The MGA With An Attitude

At 06:44 PM 5/17/03 -0500, Edwin Vaughan wrote:
>"I recently acquired some alloy wheels pretty cheap. ......but the wheels are thicker than a Rostyle wheel where the lug bolt pass through them. Can I replace all the lug bolts with longer ones? Do I want to?"

Yes, and yes. I did this with my MGA several years ago when I installed aluminum wheels which were 3/4 inch thick in the center hub area.
wheel studs and nuts
Tap out one of your original hub studs and take it to a local auto parts store as a sample. They are 7/16" fine thread. Parts counter folk can look them up in a book (if they want to take the time). The most important feature is the diameter of the fine press fit spline under the head of the stud. For the MGA this is 0.468-inch diameter over the top of the spline. (That was measuring a used stud, so the spline may have been scrunched a bit during assembly and disassembly). This should be larger for the MGB (possibly 0.530-inch) which uses 1/2-inch wheel studs. The MGA (originally) uses different length studs front and rear. I believe the rear ones are a bit longer because they go through the bearing hub and the axle flange. I measure the lengths to be 1-9/16" and 1-13/16" (including the countersink length).

In July 1995 I bought longer wheel studs from NAPA for my gold (color) alloy racing wheels. The studs are NAPA number 641-1267 (1-3/4" overall length). The spline on these is quote as 0.475". The MGA studs have a countersunk head. The replacement studs I bought at NAPA do not have the countersunk feature, are flat on top and bottom of the head, but they work just fine regardless. These are longer as my wheels are 3/4-inch thick in the center and have standard counter-sunk holes for the lug nuts, so the nuts sit on the front surface. Someone else reports using NAPA 641-1268 studs (2-1/8" overall length) on a ZB Magnette (same hub parts as the MGA. The NAPA 641-1268 stud is listed with 0.48" spline (may be a round-off error). These may be different length as needed for different thickness wheels. Alloy wheels with cylindrical holes and cylindrical shank lug nuts can use shorter studs, possibly even the original studs. See WL-150 for Alternate Lug Nuts.

I was at the time regularly switching between stock steel wheels and the alloy wheels. When using the steel wheels the studs were longer than necessary. I bought long chrome acorn nuts that are long enough to cover the extended length of the studs and work with either wheel. The long acorn nuts are NAPA number 735-2145 (package of 4).

You can tap the old studs out with a hammer. Put a flat faced nut on the stud first to avoid damaging the thread, just in case you want to keep the original studs. To install the new studs use a flat face nut (or standard lug nut on backward) and a stack of flat washers (or a larger nut) for a spacer. Tighten the nut to pull the new stud into place until the head is properly seated against the back side of the hub flange. If torque required to do this is exceeding the specified torque for lug nuts holding the wheels on, the spline fit is too tight. See the following article for more information about size and fit of the splines.

Original MGA stud part numbers are: 1G7435 rear all DW --- 1-13/16" long including countersink ATB7201 rear all WW 1G4359 front 1500 DW --- 1-9/16" long including countersink ATB4124 front 1500 WW ATC4257 front 1600 DW BTB104 front 1600 WW

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