Wheel bolt Torque

Anyone know the proper torque one the wheel bolts for a 328? Does it matter as long as they are tight?

 

Correct wheelbolt torque is 72 ft lbs or 98 nm.

 

Yep, 72 ft lbs. It's in the "SPECIFICATIONS" section towards the front of your owner's manual.

 

Great! I knew those manuals were for something. Thanks guys.

 

I use 80 ft/lb... the extra 8 ft/lb won't really hurt anything... and it gives me a little more piece of mind (72 just feels way too loose to me on a 22 year old car).

 

Man, you're lightweight! I use my trusty SU-30XL to make sure those bolts are NICE and tight. With 30,200 ft/lb of torque, those suckers aren't going anywhere

 

LOL - just bring the car over and we'll weld those bastards on!

 

I use 80 as well, just a little extra without going overboard. I also use anti-seize which provides a little lube for torquing and makes sure they come out easily.

 

Hell, why stop at the SU-30XL, step on up to the SU 60 (60000 ft-lbs. of torque). Those wheels will never come off again!

 

Note that the torques are for dry threads. The key isn't the torque, but rather the bolt stretch. If you lube the threads, it takes less torque to get the same stretch.

 

I agree and mechanics have said the same thing to me. I was doing 77 ft/lbs per a tire companies computer recommendations but bumped it up to 90 ft/lbs. 77 seemed like not enough given the age. Common sense tells me a bit more is better and what's most important is that the lug bolts all be the same on each wheel.

Jeff

 

72 lb-ft also seems too loose to me also. I torque to 90 lb-ft also.

Bob

 

Hassle factor - finding the tool and looking up the numbers:

Every few years I do it the 'right' way, with an excursion into the manual and use a decent wrench to get a 'feel' of proper torque. Thereafter, I just use muscle memory. Anyone fault the practicality of my system?

 

Heck no!
Half of the cars on the road (that have had their wheels off) were done the same way.

What I really don't understand is why people think an older car would call for a higher mounting torque...??? I see people citing that the lug torque spec seems too low, perhaps based on other vehicles they've owned, but none of those others use M14 (and aren't they fine thread?) lugs, either! I don't really think it's a big deal one way or the other, but wonder if this movement relates to the "those oil pressure specs were developed 30 years ago" movement???

 

My 77 owners manual simply says "tighten". The GT4 service manual says nothing. Its only in later paperwork with service bulletins that I find the 72 ft. lb. reference. Few are ever going to have a torque wrench out on the road, you have to go by feel. I figure its a track car, and they dont torque the wheels on in a pit stop, they buzz them on with an air wrench. Muscle memory is as good as anything brudda.

 

If doing it to spec is good, doing it tighter is not necessarily better. Remember that these are true magnesium alloy wheels, not steel or aluminum like most modern wheels.

 

For all you torque nuts, here's the factory specs on a bunch of torque settings. Your 308 is last column.

DM
View attachment torque settings chassis-motor-p1.pdf
View attachment torque settings chassis-motor p2.pdf

 

Mine are aluminum, not magnesium. I'm going on knowleagable recommendations. Just feels too light. Can't imagine it makes a big difference, just a bit more piece of mind.

Jeff

 

I thought most of our wheels were aluminum?

I agree with you that tighter is not always better. Especially if you happen to tighten to the point of permanently distorting/damaging the threads. A fastener that is stripped is not any safer than a fastener that can unscrew itself due to movement.

And adding any type of lubricant to the threads will greatly affect the torque applied. It does not mean it should not be done but you must make the appropriate compensation when tightening.

 

They are a magnesium-aluminum alloy. That's why in the various refiishing threads, you see folks talk about the special zinc-chromate primer required if you go down to bare metal.

 

Not true at all. The impact wrenches are all set to a specific torque. When I track my BMW track car we check the torque settings before we start, and at least once again during the day. You'd be amazed at how easily they come loose.

I also question the need for torquing over specs. They should be tightened to what the manufacturer has specified. It has little to do with the wheel falling off, but rather with the forces at work and not distorting anything by over tightening.

 

Good luck trying to convince anyone of this I have no doubt that there are folks that think if 72 is good then 80 is better. Then maybe they put on a little oil or grease on the threads so now you've actually tightened higher than 80 (maybe 90? who... knows) and then they just give the torque wrench a little extra push after it has already clicked "just for good measure." You might end up with 95 or 100 foot pounds. On top of that maybe the torque wrench is reading 5 or 10% low to start with (certainly quite possible). Now add that to the amount you're already over. Granted the wrench could read high also but my point, and it seems yours, is..... there's really not much point using a torque wrench if you don't follow the specifications. Saying "72 feels loose to me" or "85 feels just right" etc. is second guessing the manufacturer in a completely unscientific manner. We won't even talk about the folks that jerk the wrench instead of using a slow, smooth pressure on the wrench!

I use what is indicated as 72 foot pounds on my wrench, with dry threads, and never found a bolt loose.