Everett Ogilvie

OK, I am a pretty sharp guy I think (BSME, 40 years+ experience building race vehicles, etc.), and I am baffled by these BS ARP wheel studs. I could not put them in and everyone said it takes a bench press so I took them to my local guy who has built thousands of Corvettes from the ground up. His 20 ton bench press is bending the header, so he goes and gets a 70 ton press and it puts the studs in (barely). I get the hubs home and the hat/rotor won't fit over the studs because they are SPLAYED just enough that the hat won't go on (let alone wheels).

So my question is - why in the hell would these studs need to be .010 over such that they go in so hard that if not absolutely perfectly seated, they are splayed? There is not one reason for them to be .010 over.

.002 - .003 would be just fine, after all they are not going to spin.

I am baffled (and pissed if you can't tell). ARP will be hearing from me.

wallyman424

i had a hell of a time putting them in w/ a press.

they go in like BUTTER w/ the washer and impact gun trick. Also a dab of gear oil on the spline works wonders.

NASAblue

Some spray lube and axle grease between a bunch of washers and a lug nut/impact/breaker bar application still might straighten them out and make sure they are completely seated.

John Shiels

That is how I did mine years ago with no problem

Everett Ogilvie

Thanks, clearly I have to get them fully seated, which they are not if they are splayed.

My question is around poor design - there is no conceivable reason they need to go in this hard, i.e., no conceivable reason they need to be this much oversize. As a ME I can provide the complete yield/force/stress analysis, and the only forces they are subject to are tensile forces. As controversial as this may seem to some, they are not even subject to shear or bending, for several reasons; 1) the clamping force should be enough to completely eliminate shear and bending, and 2) if the wheels are hub-centric (which they should be) the studs are again only in tension - THUS no reason for this extremely tight fit.

And before someone asks if perhaps my specific hubs have "bad" (tight) clearances for some reason, two of them are brand new SKF race hubs and two are stock Chevy OEM parts with 2000 miles on them, i.e. new parts from different manufacturers. The studs are splayed in all of them. I can see Timken and SKF units varying by a couple of thousandths and ARP needing to design for that, but 10 over is not even in the ballpark.

This is poor design and would not be tolerated by my company (without some sort of disclaimer attempting to explain why the fit is so tight).

NASAblue

The more difficult press fit may be a factor of the metal hardness being greater with the ARP stud and since it is designed to be an interferance fit, more effort must be exerted in yielding the harder material. WHich you already know.

I don't think it'll be some sort of design flaw though. I guess they could back off the interferance tolerance to compensate for the material properties. It's hard to believe a lug nut, washers and grease with a little leverage can exert that sort of pressure. Simplicity is beautiful.

On another note, I've often wondered if you can replace arp head bolts or studs or what have you with bolts of the same material properties from granger or fastenall. Seems like you could... Right threads same material properties, why not?

With that said, I definately use ARP on my heads not granger bolts... but I used high strength bolts from them in all sorts of other applications.

Sorry for the tangent, good luck.

Everett Ogilvie

No tangent, good thoughts and along the lines of the discussion I would like. Thanks.

Like you, I can't believe that an impact gun and a nut can generate more force than a 70 ton press and get them straight, which the press could not. I can possibly see it coming close to a 20 ton press, but I will have to do some rough calculations of the thread pitch to see the maximum force that can be generated by an impact gun which can generate XXX torque.

I have always considered ARP to be the absolute best quality fasteners there are, which is part of my dismay. Anyone can make a "hard" part - getting the total design right is what counts.

fatbillybob

I 100% agree with you. I just did this on my skf hubs. First I tried the press. NO WAY. Then I used a 1" spacer and some washers and my impact gun and drove them home with a lugnut. Super easy very fast. My concern is that the studs are so oversized they will fatigue crack the hub holes. That is a total accident waiting to happen and you can't inspect the hub for such cracks without taking the rotors and calipers off! What a PITA. When you call ARP you tell them I won't use their product again either and I'll tell anyone why not.

CHJ In Virginia

OK guys take a step back. Check the ARP part number again to make sure that you got the correct studs for the Vette application. The last set I installed, 6 months ago, seated fine using a 15 ton press and no lube. The hubs were replacement SKF hubs from Auto Zone. Took me less than 30 minutes to press them in for all 4 hubs and seating was not a problem. Something is not correct here - 0.010 over is too large. Did you mike the studs compared to the OEM studs that were removed (measure to the outside of the splines) ?? Did you mike the ID of the hole on the SKF hub compared to OEM ? Who was doing the press work and what is their level of experience ?? How were the press and dies set up ?? Not trying to throw stones here, but something definitely is not correct and detailed measurements are in order to figure out what is FUBARRED.

flink

Yeah, check that the correct parts were used.

