Exhaust studs

[Geocamper]

Just ordered new engine studs as the ones I have are quite worn and the brass nuts keep slipping off. What is the best way to extract the old studs? I have heard something about putting two nuts on the thread ? Are there any video links anywhere on how to do this?

[Dimitrios_231]

I use heat and stud extractors

sometimes the double nut method doesn't work on stuck studs, especially if it is an old original cast barrel.

This is a video with the double nut method.

https://www.youtube.com/watch?v=66ATKL4G04M

[Geocamper]

Where can I buy them from? Looks a much safer way.

[Dimitrios_231]

Search for Stud Extractor Set,I'm pretty sure there will be millions results with shops located in UK

If you don't already have one,try first the double nut,you don't have to lose anything.
The double nut method is good if someone wants to reuse the stud,using the extractor set,the stud will probably get damaged on the thread.

The 6mm one, is good for all the M6 and M7 studs.

[Geocamper]

Thanks dimitrios . The size of the stud was going to be my next question.lol. Looks like my local machine mart sells them so I'll pop down there in the morning.

[Geocamper]

Just bought the stud extractors from machine mart and they come in 6,8,10 and 12mm sizes. I know only realize that the stud on my scoot is 7mm!! Is there anyway around this apart from buying a 7mm extractor?

[Tractorman]

You might not get a 7mm one, it's a 'funny' size, so they keep telling me. Try the double nut method.

[Dimitrios_231]

If you insert the 6mm extractor 'carefully' it will fit the M7 stud.
Try to screw it slowly on the stud.

[Geocamper]

[quote="Dimitrios_231"]If you insert the 6mm extractor 'carefully' it will fit the M7 stud.
Try to screw it slowly on the stud.[/]
As I'm working under the scoot it's quite difficult to attach the extractor to the stud because all the gubbins inside the extractor tend to fall back inside the extractor by 1-2mm. Then I have nothing to attach to. As for the double nut method, There is not enough grip on the stud thread so that the nuts will sit nice and tight. Really had a right tit full of this machine!!

[Dimitrios_231]

Lambrettas

I just double checked it and yes, I'm positive that you can use the 6mm one for the M7 exhaust studs
On the middle picture,I fully inserted it.
In general,even a few mm of a good grip, are enough to extract the stud.







Is it possible to turn the scooter upside-down?

[Geocamper]

Fair play, At least you have a sense of humour.lol If I could turn the Lambretta upside down I would.lol thanks for the pictures. I'll have another crack at it later when I'm not feeling so pissed off

[Dimitrios_231]

I feel you,it is quite difficult to work with the engine on the frame.
Just a thought,it might work it might not.
Use a small flat bladed screwdriver trying to lift the gabbins,hoping that they might grip the stud.
Good luck.

[Geocamper]

Dimitrios, I owe you one pal. Put the 6mm onto the stud and with a little persuasion with a hammer. It must sat on enough to turn the socket anticlockwise and the stud just rolled out. Easy!! The new ones should be here tomorrow so fingers crossed I won't have as much trouble putting the new ones in. Cheers

[Dimitrios_231]

Nice ,
for the opposite procedure,
you'll need the double nut method,
apply first a small dab of threadlocker and use a torque wrench to tighten it.

243 (medium strength) or 270 (high strength) Loctite if you know what you are doing, 8-12 N-m will be enough.

I don't know what type of engine you have,
If it is a small block,make sure that the stud won't be long enough and won't foul the cylinder studs.
If it is a large block,you won't have this problem.
Double check that once the stud is fully tighten,after fitting the exhaust gasket and stub or manifold,only the threaded part of the stud is exposed,this way you'll be able to tight correctly the brass nut.

In that case I'd prefer to use a small dab of a high strength threadlocker.

[Geocamper]

Nice ,
for the opposite procedure,
you'll need the double nut method,
apply first a small dab of threadlocker and use a torque wrench to tighten it.

243 (medium strength) or 270 (high strength) Loctite if you know what you are doing, 8-12 N-m will be enough.

I don't know what type of engine you have,
If it is a small block,make sure that the stud won't be long enough and won't foul the cylinder studs.
If it is a large block,you won't have this problem.
Double check that once the stud is fully tighten,after fitting the exhaust gasket and stub or manifold,only the threaded part of the stud is exposed,this way you'll be able to tight correctly the brass nut.

In that case I'd prefer to use a small dab of a high strength threadlocker.

Cheers for the information dimitrios. I have bought a torque wrench this afternoon and have set it to 12nm ready for when the parts come on the morning. I have bought loctite,248. That's the only one I could find at short notice and also copper gasket seal. Wish me luck,lol

[Dimitrios_231]

Good luck

Reset the torque wrench,you don't want to stretch it when not in use.

Start with 8 N-m,if you feel that it can go higher,then increase to 12 N-m.
You don't want to strip the cylinder exhaust threads.
If you feel that the two nuts are starting to move and the stud not,stop.

Ideally the exhaust threads should be in good shape,use of a M7*1 tap wouldn't harm,(oh my god all of these are more difficult to do with the engine on the frame ) let the threadlock after installation a few hours to get set.

[Geocamper]

Cheers pal