Retorquing Prop Shaft Bolts?

[Ben]

65 foot-pounds, or 65 inch-pounds?

I don't know what they use for u-joint bolts on a 'Yota, but I'm pretty sure 65 foot-pounds would shear off the ones on my Jeep.

Foot pounds.

[Cliffh]

65 foot pounds is a lot.  That's what small block chevy head bolts are torqued to.

[BobR]

65 foot-pounds, or 65 inch-pounds?

I don't know what they use for u-joint bolts on a 'Yota, but I'm pretty sure 65 foot-pounds would shear off the ones on my Jeep. Factory spec calls for 14 foot-pounds.

Use 88 Nm and call it good, none of that weird inch or foot stuff.

bob

[dogmush]

Gents, Ben is talking about the bolts that hold the Driveshaft flanges to the differential and transfer case companion flanges.  On that 4Runner they are probably  10mm or 12mm 10.9 bolts.  65 ft-lbs is right in the range for those.

My F150's spec is 83 ft/lbs.


In any case, if they aren't loose now, they are unlikely to work loose.  I would skip the whole thing unless you drop the driveshaft. Which you'll probably want an impact for.

[dogmush]

Use 88 Nm and call it good, none of that weird inch or foot stuff.

bob

3 ugha-dugas of a 1/2" impact is probably what the dealer is using.

[Cliffh]

Gents, Ben is talking about the bolts that hold the Driveshaft flanges to the differential and transfer case companion flanges.  On that 4Runner they are probably  10mm or 12mm 10.9 bolts.  65 ft-lbs is right in the range for those.

My F150's spec is 83 ft/lbs.


In any case, if they aren't loose now, they are unlikely to work loose.  I would skip the whole thing unless you drop the driveshaft. Which you'll probably want an impact for.

Huge difference in what he's working with & what I thought he's working with.

[Ben]

3 ugha-dugas of a 1/2" impact is probably what the dealer is using.

If it's the same kids that do the oil change, that's probably better than a torque wrench since modern math has 2+2=5. Who knows what they'd set the wrench for? 

[Hawkmoon]

Gents, Ben is talking about the bolts that hold the Driveshaft flanges to the differential and transfer case companion flanges.  On that 4Runner they are probably  10mm or 12mm 10.9 bolts.  65 ft-lbs is right in the range for those.

My F150's spec is 83 ft/lbs.


In any case, if they aren't loose now, they are unlikely to work loose.  I would skip the whole thing unless you drop the driveshaft. Which you'll probably want an impact for. Jeeps use U-joint straps.

Ah. Thanks for the clarification. I've never owned or worked on a vehicle that used a flange to attach the drive shaft to either end.

[Hawkmoon]

3 ugha-dugas of a 1/2" impact is probably what the dealer is using.

    

[ConstitutionCowboy]

When talking bolts of the high grade they likely are, it is not so much as the bolts getting loose as it is the metal parts they are holding together being much less hard and subject to "squishing" under load and stress, thereby relieving some of the torque on the bolts. Torque them.

Woody

[dogmush]

When talking bolts of the high grade they likely are, it is not so much as the bolts getting loose as it is the metal parts they are holding together being much less hard and subject to "squishing" under load and stress, thereby relieving some of the torque on the bolts. Torque them.

Woody

I would bet a nice bottle of whisky that short of welding the wheels to the ground there's no way that 4Runner has the torque to appreciably squish the holes in those flanges.

[ConstitutionCowboy]

I would bet a nice bottle of whisky that short of welding the wheels to the ground there's no way that 4Runner has the torque to appreciably squish the holes in those flanges.

The torque alone likely won't do it. Side loads, thrust, heavy hits that bottom out suspension and the like could very well do it. Not much happens standing still. Torque your bolts - nuts on studs, too.

Woody

[Ben]

nuts on studs, too.

Leave my nuts out of this.

[dogmush]

The torque alone likely won't do it. Side loads, thrust, heavy hits that bottom out suspension and the like could very well do it. Not much happens standing still. Torque your bolts - nuts on studs, too.

Woody

If you side load the differential flange enough to squish it you are going to know long before those bots back out.

