Help the nuts won't come off

[harbourseal]

Back at the gearbox today.
two nuts won't budge The Sinpar factory dented the nuts onto the treads as safety precaution I thinks. They are completely stuck.
Any ideas on how to undo them are welcome.

@mr-reno-139 @Andrew4Renaults or others

The one on the second photo i have tried to undo by tapping the indentation outwards but I can't really get to it where I am supposed to get.

 

[Cornish4]

Hi Robert. All I can suggest is using a small grinder, like a Dremel, to gently grind away the indent. The nuts might be replaceable, which would be a bonus. Regards Brian.

 

[JdeW]

Maybe these sites offers some help http://www.retro-meca.com/technique/bvsinpar/bvsinpar.htm
http://www.retro-meca.com/restaurations/bvsinpar/bvsinpar.htm

 

[harbourseal]

Thank you Joop.
Unfortunately it is anout the wrong type of gearbox. I don’t have a HAO gearbox

It’s a 334 with Sinpar build up.

 

[JdeW]

Ahh you've got the "round" gearbox hmmm maybe la4ldesylvie may help describing the 334 sinpar gearbox http://la4ldesylvie.fr/index.php?option=com_content&view=article&id=217
Maybe interlocking the gears and a bigger lever may help...

 

[harbourseal]

The interlock isn’t a problem engage reverse and fourth gear and everything is blocked.
But then no movement on the nuts.

 

[mr-reno-139]

Would suggest using snap on or similar half inch electric impact wrench the torque available on modern ones is massive

 

[André4Renaults]

I'd suggest a very accurately fitting socket, a tin of WD40 and a long torque bar. If strength fails you a slice of Christmas cake and a few mince pies might help! I wish you well with this and it ought to undo with enough gentle leverage.

 

[angel]

Make sure you are trying to undo these the right way round - left hand threaded nuts are common on gearboxes. Check if this is the case on yours.

Leverage works better than impact tools on staked nuts, I have found. The problem is that the gearbox will need to be fixed somewhere (e.g. engine stand) as it's very light.

 

[Rhys Nolan]

I have only done these twice. Once I ruined the thread on the shaft trying to undo it. The second time I used a dremel to machine off the staking and then the nuts needed massaging to stay fixed when I put it back together, but the shaft remained excellent.

 

[Mike Cordeiro]

An air impact socket wrench should loosen it up. when I can`t get a bolt loose with my 1m power bar, the air wrench usually does it effortlessly. as a matter of interest, my power wrench is a 750NM.
Good luck.

 

[harbourseal]

Progress at last.
I placed the gearbox in a second motorstand that we have and used a 27mm socket and a killer for some extra leverage.
Finally the nuts came off.

The thread is a right handed one, so going left like a normal nut makes it come of. The extra leverage did the trick.

 

[JdeW]

Well done Robert, just like I said, a bigger lever.
At a first glimps, the sprockets look in excellent condition.