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Jensen Healey Extended length wheel studs - "knurl" dimension?  Rate Topic 
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 Posted: 11-22-2021 08:49 pm
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discogodfather
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Recently doing some wheel work again on the JH. About a year ago I replaced the front wheel studs with some original factory studs from Greg.

I've been using a set of John Brown wheels in 4 x 106.5 that were meant for a mini cooper (the original kind). What I have noticed recently is that the lug nuts (some aftermarket aluminum ones with a beveled edge to suit the beveled edge on the John Brown Wheels) don't really seat that far, maybe only around .6" deep.

The factory wheel studs just aren't very long, and with thicker flange aluminum wheels it seems like it's just too short. I always use a bit of anti-seize on the studs and it only really torques to about 40-45 ft lbs.

There are many different kinds of extended length 7/16" X 20 wheel studs out there but I am unsure of the "knurl" dimensions on the factory wheel studs. Does anyone know off hand? The "knurl" is usually measured in a dimension like ".560", ".450", etc. Also I have seen them in metric, in mm. I am assuming if the thread is Imperial, then the "Knurl" should be as well?

Is there more to the fitment than just the "knurl" dimensions? I see a lot of geometry there.

Here are what the original wheel studs look like:





Some aftermarket extended from Moroso and ARP:




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 Posted: 11-28-2021 02:49 am
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discogodfather
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Thanks to Bruce for getting some great measurements on the "knurl". Looks like these are around .520" (or 31.1mm).

As usual, when I try to locate some aftermarket ones (there are a bunch available in 7/16"-20 from companies like ARP, Moroso, Dorman, etc) there is nothing that comes close to the .520" dimensions. There are a few around .507", and the question does come up: how are the "kurls" really measured technically- is it outside diameter, inside, or some kind of cross between the two?

There are quite a few oversize at about .550". so I could always drill out the hubs a bit and press them. Acceptable sizing for the hole seems to be around .01"-.09" undersized.

There is also a question of moving from 7/16"-20 to something like an M12 thread.

Have to put my thinking hat on for this latest custom job.

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 Posted: 11-29-2021 02:08 am
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Tom Bradley
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Not sure if this helps, but many years ago I found some replacement aftermarket wheel bolts that worked. (See comparison pic). I measure slightly less than Bruce: 0.518"-ish on the outside. The flat part of the replacement bolt looks flush with the inside depth of the knurl and measures 0.494". Assuming that this was a standard size and not something weird, my guess is that the 0.507" sized bolts will likely work.

Attachment: wheel studs.jpg (Downloaded 100 times)

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 Posted: 11-29-2021 06:22 am
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discogodfather
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Tom Bradley wrote:
Not sure if this helps, but many years ago I found some replacement aftermarket wheel bolts that worked. (See comparison pic). I measure slightly less than Bruce: 0.518"-ish on the outside. The flat part of the replacement bolt looks flush with the inside depth of the knurl and measures 0.494". Assuming that this was a standard size and not something weird, my guess is that the 0.507" sized bolts will likely work.

Yes I think you are right Tom. ARP has a web page with some instructions on fitment and they say the hole needs to be anywhere from "0.006-0.016˝ smaller than the Knurl". I tried measuring a bare hole and get around .501" so .507" would be right at the small end of the tolerance.

Some assumptions for sure but I think it all is within a range that can be reasonably assumed is ok.

I found a set of right sized ARP studs with a .507" knurl meant for a Miata that are quite a bit longer than stock (at least .6" for a total threaded length of around 2.1", where as stock is about 1.45"). It will change the thread to M12x1.5 but I doubt this is anything but good as well since there are so many more lug options. I found a good set of open head steel lug nuts on Amazon for $20.

Looking at how the hubs have slightly recessed areas on the thread size and reading carefully about how ARP mandates that there needs to be slight chamfer on the threaded end of the studs (not sure why this is, but it apparently can lead to stud failure without) I felt really uncomfortable drilling out the holes for a slightly larger size. The next size up was around .56" and that requires a 14.5mm hole.

