TR4/4A Advice on stripped Rear Hub wheel stud for TR4

[6T2TR4]

One of the four wheel studs has been stripped for a while, but now I am getting ready for a back-road trip to Vegas in the 62 BRG beast and I want to have the wheels on tight for the desert cruise. A new rear hub from Moss is $324 and it seems excessive for a one stud problem. Should I run a long stud through the stripped hole and weld it on the back or try to weld a nut back there? I am not much of a welder but I can do light brazing. If I heat up the hub on the car will it ruin the grease or damage the bearing in the hub? Should I drill and tap the hub and try to get someone to make a custom stud? I know these are fairly basic machinist questions but I do appreciate any help.
Paul

 

[Tinster]

Paul,
I too once had a missing rear wheel stud.

best of luck.
Dale(Tinster)

 

[TR3driver]

You're saying that the hole in the hub is stripped, right? In that case, my approach would be similar to what Dale suggested, get a knurled stud and drill the hub to suit (just slightly smaller than the OD of the knurls). I wouldn't weld unless absolutely necessary as it's been my experience that welds between high tensile steel and cast iron frequently break later.

Used to be that Moroso sold fully threaded studs in 7/16NF, but I couldn't find any last time I looked. Apparently Moroso discontinued them, but someone must be making them as I bought a pair of alloy front hubs that had them, just a few years ago.

Another alternative would be to look for a used hub; they usually go pretty cheap. Only caveat is to be sure it didn't get distorted while separating from the shaft. I'd offer you one, but I don't currently have any safe way to get them off the shaft.

 

[martx-5]

Normally, when threads strip in something, the usual repair would be to install a Heli-Coil. But in this situation, I think that the hub probably isn't thick enough to accept one.

You should be able to find a knurled press in stud that should work, although you will have to drill the stripped out hole to the proper size.

Look on page 6 of this pdf and you will see what I'm talking about. I have wire wheels on my car, or I'd go out and check the actual lug threads. I believe they are 7/16"-20 for the TRs. Someone correct me if I'm wrong. Once you know that, you can hunt around for something usable that you can insert from the back side and not have to deal with the threaded lug business.

 

[AweMan]

Randall is right, Welding the stud in place wouldn`t be my first or last choice! {in other words I just plain wouldn`t do it}
#1 it isn`t safe! Eg. heat from the welding and stress caused by the welding could cause the hub {If cast iron} to crack}
#2 heat from the welding will in fact change the tensile strength of the stud!
It is possible the hole in the hub could be welded shut and re-drilled, BUT ...... It definitely isn`t a D.I.Y. job!

On some hubs the Drum is cast iron and the mounting plate {Hub} is cast steel, if this is the case with your hub any weld/machine shop can repair the hole and re-drill it.

If the hub is cast iron .... Take it to a weld shop that specializes in cast iron repair, {they can weld it, normalize it, and stress relieve it with the proper equipment} get a bid {you may decide that the price of a new or used hub is justifiable}!
I know .... not what you want to hear ....... But my nickles worth anyway.

 

[prb51]

Had the same issue on my TR3. I overtightened at when I got the car before I knew that the studs were just screwed into the hubs.
Welding won't work don't do it.
Drill out and insert a proper lenght bolt from the rear (knurled flat head) or get a new hub.
I purchased machined steel hubs for safety as I thought the screwed in nut was screwy to begin with. These all came with proper bolts put in place the conventional way.
So redid the bearings, seals etc and properly set the hub axle throw out with the shims that was off anyway...off like in no shims whatsoever.
Never have to worry about losing a stud that way.

 

[TR3driver]

If the whole thing is cast iron .... Take it to a weld shop that specializes in cast iron repair, {they can weld it, normalize it, and stress relieve it with the proper equipment}

Just curious, Kerry, what would you say are the chances that the hub will keep it's shape during that process? We have a tapered bore, with a keyway, plus a flat face and the location of the 4 studs to worry about. It's possible the factory did some heat treatment before machining them originally, but it seems unlikely to me.

And I'm pretty sure they were cast, although they are machined all over.

