Long Wheel Studs break street driving

Hi Tom,
Just at a glance it looks like you had too much of an interference fit. The knurled splines on the studs should not be flattened like that. Also 20 tons of needed force to assemble is too much. It also appears that they may not have been bottomed out. (Which would cause the nuts to loosen). Why isn't the knurl flattend all the way to the shoulder? Was there that much chamfer on the back side of the axle holes? The one on the right, (the unbroken one), appears to have bottomed out, while the other two look very suspect! But even the unbroken one looks like it had too much of a press fit, as it almost totally flattened out the knurl.
You are best to use screw in studs. Have the axles tapped 1/2-20UN and use SHCS type studs. Torque them into the axle to the recommended number and be sure to use some Loctite thread locker on them. I prefer to use the #262 or even the #266. These require a small amount of heat to remove.

I would say that you definitly had "press fit " issues with the knurl and hole diameters. I don't believe that you ever had "full engagement" into the axle with the broken studs.

Just my observations from many miles away!!

Steve

 

You might send one to Moroso and ask them what caused it. From their site: For immediate technical assistance, call 203-458-0542, 203-458-0546 OR
E-Mail us at techhelp@moroso.com

- Bill

 

Steve,

I was not expecting that 20T force would be required to seat the bolt but all the bolts were bottomed out on initial install. Could be the bolts may have later worked loose due to an inadequate clamping force later and then started to move and dig in. This could have been from:

A yielded bolt or two on the one wheel , thereby taxing the clamping load.

Nuts that did not engage properly for Weld's 3 peice construction.



Regarding the threaded ARP bolts that I was supposed to recieve ended up as press in so Iam now using 1/2" threaded Strange Engineering units. They come with a lock washer but the plan is to use the Loctite that Steve mentions.More pic's to come after tonite on the old wheel.

Tom

 

I see the 7/16's come in two sizes, is it possible you had the wrong ones?
46150 Wheel Studs—7/16"-20 x 2-7/8" Press-in, .480" dia. knurl and quick start dog end, fits most late GM drum brake applications. Standard hole size: .472" to .479"
46160 Wheel Studs—7/16"-20 x 2-7/8" Press-in, .560" dia. knurl and quick start dog end, fits most late GM disc brake and early drum brake applications. Standard hole size: .552" to .559"

- Bill

 

More Pics Difference in new and old studs Also wheel that departed





Tom

 

I wouldn't use that wheel again.

 

Just finished installing the big studs. These are beefy and solid.



I enlarged the old drum stud holes with a 17/32" drill, slid the drums on, hand torqued the wheels to 90 ft lbs and the car rolls again.

It even looks like the damaged lip will roll out and require minor work.

From here on in its checking stud torque on a regular basis.

The dark grey deposits on the rim that look like brake dust were from movement of the wheel. Check yours for early detection of a problem and avoid what I went through.

Tom