I agree that on install, they should be torqued to spec, but as a scheduled maintenance item, there's no need in this application. Do you pop the diff cover and torque the carrier bearing caps every 5000 miles? Pop the cam covers and torque head bolts at every oil change? Drop the oil pan and torque the main caps? All of those get way more heat cycling and dynamic loads than the differential flange.

I have no idea why Toyota originally added this to scheduled maintenance,  but unless there's some history of Toyota driveshaft falling out, this application does not need scheduled torque checking.

I am familiar with applications where there is a need for periodic retorqueing. This just isn't one of them.

[Hawkmoon]

When talking bolts of the high grade they likely are, it is not so much as the bolts getting loose as it is the metal parts they are holding together being much less hard and subject to "squishing" under load and stress, thereby relieving some of the torque on the bolts. Torque them.

Woody

I would bet a nice bottle of whisky that short of welding the wheels to the ground there's no way that 4Runner has the torque to appreciably squish the holes in those flanges.

It's not the engine torque that's the problem.

We torque bolts in order to slightly stretch the metal -- within its limits of elasticity -- to generate clamping force between the parts. What CC's quote refers to is that if the bolts are significantly harder than the metal of the flange they're screwed into, the flange may deform more than the threads on the bolts, which could result in loosening up over time and use.

That said -- I have never heard of period retorquing of driveshaft bolts, even flanges.

I would be more worried about the result of doing it. Years ago, I was active in a car club that hosted autocrosses, and many of our members also participated in a state-wide series comprised of events hosted by several clubs around the state (including ours). One of our members had a habit of giving the lugnuts on his car a check before each event, just to be sure they were tight. By the end of the season, he had literally (yes, I mean "literally") pulled the lugnuts right through the holes in the wheels.

If it ain't broke -- don't fix it.

[Ben]

I have no idea why Toyota originally added this to scheduled maintenance,  but unless there's some history of Toyota driveshaft falling out, this application does not need scheduled torque checking.

That's the head scratcher for me. I've done some significant gazoogling, and can't find any history that would cause them to add it to the manual, and have yet to see any info on other automakers having this as a maintenance item. It does appear that it only applies to Toyota SUVs and trucks, but includes stuff like the RAV4, which is more of a "drive to the ski slopes" kind of a vehicle.

[Tuco]

That's the head scratcher for me. I've done some significant gazoogling, and can't find any history that would cause them to add it to the manual, and have yet to see any info on other automakers having this as a maintenance item. It does appear that it only applies to Toyota SUVs and trucks, but includes stuff like the RAV4, which is more of a "drive to the ski slopes" kind of a vehicle.

The Subaru factory manual contains many crptic phrases.  Odd syntax and word choice. An example.might be "hold tightly against coiled part" instead of "spring under tension" Could this Toyota propshaft torquing item be a bungled Japanese - English translation?

[230RN]

Or added by a lawyer who heard of one bad incident five years ago, Terry remarked, not jokingly.

I agree that untorqueing and retorqueing is fundamentally a bad idea, except in some really really special circumstances.  I added the "really really special circumstances" just to cover my ass for something I might not know about.

If in doubt, I would set the torque wrench at just below the specified torque and test to see if they were tighter than that setting, then SAE a Hail Mary and keep going that way.

"SAE..." "say?"  Get it?  Society of Automotive Engineers?"  <taps microphone>  "Is this thing on?"

Terry, 230RN

[Ben]

The Subaru factory manual contains many crptic phrases.  Odd syntax and word choice. An example.might be "hold tightly against coiled part" instead of "spring under tension" Could this Toyota propshaft torquing item be a bungled Japanese - English translation?

No, the language and syntax are no different than my Ford manual. My South Korean tractor's manual on the other hand... 

[ConstitutionCowboy]

Leave my nuts out of this.

I ain't touchin nuthin!

Woody

[JTHunter]

Leave my nuts out of this.

Wouldn't that be a "dead end" anyway?   

[charby]

Wouldn't that be a "dead end" anyway?   

Probably really rusty from lack of use.

[230RN]

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Many are good lubricants as well, but one requires 3-4 hours to dry.

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Terry, 230RN