So the upper strut mounts on my G35 sedan keep loosening up. First it was one side, now it's the other, I have a feeling it will just be back again since the roads in NYC are terrible.
I looked at the OEM parts, and Infiniti only uses a non-serrated flange nut, which is crazy. So I want to swap it to nylon locknuts.

I don't know 100% for sure what the original size / pitch is. I know replacements are usually M8x1.25 30-40mm bolts.
Can anyone confirm if M8x1.25 is in fact the OEM stud?

 

I'm 99% sure its M8x1.25
Japanese cars seem to use 1.25 pitch quite often, 1.0 pitch seldom, and I've never seen 1.5 pitch.

 

I�ll take 99% sure as good enough to order a few bucks of hardware and report back if it�s off. Thanks.

 

Are you talking about the single nut at the top (30ft/lbs) or the two nuts that bolt the flange to the chassis (28 ft/lbs)?

Are you sure you are TORQUING them?

The single nut at the top is not a reusable nut, it's one of those tri-squeeze locking nuts that are good for ONE USE.

Nissan part number 55269-4U00A they're like $1.50 apiece at your local Nissan. If that's the one that's loosening I can guarantee it's because you are reusing the old ones.

 

It�s the two that go to the upper mount, not the thrust nut. My jack and stands are all packed up for moving so my mechanic is doing it. Is he torquing to spec? I dunno. But I�m not about to pay Infiniti 2 hours of labor for them to tighten 4 nuts, and the dealers won�t even put the car on a lift if you don�t show up waving around at least $300.

 

Yeah I wouldn't pay for that either, just make sure the mechanic is torquing it to 28 ft/lbs. You typically won't find any kind of locking fastener (serrated flange nuts, lock washers, etc) on components like that because they will tear the paint/coating off of the chassis which will allow for rust to form. Typically it's just flat-faced flange nuts torqued to spec. If you still can't get them to hold then add a little loctite 242 or 243 to it.

 

It�s just the upper strut mount, not the chassis (which has studs) but those seem like reusable parts so your point on the paint makes sense. I do like the Loctite idea, Loctite Blue is probably good for this application. I hate Loctite red especially on stuff prone to rusting. Thanks.

 

Yeah the blue loctite 242/243 would be best, red loctite 271/272 is great but you have to hit it with a torch (heats up and turns back into liquid) to remove. I use both for different applications, red is great for things like flywheel/flexplate bolts where you have plenty of room for a torch. Blue for things like adjustable suspensions or any other chassis fasteners that might wiggle loose from vibration.

 

Yep. Loctite Blue is specifically for this application: removable nuts/bolts that are loosening from vibration. A match made in heaven. Thanks for the idea, I totally did not think of that.