Question for Mike, Ross regarding 5 bolt conversion

[silicone boy]

Ok guys, I was just now drilling out my rear stub axle (280Z) for a 5 hole bolt pattern. I used an old rotor (300zxt) for a template and I'm doing it off the car on a drill press, so it's about as accurate as you can get. Obviously, on the squarish shaped flange, 4 of the 5 holes are going to be close to the edge of the flange. I have about an eight of an inch of metal left on the edge. Have you found any problems with this? It seems like it would be kind of weak to me, but I guess it's OK since many people on the board have mega HP cars. Right now, I wished I would have stuck to the 4 bolt pattern, but I'll feel differently when I'm done. By the way, you mentioned you used ARP wheel studs for GM cars. What diameter? The stock ones look to be just over 1/2" and I don't really want to drill it any bigger because of the above problem. Thanks in advance.

[Modern Motorsports Ltd]

-are you doing it with centre/transfer punches and progressive drill bit sizes? If so that's about as accurate as you can get doing it without actual machinists tools I suppose. I drilled mine by hand but have some mild vibes that might be attributed to the drilling or old bushings..I'm replacing them with a machinists set done on the rotary table just for my own piece of mind when I do my upcoming rear control arm swap.

 

-2 of the 4 holes are very close to the edge, from the DIY's I've read they typically leave those holes as is and it can be very thin at that outer edge (ie. 1/16" or less depending on your flange/drilling accuracy/knurl size)

 

-all of my 'prepped' 5lug axles have 'eyelets' welded up on those two tight sides to provide complete safety. It's likely not an issue as the full stud head has to pull out or shear laterally which would be quite a failure but I like 'em welded up nicely as I get a little anal about safety details that are easy to add at nominal cost and of simple benefit. Especially with parts we very rarely if ever service such as these...if you've pulled 'em once you don't want to do it again

 

-I typically use 7/16's ARP's on my 'prepped' stubs and on occassion 1/2" for special app's . Keep in mind what you plan to mount on them and whether or not spacers may be required. Slipon's are commonly used on my prepped rears FWIW. I prefer them to bolt ons but you want to be sure your holes are dead plumb as it takes very little eccentricity/out of plumb over a 3" stud to be noticeable on a nice custom made snug fitting spacer or redrilled rotor.

 

Here's a pic of one pair. You can see the modified dust seal reinstalled in the side pic as well. Those are 3" ARP 7/16's studs which will accomodate up to a 1.5" spacer with mag wheels and a rotor included.

 

HTH, any more q's feel free.

 

[silicone boy]

Ross, thanks. I read in another posting that most people take them to a machinist, and considering that I would probably spend a small fortune in drill bits, I'm going to take them to a machinist as well (I've only done two so far). I agree with welding it up on those thin ones. I'll do the same. If I mess it up, I'll contact you about purchasing a couple of finished stub axles. I didn't know you sold them. How much are they anyway?

[Guest scca]

i;ve done many and never welded the edge of the hub and IF you didnt use a punch to mark the pattern you will likely be off a few thou and that WILL vibrate..

 

been there done that..

 

early 300 stubs are the same length and i have been looking into machining up pieces to enable to use that stub axle in a early car. not done yet but its a possibility and that will be much better than any drilling - and its got the larger splines for easy cv conversion

[Guest Anonymous]

I would try to do any thing in fabrication or modification but drilling those flanges for wheel studs is one prescion job and off a hair could cause annoyance to the extreme like vibrate your dental fillings out. But I like the washer reinforcement behind the flange but only spot welded sparingly.