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JMortensen

CV bolts loosening

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I've seen threads about this from time to time. Always thought it was particularly the Wolf Creek CVs and it was flex between the AL adapter and the steel CV that caused it, but mine is steel to steel and still having the same problem. Figure I'll post up my problem and solution and whether it works. 

Problem: Z31T CV 4 bolts are loosening when racing. I replaced the hex bolts with allen bolts because the hex head was so close to the CV body that it's impossible to get a socket on it. Using 12.9 grade bolts. Ran 1 autox, they were loose again. Red loctite. Ran another autox, loose again. 

Solution: drill and safety wire the bolts. Bought a bolt drilling jig off of Amazon for a whopping $25. Hopefully it works well and I can safety wire the bolts. Already have pliers and all that from wiring my front rotors to the hats.

Anyway, will report back when the tool comes and the install is done, then report again later on when I take the wire off and check for bolt stretch probably in the winter.

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Thanks. I use bacon grease for cutting fluid. Machinist taught me that one, works great.

As far as drill bits, I'm hoping my cobalt bits from HF do the trick. They're shockingly good drill bits, but the bolts are 12.9 so might be hard to get through...

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It is surprising that the red locktight didnt work, that stuff is a pain to get off. I have 12.9 grade hex bolts with low profile heads (from fastenal) with lock washers and I havent had this issue. I wonder if it could have something to do with the CVs binding? did you shorten the axles?

 

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I have longer than stock control arms. Definitely not binding. I actually sold the short axles for a while to solve that problem, but that was after I fabbed up the control arms for my own car to fix.

Might have something to do with my flexplate/button clutch, which is extremely aggressive, or the 14" wide slicks. Whatever the reason, it's happening and I'm gonna fix it.

I did look up the torque spec and it's 55 ft/lbs, so I was definitely undertorquing them.

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Jon, what size allen bolts are you using?  You can usually find pre-drilled allen or 12 point bolts for CV axles.  Vendors like Swayaway and Kar Tek carry most common sizes in pre-drilled.  Might be worth the extra expense just to avoid the hassle of drilling 2 dozen bolts.  :-)

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They're 10x1.25, so no, none of those will work. Drilled 2 so far. Really not that bad. Takes about 5 minutes per bolt. Problem is that when the drill bit pierces through the far side of the bolt it breaks. 2 in a row. I'm just going to keep moving up in drill bit size. Hopefully as they get bigger they'll get tougher. I have 2 complete cobalt drill indexes so I'll have enough, but it's going to be a bummer losing 8 drill bits (4 bolts on Z31T CVs x 2).


 

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Tool: https://www.amazon.com/gp/product/B074J83Q2V/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

There is a larger hole on one side and a smaller on the other side of the piece that locks onto the head of the bolt. I'm using .031 safety wire, so I used the smaller side. When drilling through the round head, it barely hit the bolt at all, so I just drilled a hole farther over. 

It's a cheap tool and really there are super hard drill bushings that you can buy that would make this thing a lot more durable but probably increase the price a lot. My self drilled hole has already wallowed out quite a bit, but it will work for 8 bolts. If I was doing this a lot I'd buy a better tool. I'll take a pic when I get out to the shop today.

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I also figured out that if I set up the drill jig in a way that the drill bit hit the inside of the Allen head flat, that was better than hitting an angled surface. You can see how oblonged the hole in the tool is, but as you said earlier, placement doesn't really matter, just need to get a hole in the bolt for the wire to pass through.

drilingtool1.jpg

newoblonghole.jpg

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Might try the colbolt bits from McMaster. They are a bit harder than the HSS bits but not as fragile as carbide. I have used them in harder material. 

 

I had a real problem with loosening drive shaft bolts. I ended up taking the nuts, placing a chisel across the face and giving it a solid whack. It peens over the edge and stopped my loosening problem. Safety wire is probably a better idea though. I may go ahead and do this when I assemble my CVs. Keep us posted on how it works out

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I got through all of them with 3 Harbor Freight cobalt bits. Broke the first 2 bits on the first two bolts. Once I changed the angle I was drilling at, no problems at all. I agree cobalt is the way to go though. I used to get Harbor Freight gift cards as credit card rewards so I have a ton of their tools and have tried all their bits. They all suck, except the cobalt ones, which are pretty amazingly good IME.

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