MRC Forum- brought to you by www.morini-riders-club.com Member: g7AW3f

As I remove things bit by bit I was pleased with my newly delivered exhaust tool (ordered yesterday from NLM, delivered this morning, fab!) the rear nut came off very easily.
The front one is a different matter, I have moved it slightly, I know this as there is now some movement in the front downpipe, but now its stuck.
The tool itself seems only to fit some of the notches and is beginning to chew them, (they're brass- I didn't expect that) so I've left it for tonight.

Whats the best way to get it off?

With or without the special tool, preferably without damaging the header. I'll sacrifice the nut if I have to.

Presumably it has been well soaked in the one true penetrating fluid. That is Plusgas.

72degrees wrote:Presumably it has been well soaked in the one true penetrating fluid. That is Plusgas.

Haven't heard of that before, but after a quick search I've ordered some and will give it a go. Thanks.

I've been doing this, but in reverse, recently. Trying to do up nuts that are "past their best". That is, they have chewed up lugs so my C-spanner can't grip them very well. A couple of things that "should" make it easier, if you haven't done so already:

a) tank off - more space for leverage plus no chance of slipping and denting it!
b) rocker cover off - again, more room to play with.
c) good quality C-spanner. I know you have the NLM one but try a different type
d) penetrating fluid as mentioned.

I have just taken each nut and filed the lugs so they as many as possible now give a good purchase with the C-spanner. Also, use a small diameter wire brush on an electric drill and clean out the internal threads in the head, and on the nuts. Then use copious quantities of copper paste on reassembly.

I'm going to get the NLM spanner at some stage, but get new stainless nuts at the same time. Then I shouldn't have the problems we've both described.

Stainless Steel screwed into aluminium is a no no in(aircraft) engineering as is the use of copper slip, owing to the two materials fretting (metallurgically combining) together and seizing which usually results in the threads ripping out with the nut. Graphite based anti seize paste (Molyslip) should be used on aluminium not copper based pastes. If you look at all instances where nuts are screwed into aluminium where heat is applied the nut should be made from phosphor bronze or one of the 'brasses'
If your nuts are seized then try heat on the head which should owing to differential expansion, just break the seal. If your nuts are knackered try a stillson on what is left of the nut. I now make my nuts from cast phosphor bronze and have no problems especially as I use circumferential holes rather that castellations.

Harry wrote:Stainless Steel screwed into aluminium is a no no in(aircraft) engineering as is the use of copper slip, owing to the two materials fretting (metallurgically combining) together and seizing .....

But then you have this .... http://inoxbolt.co.uk/zen/index.php?mai ... anti_seize ...

When stainless steel is fastened ‘dry’ into Aluminium, galvanic corrosion can occur as the result of two different materials at opposite ends of the ‘metal nobility’ table being interfaced. In practical terms this means that alloy crankcases can oxidise around the fastener area very quickly. Copper based anti seize provides a third metal as the ‘sandwich’ and, as copper is placed in the centre of the ‘metal nobility’ table, it prevents Galvanic corrosion. Ordinary grease or oil will not work as they do not contain the vital element. UNDER NO CIRCUMSTANCES use Aluminium grease of any sort - including aerosols - as it will probably seriously damage the castings.

From my own experience plus that of others I'll be quite happy to use a stainless nut plus copper slip. To be honest, though, I'll bet that most of the issues with not being able to tighten/untighten the nuts are to do with damaged lugs and/or not enough lube when assembles and/or low quality spanner being used. New nuts PLUS a new spanner (along the lines of the NLM one) should sort out all the issues.

My castellated nuts were very tight and even with the heads off I struggled. The nlm spanner was useless. Bending immediately and as indicated it does not fit many slots. The solution posted by Harry is the ideal. Radial holes and a peg spanner but no one appears to supply them in bronze. Perhaps this is an opportunity for Harry for produce a batch?

OK. I was assuming that the NLM spanner was like the one here .... http://81.122.83.150/foto-accessori/DSCN4657.JPG ... ? Is that not the case? If it was, then, as I said, starting off with new nuts/spanner would be the ideal solution.

[From this page ... http://www.morinispecial.it/joomla/inde ... Itemid=168 ... ]

The spanner I have is flat, not like that one. I'll need to wait for the plusgas before trying again.

Thats a good site dvhttn, I also note they supply new bronze nuts.

I use a Britool 'articulated hook' spanner. It gets a really good grip of the castellations and certainly won't bend. No longer available I think but Draper do something similar.

http://www.tooled-up.com/Product.asp?PID=91540

I've now tried the plusgas and it hasn't seemed to help, the spanner is just slipping off now and the castellations are getting chewed.
I've taken the rocker cover off to allow me to use the part of the nut that I cant reach otherwise, but no progress.
Frustratingly I did manage to move it a few millimetres the other way as the plusgas instructions suggested to crack the hold it had before undoing it but that was the only movement thats occurred and I couldn't even get it back to where it was before.

I'm now looking for the best way to get this off now as its holding everything else up.
I really dont want to damage the header but the nut itself is junk and I will be buying new ones.

I'm wondering whether drilling straight through it and using a steel bar as a breaker bar may be an option.
This of course will mean drilling through the steel header trapped within but I'm wondering whether that could be fixed properly by a decent welder.

This seems to be a common issue, how has everyone else dealt with it?

if the nuts are starting to get slightly chewed up...might as well give them some more modification.....i've used an old blunt wood working chisel (or screw driver) at a an angle then tapped(ahem) the nut with a hammer.

I have the Draper C-spanner linked to above. Very good for a C-Spanner - but it's got to have something to grip, and enough leverage to move the nut. I managed to "extend" the handle with some "bits" I had lying in my tool box. The main one being a very long reach spark plug spanner like this ... http://images.esellerpro.com/41/I/662/0 ... panner.jpg ... which I hammered "slightly" flat until the C-spanner went in. Worked a treat for tightening!

If still no-go, how about removing the head with the nut/header pipe still attached? That way you "should" be able to get at it easier. And as mentioned above, a big hammer can work wonders ....

Dave

stillooking wrote:if the nuts are starting to get slightly chewed up...might as well give them some more modification.....i've used an old blunt wood working chisel (or screw driver) at a an angle then tapped(ahem) the nut with a hammer.

Sounds horribly as if someone may have cross-threaded it. A suitable drift and a hammer may do it if access allows a suitable angle of attack and a good swing. Unfortunately differential expansion is a bit hard to organise unless the engine can be run hard enough to get it good and hot.

The engine cant be run now as the only bit left attached is that header pipe, all the rest and the wiring are now placed on a shelf.

Would heating it help?
If so with what and which bit to heat.