10 replies to this topic

[minisilverbullet]

Just a quickie - what size is the nut on the top and lower shock pins/bolts. Ive searched and it came up as 3/8". Now i replaced the shocks yesterday and certainly didnt use a 3/8 socket as that seems way too small.

About to buy replacement nuts but really need to know the size.

Maybe a stupid question, but i always get stumped when it comes to imperial and metric nuts and bolts on the mini, is there a way i find the correct nut and bolt sizes?

[Cooperman]

The thread size is 3/8" UNF which requires a 9/16" AF spanner/socket.

[Guess-Works.com]

3/8" is the thread which has nothing to do with the size of spanner...

The nuts will probably be 9/16" AF, but sometimes they can be 11/16 or 5/8 depending upon application... but the thread is still 3/8" UNF.

[minisilverbullet]

HAHA (if i am aloud to say) I consider myself a reasonable smart guy, I am one year away from completing my Phd - but I cannot get my melon around this!

I used a 9/16" socket

Do I buy a 3/8" nut or a 9/16"?

Edited by minisilverbullet, 26 October 2010 - 01:41 PM.

[Cooperman]

You need a 3/8" UNF nut. UNF stands for UNified Fine Thread. The nominal diameter of the thread is 3/8".

[minisilverbullet]

You need a 3/8" UNF nut. UNF stands for UNified Fine Thread. The nominal diameter of the thread is 3/8".

Brilliant!

I will get there!

Cheers Craig

[Ethel]

If you think about it, it's much more important that the male & female threads match than what size spanner you need - threads are specified by the outer diameter: i.e. what size hole you'd drill to fit the bolt through.

[minisilverbullet]

Yeah that's clarified it for me. Makes perfect sense really; just new ground for me.

[MRA]

If you think about it, it's much more important that the male & female threads match than what size spanner you need - threads are specified by the outer diameter: i.e. what size hole you'd drill to fit the bolt through.

Not quite...... the hole that you would drill to put a bolt in would be either a tapping size or a clearance size.... 3/8 unf would not work if yo udrilled a 3/8" diameter hole, and should be too tight to fit a bolt through.

The standard for head sizes (ie AF or Across Flats) is 1.5 times the thread size, so your 3/8" unf should require a spanner / socket etc od 3/8 x 1.5 = 4.5/8 or 9/16"

This doesn't always work out as Guessworks has explained above, they can be different sizes Across the Flats and as Ethel says use the nut that fits the application NOT the spanner / socket etc.....

This should do the job...............

http://mra-minis.co....nut-3-8-unf.htm

[Ethel]

Well yes, the nominal size is actually from the stock diameter bar you'd use to cut the male thread on. A setscrew would clear a hole of the same size but the unthreaded shank of a bolt shouldn't. But then, the actual diameter of a drilled hole is likely to be less accurate than the shank of a factory forged bolt.

If I want to drill a hole for a bolt in the sort of stuff (body panels, bits of alloy plate...) that most of us do in our garages I use a drill bit the same size as the bolt (it's usually too short to have a shank anyway). I accept it wouldn't do in an engineering works, I just thought it was an easy way of illustrating the point.

[MRA]

Yes Ethel it works, and if it is still tight.... a quick go with a round file normally does the trick It works fine you don't need 20,000 drilll bits, so it also saves a bit on tools, an 8mm drill is reccomended to create a clearance hole for 5/16".

5/16" = 7.9375mm

Edited by mra-minis.co.uk, 27 October 2010 - 12:28 AM.