Input/output shaft welding job anyone ...

[Wightsparks]

As part of the creation of "Frankenbox" for my Sandrail engine swap
I need to weld a male spline to a bit of MX5 engine output shaft and a female spline to a bit of VW gearbox input shaft. Originally I was told by local shop that it could not be welded and would need to be pinned, but then I was later told by someone more automotive orientated that it could be.
That chat was a week ago and they have not been back to me so I thought I would ask if on here as I need to get this moving, so to speak.

As far as I can tell the parts are case hardened not through hardened, but basically they just need to be welded on straight. It is as per the thread linked above but a summary in the attached PDF. Let me know if it's something you could help with - beer tokens involved of course.

 

[Tinbasherdan]

I would centre drill one and turn the other so they press together first, then weld

 

[Ian James]

If anything I would get it pinned before even thinking about welding it 1mm tolerence is not a lot if you get. It wrong you will eat bearings and snap shafts I would of thought

 

[Ian James]

I would look at having new shafts made up by some one like RAKEWAY LTD but they won't come cheap I looked at having 4 small gears made recently by a firm of gear manufacturers and they came to over £ 400.00

 

[pedrobedro]

I would get a shaft made with the appropriate splines on either end if it's going to be under a lot of pressure.

 

[andymfell]

looks like a job for electron beam welding but its not a cheap process

I wouldn't cross drill & pin as it will introduce a weakness in the shaft ( seen loads of articles that have snapped at the drilling
what amount of torque will the engine produce ?

 

[dannyp]

Why do you actually need to modify the shaft ? When I’ve done cross marque transplants I’ve usally done with a franken clutch.

Sometimes adjusting the release bearing and putting say a vw clutch disk between Subaru or whatever flywheel and pressure plate or even drilling the flywheel to take s fiffrent pressure plate

 

[Wightsparks]

Staying with the MX5 clutch and set up was the recommended route by others doing this sort of thing It brings the benefit of a nice big bearing supporting the shaft between clutch and gearbox as well as using a 2002 clutch rather than a 1968 one. At the time joining 2 pieces of metal didn't seem such an issue!

I have just last night figured out a simpler way to do by modifying the way the VW end attaches, but I still need to join the two shafts permanently. - If that is not possible then yes back to the drawing board...

 

[Wightsparks]

I would centre drill one and turn the other so they press together first, then weld

That was my thinking, now I only need 2 shafts welding together - something you could do?

Updated version

 

[Tinbasherdan]

if you get desperate i can give it a go, certainly

 

[Wightsparks]

Thanks. I spoke to Rakeway as mentioned by @Ian James above, their opinion was that welding it and keeping it true would not be possible and it was a likely failure point and I needed a complete new one made for £££. Obviously they look at it from a racing POV, whereas I think of a couple of thousand miles a year of not very stressful driving. Opinion is certainly divided!

Following @dannyp 's comment I looking at a Franken clutch. But I'll post thoughts in my build thread as it's automotive and OT here.

 

[Tinbasherdan]

ive seen welded shafts run quite succesfully in some landy conversions so they cant be that bad

 

[Wightsparks]

That's good to know, do you mean drive shafts or engine/gearbox shafts?

 

[Tinbasherdan]

gearbox, couple guys running cummins conversions with a welded transfer box input

 

[Gritineye]

Bore one turn spigot on the other, press together, weld it then straighten it, no skill needed at all, easy peasy..

Seriously, I've cut a flange of one shaft and welded it onto another shaft, it ended up a bit wobbly (but it had coupling each end) it's taken getting on for 1000 ft/lbs tourque for years, but not done it in the middle of a shaft.

Didn't know what the steels were so pre-heat and cool down in Rayburn fire, and used dissimilar metals rods.

 

[Ian James]

Bore one turn spigot on the other, press together, weld it then straighten it, no skill needed at all, easy peasy..

Seriously, I've cut a flange of one shaft and welded it onto another shaft, it ended up a bit wobbly (but it had coupling each end) it's taken getting on for 1000 ft/lbs tourque for years, but not done it in the middle of a shaft.

Didn't know what the steels were so pre-heat and cool down in Rayburn fire, and used dissimilar metals rods.

Yep it's a totally different ball game if you have a joint with flex in especially at rather end

 

[dannyp]

I would allways hybrid a clutch out of preference. I’ve done it quite a few times I’d say with the vw box the issue isn’t the clutch and you can get plenty of tougher friction disks for them.

Welding shafts together I’ve done it plenty of times as well. Sometimes they weld with no fuss or bother. Other times they seem to weld fine and straight but shear, usally on a hard gearchange