A Heli-coil would be a possibility I guess. Although I've never liked those headless thread-in studs, I've only had one incident where they failed (and presumably the nuts came loose first). Still, that remains the closest I have ever come to flipping a TR3, so it's not the way I would choose to go.

A Dremel with an abrasive cutoff blade works well to trim any excess length from a Helicoil insert. Just install as you would normally and then cut it off. The length changes as you turn them in, so it's difficult to judge where to cut in advance.

 

[dklawson]

I don't want to post a suggestion without asking a question since I'm not familiar with TR3s.

On the cars I am familiar with, the stud is headed with straight knurls along the shank just after the stud's head (before the threads start). Am I correct assuming the TR3 uses the same type?

 

[TR4nut]

On the cars I am familiar with, the stud is headed with straight knurls along the shank just after the stud's head (before the threads start). Am I correct assuming the TR3 uses the same type?

Nope, actually TR3 and TR4 used threaded rear studs that were peened over. Not easy to change out.

 

[TR3driver]

Right. Not just threaded into the hub, but threaded in from the face. The peening in the rear is the only thing that keeps them from unscrewing from the hub and coming out with the nut still attached.

Also used on non-IRS TR4A I believe.

 

[PeterK]

Also used on non-IRS TR4A I believe.

Correct. And if you've ever had to r&r a broken stud, you wouldn't worry about them coming out on their own. It takes a lot careful grinding to remove the peened over stud.

Last time I did it by drilling with a large bit (5/8") or so so that the drill would scrape off the peening, little by little. Of course to do this, I had the hub off the axle and on my drill press.

 

[6T2TR4]

Thanks everyone for the great help and ideas. I think I am going to go the helicoil rout as this is something new for me to learn. If it does not go well, I can always punt and buy a new hub. I do have a question for those in the know about removing the rear hub from the axel. My manual states to extract the rear hub using Special Tool No. M.86.A. Is this really necessary? Can I pull the hub off using a standard gear puller? Maybe I should just install the helicoil with the hub on the car, although I am concerned that if it is not square the stud may not fit into the wheel when I am done.


Sorry, correction, after looking at helicoils closer I agree with Art and will try the simple press-in wheel stud. Do they give you the drill size or should I just press it into the hole as-is?

 

[PeterK]

Removing the hub from the axle is a whole 'nother discussion. But to answer your question about using a standard gear puller, the answer is no (way).

Another option would be to remove the axle with hub attached and take it to a machine shop for them to fix. Depends on how handy you are.

Search for rear hub Churchill tool.

 

[prb51]

Without a special shop tool the only way to get the hub from the axle is a large press..used a 20 ton shop press and loosened the axle/hub nut but unscrewed it to the end of the threads leaving abour a 1/4 inch from the hub before apply the press. The 20 ton press was straining at the time too...50 plus years in place has a lot of memory.
When they seperate it's like a gun shot and the nut keeps everything from flying about.

 

[dklawson]

Thanks for the explanation on the TR3/4 wheel studs. That sounds very different indeed.

 

[TR3driver]

Thanks for the explanation on the TR3/4 wheel studs.

Only applies to rear studs, BTW. Front studs are conventional with knurling and heads.

 

[TR3driver]

Also used on non-IRS TR4A I believe.

Correct. And if you've ever had to r&r a broken stud, you wouldn't worry about them coming out on their own.

Clearly the factory got them in there solid, as it's not a common failure. But I had 2 of them come loose, just rolling down the freeway. Probably should have noticed the problem sooner, but being young and foolish (as opposed to old and foolish

), I didn't notice anything until the car went sideways on the offramp. It had been a long trip and I was kind of tired (1000 miles with no money for a motel). Didn't help matters any that I was still doing nearly 80 at the time.

But I can tell you that it woke me right up!

 

[TR3driver]

Without a special shop tool the only way to get the hub from the axle is a large press..

Which is also a good way to distort (ruin) the hub. In fact, some have suggested that the reason they are so hard to get off that way is because the hub pinches closed on the shaft and grips it tighter.

