prop shaft

[Migge]

Have never had a propshaft shorten so I need some other opinions. The shaft went to a company doing this game for ages, should be ok I thought. Got it back a week later and I was not really satisfied with the result, visual. The weld was done in the middle of the tube not at the end where the u-joint connects and where I thought it should be. It looks like a very big seam the was milled down after the welding, not just the top, the sides too. Is there a inner tube to stiff it? Anybody knows something how it is done? It just looks not very proffesional I think. Any ideas?

Regards
Migge

[Slowjoe]

Hi Migge,I had my propshaft shortened a couple of weeks ago.Just looked at it to see where it was cut and weilded.It was at the end of the tube where the splines are it was also ballanced It only took an hour.My propshaft is off a mgb so don't know if that makes any differance.

[Roger King]

Hmmmm. Propshaft work is often a bit 'agricultural', in my experience - but I must admit I've not seen it done in the body of the shaft before.
This may be to do with balancing - or there may be a reason they couldn't do it effectively using an end.
Either way, as long as it's in balance I wouldn't worry - I've seen much rougher welding jobs than that on props before now. Also doesn't matter what it's off - apart from UJs, splines etc. a prop is a prop is a prop.
Spray it satin black, fit, lubricate, forget.

[James Baxter]

I think it looks terrible!
Why turn off a weld afterwards? Only when its a chicken shit weld (looks like a chicken shat on it). The strength of the weld is drastically reduced when you do, as the raised bit has high tension in it, which when removed, removed strength. Mind you it looks like they welded weld upon weld so its probably still strong enough.
I think the advantage of cutting and welding at one end is that you will get a spigot location from one of the solid ends (the hardyspicer fitting or spline) so its easier to weld concentrically. From the view you gave us, it does look concentric too to be honest, so prob ok. Still as good viewed at 90 degrees?
Makes you wonder if they V'd out the pieces before welding though. Have you got one of the propshaft catching brackets?
Gerry does them, to stop flailling propshaft killing you.
Archie Frazer Nash called it a knacker-catcher on his cars (danglish leather strap) - it prevented pole-vaulting. Have I used enough foul language yet?
JB

[Migge]

The whole prop shaft is just 460 mm long and it's a two piece version, for sliding you know, LT77 Gearbox with flange. It's welded maybe 200 mm from the rear and it's balanced too and it seems it was V'd. I'm just a bit concerned if the welding is okay and strong enough. A prop is a prop, that's true Roger. Satin black is okay, nobody will see it anyway. The little problem: I know how it looks . Just don't want to mess with the prop or other things when everything till now was the way I like it. I don't need always 100%, but if you go for 80 or 90% the next step is 70% . Don't need a catching bracket, got a weldet tunnel so the prop will get not chace to hit me.

I'll give the company a call.

Cheers
Migge

[Roger King]

The machining on the weld will be for balancing, obviously you can't leave an un-dressed weld on a balanced item.
A weld properly done is stronger than the metal adjacent to it. Do you have any reason to assume this weld is not done well? I'd have thought that if they're doing this all day and every day they should know what they're doing...
Is there a lot of spatter? Do the welds 'sit on top' of the metal, or do they look like they've penetrated properly? I don't know about your application, but these props are so short I doubt failure is very likely. My 'other' car's one-piece prop is about 4 feet long, which may be a different matter, of course.

[Migge]

Went to the company saturday and found the guy who made it. He confirms that it looks not really perfect but offered me to cut it again watching me to show me how it looks inside. He said that they never weld just two tube pieces together (there were laying around hundreds of modified prop shafts from maybe 1" to 4" diameter). He also garanties that it will take more torque my car will ever have. He said the the massive part of the sliding piece is going into the other tube by approx. 1" lenght. So he weldet the two pieces together and reachng inside the massive stump. He will clean it up, weld it again to reach a better looking result.

Found out that a well known company in Germany who sell Cobs and kits are also get their prop shafts made there.

The "visible crack" is the part where one seam touches the next one. The shaft is mounted into a rotating bracket and is welded in three parts partial and then again in three parts all around the tube.

Thanks for comments guys.

Cheers
Migge

[James Baxter]

The machining on the weld will be for balancing,

Really? It looks to be circumferential machining, ie turning, to me. I wouldn't balance using a weld, unless it were a weld put there especially for the purpose. ie the weld did not join two pieces together as well.

... obviously you can't leave an un-dressed weld on a balanced item.

Why not? Ordinarily, for max strength, welds should not be dressed.

I don't know about your application, but these props are so short I doubt failure is very likely. My 'other' car's one-piece prop is about 4 feet long, which may be a different matter, of course.

How does the length of the prop affect the strength/importance of the weld?

[Roger King]

The machining on the weld will be for balancing,

Really? It looks to be circumferential machining, ie turning, to me. I wouldn't balance using a weld, unless it were a weld put there especially for the purpose. ie the weld did not join two pieces together as well.

Well, that's why I'm talking about 'the machining on the weld', not the weld itself... Given that the weld is there, to join the modified halves of the prop, it has been turned to help ensure a decent balance.
Having said that, I've had props balanced both ways - more often with a plate either spot- or tack-welded onto the shaft. Wembley Props used to add weld and grind back to the desired weight (much less pretty, but effective).

.. obviously you can't leave an un-dressed weld on a balanced item.

Why not? Ordinarily, for max strength, welds should not be dressed.

Because it would affect the balance, if it's as rough a weld as we're told this one is. Removing material in the amount and distribution shown in Migge's photos of the turned prop is not going to compromise strength unduly.

I don't know about your application, but these props are so short I doubt failure is very likely. My 'other' car's one-piece prop is about 4 feet long, which may be a different matter, of course.

How does the length of the prop affect the strength/importance of the weld?

Um - I didn't say that it would... I'm saying that the length of the prop will have some bearing on its own overall strength if there is a problem with the weld and/or balance: it won't affect the strength of the weld.
A longer shaft will be more prone to whip, hence the modern car (at least the very few that retain RWD)'s use of Plummer blocks.

I have that creeping suspicion that we're arguing the same points here...
Basically, it's not a pretty job, but it'll work OK, and they've offered to tidy it up!