Wheel stud difference front to back

[GotToGo]

Hi Guys,

I was just looking for a new set of wheel studs and found out the fronts are shorter than the backs.

Is it that big of a deal or will the front size also work on the back?

[pennyman1]

They will work, but you may need different lug nuts if they are the closed end type. They are shorter due to the fronts have to go through the hub, where the rear only has to go through the axle shaft and drum which is much thinner than the front hub.

[GotToGo]

Thanks!

[SubGothius]

Gonna necro this old thread for some clarification and to keep the info in one place.

I need to replace a busted rear lug stud and found RockAuto lists 4 different lug studs for my '87, but no application notes (front vs. rear wheels, or RWD vs. 4WD), apparently in 2 slightly different styles along with some puzzling differences in dimensions:

Short 7mm shoulder:
PTC 97188 (https://www.rockauto.com/en/moreinfo.php?pk=9840624&cc=1096286&pt=7680) - Thread length 37.5mm
DORMAN 610262 (https://www.rockauto.com/en/moreinfo.php?pk=1060256&cc=1096286&pt=7680) - Thread length 27.8mm

Long 12.5mm shoulder:
PTC 97232 (https://www.rockauto.com/en/moreinfo.php?pk=9840780&cc=1096286&pt=7680) - Thread length 44.5mm *
DORMAN 610312 (https://www.rockauto.com/en/moreinfo.php?pk=1060215&cc=1096286&pt=7680) - Thread length 28.266mm
(*I think this spec may be in error, as it's greater than the spec'd Overall Length 42.25mm!)

Based on the prior posts in this thread, I'd infer the short shoulder is for rear drums, and the long shoulder is for front discs. Anything else to bear in mind or explain re: the differing thread lengths?

[FMS88]

Online parts catalogs (PartSouq, Amayama) described the 4WD front stud, MB301509, as 12x36mm, and an Amazon listing from a search of the P/N states the shoulder as 7mm.
https://partsouq.com/en/catalog/genuine/unit?c=MMC202501&ssd=%24%2AKwGbr76IhJ7nnsGF_sy_icPX9_Dun5CdnI6hktrc 7_vn4-Hip7Cc9tjc2On_5vexrKabkuOcmZjRzrCFwN2KlYzzioOPk9zY m9XR2-nTjdnSxMDzioOMysaNl9K815ubn5mZnu6P3NyBwIqVnIWK2o_K 3NCfhZ6bmYqDj5nc2IuZnZiGmZ2br8_XmZv-4p3sn_nSg5zfzcfu0orMj8rewOudnZ2Zn5-bsdzOiYrCjJOIjebDzbaLhI-MysSNl9Dct-f745yL1QAAAAB4_XIN%24&vid=0&cid=2&uid=36240&q=

https://www.amazon.com/Wheel-Bolt-Front-Rear-MB301509/dp/B0DJZ8YPXN

The catalogs list the rear studs (P/Ns MB393409 and MB584750) as 12x43mm. Didn't find any other sources that mentioned the shoulder length of the rear studs.

https://partsouq.com/en/catalog/genuine/unit?c=MMC202501&ssd=%24%2AKwEYLD0LBx1kHUIGfU88CkBUdHNtHBMeHw0iEVlf bHhkYGJhJDMfdVtfW2p8ZXQyLyUYEWAfGhtSTTMGQ14JFg9wCQ AMEF9bGFZSWGpQDlpRR0NwCQAPSUUOFFE_VBgYHBoaHW0MX18C QwkWHwYJWQxJX1MdBh4cGgkADBpfWwgaHhoFGh4ZLE9QGhh9YB tqHXpRAB9cTkRtUQlPDEldQ2geHh4aHBwYMl9NCglBDxALDmVA TjUIBwwPSUcOFFNfNGR4YB8IVgAAAACLSVb4%24&vid=0&cid=2&uid=36241&q=

[GotToGo]

Gonna necro this old thread for some clarification and to keep the info in one place.

I need to replace a busted rear lug stud and found RockAuto lists 4 different lug studs for my '87, but no application notes (front vs. rear wheels, or RWD vs. 4WD), apparently in 2 slightly different styles along with some puzzling differences in dimensions:

Short 7mm shoulder:
PTC 97188 (https://www.rockauto.com/en/moreinfo.php?pk=9840624&cc=1096286&pt=7680) - Thread length 37.5mm
DORMAN 610262 (https://www.rockauto.com/en/moreinfo.php?pk=1060256&cc=1096286&pt=7680) - Thread length 27.8mm

Long 12.5mm shoulder:
PTC 97232 (https://www.rockauto.com/en/moreinfo.php?pk=9840780&cc=1096286&pt=7680) - Thread length 44.5mm *
DORMAN 610312 (https://www.rockauto.com/en/moreinfo.php?pk=1060215&cc=1096286&pt=7680) - Thread length 28.266mm
(*I think this spec may be in error, as it's greater than the spec'd Overall Length 42.25mm!)

Based on the prior posts in this thread, I'd infer the short shoulder is for rear drums, and the long shoulder is for front discs. Anything else to bear in mind or explain re: the differing thread lengths?

Your question prompted me to do the wheel swap I've been planning so I got a better look at the studs today. It didn't help much. :)
The drum was in the way on the rears so I wasn't able to verify which stud I have on the rear.
But I could on the fronts. I found an old stock stud that I saved and it was a match for the front. 13mm shoulder/29mm thread.
And these are not the most accurate measurements. But I think they do corroborate your inference. Just stick with the 28ish thread lengths.

I also noticed that F and B studs all protruded 25mm of thread with the wheel off.
I measured the depth of the stock acorn lug nut to be 28mm.
So it's not going to bottom out.

Hope that helps, and good luck!