hi all
I am aware that there a few posts on this but I have some questions
first my aim > extend fiesta drive shafts , one by 4" the other by 8" @

I am aware you can get custom drive shafts but want to consider cut and extend

I know there have been some failures of cut and shut welded shafts , but my thoughts where to cut and then make some very tight fitting tube extensions , hammer in say 4" each end then end weld and maybe puddle weld in a few places.

question has any one tried this and has anyone heard of failures on this type of extension .

I know ill get some abuse but I need to ask the question .

regards Bart

What could go wrong ?

But seriously, it's quite common in the 16V Mini community.

Firstly the shafts are cut to the correct length. This was the required length plus 7mm extra each.
Next the ends were machined ( turned/ trued) down to the same size using only minimal cut on the smaller shaft.
Then each was ' dogged' a 7 mm deep semi circle left on each shaft end
Then a 6 mm thick sleeve 60mm long was machined to press fit over the two shaft ends ( this holds them true) This sleeve also had 4 off 12mm dia holes at 90 degress to each other near each end .
When all assembled ( and true) a powerful MIG welder welded in the 8 holes to hold the lot together.




[Edited on 1-12-14 by ken555]

I posted this in another thread, I saw chrisf shafts shear at the join on his fireblade 7. That said it was very lightweight sleeve and weld. I think it could be done safely but you'll probably ruin any heat treatment where you're welding.

I'll tell you chaps what! I'll bring my welded ones in to work and hardness test the shaft up through the haz and up to the weld!
It'll be interesting.



http://locostbuilders.co.uk/viewthread.php?tid=170402

re hardness > that would be interesting . I suspect the shafts are not hard just heat treated at the ends .
having said that welding the shaft could make them brittle around the HAZ etc . that was already one of my concerns .

ps I agree what could go wrong with the above picture

[Edited on 1/12/14 by bart]

welding hardenable alloys can be done, but needs to be done by someone who knows what to do. Generally, lots of pre-heat!

well
I have just striped my shafts .
I have 2 different type shafts 1 focus which is hollow tube
and the other fiesta
both are not bearing hard but hard enough for the hack saw to bounce off
now I am worried , think its a none starter for conventional welding, looks like its new shafts , another £400 to spend !

apart from Beresford engineering anyone know of decent quality but cheaper ?

any one used cps

I spoke to them and they add extra length by friction welding the original material to half a new shaft. sounded very knowledgeable on the phone

You could try these guys

http://www.jandrcvjoints.co.uk/

I shorterned mine, just chopped out the middle bit and sleeved with some 3/8" walled tube, on an autosolo booted it in first and the sleeve twisted and snapped like a carrot on road tyres, I have now ground the mess off, machines the ends and butt welded then sleevee and it's been fine spinning up slicks every since, a lot more stress.

If you are extending make sure it's good thick tube or drop a bit of metal inbetween and have two butt welded joins under the sleeve and you should be okay.

I aligned and welded the shaft with it in my lathe to ensure everything stayed aligned, I bottom imbalance could be nasty.

There is a company called CPS Drivelink, if you send them a mock-up, made of all the right bits, tack welded any way you like as long as the length is correct, will return it to you like it came out of a factory. They use a technique called friction welding. For a small amount they will also rebuild the cv joints etc. I cannot recommend them highly enough. They did the drive shaft shortening on my Sylva. T0191 482 1690