- Nov 11, 2009
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Is a greatly increased clamping force with a lubricated bolt necessarily a good thing? You don’t get something for nothing?
I agree, there is a danger with torque settings.
When the paint has worn off the tapered bolt location, does the mean the clamping force is reduced or increased?
Does the graphite in the cast drums have and lubricating qualities?
Would new bolts every time a wheel is off produce any benefits?
Should the threaded bolt hole, be gauge checked to see if they are still in spec?
But torque setting are just the amount of force applied to the bolt. This doesn't give you a guaranteed clamping force.
I thought the video, although dated, gave me a good understanding of what's going on.
Most critical bolts on machinery/ cars etc. are torqued to a quite low number, then the bolt is stretched beyond elastic region into the plastic region, by applied angled increments. It quite scary, I always think the bolt is about to snap!
I've ordered 2 sets of wheel bolts, and at least one brake drum. And lots of other expensive caravan parts, ouch!!.
Due to go in at the end of April. At the moment it sitting at home looking neglected.
You can tell I've too much spare time, no caravan.
When the paint has worn off the tapered bolt location, does the mean the clamping force is reduced or increased?
Does the graphite in the cast drums have and lubricating qualities?
Would new bolts every time a wheel is off produce any benefits?
Should the threaded bolt hole, be gauge checked to see if they are still in spec?
But torque setting are just the amount of force applied to the bolt. This doesn't give you a guaranteed clamping force.
I thought the video, although dated, gave me a good understanding of what's going on.
Most critical bolts on machinery/ cars etc. are torqued to a quite low number, then the bolt is stretched beyond elastic region into the plastic region, by applied angled increments. It quite scary, I always think the bolt is about to snap!
I've ordered 2 sets of wheel bolts, and at least one brake drum. And lots of other expensive caravan parts, ouch!!.
Due to go in at the end of April. At the moment it sitting at home looking neglected.
You can tell I've too much spare time, no caravan.
The only way there is more clamping force is because the bolt tension, and directly with it the tensile stress is increased.
That tension increase comes from the lubricant easing the coefficient of friction, within the threads and within the bolt/register seating surfaces. With the eased friction more of the torque goes into tensile loading of the bolt, no more complex than that.
Sometimes, in combination with a lubricant it can be a massive increase, say with new bolts of high quality thread finish, themselves with a plating that acts as an extreme pressure lubricant, going into nicely burnished female threads.
It is an absolute "NO NO" as here where the quoted torque up is for dry components , and where again as here the torque up is pushing the specified grade bolt close to its limiting tensile value.
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It's wrong to accredit spigot hub/wheel designs as "fail safe", it never is "safe" to run with an unsecured vehicle road wheel even if for a few moments it can hang more or less together as progressively it fails.
This is even more so with trailer wheels, where the vehicle dynamics are not so directly coupled to the person holding the steering wheel.
Guilty me lud.
I had the hubs off this winter .
I brushed out the dust.
I checked the brake shoes had enough friction surface and the lining material hadn't delaminated.
I checked nothing had fallen off or gone rusty.
I fitted new axle nuts but not wheel bolts.
I replaced the tyres.
I lubricated the inertia coupling, checked the cables and rods.
I changed the 13 pin as water had penetrated the plug.
I checked the resistance of the wiring .
The caravan spent winter on axle stands. A couple of days before the catastrophic journey, I spun the wheels and applied the handbrake, released it and checked the wheels ran freely
I lowered the van and torqued the wheel bolts.
On the day of travel I moved the van to the front of house. Connected the car and ran through our check list, AND
re torqued the wheel bolts.
Its a legacy of my old job. Check and recheck.
I had the hubs off this winter .
I brushed out the dust.
I checked the brake shoes had enough friction surface and the lining material hadn't delaminated.
I checked nothing had fallen off or gone rusty.
I fitted new axle nuts but not wheel bolts.
I replaced the tyres.
I lubricated the inertia coupling, checked the cables and rods.
I changed the 13 pin as water had penetrated the plug.
I checked the resistance of the wiring .
The caravan spent winter on axle stands. A couple of days before the catastrophic journey, I spun the wheels and applied the handbrake, released it and checked the wheels ran freely
I lowered the van and torqued the wheel bolts.
On the day of travel I moved the van to the front of house. Connected the car and ran through our check list, AND
re torqued the wheel bolts.
Its a legacy of my old job. Check and recheck.
- Nov 11, 2009
- 23,297
- 7,925
- 50,935
Yes, "massive" differences as I said, and my own testing also found. If the torque up value is not referenced to very specific lubricants and bolt states, don't do anything but assemble dry.
Graphite grease, I similarly found was as bad as it got, but there were fitters using it, innocently though naively believing it was good practice!
I agree using lubricant increases clamping force. (not to be used unless specified as you correctly say).
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