Stripped lug in drum

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pillowmeto
Posts: 103
Joined: January 5th, 2008, 12:54 am

Stripped lug in drum

Post by pillowmeto »

Over the weekend I stripped the lug threads in a new front german drum while torquing to 74 ft/lbs. Has anyone fixed this by installing a threaded insert (e.g. Helicoil), and if so did you have any problems with it?

-Matt
smsazzy
Posts: 703
Joined: June 24th, 2006, 5:56 pm

Re: Stripped lug in drum

Post by smsazzy »

I recommend only tightening to 65ft/lbs. I would not go over 70 for future reference.

I have not ever had to helicoil a drum, but if I did, I would likely replace it. I would expect the process to warp the drum.

Don't take my word for it though, I am sure there are plenty of people who have done it before.
Stephen Saslow
FV 09 NWR
FV80
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Re: Stripped lug in drum

Post by FV80 »

Matt,
The "proper" way to fix that problem is to go find some 14mm lug bolts from the later model drums. The 'standard' ones are 12 MM and the stripped out hole is just about right for a 14mm tap. In a pinch you can do just one, but I generally go ahead and do them all so I get some semblance of 'balance' (such as it is) back on the drum. It also means that, when you're in a hurry, you don't have to figure out WHICH hole has the different size lug :mrgreen:. Of course, you'll need a 14 mm TAP for that too - NAPA should have it.

You can either get the lug bolts from your local VW junkyard or order them from someone like CIP1.com ... of course RaceCarSupply *MIGHT* stock those as well.
Steve
The Racer's Wedge and now a Vortech, FV80
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Ed Womer
Posts: 245
Joined: July 19th, 2006, 8:53 am

Re: Stripped lug in drum

Post by Ed Womer »

Heilacoils are fine and I used them on front drums for many years until the drum was to worn. The only problem is they will start to back out of the hole and you will need to replace them. I started to use locktight to stop them from moving.

Check you torque wrench since it might be off and that is why they stripped, which was my original problem. Also I only torque to 65lbs.

I repalced my worn drums with ones with parts from my local VW shop and they were Mexican and I like them since the hole to adjust the brakes is very large and makes it easy.

Ed
brian
Posts: 1348
Joined: June 26th, 2006, 12:31 pm

Re: Stripped lug in drum

Post by brian »

Heli coils are available but the kit will cost nearly $90. Upgrading to larger studs sounds like the hot set up.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
VDF1
Posts: 127
Joined: June 28th, 2006, 2:18 am

Re: Stripped lug in drum

Post by VDF1 »

I had helicoils installed in my drums at a local automotive machine shop for about $10 each because they had the kit so I just bought the threads and paid for the drilling and inserting.
Life atrophies if it gets too far from risk
problemchild
Posts: 902
Joined: June 25th, 2006, 9:34 am

Re: Stripped lug in drum

Post by problemchild »

I used helicoils for years. I would consider it a proper fix and preferable to big ugly newer wheelnuts.

They did work out occasionally .... because the hole was so shallow, they did not really dig in and anchor .... but it was easily fixed and once aware of the tendancy, rarely re-occurred.
Greg Rice
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jpetillo
Posts: 754
Joined: August 26th, 2006, 2:54 pm

Re: Stripped lug in drum

Post by jpetillo »

Ed Womer wrote:Check you torque wrench since it might be off and that is why they stripped, which was my original problem. Also I only torque to 65lbs.
Yes, always a good thing to check.

Another thing, when you use a clicker torque wrench, throughtout the weekend as you check your lugs nuts each time the "click" will nudge it a little bit more when it hits the stop and you end up with them very tight after many times. When you let the wrench click you should feel for it and not let it hit the stop hard.
sharplikestump
Posts: 183
Joined: January 12th, 2009, 2:28 pm

Re: Stripped lug in drum

Post by sharplikestump »

I don't believe we ever need more than 65 #s torque. In fact, when I raced in the rain, I dropped this closer to 55#s, as the rain acted as a lubricant. The proof if this is that when you went to remove the lugs after things dried, it took conciderably more torque than what you used installing them.
The other thing is that few of us check the threads on the lugbolts. Due to the number of cycles that we torque them, along with the high torque value that some of us use, we start moving the threads on (off) the bolt. Check em, and many of us will find that the treads start looking like a saw blade. Using a bolt like this gradually destroys the drum threads.
Also, heli coils should not back out if you make them short enough and install them at least 1/2 rev below the face of the drum. Same goes for the sparkplug hole. Don't worry about giving up that 1/2" of thread, as the holding power of the heli-coil is several times that of a new drum.
Bill Carroll
Posts: 72
Joined: January 21st, 2009, 8:33 pm

Re: Stripped lug in drum

Post by Bill Carroll »

My experince with helicoils on many applications, including aircraft is very postive, when installed correctly (proper drill, tap and use lock tight) they are better than the origional thread and will not warp the drum. Same reason we install inserts in the case for our cylindar head studs, mechanical advantage over stock part. I use my old trusty bar torque wrench to 55# and I run 150+ miles per weekend, I haven't found one "loose" yet (I do not have helicoils). I do check the torque several times each day and the only time I think I see them move is the after first run after changing wheels I am not saying that I know more than the others here, I just know what I am seeing with ammount of time each weekend. Rain causes rust, lubrication such as WD40 or antisieze will give you a tighter lugs with the same torque. A FV manual I read says to torque the wheels to 55-65 but never more, (the drums are soft).
DanRemmers
Posts: 293
Joined: June 24th, 2006, 7:21 pm

Re: Stripped lug in drum

Post by DanRemmers »

sharplikestump wrote:In fact, when I raced in the rain, I dropped this closer to 55#s, as the rain acted as a lubricant. The proof if this is that when you went to remove the lugs after things dried, it took conciderably more torque than what you used installing them.
Could that be caused by rust forming on the wheel, lugnut, and threads?
sharplikestump
Posts: 183
Joined: January 12th, 2009, 2:28 pm

Re: Stripped lug in drum

Post by sharplikestump »

Dan (and others),
Refer to Bill C's comment as to what happens when you spray the bolts with WD40 or use anti-sieze compound. It is no different than lubing/not lubing rod or head bolts. You get a higher degree of tension with the same torque. Granted, water may not be as lubrious as oil, but it does lubricate to a degree in this case.
wroché29
Posts: 163
Joined: July 10th, 2006, 8:44 am

Re: Stripped lug in drum

Post by wroché29 »

Hi guys!

"standard" "stock lug threads: 12M x 1.75?? or something else?

Thanks
Bill Roché
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