drive Axle length

[ASR]

Hello,
We are trying to get a drive axle to our exact length. Unfortunately making a new one and heat treating is not an option. Has anyone of you tried friction welding the axle ? I will be concentric and strong. Any thoughts ?

Anbu Sivaram
TeamUnwired

[Paul Achard]

Just out of curiosity: how do you intend on friction welding your driveshafts?

[MCoach]

I have a few thoughts:

You could machine a new one and...not heat treat it *gasp* the horror!

I have not tried to friction weld anything other than pistons.
Which worked successfully and is a market hit.

I don't know exactly how you plan to do friction weld your components.

If you are not able to make one a new one, what about just using steel bar stock?
From what you have listed, you appear to be from India and materials seem to be a little on the scarce side over there. It may be worth your time to throw your factor of safety out the window to make a component feasible to manufacture.

[ASR]

Thank you guys for your reply. I know an alumni who is making friction welding machines for welding rear drive shafts for vehicle.

http://www.etatechnology.in/Fr...chines_machines.html (http://www.etatechnology.in/Frictionweldingmachines_machines.html)

I was just curious if anyone have tried it.

[AxelRipper]

So you're saying heat treating is not an option, but friction welding is?

O__O

[Owen Thomas]

We tried cutting and re welding a heat treated drive shaft once. If I recall, it was properly grooved, pre heated, tig welded (multi pass), and allowed to cool in a "hot box" (old fish tank with a towel over it) for a number of hours. It broke immediately. I mean that in the most literal way possible, the car did not even twitch when we (slowly) released the clutch. Welds are not good in shear, and the heat treatment on the Taylor Race shafts is a marvel of engineering, which makes it very hard to get a good weld.

If you can actually friction weld it, you probably won't have a problem, although to be honest I don't know a whole lot about the mechanical properties of a friction welded joint. Just thought you would appreciate some anecdotal evidence about welding and drive axles.

[ASR]

Owen,
I am not very good in metallurgy. I think heat affected zone from welding on the heat treated shaft will make the shaft brittle. But friction welding is a solid state welding process. It retains the structure of parent metal. Also Friction welding produces a 100% cross sectional weld area. Its definitely a good area to look into. Thanks for your heads up.

The main problem is EN-24 or SAE 4340 material is not commonly available in India.

Anbu Sivaram
TeamUnwired

[MCoach]

To add a different side to a welded shaft story:

Our Baja team used 1" x .095" (?) wall tubing and cut and re-welded each axle in about 3 different areas. I remember there being a total of five welds so I guess he got it more right the second time. These things were put in a lathe and straightened by being beat with a hammer until they were relatively concentric, measured by eyeball.

The car then went to competition where an attachment point on the upright failed and I think they lost both of their radius rods (essentially two toe links). The kept running for the next hour and a half on only the single swing arm attachment and the driveshaft. Did the welds ever break? Nope, those shafts are still in use. The downfall of the car came from the suspension folding under the car after a jump and finally shearing the shock attachment.

So. It can be done, but it is something to note that Baja doesn't exactly see the same pattern of forces as formula.

[Kirk Feldkamp]

I welded our axles back in the day. These were the "good ol' days" before Taylor had come out with their shfancy axle components. This was when the Torsen and some bulk splined stubs were all you had to work with. After welding, we normalized and then heat treated the whole welded assembly. Then they were straightened with a hydraulic press and some V-blocks. We never had any issues, and that with a turbo engine with a ton of juice. Proper chamfering and penetration will go a long way... as well as adding some rosettes to the overlapped stub inside the tube. Don't expect two butted pieces to last very long.

To the original post, why do you need to get axles "to [an] exact length"? One of your two joints (per side) has plunge in it, right? The plunge used through range of suspension travel will likely not even come close to the plunge capability of the joint. In other words, you probably have some tolerance in there... it may need to be +-1/8", not +-0.005". If you want a super accurate location, then post-machining/grinding is your best bet.

-Kirk

[Canuck Racing]

Welded axles should have no problem. I know of quite a few higher level [real, $350,000] race cars that use welded prop-shafts with no problems.

I am quite curious though why you had such issues Owen. For one, it sounds like you tried a simple butt weld which Kirk already mentioned to avoid. I would also expect that the taylor axles are 4340 and you didn't use 4340 filler rod. That can have a surprising affect on weld quality, though I still can't imagine it failing instantly.

[AxelRipper]

Well there's always this gem of driveshaft welding from down at the Aussie comp: http://sphotos-a.xx.fbcdn.net/...618_1164049206_o.jpg (http://sphotos-a.xx.fbcdn.net/hphotos-ash4/241904_256850044444618_1164049206_o.jpg)

And we've run welded stub shafts for the past few years. We take the stock Honda splined tripod housing, machine it down to a spline, then weld it to a plate so we can run Taylor tripods. Lots of heat, slow cool, and good filler rod does wonders.

[MCoach]

I...wha....how the...


When you said gem of a driveshaft, I was expecting something to the like of a tree limb being MIG welded into place of an axle, but that's just beautiful!

[ASR]

@kirk I am using a torsen diff with a inboard brake rotor. I have trouble centering the diff.

Anbu Sivaram
Team Unwired

[Owen Thomas]

It is most certainly possible to use welded drive shafts, I was just relaying one particular experience. The key is post-weld heat treatment I think, at least when dealing with highly heat treated base material.

MCoach: Ah... Baja. Fortunately for them, even nightmarish butt-welded MIG joints will hold up to that briggs motor.

Canuck: The weld was grooved (chamfered), but I believe we were using our 4130 filler material and nearly out of argon. Naturally, this was <2 weeks to comp and was done with haste, but we were also surprised at how quickly it failed.

[Kirk Feldkamp]

@ASR: So... don't center it? It doesn't matter that much if your axles are equal lengths.

-Kirk

[MCoach]

Originally posted by Owen Thomas:
Naturally, this was <2 weeks to comp and was done with haste, but we were also surprised at how quickly it failed.


We rushed things just before competition and it failed. I was surprised and not expecting it!

That might be the first clue that experience may be an outlier...

[Canuck Racing]

It's all water under the bridge now, but in case any team finds themselves in a similar situation in the future and finds this thread while wondering if they can weld their axles I'll post anyway.

If you have to weld your axles, the best bet would to be to do some form of rosette weld. This of course requires having something to slip inside the axle, which can add considerable machining time to the fix. I would then recommend notching the axle so that your butt joint has a tombstone shaped cutout and welding around that, though many will simply use a plug weld to the inner piece you machined to be a slip fit.

Since you probably don't have time for that, your axle should be cut at an angle. This takes the weld seam out of plane with the torque/sheer forces as well as increases the weld area significantly.

Lastly, and this is for all heat-treating, using the incorrect filler rod typically has most effect only after heat treating. This is because by adding incorrect filler material you change the alloy in one location of the part and there is a very very slight difference in the thermal expansion and contraction of the alloys during heat treat, and hence the internal stresses and resulting cracks.

Or course, if you weld without enough argon all bets are off anyway.