Long Wheel Studs break street driving

Anybody else have an experience with the long high strength wheel studs breaking with sticky tires on the street? I thought these were high strength spec'd and manufactured to prevent this.


Last night coming home from one of the local cruises I lost the right rear (M/T tire with 8" Weld) wheel after a brisk acceleration while turning left from a dead stop. I had just come of the expressway.

All 5 (Moroso type 7/16 dia 2 7/8"long) studs broke clean at the drum and right rear the wheel flew off the car. Fortunately for the low hanging Lakewood trac bar I was able to skid the right rear corner of the car to a controlled stop. (Ouch on the rear wheel lip though)

The car is equipped with a 12 bolt posi, hi strenth aftermaket axles, 7/16 diameter 2 7/8" (Moroso style) studs, MT street radials, slapper style bars and with 600 plus HP. All wheels on the car were torqued to 65 ft/lbs.

Any ideas why this happened. I am now contemplating using 1/2" studs.

Tom

 

7/16" studs are just too small.

 

I had 7/16 on my 11 second drag car and noticed they were twisting with slicks. Made it interesting to say the least.

 

Tom, is the rear end spooled?

Devon

 

The car is equipped with a 12 bolt posi, hi strenth aftermaket axles

 

Sorry, must've missed that the first time around.

Devon

 

1) Are the studs lubed? If so, you should increase the setting on your torque wrench by 20%.
2) I would have torqued them to 80 ft-# minimum (dry- add 20% if lubed).
3) Did you lube the back of the rim where it contacts the drum? NEVER DO THAT. I see people do this all the time, assuming it will be easier to remove.

-Bob C.

 

A twisted axle will cause them to break/loosen. I notice both of mine twisted after running the car in 1st gear with the rear jacked up and watching the tires wobble. Though they were stock 12 bolt junk.
Ray

 

Sorry for not getting back sooner


I was just out working on the getting the brake drums off and pull out the what was left of the moroso splined studs. It did seem like they were moving on the side that snapped. There must have been the right amount of torque from convertor flashing , angle/ radius of turn, grip from the the really warmed MT's to cause the the smaller studs to move and shear. My mistake for not using the 1/2" studs in the first place when repacing axles years ago.

This is the Recovery program:

Thread in ARP 1/2" aftermarket axle screw in studs (ordered today)
Mcguard 1/2" by 1 3/8" long Tough lug nuts (have )
1 new 8" 4.5 backspace weld wheel (some damage to the holes. Probably still useable but my lifes not worth the price of a wheel)
A new Pair 275 x 15 MT Drag radials (one got cut) No traction without these. Great tire but they wear real fast going to cruises
Rear quarter repair. Some rolling out of the rear wheel lip. Let's see my friend Lance match up this colour. Fortunately the damage is below the bottom crease line
And one RR wheel lip moulding.


I'll torque em dry to 80 ft lbs.


BTW No damage to any of the underside of the car due to the low slapper bar (I was going to ditch them but probably won't now.)


Tom

 

What do you mean that the studs "were moving"? Were they loose in the axle flange?

I want to re-iterate that the inner surface of the wheel must make very good contact with the outer surface of the drum. A lot of people think that the studs turn the wheel- they do not. The studs only pull the wheel against the drum (like a clutch), and the friction between the drum and the wheel is what turns the wheel. If you lubricate this surface, it is essentially the same thing as oiling the surface of a clutch. And, if you are not holding the wheel hard against the surface of the drum, the wheel can slip (which will shear all of the studs). Since you say the studs seem to have sheared at the surface of the drum (as opposed to the axle flange), it sounds like your wheel did not have good contact with the drum.

Of course if your studs were loose in the axle flange, that probably didn't help matters either.

I also don't like painted drums for this very same reason - you should leave the surface of the drum bare for the highest amount of friction to the wheel.

-BC

 

Bob c455

No paint , no oil

The studs were tight in the axle and not floating around. I had to use an impact hammer to drive them out along with several hard blows from a hammer.
When you look at the contact area where the stud meets the axle flange on one side of the stud splines and what seemed to have shiney spots and deformation. Maybe this happened on stud install but I suspect it was from movement. The left wheel studs looked normal.

Perhaps the one Weld wheel didn't center correctly on the center of the axle flange, allowing movement.

Once I get my camera up and runnung I post some pics.

Thanks for your reply's.


Tom

 

Some pics

Notice the galling on the broken studs, while the long left wheel stud splines all looked uniformly pressed into the axle.

Some other pics of the car in its present state.

The Ouch caused by the wheel departing.

Tom

 

Sorry technical difficulties. Will try later
Tom

 

Pictures

Notice the galling on the splines of sheared studs while none exists on the left side wheel.



Tom

 

Pictures

Sorry for the size.
Photo bucket is not cutting it for me with the uploading of the Pics with this new computer, software and camera combo.


Tom

http://i726.photobucket.com
[IMG]http://i726.photobucket.com/albums/ww266/stage1_2009/1113.jpg

 

I think I'm using 100 ft/lbs on my Welds. I can't imagine 65 ft/lbs is anywhere near enough. Where did you get that spec from?

 

They look like they had loosened up to me.

 

Torqued 455,

I did searches on other forums for people using Weld drag stars. The Chevelle forum had members recomended 7/16 studs to be torqued to 65ft lbs. 70 Max.
The Mustang race boys go 85 to 95 with 1/2" studs.

Whamo,

You could be right they look like they loosened. They were in tight. We used a 20 tons of Hydraulic force to drive them into the axles. They were at 65ft/lbs. The mystery is one side only.

A local 8 sec racer/ perf shop was skeptical over the quality of many of the the lug nuts and claimed he had a customer with a similar episode. His recomendation was to only use the Mc Guard (tough) racing lug nuts.

Someone else on the Chevelle site had his RR bolts break away, on a left easy turn also, similar to mine. Sticky tires, Welds, 7/16' studs etc.




Tom

 

What did the wheel look like? Where there any signs of lugnuts coming loose?

 

This may sound like a dumb question but,I would like to know a couple answers before I get my car road/track ready. Are the 1/2 inch screw in studs left hand thread? If not,what keeps them in the axles when you tighten the wheels? How difficult is it to have them drilled? I have 30 spline Moser axles and am about ready to get the longer studs,so I thought this would be a smart upgrade. I have too much in this car (as well as my dumb ass) to skimp on smart things like this..