• UPDATED INFORMATION & ADVICE - PLEASE READ NOW

    'I didn't know/I wasn't told' will not be a valid defence if you fail to comply and lose your access to the off-topic area, core topic areas, or the entire YBW forum as a result. Full details can be found here, please read before you proceed.

Failed to remove the shaft coupling

fisherman

Well-known member
Joined
2 Dec 2005
Messages
16,372
Location
Far S. Cornwall
Use the gearbox flange, it's held on with a nut so not going to affect the G/B, not going to push the gearbox shaft out. basically it provides a robust puller, put a spacer on the shaft end, four bolts through the flanges, oil on the nuts and washers ,and wind up. You are only pressing the halves together, no endways pressure on the gearbox, as long as you don't start with the hammer.
 

Hurricane

Well-known member
Joined
11 Nov 2005
Messages
8,330
Location
Sant Carles de la Ràpita
Use the gearbox flange, it's held on with a nut so not going to affect the G/B, not going to push the gearbox shaft out. basically it provides a robust puller, put a spacer on the shaft end, four bolts through the flanges, oil on the nuts and washers ,and wind up. You are only pressing the halves together, no endways pressure on the gearbox, as long as you don't start with the hammer.
The OP said above that he doesn't want to risk damaging the gearbox flange.
I think his current approach is to do the same as you are suggesting but with a steel plate/disc instead of the gearbox flange.
 

fisherman

Well-known member
Joined
2 Dec 2005
Messages
16,372
Location
Far S. Cornwall
The OP said above that he doesn't want to risk damaging the gearbox flange.
I think his current approach is to do the same as you are suggesting but with a steel plate/disc instead of the gearbox flange.
OK. Can't see what damage would be possible. An old knackered flange would do for a puller.....
 

Mistroma

Well-known member
Joined
22 Feb 2009
Messages
4,157
Location
Currently in Scotland, boat in Greece (Ionian)
The OP said above that he doesn't want to risk damaging the gearbox flange.
I think his current approach is to do the same as you are suggesting but with a steel plate/disc instead of the gearbox flange.
Yes, I spotted that. Perhaps he was under the impression that he was pulling on the flange. Most flanges are pretty thick and strong. I didn't even consider a puller with mine, just a spacer with longer bolts to squeeze the flanges together and some heat.

It is a puller, because it is pulling the coupling off the shaft. OP should think of it as a "pusher" because it is pushing the end of the shaft by applying compression between both flanges.

It was several miles to reach somewhere selling bolts and I decided to get a guy with the proper tools. Guess what, he used longer bolts, a steel billet and some heat. :D:D
 

Lucas Gan

Active member
Joined
5 Oct 2018
Messages
424
Yes. I just received some 120mm long bolts and just waiting for a piece of 20mm thick steel plate to do that. I will avoid using the gearbox flange because I don't want to damage it, and it's too little room between the gearbox and its flange. It is very hard to tighten the nuts there.
 

John100156

Well-known member
Joined
31 Oct 2007
Messages
2,319
Location
SANT CARLES DE LA RAPITA
Just a thought, as 1.3/4" is so close to 45mm, could 'they' have possibly heated an 1.3/4 flange, and then fitted it to a slightly bigger 45mm shaft? Would make it blooming tight when cold, although I doubt it what with the key....
 

TK Blue MAX

Member
Joined
27 Apr 2015
Messages
85
Location
Staffordshire / Torquay
Just a thought, as 1.3/4" is so close to 45mm, could 'they' have possibly heated an 1.3/4 flange, and then fitted it to a slightly bigger 45mm shaft? Would make it blooming tight when cold, although I doubt it what with the key....
Half a mm is massive on shaft fits, you would need the flange almost molten to get a 1 3/4" onto a 45mm shaft
:ROFLMAO:
 

fisherman

Well-known member
Joined
2 Dec 2005
Messages
16,372
Location
Far S. Cornwall
too little room between the gearbox and its flange. It is very hard to tighten the nuts there.
Get round that by putting bolts in from the shaft end, nut on g/b end, with an extra nut at the bolt head, which you wind in while holding the bolt head if needed. But it sounds like you are nearly there anyway.
 
  • Like
Reactions: vas

John100156

Well-known member
Joined
31 Oct 2007
Messages
2,319
Location
SANT CARLES DE LA RAPITA
Half a mm is massive on shaft fits, you would need the flange almost molten to get a 1 3/4" onto a 45mm shaft
:ROFLMAO:
I remember (many years ago) when I was rallying and rebuilding engines, we use to heat up the con-rods before pressing-in the gudgeon pins to assemble the pistons - not sure what the rate of expansion was...! :ROFLMAO:
 

Falling Star

Member
Joined
4 Mar 2011
Messages
524
Location
Essex
Yes. I just received some 120mm long bolts and just waiting for a piece of 20mm thick steel plate to do that. I will avoid using the gearbox flange because I don't want to damage it, and it's too little room between the gearbox and its flange. It is very hard to tighten the nuts there.
I do wish you luck with it and hopefully that will work. Doing it that way, there is a risk that the threads may strip before it releases.
Take your time and maybe continue using heat and some taps with a hammer as you tighten the nuts.
 

burgundyben

Well-known member
Joined
28 Nov 2002
Messages
6,583
Location
Niton Radio
I remember (many years ago) when I was rallying and rebuilding engines, we use to heat up the con-rods before pressing-in the gudgeon pins to assemble the pistons - not sure what the rate of expansion was...! :ROFLMAO:
You only need a few thou! Not half a millimetre!


Hole Expansion Ratio, HER, quite a complex set of calcs with a number of factors.
 

Bandit

Well-known member
Joined
30 Jun 2004
Messages
3,280
Location
Guernsey
Its a British Fairline I am sure they are all inch and three quarter. Mine was and every Turbo 36 and Sedan I have seen is.
 

Croftie

Active member
Joined
19 May 2015
Messages
523
Its a British Fairline I am sure they are all inch and three quarter. Mine was and every Turbo 36 and Sedan I have seen is.
I asked him to double check, he said "@Croftie Yes. It's metric 45mm. "
Probably in a week will be asking how to shim up a 1.75 shaft to fill a 45mm coupling :oops:
 

Lucas Gan

Active member
Joined
5 Oct 2018
Messages
424
@Bandit. No worries. I appreciated your input.

Finally received the 20mm steel plate. I am going to drill holes on it today and try it on the coupling tomorrow.
 
Top