I'll post some picks when I get things ready to press in.

Wow was it hard to remove the rear half shafts from the axle. Had to rent a slid hammer and I nearly knocked the car off the jack stands getting them out. Good thing, one bearing was pretty much gritty and toasted.

Getting this bearing off the shaft is also giving me a headache. My press doesn't have a wide enough mouth to push it off, so I will try and get it done at a friend's shop. That retainer ring is bothering me- might it crack if I press it off? Not sure if they are available, will have to call Delta tomorrow.


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 Posted: 11-29-2021 07:32 pm
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redracer
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Disco: have done many of these bearing replacements. Use a small cut-off wheel(think DREMEL) and cut the retainer at angles until nearly through. A chisel and a small sledge will crack it. You will likely need to do the bearing in the same manner.
I believe even the workshop manual suggests this method.
good luck, bruce

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 Posted: 11-30-2021 10:00 pm
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discogodfather
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redracer wrote:
Disco: have done many of these bearing replacements. Use a small cut-off wheel(think DREMEL) and cut the retainer at angles until nearly through. A chisel and a small sledge will crack it. You will likely need to do the bearing in the same manner.
I believe even the workshop manual suggests this method.
good luck, bruce


Thanks Bruce, will do. Found the passage in the workshop manual. I will just cut it completely off rather than using the non-existent specialty tools.

Last edited on 11-30-2021 10:01 pm by discogodfather

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 Posted: 11-30-2021 10:12 pm
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redracer
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For pressing both the bearing and locking collar on, I went to our local hardware store and got/had made a length of pipe that just fits around the shaft and obviously long enough.
good luck, bruce

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 Posted: 12-06-2021 05:14 am
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discogodfather
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Got the old bearing and retainer off cutting it. Then I repainted everything and pressed in the new wheel studs. Crazy thing: the place I ordered from sent me the wrong wheel studs- different from the Miata kit I ordered, instead they sent me 100-7708, which is late GM kit. They are longer and not bullnosed, and they had a .509" knurl. They also are in M12 x 1.5.

After looking at these GM studs, I concluded they were actually better. They are about an inch longer, and the .509" give a little more tightness to the fit than the .507"'s. I needed 2 tons of press pressure to seat them fully, and it feels right.

New bearing kit from Mike at Delta. The bearing are now $92 a piece! New shaft retainers included. Delta also has the paper gaskets.

A note on pressing bearing in: you need the cover plate AND THE GASKET in place before you press, or else you will be extremely sad when you realize they can't go on with the bearing in place. The gasket can't fit over the bearing either.

Looking good, more to come.......

Stud length difference:







Old



On the press:





Last edited on 12-06-2021 05:20 am by discogodfather

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 Posted: 12-06-2021 03:01 pm
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redracer
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Interesting last photo; looks like you have the press in your library!

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 Posted: 01-25-2022 11:05 am
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discogodfather
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Disaster on the first studs, they were simply not seating correctly in the stock holes. Looks like they were about .002 under and it will just not work- they wiggle a bit.

Another problem- the geometry of the threaded area isn't right. The stock studs end their threads before they contact the drum, so the studs basically don't support the drum using the threads only. The ARP studs (from the GM late model kit) don't do this- it's all threads.

So back to the drawing board, this time really analyzed the geometry needed. Found an Evolution 8 ARP kit (Mitsubishi) and it was oversize on the "knurl".

Used a 14mm drill to make new holes, using a drill press, as noted in the ARP online how to. Pressed in the new studs one at a time and got a good 4 tons of pressure on each one, now very firmly seated and zero wobble.

Also drilled the drum holes out to accept 12mm, had to used a 12.5mm drill bit because at 12mm it was just too tight.

New studs are better than the old ones in that they have the "speed" smooth ends that look good and are very practical (saves the threads). I think ARP calls this a "speed stud", ala Nascar.

Now I have to do the fronts!





















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 Posted: 07-06-2022 04:26 am
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discogodfather
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And finally on the front wheels.



Last edited on 07-06-2022 04:26 am by discogodfather

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