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Deferring to the knowledge of those who have more experience/education than I have on these matters, safety seems to dictate that the hub be replaced. Understood. Apparently welding the stud in is a poor option per Palm et. al. (possible cracks, distortions and the like).
Greg, why is it that I shouldn't just replace the hub proper in lieu of replacing the hub and driveshaft as a unit? It seems that by pulling out the hub and driveshaft that there are all sorts of bits (bearings, spacers, seals, rings...) that have an opportunity to "go out of line" if I pull the entire drive shaft out. Not suggesting yours is bad advice, but just trying to grasp the implications of this vs. just replacing the hub.
Thanks!
John
John,
I am not in the least bothered by follow-up questions, please be assured!
Separating the hub rotor from the actual hub aluminium casting/driveshaft splines, can be extremely hard to do. If you look at my thread on the Dana Differential Demystified and related links on re-UJing the driveshafts, you will see it took a heavy duty industrial 40 tonne pulsing press to get mine out! And to get it onto the press, the driveshaft will have to be unbolted from the flange and the lower fulcrum anyway. Now it is possible you will be able to just undo the castellated nut and your hub will pull out easily, leaving the outer driveshaft splines with no bother, but I doubt it. Then you will still have to replace the bearings including the outers in the aluminium hub casting (which probably means too that he casting has to come off the car) as I doubt the old bearing centre races will come off the hub rotor undamaged.
Even if your hub rotor pulls out easily, and the bearings all come off intact the replacement rotor (the availability of which is dependent upon the spare assembly also coming apart easily) the repacement piece will require endfloat setting up. This is turn means careful measurement and requires the correct thickness of precise phosphor bronze shims. These are hard to find, but if you measure the endfloat without them, I can send you the required ones FOC apart from the postage, as I lucked into an unobtainable hoard of them!
By contrast, undoing the driveshaft at the inboard flange is straightforward. Undoing the lower wishbone fulcrum pin and driving it out from the hub is dead easy, and the grease will be so solidified that as long as you do not drop it, the bearings and shims will not go out of line.
Finally, you lose nothing by trying the easy way, as if it does not work, you will only have to do what you would have done before trying it! You can just see the driveshaft hanging down at the bottom of the pic Rusty bits all apart
Last edited by Greg in France; 03-07-2021 at 02:58 AM.
I have to ask this question because it's been kindah burning in my mind since I saw the photo of the drilled out lug. Yeah, I'm weird like that - I worry about situations with damaged or deranged wheel/lug studs myself...
What if the hole made by the drilling was cleaned up, made threadless, and a proper sized and length bolt was inserted, then welded to the back of the hub, and then ground down some to flatten out the head to remove excess weight and to lessen its distance so as not to be so poking out of the back side - and stuff?
Others will chime in with a more detailed reply, but from my studies it seems that there is a possibility of introducing a weak spot, a warp or a crack in the hub by welding. I don't know what the odds of that happening are, but a weak spot or crack could cause a failure of the entire hub, which could lead to a really bad situation. I'm not a bad welder, and I was initially thinking of doing something similar to your idea/question (just because I have all the equipment to do it and it would be fairly quick) but the safety issue is making me think it's not worth the risk.
Greg,
To summarize, the problem wouldn't so much being getting the castle nut off but would be getting the hub to pull out of the drive shaft. Not having access to the Big Blue Machine, I think I'll steer clear of trying to undo the nut. Thanks for the explainer.
I've one more idea I need to ponder and sketch out, stand by .
There have been suggestions to just get a bolt with the same threading, stick it through the stud hole (after drilling the buggered-up threads out) and let that serve as a stud. Two concerns there are a), possible balance issue since the bolt had a head and a stud doesn't, and b) how to keep the bolt from rotating when, in the event I have to change a tire on the road, I try and take that lug nut off and the bolt just rotates with the nut leaving me with no way to get the tire off.
The drawing below shows a possible solution. I take the appropriate size box wrench, cut it into three pieces, and reassemble by welding. I now have a tool that I can stick through the hole in the starfish wheel to grab the bolt head and secure it while securing or removing the lug nut. If the bolt starts to rotate it will push the tool against the side of the hole so the bolt will be *fixed* in position while I turn the lug nut.
The only difficulty I see with this scheme...wondering if the extra weight of the bolt head will throw things out-of-balance. The distance between the axis of the axle and the center of each stud is 60mm. Is the extra weight enough to make a difference? I don't know.
I have a few studs on the way from Moss Motors, and I'm going to buy a few appropriate-sized bolts. I'll cut the head off one of them and weigh it to see how much weight I need to remove from the other bolt. The two ways that come to mind to remove some weight is to shorten the bolt somewhat, drill the center of the bolt out a bit, or both.
If this works, it negates the need to remove the axle assembly from the car (I have to do all this in my garage and without buying more jacks I have precious little room to work under the car) and it doesn't involve welding anything to the hub.
But, I'm not a mechanical engineer, so comments/suggestions would be greatly appreciated.
I ain't one ta argue,,, but if it was to be taken as a direction, I think a competent welder could touch a bolt on there in 2 or three places and leaving feeling fairly confident as to not having altered the strength of the steel, run any cracks or warp-age. My pops was good welder (a little more than good working for military suppliers) but he's since passed. I miss him in moments like these,,, and LOTS o others...
JCR
If you are determined to go ahead with a repair, I would drill out the hub hole a touch and tap it. Then get a length of high grade steel rod large enough to cut the thread to the new hub-hole thread size and depth, plus a few mm. Then have a machine shop turn down the unthreaded part of the rod to the size required to tap that part to the wheelnut thread size. So you end up with a home-made stud with the larger end threaded to the new hub thread, and the smaller longer part threaded to the wheelnut. Then screw in the stud to the hub usiing the strongest loctite (the type that requires 400 degrees C to undo) to lock it, peen over the slightly extended rearward part. Job done.
The hub is a forged piece, carefully machined. A weld on it will never be as strong as the original, the above fix would reproduce the original.
Last edited by Greg in France; 03-07-2021 at 12:53 PM.
If this were my car, I would put in a new stud, put a couple spot welds on the back side of the hub, put anti seize on the threads, and never think of it again. Maybe I'm the idiot here, but I think the chances of cracking the hub on a normal street driven car is minimal, and if it does crack there will still be 4 other lugs holding the wheel on. If I were racing or running wide, sticky tires, I might reconsider.
Thanks for all the input. I was playing around with the bolt idea. A stud weighs 35 grams, my modified bolt weighs 37 grams. If two grams make a difference I need to slow down .
The other day a dislocated my left shoulder, so I'm strongly leaning toward the bolt solution, at least as a temporary fix, as in my current physical condition I have to go with a solution that involves the minimal amount of physical strength. Hiring it out isn't practical as the only guy around here who worked exclusively on Jag's retired, and I've not had a lot of luck getting the average mechanic around here to do anything right with the car. I am going to call around to machine shops to pursue Greg's ideas.
Oh, the bolt is stainless steel and is not drilled completely through.
Only reason it's stainless steel is that locally I can't find a Grade 8 with fine threads. I'll see if I can hunt one down on the internet, not it a big rush to drive it at the moment.
You can do helicoil installation your self, kit may be cheaper than paying machinist minimum of 1/2 hour labor.. Some one in the past has over torqued this stud, there may be another that is on other three wheels ???? I always look for a chance to add tools to my garage.
03-07-2021, 02:49 AM
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