Repairing external threads

I rebuild steering columns as a part time venture. I have several
columns that someone has used the BFH method of steering wheel
removal. The end result is that the 9/16 X18 threads are destroyed.
I'm considering methods of repair. One is to turn the threads off,
bore the shaft and turn a new section from a grade 5 bolt to fit in
the bored hole, crosspin with 1/8" rollpins and attatch with loctite.
I have not been able to find another way to restore the threads,
helicoils and the like just don't seem to be used for external
threads. Do any of you have a better way to do this repair that I am
missing? Other columns use 9/16" X 27 threads and no longer have the
nuts available to suit. Would like to use the same method to convert
them over to 9/16" X18 as well. Steering columns are too rare for
these cars, MGs, to just toss the damaged ones in the trash. TIA
Reply to
Gerry
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Why not just turn the damaged threads down, and then turn a bushing of the proper size that will slip over the end of the shaft. Braze the bushing on and re-thread. There was an article in Home Shop Machinist a while back about repairing bearing surfaces this same way.
Reply to
Gary Brady
I have had parts built up with weld and recut the threads.
Reply to
Jim Sehr
Thread file. JR Dweller in the cellar
Gerry wrote:
Reply to
JR North
According to Gerry :
[ ... ]
Are you sure that those are even standard Unified threads? Given that they came from MGs (you didn't say which model), they could be Whitworth (55 degree) thread form instead of the 60 degree which is in US threads, Unified threads, and Metric ones.
Others have already posted good suggestions for ways to deal with your problem itself, so I won't duplicate that.
Which MGs? I have owned and driven a couple of MGAs in my time. The original 1500, and the last 1600 MK II -- that latter one with a MGB 1800 engine in its last years.
Enjoy, DoN.
Reply to
DoN. Nichols
MGs are Bs No Whitworth threads after the TF's as far as I know. Almost everything is good old UNF except a few items like carbs and fittings. I had thought about turning a bushing to silversolder in place but am a bit concerned with the strength of the solder when it gets under shear forces when the nut is tightened. Welding up stuff in the past I have found the new metal was harder than I wanted to use a dienut on. Can't thread it in my lathe because most columns have a bit of a bend and would make threading accuratly mighty hard. The 9/16 X 27 seems to be a bastard thread when it comes to finding nuts to fit it.
Thanks for the suggestions! One of the great thing about BBS is the vast aray of solutions that members come up with
Reply to
Gerry
Depending on dimensions I suspect that the simplest method would be to face off the threaded portion of the shaft and drill and tap for a bolt. If I remember correctly the steering wheel fits on a spline so the threaded portion serves only to keep the wheel from being pulled. If the threaded portion is 9/16" then installing, say, a 3/8", grade 5 or better, bolt should be sufficient. You might need to make a new washer to retain the wheel though as a standard 3/8" washer might not have a large enough diameter.
Bruce in Bangkok (brucepaigeatgmaildotcom)
Reply to
Bruce
Gerry,
A serious "Silver Brase" on a 1/2 inch or so of length on the sleeve is gonna be as strong (or stronger) than your threads... That's the way I'd go...
FWIW I'm an old Triumph man.. Had a '68 GT6 with O-Drive that I managed to buy a tree with.... Found a '64 SpitFire with a tosted engine-tranny.. Lifted the Spitfire body and stuck it on the GT6 Frame... Just a little torch work to fit the traction bars in the right place and and fab some rear shock mounts... The damn thing would eat anything in it's class alive.. .. called it the "Spit-6".. :-) Uhh.. had to put a scoop on the hood to clear the front of the motor.. looked AWESOME.. (and yeah I couldn't us the hood from the GT6.. uh ..it was.. uh .. scrapiron where the tree bit it... lol..)
--.-Dave
Reply to
Dave August
With a joint with lots of area like a coaxial bushing on a shaft, a good silverbraze will be considerably stronger than a couple of transverse rollpins. Later abuse would strip new threads before the joint fails. Use something like Handy & Harmon Easy-flow 45. Leave about .003" clearance so the stuff can wick in. If the joint is clean, fluxed and then slowly and evenly heated, the alloy will wick into the joint by capillary action and completely fill the void.
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Reply to
Don Foreman
The thread repairs on the bottom of p.3180 in McMaster-Carr might work.
