Locking Wheel Bolts - Some Questions

[E55BOF]

The W164 is in with BJV Engineering in Flaunden having its wheels refurbished. They rang me today to say that they couldn't get the locking wheel bolts to undo because they were very tight, and the key had broken, and asked who had done them up. I told them I had, to 150 nm as specified in the Driver's Handbook. I was told that they always do Mercedes wheels up to 120 nm, and that locking bolts should just be nipped up, not torqued to the same figure as the ordinary wheel bolts.

Fiurstly, I don't like the sound of that, but I'd be happy torquing them up to, say, 50 nm to keep them secure. Does anybody have any thoughts on this?

Secondly, with the tyres costing £250 a pop new, and the wheels newly refurbished, I intend to fit locking bolts again. It looks as though either McGard Ultra or EVO MK 5 bolts may be the best bet, and I've also found a firm called Heyner that look quite promising, though I've never heard of them before. Does anybody have any thoughts or recommendations they would care to share?

 

[Chrishazle]

IMHO your best bet is to replace all the bolts with non MB (instant rust) non rust wheel bolts like those you can get from alloywheelsdirect.net or Ebay. People do not seem to nick wheels these days - it's the whole car, and the number of folk who, like yourself, have had problems with lockers and broken keys, it's not worth it! I've done exactly that on my SLK and should do the same to the 17" AMG rims on the S204 - the less than £30 I paid on Ebay for the 20 SLK bolts is similar to a set of lockers.

 

[st13phil]

and that locking bolts should just be nipped up, not torqued to the same figure as the ordinary wheel bolts.

Never heard of that. And from a basic engineering perspective it doesn’t sound like good practice to have uneven tightening of the wheel bolts.

 

[whitenemesis]

Heyner would suggest torquing to the car manufacturer's spec..
IMPORTANT: Tighten lock to the vehicle manufacturer’s recommended torque- do not overtighten and do not use an impact wrench/air gum ( This will invalidate the warranty)

Fitting instruction for locking wheel nuts

heyner.co.uk

 

[Will]

I’m sure the MB supplied locking bolts are made by McGard.

Perhaps the locker had been previously abused with a rattle gun (you can usually see the tell tale signs of this on the key if you look closely)

Out of interest, did you grease your bolts of the threads previously?

BJV are good guys IMHO, they’ve been around a pretty long time now (20 years at least I reckon?) - sounds strange about the mixed advice but I guess they’re probably equally frustrated if the key has broken on them - this can happen, replacements used to be about £20 from MB - perhaps a little more nowadays?

 

[whitenemesis]

Out of interest, did you grease your bolts of the threads previously?

Is this good practice?

 

[Will]

Is this good practice?

Nope!

 

[SmartAmg]

Wouldn't bother with locking wheel bolts at all. They are a pain in the @rse, as you've found out. As said when was the last time you heard of someone's alloys being nicked. I also put a little dab of Copper grease around the threads of the bolts.

 

[SpikyMikey]

The W164 is in with BJV Engineering in Flaunden having its wheels refurbished. They rang me today to say that they couldn't get the locking wheel bolts to undo because they were very tight, and the key had broken, and asked who had done them up. I told them I had, to 150 nm as specified in the Driver's Handbook. I was told that they always do Mercedes wheels up to 120 nm, and that locking bolts should just be nipped up, not torqued to the same figure as the ordinary wheel bolts.

Fiurstly, I don't like the sound of that, but I'd be happy torquing them up to, say, 50 nm to keep them secure. Does anybody have any thoughts on this?

Secondly, with the tyres costing £250 a pop new, and the wheels newly refurbished, I intend to fit locking bolts again. It looks as though either McGard Ultra or EVO MK 5 bolts may be the best bet, and I've also found a firm called Heyner that look quite promising, though I've never heard of them before. Does anybody have any thoughts or recommendations they would care to share?

No idea about their lockers, but Heyner wiper blades are very decent.

 

[E55BOF]

I’m sure the MB supplied locking bolts are made by McGard.

Perhaps the locker had been previously abused with a rattle gun (you can usually see the tell tale signs of this on the key if you look closely)

Out of interest, did you grease your bolts of the threads previously?

BJV are good guys IMHO, they’ve been around a pretty long time now (20 years at least I reckon?) - sounds strange about the mixed advice but I guess they’re probably equally frustrated if the key has broken on them - this can happen, replacements used to be about £20 from MB - perhaps a little more nowadays?

Grease wheel bolts or studs? No, I don't; I just derust and clean them with a wire brush in a drill, and use a straight tap to clean up the female threads.

I needed a replacement wheel bolt key from MB when I had the ML500, which must be at least five years ago now, and it was £40 or so.

