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Prop shaft too short?
Posted: Wed Feb 24, 2010 9:53 pm
by Bradmoneypit
Hi,
I have a 1960 2 door saloon and have just replaced a 948 engine gearbox and diff wiith 1098 bits. The trouble is propshaft is about an inch too short.... well it just mates with the gearbox splines. The car was a basket job to start with and I didn't notice if it was too short with the 948 set up when I took it apart.
Is there a possibility that it is a propshaft for another BMC car? I can't find any technical details even in the workshop manual as to the actual length/spec of the prop that should be fitted.
Can any make a suggestion... well other than driving into a wall and shortening the car!!!
Re: Prop shaft too short?
Posted: Wed Feb 24, 2010 10:34 pm
by bmcecosse
How strange! Both 948 and 1098 Minors use the same prop. I've no idea if the A35/A40/Spridgets used shorter shafts - I suppose it's possible.
Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 7:36 am
by jonathon
Are you sure that its not just the free play you are seeing. The prop if pushed right ito the box will appear around 20mm short, this is needed to allow for shunt/movement in the box.
Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 9:48 am
by Bradmoneypit
Thanks for the replies, in answer to the last post, I have tightened the gearbox restraining cable as tight as it goes with the gearbox mountings loosened. The rebound rubbers are in the same place on the body bump stops over the rear axle. The mouth of the propshaft just about mates with the splines on the gearbox. In fact the rim of the gearbox oil seal is just showing below the outer cover of the propshaft.
I could bodge it and drag the rear axle forward a little, but I am loathe to do this. It seems a little strange but then again it is a Moggie and that's the attraction for me.
Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 10:02 am
by Jefftav
Your going to have to measure the propshaft and then it can be compared to a known correct one.
Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 10:47 am
by Bradmoneypit
Just popping out with my tape measure. Does any one have a known Minor 1000 propshaft they could measure for me so I can compare mine with a good one. I will be measuring between the diff end flange and the very tip of the of the gearbox end.
If any one can post me the measurement for their prop shaft between these two points it would be appreciated.
Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 11:05 am
by Jefftav
Sorry mine is buried in snow, post the measurement anyway and someone will come along soon who will be able to help.
Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 11:53 am
by Declan_Burns
This might help
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Regards
Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 1:35 pm
by bmcecosse
The gearbox cable should NOT be tight - 'just loose' is enough.
Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 2:05 pm
by Bradmoneypit
Declan thanks for the measurements, oh dear my propshaft is 51.5 inches as well. That's a pain. Looks like I'll have to shorten the car by driving into a wall after all!
Thanks for the tip about the gearbox cable as well. I will give mine a little slack.
Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 2:57 pm
by bmcecosse
If you really do think there is s problem - you would be better to make up a spacer to go between the diff flange and the prop flange - rather than 'drag the axle forward'.
Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 3:33 pm
by katy
Are you sure that the rear springs are in the correct way 'round and not front to back?
IIRC the rear axle ass'y sits off centre on the springs.
Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 7:09 pm
by Bradmoneypit
I didn't notice that about the rear springs being reversible. I will have a play over next couple of nights and see what happens. If it works I will post the results on the notice board. Thanks for the suggestion.
Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 7:38 pm
by bmcecosse
Springs can go either way round - makes no difference.
Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 8:14 pm
by Bradmoneypit
Thanks BMCecosse I have just come in from measuring the springs and they are both 580mm to the centre suspension bolt through the bracket from each end. Oh well that gave me some hope for a while.
It looks like I am going to have to drill a new hole in the rear shock brackets about 15-20mm further back to try and move the rear axle forward, before I resort to making an insert plate to go between the diff and flange, I'm not keen on that idea it would have to be pretty accurate or it might then cause balance problems.
Its a weekend end job, so if anyone has any other ideas before I start to further modify the original please feel free to let me know.
Thanks everyone for their suggestions.
Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 8:36 pm
by bmcecosse
Damper brackets won't make any difference to the rear axle position! The axle is located by the leaf springs - and the springs are held to the body by the front mounts - the rear end 'swinging' on the shackles. Only sensible possibilty is that the front mounts for the springs have been renewed - and welded on too far back ?? OR - is the engine mounted too far forward ? Seems highly unlikely - is the clutch bellhousing tight to the crossmember - no big gap there ? This is a most strange and unusual thread!
I see you are in York - I'm sure there are other Forum members in/around York - maybe one would take a few minutes to pop round and have a look at this for you ?????????
Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 9:44 pm
by cormorant
I wouldn't go trying to modify the back axle as you say the bump stops are in line with the welded plates so all seems well there. Prop is correct length so that's ok. I am wondering how much clearance you have between the rad and the fan.
Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 10:16 pm
by Mogwai
something else to check, are the engine & gearbox mounts the right way round as I think there is a slight offset in the brackets.
Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 10:21 pm
by linearaudio
Whoa there! Don't go modding the car yet! There
must be a simple answer- your Moggy can't be unique! I'll have a lie under mine and think about it tomorrow (if the rain stops)

Re: Prop shaft too short?
Posted: Thu Feb 25, 2010 10:50 pm
by PSL184
If the engine mounts are fitted to the wrong side then the engine will be about 3" too far forward. Have you had the turrets off and put the LH one on the RH side? If you look directly from the front of the car the angled face of the mount should be facing the radiator and the verticle face should be facing the bulkhead...??