I ordered a conversion kit from Motorsport Hardware for my Crossfire and just finished the installation. It consisted of a full set of 75 mm studs, a set of ball seat nuts as well as a set of conical seat nuts. Why? I mount my stock rims and tires for daily usage with a spacer on the front to clear my Stoptech's. For the track I have a set of rims and sticky tires that require conical lugs and finally a set of AMG reproductions with drag radials for the 1/4 and 1/2 mile. The tire shops I've used have stripped several of my lug bolts over time. They were warned to torque the bolts but what can I say, air tools is what they use and any damage was "prior" to their encounter with my car. A&&holes. The stories I could tell ..... but I digress. Being worried about the length of the studs and not knowing exactly how they were measured I resorted to google for answers. I came up with 75mm as the perfect length. Well, I was right about that but I ended up with bullet tipped studs. The last 5 to 8 mm doesn't have threads. A test fit indicated it might be enough length. I took some pictures, see pics. I left the rotors on but loosened the screw that secures it to the hub. The next thing I did was use a tap to clean up the threads. The rears were fine, the fronts were a mess. All I can say is thank goodness the bolts are made of a much softer material than the hubs. After repairing the treads with the tap I sprayed them with brake fluid. I'm sure you know to use lubrication with the tap, don't you? Brake cleaner gets the thread's ready for the Loctite. Loctite Blue was my choice for the studs. I torqued to 20 ft. lbs. I found conflicting info on how tight to torque them and chose 20 as the number for me. The hub center covers clear the studs so you can keep the stock look. However, with my 10 mm spacer and the bullet nose studs, not enough threads are engaged by the nuts. If the studs were threaded to the end ..... perfection. The 10mm spacers had to come off for some 5 mm I had in the closet. So now you know what will work with a stud conversion kit. 75mm threaded to the end.

As you can see, if your lowered and take your car to the limits around corners, you will have interference with the wheel well. Perhaps running -1.5º of camber is part of the reason. Seeing is believing, don't you think?

Les

 

Well worth the investment, I did this 2 years ago....you have better quality studs than I got from WheelDude though.

 

Question: Why did you tap the holes? Just cleaning them out?? Or was there damage from the stripped bolts?

 

I run spacers with the stock front rims and had several of the bolts damaged (stripped to varying degrees) by tire shops using air tools. The bolts are softer than the hub material but they still needed the threads straightened. The locktite needs a clean surface to bond too as well. Considering the stress I subject my car too it seemed best to run the tap in all the holes. Besides, my tap set has been sitting hardly used for years, I couldn't pass up the opportunity to use them.

Les

 

Did you mean brake cleaner?
Inquiring minds need to know.
I'd also mention that this is not a job for cheapo Chinese taps, these often cut oversize and you do not want that at all.

 

Yeah, brake cleaner. I'll go back and edit it so future generations aren't confused by my ADD.

Les

 

It is amazing how others spot our mistakes when we are sure that there is no error to be found. I am pretty good at spotting the mistakes of others while being totally oblivious to my own. Sadly the same can be said of our personal faults.

The higher one gets in the hierarchy of management the less mistakes one makes as they can always be attributed to others, you can then be seen as lily white and free to accept all the honors for those things that are a success.

 

something I have considered for a long time...thanks for sharing Les...

 

A note about how these are measured. From tip to tip. If you buy 75 mm that's from tip to tip. So you have to subtract the portion threaded into the hub, the rotor depth, etc. so it's not as simple as it would seem. The lugs need to have 5 full turns on the stud, well that's what I read.

Les

 

If you value your nuts and who doesn't, you should have about the same engagement as the stud diameter. Generally you could get away with about .80 x the stud diameter. However some nutter with an air wrench can wreak havoc on those studs and nuts if the engagement is too little.
Five full turns is 7.5 mm and that is only .62 times the stud diameter. I always thought the stud engagement in the axle flange was too little and that would lead to stripped threads and it has.

 

Thanks! I want these so bad!

 

Just to add a little bit of info, any m12X1.5 stud will work. We used 90mm on our car with a rounded nose, with the rounded nose you cna put the lug in a gun and just zip it on. No need to start the lug by hand. The length is good for up to a 15mm spacer but obviously too long for stocker rims without spacers. Here's a link with all the info you need.
Apex Competition Systems - Auto Racing Parts and Equipment

 

Just to be clear, I have plenty of thread engagement with the race rims. Where I'm a little close is the stock rims with a spacer. Right now I'm kicking myself for getting the bullet nose studs so learn from me. I'll measure the depth of engagement to be positive as I'm racing TOMORROW! YEEEHAAA! Can't wait! Can we say "torture test"?

Les