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broken wheel studs, help!

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Jedi Warrior
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I have a '74 mg midget. Has a 1500 engine in it (1275 is standard for the '74) a previous owners installed the 1500 engine and transmision. Last night I had my passenger wheel studs brake off while I was driving (no damage or accent to the body or me thankfully). I was able to get a tow safely to home.

I have some of those minilites wheels installed.
When I installed the minilites I installed new wheel studs (either from Moss or VictoriaBritish, can't remember where I received them from) since the original studs where a bit beaten up. When I installed the lugnuts for the new wheels I torque them (with a torque wrench) to the require spec from the Haynes repair manual.

Maybe the torque spec needed to be higher since these are not stock wheels?
Any idea what the torque needs to be different with the minilites installed?
The studs broke off by the head of the stud next to the wheel bearing hub?

Other than loose lug nuts any ideas of why this failure occured?
Maybe the studs where a softer material than required?
 
It sounds like defective studs since they broke at the head to shank junction. Higher torque would probably have only made them fail sooner, perhaps while torquing. I suppose it's possible that the studs were damaged on installation, but this is really a reach as most will pull in using a nut and washers at much less than maximum torque. Have you had the tires or wheels serviced by a shop since you installed them? The most common cause of broken studs is over torquing by a shop with an impact wrench set to the torque specs of larger diameter studs. An impact gun can pop a 3/8" stud in a hurry when set to 75 foot pounds or higher which is a common torque for larger studs.
 
a tire shop installed the tires on the wheels. I installed the studs, lugs and wheels onto the car. Installed the lugs with a torque wrench (impact wrench has never touched the lugs).

What it be good to install the lugs with the recommended torque as stated in the midget car manual for the stock wheels? Even though the minilites are aluminum.
 
I'm going to suggest that the wheel worked itself loose and broke the studs. Do the wheels have inserts for the lug nuts? What size lug nuts are you using? Did you retorque the lug nuts after the first 75 miles? Are you sure the studs were completely seated before installing the wheels? Did you lube the studs as you pulled them into place?
 
I really can't recommend a torque spec for minilites on 3/8" studs, when I had the 3/8" studs in my car I just tightened the lugs with a standard 4 way lug wrench and went my way, didn't have any problems with the alloy wheels coming lose. When I went to the 7/16" studs I began to torque them to 75 foot pounds, but that would be far too much for a 3/8" stud. I'd guess no more than 50 foot pounds would be about max, probably more like 40 to 45 would be better though. You'll know if you keep checking the lug tightness for the first few miles, if they get loose you'll need to up the torque just a bit.
 
how where you able to upgrade to 7/16? did you just drill out larger holes in the bearing hub which retains the wheel studs?
 
The wheels do have a centering feature for the lug nuts (if that what you mean by inserts?).

I will have to check later tonight when I get home on what size of lugs.

I didn't retorque after 75 miles.

Studs where completely seated when wheel was installed (the studds required a press fit on the knerl of the shank into the wheel hub).

lube? do you mean somethink like anti-sieze? I can't remember if I used anti-sieze or not. Why do you ask?
 
I meant oil on the knurl as it was installed to help be sure it pulled completely on. And it is good to put a little oil on the studs as you install the nuts so that the threads do not bind as you torque them.

Aluminum wheels with inserts need to be retorqued frequently when they are first installed until things are well seated. I also check mine with every oil change, and whenever I happen to do any maintenance on my car.
 