 

[AweMan]

If the whole thing is cast iron .... Take it to a weld shop that specializes in cast iron repair, {they can weld it, normalize it, and stress relieve it with the proper equipment}

Just curious, Kerry, what would you say are the chances that the hub will keep it's shape during that process? We have a tapered bore, with a keyway, plus a flat face and the location of the 4 studs to worry about. It's possible the factory did some heat treatment before machining them originally, but it seems unlikely to me.

And I'm pretty sure they were cast, although they are machined all over.

A Heli-coil would be a possibility I guess. Although I've never liked those headless thread-in studs, I've only had one incident where they failed (and presumably the nuts came loose first). Still, that remains the closest I have ever come to flipping a TR3, so it's not the way I would choose to go.

A Dremel with an abrasive cutoff blade works well to trim any excess length from a Helicoil insert. Just install as you would normally and then cut it off. The length changes as you turn them in, so it's difficult to judge where to cut in advance.

Although the possibility of distortion does exist, because of the pre heat required to properly weld on any cast iron casting. The preheat temp would remain under 500 degrees, The whole casting {Hub} would need to be brought up to temp {approx 450 - 500 degrees} in order to prevent the possibility of stress cracking, Having said that, the local area {Weld} would receive a much higher heat range {approx 2,000 degrees}. As soon as the repair is finished, the part {hub} is then placed in an oven where it is allowed to slowly cool, brought back to room temperature {Normalizing} by decreasing the oven temperature slowly hour by hour. The initial oven Temp would only be in the 6 - 700 degree range. {just enough to keep the casting ductile during the initial normalization process} Pre Heating and then normalizing the whole casting in this manor helps to prevent distortion.
Chances are good that IF the weld shop that does the repair knows what they are doing all should be fine!

On a side note, it would be interesting to know if this casting is actually cast iron or cast steel {two completely different dogs}
One could conduct a spark test to tell, Hit an inconspicuous place with a small grinder {Dremmel} White sparks = steel reddish to straw yellow = cast iron. ..... <span style="font-weight: bold">NOTE:</span> steel can sometimes be yellow also, depending on the carbon content. If this is the case further definition can be resolved by the streamers {length and shape of the sparks thrown off}
This website gives a pretty fair description of what to expect when conducting a spark test.
https://en.wikipedia.org/wiki/Spark_testing_metals
And .... I agree, you will never remove a tapered fit hub with a common wheel puller, It isn`t happening!

 

[TR3driver]

My manual states to extract the rear hub using Special Tool No. M.86.A. Is this really necessary?

In a word, yes. Of course, you can also pull the shaft & hub together and ship it to someone that has the proper tool. I believe Herman van den Akker still offers this service (when he has time) or there are numerous other LBC shops that have the proper tool.

I plan to build a replica of it myself, but haven't gotten to that point yet. Also haven't decided whether to try to copy Herman's hydraulic design or just the factory forcing screw.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Maybe I should just install the helicoil with the hub on the car, although I am concerned that if it is not square the stud may not fit into the wheel when I am done.[/QUOTE]One way to address that would be to buy or make a tool to help hold things square during the operation. Eg,
Tap Guide Block

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Do they give you the drill size or should I just press it into the hole as-is? [/QUOTE]My experience has been "neither one" if you just buy studs at your FLAPS. But Moroso specifies an interference of .001" to .008" for their studs
Moroso wheel studs and I believe the same would apply to other makes as well.

I'd shoot for the low end, though, as when I tried to do this many years ago (in my buddy's driveway 1000 miles from home), it just sheared the knurls right off the stud & left it loose in the hole. Some quality time with a rat-tail file to put a chamfer on the back of the hole should help too (didn't think of that at the time).

PS, if anyone is interested, I have a PDF of an article by Gene Wellenstein describing the hub breaker he built from heavy pipe flanges and other stock components, with no welding and minimal machining (just cutting and drilling). He claims the operation was totally anti-climactic, no loud noises or jumping around

<span style="font-style: italic">"The only indication that the hub is free from the axle is when the Acme screw looses tension."</span>

How boring is that :laugh: