stress of an impact and wear out vs shatter and throw shrapnel everywhere like your normal sockets and extensions. But truthfully a mechanic actually understands their tools.

As a mechanic I'd say you're torqueing them the hard way. You have 4wd put the truck in 4wd and in Park with the ebrake on. Even with the front wheels jacked up guess what the DS won't turn and you won't be marring up your driveshaft. Or just stick a big screwdriver/prybar in the yoke where the zerk is not and you'll be fine. Better than marring things up. But I'd just use my smallest lightest impact and turn it down and give it a few ugga duggas or use my calibrated torque elbow.

I love when shade trees post crap like this thinking they are smarter, faster, or know more and better than actual professionals. If you want to know truths on the torque and yields of those bolts go actually look them up I can guarantee they are a lot higher than the spec, MOST torque values for these are just an arbitrary math number thrown out by an engineer, then if you're GM you throw loctite on everything because you're afraid your shit will still fall apart driving down the road. You see in a lot of cases there are torque specs on fasteners that you cannot get anything but an open ended stubby wrench on. Guess what not once has a DS come flying off had issues or damaged anything. But I have had to fix, on many many occasions, shade trees work or trying to diagnose something via the internet and thrown everything at it and still can't fix it.

 

Here's a read on toque values using a straight extension vs offset.
https://www.utilityproducts.com/lin...just-torque-values-when-using-torque-adapters

A straight line extension has little flex when used for a bolt smaller then the diameter of the extension. The torque wrench will click, beep or vibrate before torque value is seen in the extension.

 

this works for me every time. I never torque the driveshaft bolts. Blue loctite and nice and snug than 1/2 turn more, these are high grade bolts and you won’t snap them.

 

I carefully use a medium size pry-bar to counter hold the yoke while tightening.

I winced when I saw lock-jaw pliers around the driveshaft . Scratching the shit out of your own stuff is one thing, if a customer saw that after I worked on it they would be pissed

 

Park on essentially level surface, pop in 4hi, use drivetrain to hold shaft from spinning, simply move truck forward or back in neutral a smidge to spin the driveshaft.

 

Guess Im curious why you're pulling the front DS to begin with?