I suspect that if the threads on the bolts had been cleaned the last time the wheels were disturbed, there wouldn't have been a problem. The wheels had been off just before I bought the car last July, I think, for one of those wheel refurbishment companies dealers use to quickly (and cheaply...) tart up the kerbing marks; the outer faces were well-nigh perfect, but the coating was scabby and flaking off on the inner sides of the wheels if you looked closely enough. I doubt the threads would have been cleaned up then, and I'd bet the wheels had been refitted with a rattle gun, too.

I've used BJV a couple of times before; they're excellent, and sensibly priced. I don't think I'm going to take their advice on this occasion, though.

 

[chic0821]

Out of interest, did you grease your bolts of the threads previously?

Roadwheel nut and bolts are designed to be tightened up to a specific torque based on both contact surfaces being clean and dry.

The addition of any form of lubricant will reduce the friction and will decrease the torque at which point the nut bolt would be at the correct design torque. By still turning the torque wrench to achieve the designed reading the bolts or studs would stretch thereby weakening them.

 

[Will]

Roadwheel nut and bolts are designed to be tightened up to a specific torque based on both contact surfaces being clean and dry.

The addition of any form of lubricant will reduce the friction and will decrease the torque at which point the nut bolt would be at the correct design torque. By still turning the torque wrench to achieve the designed reading the bolts or studs would stretch thereby weakening them.

Totally aware of this

 

[E55BOF]

I'm not sure a little smear of copper grease would make a significant difference when you're looking for 90 ft-lb of torque, but I'm a bit OCD about torque settings through stripping too many threads when I were a big strong lad...

 

[SmartAmg]

Roadwheel nut and bolts are designed to be tightened up to a specific torque based on both contact surfaces being clean and dry.

The addition of any form of lubricant will reduce the friction and will decrease the torque at which point the nut bolt would be at the correct design torque. By still turning the torque wrench to achieve the designed reading the bolts or studs would stretch thereby weakening them.

Fair enough. But I've been doing it since I've been driving. And never had a wheel overtake me yet. I check them every so often and they are always perfect. And never struggled to get one off, including lockers, when I used to use them. Don't use lockers at all now. Each to their own, I suppose.

 

[SmartAmg]

I'm not sure a little smear of copper grease would make a significant difference when you're looking for 90 ft-lb of torque, but I'm a bit OCD about torque settings through stripping too many threads when I were a big strong lad...

Your right, it doesn't.

 

[ALFAitalia]

Here we go again!!!

 

[st13phil]

Roadwheel nut and bolts are designed to be tightened up to a specific torque based on both contact surfaces being clean and dry.

The addition of any form of lubricant will reduce the friction and will decrease the torque at which point the nut bolt would be at the correct design torque. By still turning the torque wrench to achieve the designed reading the bolts or studs would stretch thereby weakening them.

As a more general point, it's very rare for any threaded fastener to have a tightening torque value specified for anything other than clean, dry, unlubricated threads. In the rare cases that lubricated threads are expected attention is drawn to that when the tightening torque is specified.

As mentioned, tightening to the specified dry torque setting when the threads are lubricated will often result in deformation of the threads and in extreme cases the threads stripping. Where it's bolts with a domed or conical seat on an alloy wheel it can result in damage to the wheel.

 

[SmartAmg]

Here we go again!!!

Nope, had me say, nuff said.

 

[Chrishazle]

In my working days drilling and repairing oil and gas wells we were daily screwing threaded metal pipes together, some of which had metal to metal seals at the bottom of the male and female threads. All these had a specified torque requirement, and would be lubricated with a thread lubricant. The normal one was "API Modified" - American Petroleum Institute modified pipe dope - which had a torque correction factor of 1.00. However, we would occasionally have to use a different thread lubricant, which also had a specified torque correction factor (normally less then 1.00), especially on the special threads with metal to metal seals.

 

[190]

There is no question that from an engineering standpoint, the recommended torque settings for wheel bolts is for dry threads and that the torque setting should be reduced if they are lubricated. Back in the real world I've used a trace of anti seize on wheel bolts for the last 50 years without any problems.

10 years ago when I first bought my W204 I told the story here of how the wheel bolts had been so overtighten I really feared for being able to undo the locking wheel bolts. To get one of them out I had to resort to positioning the car close to a brick wall and then using an old scissor jack forced the key hard in to the locking wheel bolt so it couldn't cam out under the torque that I applied using a 4ft power bar. The locking wheel nut freed off with a loud crack so problem solved. But at the side of the road if I had to change the wheel - impossible.

The real problem is who tightens them and by how much and that's a much bigger issue than whether or not to use anti seize.