Increasing the lug size to 7/16" isn't hard to do, but takes a bit of drilling, preferably with a drill press to keep everything as precise as possible. When I changed my car I just removed a stock stud and took it to the local auto parts store along with my vernier calipers and did some comparison measurments while refering to the specification page in the lug stud catalog. I found a stud that had a rather small diameter knurled section and a small head that was long enough to work, the front stud is longer than the rears, and ordered them. I then found the closest drill size to the knurled portion that would still allow it to press in and hold well and enlarged the holes in the front and rear hubs to match. I had to press the rear studs into the hubs and drill the axles slightly larger to just slip over the shoulder of the stud. With the studs I used I found that I had a slight interference with the rear brake cylinders, but a slight bit of grinding on the heads gave the needed clearance without any major reduction in strength. Not a difficult thing to do and well worth it if you plan on running wide tires or slicks and autocrossing.
 
where/how did you know that on aluminum wheels the lugs need to be retighted every so often? (just trying to see where you are basing your info from).
 
I don't know how Trevor Jessie found out but I learned it the hard way when a wheel nearly fell off my car on one of my first drives in it after the rebuild. I had installed the wheels in the garage and only tightened the lugs with the 1/2 ratched wrench and forgotten to torque them or tighten them with a longer handled tool. After that I torqued them on installation and bought a cheap torque wrench to keep in the car just in case I had to change a wheel on the road. I've never had one come loose since then, so I'm a beliver in torqueing aluminum wheels.
 
The instruction that came with my wheels emphasized re torque them. My father learned the hard way with some very expensive rims on a very expensive street rod.
 
Nial once lost a wheel due to what he thought was cheap replacement studs from one of the big suppliers. Of course he was on the race track I believe. He probably has better details. I did the 7/16" conversion. Used a press as well. A bit of a tedious job (if you want to keep from Burning out bits) plus you have to drill larger holes in the Axles, Drums and rotors to fit the larger stud. The studs I got from WC also had to have the heads ground on one side to clear the Housing. (This may be a double bearing hug thing though.)
 
Do you know what the torque specification is when using 3/8 studs? Do you have a copy of the instructions that you can scan in and post it on this thread?
 
Retorquing Aluminum Wheels Especially is Practice when Racing. The aluminum Rims are more prone to heat expansion and therefor need to be re-torqued as a safe practice. I dont see why this wouldnt also hold true on the street. I rarely find that my steel wheels ever need re-torquing. Tighten them both down to 40 foot pounds
 
I never exceed 35 ft/lbs with the lugs on my Minator wheels, and retorque before every drive (ask me why!). I think I really prefer the lug system of the old real Minilites, with the sleeved lug which engaged about ten threads instead of the tapered Minator lug which engages about six, at best.
 
I will go ahead and ask you why... I assume you have had issues with the studs like me, so that is why you retorque them before every drive?

Is there anywhay to avoid (any modifications?) having to retorque every so often? (other than use different wheels?)
 
Yep, 35 ft. lbs is the spec for 3/8 studs, here the deal I bet the tire store guys over torqued them, it could be easy enought to blame them but I want to know what retard engineer at the BMC factory decided to put 3/8 studs on the Spridget to begin with, going up to the 7/16 stud is one of the very best things you can do to a Sprindget.

Dang Bill, you strong beast you :smile: 75 ft lbs on a 7/16 is kinda on the high end, most of use racer types torque the 7/16 stud to 55-60 ft lbs tops, never had a problem a that spec, I guess if you are not having any issues at 75 ft lbs, then you're ok, just never heard of anyone going that high, heck that what I torque my MGB 1/2 studs to, remind me to never arm wrestle with you :smile:
 
Hap, I'm not that strong, just finally figured out what "leverage" meant, get a long enough breaker bar and use some body weight and 75 is easy. Probably more than necessary, but I'm not going to argue with success in my case, 10 years now and no loose wheels and I don't bother to check them now once they're installed and torqued, they stay tight. One thing to remember though is to make sure you have a tool in the boot that will give you the needed leverage to remove them if you have a flat. That's the problem most people run into with the wheels tighted by the tire stores with their impact wrenches, you can't break them loose with the factory lug wrench. I carry an 18" torque wrench and socket in the car, just turn up the torque setting to around 100 to break them loose and then drop it to 75 to reinstall.
 
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