According to the ARP FAQ (which seems to have disappeared, but it's in the google web cache):

And +1 on using the nut-and-impact wrench approach. Lots of lubricant and use a 14mm nut as a washer, because plain old washers get mangled. The thing I like about pulling the stud in is that it's more likely to get pulled in nice and square, whereas it could wander off-axis if you're pushing it.

Everett Ogilvie

Thanks again for the inputs guys. I wrote another post earlier detailing how my guy asked me 4 times if I had the right part and how we verified it again on the web site vs. the part number on the packages etc. I also detailed how he owns a Corvette specialty shop, so he knows what he is doing. I said that he used grease, he hated the hard surface of the studs which resists any compression (which it HAS to do b/c they are so oversize) and how he was extremely nervous about cracking one of my hubs b/c it takes so much force. He also said that if a guy broke one of these at the track he might be able to hammer it out, but no way in hell could you put one in at the track. Like I said, I wrote a long post with all this info, and in the end decided not to post it. Guess I just did. Oh, I also wrote earlier, but did not post, that 2 of the hubs are SKF and 2 are OEM Chevy , so 2 different manufacturers of the hubs have the same issue - it is the studs, not the hubs. In another thread a day or two ago I posted the info about how I mic'd them when I first found out how tight they were going to go in. That was before I found they have the OD on their web site and my measurement was within a thousandth of theirs, so again it is the right part number, and this is their design target - why, I don't know. I also posted the measurements of my stock ones that I pulled out. I just want to communicate that I am not going off without some info and some thought here.

Everett Ogilvie

This is dead on, and Gary and I talked about this earlier tonight. The push may not be completely square, whereas the pull will be, so I will see if I can square them up with my impact. Thanks again.

(I still don't see why they need to be so tight....).

CorvetteZ51Racer

I ran into this problem on my C4....initially. What I realized is that with the press method, if you don't line up the splines BEFORE applying pressure with the press, you will likely be driving spline into spline, thus creating a massive interference fit, requiring a huge press, and not finishing square.

The I tried the impact gun thing. What I noticed is that during the initial few hits, the new stud was turning, indexing the splines and sliding right in like butter. I then went back to the press as an experiment and made sure to index the splines, tapping lightly with a hammer to keep it aligned, then used the press and it slid in like butter again.

I think the key here is indexing the splines between the hub flange and the studs PRIOR to applying the press.

mgarfias

My first set of ARP studs went in with the hub in a vise and a breaker bar/ratchet combo.

The 2nd set (on brand new hubs) took a press. The 2nd one I chalked up to the fact that the hubs had no studs when they arrived, thus no swaged in splines.

You could always ream the hubs 3-5 thou and get it right that way.

dfinke23

.... I ran into this earlier in the summer when replacing my stock hubs with SKF's. I pressed the ARP's in and squared them up with an impact.
Because of the force required to seat them, I am still paranoid about the hubs cracking.

flink

I think it's important to not whack on them too hard with the impact once the stud has seated - that could do damage. I suppose that if you're being super-careful you'd pull them in 99% with the impact and then finish off by hand.

But I always find that they loosen up after installation: go drive a mile then retorque the lugnuts and you'll get 1/8 of a turn out of them.

0Randy@DRM

I had no idea you where trying to press new studs into a new hub. Different ball game, different set of rules, different set of tools. It's 8 minutes to 2AM, need a shower and some sleep......

dfinke23

Please elaborate.

Kubs

I actually broke two ARP studs trying to use the washer/breaker bar method. I press them in now. I sent the broken stud to ARP and said "I thought these are supposed to be stronger?!" He told me I over torqued it and never to install them that way.

Dave Deerson

For a racing/high performance application where failure would spell disaster, I would never pull the wheel studs in with a gun. Never. Unless in an emergency at the track with 10min to go until the race etc...
I just install ARP studs(6 sets) into both a new SKF and used GM hub/bearings this morning and they went in like butter with a press(that wasn't even getting a pressure rise on the gauge). There must be something different with what you have. Either the studs were packaged wrong( did you compare advertised specs to actual measurements?) or your hub has non-stock holes. I recall only a .001-.002 interference fit when I checked.
I used the ARP part #100-7713(the longer GM stud).