Morris Minor Owners Club

Posted: **Sun Jul 01, 2007 9:41 pm**

Anyone got a well proven method for fitting 1275 pistons to the rods ?

Posted: **Sun Jul 01, 2007 9:45 pm**

Gudegeon pin? (funny guy!!)

Is there a difference in size to the standards then?

Posted: **Sun Jul 01, 2007 9:54 pm**

I was going to say "obviously with a gudgeon pin" - but then I thought - nah, the Minor lads won't be so daft as to say that - that's what I expect on the Mini forum!! I was wrong again - I guess.
All standard size.

Posted: **Sun Jul 01, 2007 10:18 pm**

a hammer. a big one.

find somewhere/someone with a really big press, I think is the only method likely to be successful.

Picky

Posted: **Sun Jul 01, 2007 10:29 pm**

Im getting a machine shop to do mine, dont want to risk breaking the pistons!

Posted: **Sun Jul 01, 2007 10:30 pm**

Oh incidently, according to AC Dodd the hole should be 11thou smaller in dia. than the pin!

Posted: **Sun Jul 01, 2007 10:31 pm**

Don't know anyone competent to do it - and doubt they would anyway unless supplying the pistons and doing the rebore! It's going to have to be DIY for me.

Posted: **Sun Jul 01, 2007 10:31 pm**

I got Arthur Smith(Smith engineering)in Coatbridge to fit mine.As he supplied the new pistons.Don't know what he would charge just for fitting.(I know every penny is a prisoner BMC

)

Posted: **Sun Jul 01, 2007 10:39 pm**

I know Smith Co well - his Dad did my cranks etc many moons ago when I was competing with Minis. Snag is I already have good pistons - I doubt he will touch the job unless he supplies the pistons etc. Every penny is indeed double locked and accounted for!!

Posted: **Sun Jul 01, 2007 10:45 pm**

bmcecosse wrote:I was going to say "obviously with a gudgeon pin" - but then I thought - nah, the Minor lads won't be so daft as to say that - that's what I expect on the Mini forum!! I was wrong again - I guess.
All standard size.

Guess you dont know me then

Seriously though, why are they a pain to fit?

Posted: **Sun Jul 01, 2007 10:50 pm**

They're press fit, unilke the 1098 which just push through.

Posted: **Sun Jul 01, 2007 10:55 pm**

Isnt it possible to just turn down the pin so its no longer an interference fit?

Posted: **Sun Jul 01, 2007 10:59 pm**

I kind of imagine that it is for a reason

Posted: **Mon Jul 02, 2007 12:52 am**

Recon its always best to ask.
Had a machine shop fit mine for a tenner and i supplied the pistons. Tried to press the old ones out and the piston disstorted before the pin moved!

Posted: **Mon Jul 02, 2007 1:29 am**

Heat the piston freeze the pin? Probably still won't just drop in, but should be a lot easier to "ease" in.

Posted: **Mon Jul 02, 2007 9:45 am**

Oh incidently, according to AC Dodd the hole should be 11thou smaller in dia. than the pin!

Thats quite a bit for an interference fit

Posted: **Mon Jul 02, 2007 6:01 pm**

The gudgeon pin is a slide fit in the piston - but tight interference in the con rod ! Yes - heating the rod and freezing the pin (although that makes relatively little difference) is the way to go - just wondered HOW to go about it! Can the rods just be heated up in the oven (when Mrs bmc is away of course) - or do I need to fire up the acetylene torch!! I have pressed pins out in the past using a DIY version of the special tool shown in the manuals - without damaging the pistons - but it's a hard game

Posted: **Mon Jul 02, 2007 9:59 pm**

my bench vice says "3 ton" on the side of it, its not a particularly special one. Maybe if you heated the little end with the torch, and then tried to squeeze it all together in a vice with a scaffold pole on the handle! maybe setup the torch held still to heat the rod as you tighten the vice?

food for thought...

Picky

Posted: **Mon Jul 02, 2007 11:24 pm**

That wont work picky... the pin needs to be pressed in without putting any real load on the piston!

Posted: **Mon Jul 02, 2007 11:24 pm**

BMC, have you got a pic of the special tool?

Morris Minor Owners Club

Pistons to rods

Pistons to rods