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I've got a question about extending the steering shaft by welding in an extension tube, as Keith Tanner shows us in his book.

The weld is right next to the lower bearing in the column.


(Photo credit - Keith Tanner. Used without permission. More photos starting here: http://www.cheapsportscar.net/diary.php?UID=213)

Is the heat on the bearing a problem? If so, how do you protect it while welding?

As for the tube itself, does it need to be any particular type?

-dave

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...nowadays people are so intellectually lazy and lethargic that they can't build ANYTHING with their hands. They'll spend hours watching whiny people marooned on an island, but won't spend a second adding anything to the world. -weconway
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I'm not Mr. Tanner, but I have done this step so I thought I'd chime in.

Get out the BFH and pount that flange with the bearing housing up toward the steering wheel end. The housing will slide up as the column housing collapses. Get it up out of the way and then do your welding. (pound it back when you're done) The shaft narrows not far up so make sure you do your cutting and welding as close to the end as possible. If you make your cut and weld too far up from the end you won't be able to get the needle bearing section back down far enough to ride on the non-tapered shaft.

Hope this helps.

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There was no pounding on my part, and the bearing does not seem to have been affected at all.

Does that mean that the bearing was in the heat of the weld?

Or does that mean the column collapsed without resorting to gorilla tactics?

Thanks to both of you,
-dave "easily confused" hempy

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...nowadays people are so intellectually lazy and lethargic that they can't build ANYTHING with their hands. They'll spend hours watching whiny people marooned on an island, but won't spend a second adding anything to the world. -weconway
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Dave I am glad you asking all these questions because I am right at the same part as you, and these are all the questions I would have asked!

J. R.

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The bearing does not seem to have been affected by the heat of the weld at all.

I resent that comment Dave. There is no way a Gorilla has the dexterity or the intelligence to gently hammer that flange back without breaking something.

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He is a wise man who does not grieve for the things which he has not, but rejoices for those which he has.

Ahhh... But the gorilla does however possess the opposable thumb necessary to grasp the BFH and get the job done. That's half the battle and if that's the case, gentle probably won't have anything to do with it.

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Sorry Chet. Here, have a banana.

-dave

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...nowadays people are so intellectually lazy and lethargic that they can't build ANYTHING with their hands. They'll spend hours watching whiny people marooned on an island, but won't spend a second adding anything to the world. -weconway
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Well, having been through this now I thought I would add my $0.02 as my experience had a little twist to what was described above. I am using a 1990 Canadian (no airbag) Miata. Following the suggestions above, I attempted to tap the flange back with the bearing to no avail (note the unsealed bearing). Thinking it was a snug fit I tried to drive the bearing back flush with a deep socket, again it would not move. though it seemed my shaft became shorter! Enter Gorilla tactics. I tried once more on the flange with a bit more intent and well you can see bellow what happened. The housng moved but the bearing was still in place.This is because, unlike the shaft pictured a the top of the thread where the 0.75" shaft diameter runs al the way down to the spline, mine had a shoulder that stepped down to 0.65" (iirc). The same dia. as the spline, as shown belowThis was a problem as the stepped shaft that was exposed below the bearing was too short to add a extention. My solution was to find a 0.75" dia bearing so I could slide the ousing back up the shaftThe O.D. of the housing was however the same DIA as thge housing so I simple tacked them together.

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Chris


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Just a quick question cboettch, how many times have you seen anyone weld to a bearing?

The type and hardness of bearing steel will simply fail along the edges of the weld in time, may be tomorrow, may be a year away, but it will happen and I would encourage you to rethink having a steering component supported with a 100% "fail" certainty.

Also another problem is that electricity is really weird stuff, you may have the earth clamped (logically) to the outside work piece but sometimes that doesn't stop balls from arcing out inside the bearing and damaging them when welding very close to one (true that it's sometimes unavoidable).

Hi
I would agree here with cheapracer that welding a bearing is not a great idea. Those bearing sizes don't make sence to me either as being a jap car would have thought that they would be metric and standard metric bearings come in 15 17 and 20mm shaft sizes with varying OD's, however the sizes you have given sound closer to 16 and 19mm. Car makers can and do make bolts bearings etc to suit themselves so it is not beyond the realms of possibilty which is a shame as you could have found a bearing with a smaller OD without welding it. Can you weld something to the shaft housing and turn it out to accept the OD of the bearing that you are using?
Bruce

Well, I think some common sense is needed. When I design an assembly or part, I think of several things 1)what is the likelyhood of it failing; 2) what is the consequence of failing 3) what is the detectability when it fails or preferrably, at the pre-fail weakened condition. 4) what have I seen that is similar that I can use as a reference point? 5) 6) and so on and so on......

As far as the failing of the bearing due to the welding of the outer race is concerned, there is probably less than 1% of the bearings rating being used in this application. The life of the bearing is not in question. It is mostly being used here just for a free moving feel. It bears little or no real structure. Insead of welding the outer race, if you welded the original shaft close to the inner race, you might get a bit of a gritty feel in the turns from possible arcing internally from the welding process. But again there is no real force here and the bearing would still last a very long time. Even if the weld did fail, you would not loose the capability to steer the car, it would just get a bit sloppy. As for a reference design, my MGA didn't use bearings at all in this application, It had 2 pieces of oil soaked felt wrapped between the shaft and the housing at both ends of the shaft housing (tube). That should tell you how little force is required. Yeah, it is turn of the century technology (the 20th century) and they got a bit sloppy after decades of use. So you replaced them when the steering wheel moved or rattled too much. Some energetic owners actually went to the point of machining a high-tech teflon sleeve to replace the felt. So the ball bearing in this application is really overkill IMO.

The best solution is the one I used. Who'd a thunk I'd say that? Don't weld the shaft or the bearing at all. Just re-bolt the universal joint and extend (weld) the interconnecting shaft. As you can see, I did cut and weld the outer bearing sleeve a bit further up the shaft. There is no detectable "grit" to the feel of the steering. It is as smooth as ..... well, you pick your own simile.

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Another note is that they sell a special 3/4" steering rod end because 3/4" steering shaft is slightly different in size then 3/4" bolts.

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