confused with lug stud sizes. help

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BYM

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well got a 1969 dodge dart swinger 340.
has the 9 inch drums front and rear.
I want to change the all of the lug studs and lug nuts.
seems that there are a bunch of different sizes, im looking into having longer studs on the rear just in case. any recommendations?

its a 8 3/4 rear and its a one legged runner
 
I always run open ended lug nuts on everything.

As far as length I think mine are 2". Not sure on that one. I'd give a call to strange and see what length they recommend
 
Something doesn't seem right. An 8-3/4 rear axle with only 9" drum brakes? Should be 10 x 1-3/4 if stock.
Are you sure it's not a 7-1/4 rear?

Anyway, I'd check Rock Auto first and see what's listed.
Then looking at the specs for the correct stud, see if there is a longer one available from Dorman with the same spline diameter and thread. Should be 7/16-20 for either rear axle.

You realize that it probably has left hand threads on the driver side? Good idea to switch to right hand threads all around since you want to replace them anyway.
 
yeah probably, havent measured them just eye balled them.. hahaha but I did make sure it was the 8 3/4
 
The Dorman web site has a database of lug sizes you can download for Excel. But it is enormous, so it is hard to find any specific application.

Why are you replacing the studs, may I ask? I can understand getting rid of the LH ones, or if you need longer ones for racing, but otherwise...
 
Unless the backing plates have been drilled to fit the 8 3/4”, the 9” brakes will not fit an 8 3/4” rear. Even then, who would go through the trouble of doing that to get smaller brakes? And a 340 car would not have 9” brakes from the factory...ever. Better check those diameters.
 
I believe they are 7/16-20 x whatever length you need
 
So depending on the rear/axle the stud is either 7/16"-20 or 1/2"-20
 
the 8.75 in my 340 4sp Swinger has 7/16 studs.
I ordered some Dorman 1/2" I think will fit if I enlarge hole a bit.
 
mbaird said:
the 8.75 in my 340 4sp Swinger has 7/16 studs.
I ordered some Dorman 1/2" I think will fit if I enlarge hole a bit.
Click to expand...
The holes in the axle are knurled to hold the studs, which are also knurled. Drill em out, no knurl. You’ll play hell trying to get the rim on and off when the studs won’t stay in place.
 
mbaird said:
will stock axles/drums and wheels accommodate 1/2" studs ?
Click to expand...
If you're very careful, probably. The issue is that no 4" bolt-pattern wheels will work, since they're all intended for 7/16" studs. There's also no need to upgrade unless you're doing some serious racing. Every GM musclecar had 7/16" studs OE, including COPO cars and big-block Corvettes. The only time I recall seeing those being problematic is on circle-burners. They've got slicks all the way around, and the front brakes (and hence studs) get exceptionally hot. Those fellas jump straight to 5/8" studs with oversized bulge-seat nuts.

Dorman A-body 7/16" stud part numbers:

Front disc brakes - 610-130
Front 10" drum brakes - 610-096
Front 9" drum brakes - 610-083
Rear - 610-186

Dorman no longer services LH thread studs so all are RH thread. Some places sell the numbers individually using the same number with a .1 at the end (like 610-186.1). NAPA often uses their own WW2-Enigma-machine part numbering system, but they should be able to cross-reference them. If you need longer than stock, look at the knurl diameter of the stud you're replacing, and find a longer option with the same knurl and similar shoulder. Since GM used 7/16" nearly across the board, there should be plenty of options. I got longer 1/2" studs for my E-bodies from Summit, both Moroso and their house brand.

The stud holes in hubs, drums, and axle shafts were not knurled; the knurl was created by the stud being installed. I helped a friend with studs for new Moser axles for a Chevy II, including calculating drill-bit size to use the oversize knurl on the stud length he wanted. The Moser axles were not knurled. The studs are as secure as OE.
 
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