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Ned Simmons
Reply to
Ned Simmons
I wouldn't worry too much about scrapping MGB steering collumns. Have a look on eBay UK to see just how little these cars sell for here. It's heartbreaking sometimes.
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far as the repair, any idea around making a new end shoud be good. Just make sure you'be got enough contact area on the soldered joint. I would also cross pin it. That way, in the unlikely event of the joint failing, the pin will hold just letting the wheel become loose rather than coming completely off!
John
Reply to
John
Wrong filler and/or to much admixture. I use either 6013 or a nickle filler with a low strength rating. You've got to turn down the old threads so they don't mix with the weld. Let the end get hot while you weld, don't quench. Use a small diameter filler and low currents for the first pass.
possible. I straighten the shaft. Turn down the old threads. Weld up to diameter. Single point turn new threads. Takes a little over an hour but I like the result. You can't tell it's a repair job.
starbolin
Reply to
starbolins
Here's a certainly overly-complicated possibilty off the top of my head. Assuming: You need to repair several of these steering column threads, There are some threads left fairly undamaged further down the shaft, You can obtain hardenable steel, and harden it, You have, or can make, a whitworth (or whatever) tap to match the male threads
Then what may be worth a try is to make a thread cutting die which can be "split" into two halves, assembled on the undamaged threads, then "un-screwed" to recut (chase) the damaged threads. I haven't done this, but it seems that if at least two or three threads were left for the split die to chase from, this may renew the threads good enough for the nut to do its job. As far as making a thread cutting die goes, I read about (in HSM) a very plausible method using drill rod, soft steel plugs pressed into the holes that form the cutting "flutes"/chip clearance on the die, then drill (probably for more than 75% thread depth) , tap with the soft plugs in place, and harden. After hardening , according to the HSM article, the soft steel plugs will fall out.
Not a worthwhile method if you're only fixing a few of these steering columns, but this reverse thread chasing method might save you from further disfiguring the original parts. You would probably also get stuck with making the the funky british tap in order to make the "split die".
A farmer's implementation of this idea would be to get a nut (that needs to be hardenable after welding): clamp a cheap,disposable (chinese) pair of vise grips onto the nut weld the nut onto the vise grips heat and quench, caseharden, or otherwise harden the nut use a 3 inch "muffler cutter" abrasive disk to split the nut (cool often in water) grind cutting grooves into the nut halves using dremel or??
use your nifty new thread restoring vise grips in several passes to reverse chase the threads.
Aren't there thread restoring tools that work on this same basic principle? Aga> >
work.http://www.mcmaster.com/>
Reply to
yooperguy3431
sometimes.http://motors.search-completed.ebay.co.uk/mgb_Cars_W0QQcatrefZC12QQfc...> As far as the repair, any idea around making a new end shoud be good.
Thank you all for your feedback
Reply to
Gerry
That was my initial reaction, too, but the thread has likely been well distorted by hammering on the end. Pitch will have been destroyed, rendering the file useless. If not, they work great in the hands of someone that is willing to spend the necessary time to remove unwanted metal.
Harold
Reply to
Harold and Susan Vordos
On Wed, 25 Apr 2007 07:03:41 GMT, with neither quill nor qualm, "Harold and Susan Vordos" quickly quoth:
I've sawn nuts in half and clamped them in the vise around the threaded shaft, then unscrewed the shaft from it, before.
I have had to use my long-pistoned CP air hammer with a drift punch to release some steering wheels before, though. Loosen the nut and use it as a guide to hold the punch in place, then pull vigorously with one hand and a knee, then pop the CP trigger a few times. They come right off.
Grind the mushroomed OD to the max thread diameter first. It works if you don't have too much distortion. I've had to do that to remove nuts from time to time.
Some people and their BFHs, huh?
- Metaphors Be With You -
Reply to
Larry Jaques
They are no longer common but there were adjustable two piece die sets that could be opened and placed around the shaft. It might be worthwhile to try splitting a regular die for this purpose.
Don Young
Reply to
Don Young
On Sun, 29 Apr 2007 21:25:19 -0500, with neither quill nor qualm, "Don Young" quickly quoth:
Yeah, I had one of those for axle shafts eons ago before someone stole it. It was a hinged style with a wingnut on one side to adjust tension. I think it went from 1/2" to 1-1/2". I had only used it once before it walked off. It was older than I was and a gift, but I still miss it.
- Metaphors Be With You -
Reply to
Larry Jaques
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Reply to
Wayne Cook

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