How many threads do you need?

[Seppi72]

I want to run the widest 15" tire I can on my 240 and I've settled upon Yokohama AVS ES100 225/50-15 rubber. However, because of my wheel offset, I need to use a 1/2" spacer to avoid rubbing on the front strut and/or spring. There's no problem with the rear.

However, when I put the spacer on the hub, I only have about 5.5 threads left exposed to engage the nuts. The only reason I have this much is because, as I have found out during the course of trying to resolve this issue, a PO swapped out the OEM front studs with some of the longer rear studs. See the discussion from 2005 at http://www.classiczcars.com/forums/showthread.php?t=18276 in order to understand what's up with that.

My question is how many threads do I need to have engaged to provide for my safety? I typically torque my wheels to 65 ft-lb. I asked a mechanical engineer with whom I work about this but he was only able to tell me the minimum torque needed to prevent the nut backing off (about 28 ft-lb).

As the 2005 thread mentions, I could get longer studs from ARP, but they would have a 1.5 pitch instead of the 1.25 that the OEM studs have. I would probably opt for the Nissan Quest stud that was said to be about 9 mm longer than the OEM 240 front stud, but that's only 3 mm more than what the rear 240 studs have to offer. That would give me about 2.5 more threads to engage, for a total of about 8 threads.

Would this (8) be enough threads to provide a safe mount considering the forces that the studs see in spirited driving (not racing)?

Edited June 25, 2009 by Seppi72

[Arne]

When I sold tires and wheels in the late '70s, '80's and '90s, the wheel companies all said a good rule of thumb was that you should have the same engagement as the diameter of the stud. So in this case, a full 12mm of threads.

A 12x1.25 bolt is 1.25mm per turn, so if you have 5.5 turns you only have 5.5x1.25=6.875 mm of engagement, not nearly enough. The Quest studs would give about 10mm of engagement—better, but still marginal at best.

Working that backwards, to get 12mm engagement, you'd need almost 10 turns on a 1.25 pitch bolt.

[zpizzaman20]

http://cgi.ebay.com/ebaymotors/25mm-114-3-WHEEL-SPACER-ADAPTER-NISSAN-240SX-280Z-300ZX_W0QQcmdZViewItemQQ_trkparmsZ65Q3a12Q7c66Q3a2Q7c39Q3a1Q7c72Q3a1205Q7c240Q3a1318Q7c301Q3a1Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem3353637e31QQitemZ220442361393QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

These kind of wheels spacers will take care of that.

[Arne]

http://cgi.ebay.com/ebaymotors/25mm-114-3-WHEEL-SPACER-ADAPTER-NISSAN-240SX-280Z-300ZX_W0QQcmdZViewItemQQ_trkparmsZ65Q3a12Q7c66Q3a2Q7c39Q3a1Q7c72Q3a1205Q7c240Q3a1318Q7c301Q3a1Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem3353637e31QQitemZ220442361393QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

These kind of wheels spacers will take care of that.

Except that they are twice as wide as needed, and could cause clearance issues from sticking out too far.

[Seppi72]

Pizzaman:

Those spacers solve one problem but exchange it for another. Now, you have to machine pockets or a channel into the backside of your wheel to accept the portion of your original stud that extends past the spacer. I had to do that years ago when I put some aluminum wheels on a Honda Accord. It was a royal PITA.

The other option is to cut down the original studs so they don't protrude past the spacer. I would think with a 1/2" (12.7 mm) thick spacer, I'd then be violating Arne's rule that engagement = stud diameter. And I'd still have machining work to do to make sure everything was equal.

Looks like I'll be buying two packs of the 1.5 pitch ARP studs from my local JEGS store tomorrow. And I just bought some really nice 1.25 pitch tuner nuts last weekend.:stupid: At least AutoZone had the same nuts in 1.5 pitch IIRC. What's another $30?:pirate:

[zpizzaman20]

When I got these the nuts were flush with the wheels.

I could not fit the 77-78 factory mags over s14 rear brakes.

Arne, I meant the style not the size, sorry for the confusion.

[hls30.com]

Pizzaman:

Those spacers solve one problem but exchange it for another. Now, you have to machine pockets or a channel into the backside of your wheel to accept the portion of your original stud that extends past the spacer.

Here is an easier and polite suggestion:

Shorten the stud...flush with the installed lug nut.

Dremmel, die grinder, hacksaw, etc...

Will

Edited June 25, 2009 by hls30.com

[Seppi72]

Here is an easier and polite suggestion:

Shorten the stud...flush with the installed lug nut.

Dremmel, die grinder, hacksaw, etc...

Will

This is exactly what I ended up doing, Will, finishing the install last evening. I shortened the ARP studs by 10 mm (they have about 3" of thread) so that my wheel nuts could actually make contact with the wheel and force it against the spacer.

I don't know what ARP uses in making those things but they are extremely hard. I went through four blades on my Tiger saw to trim just eight studs - even with 8% cobalt blades. Sparks galore. But they did grind pretty easily after that and dressed up quite nicely. I am now officially a happy camper.