7 replies to this topic

[MiniCarJack]

Hi all, I'm very seriously considering purchasing a replacement engine unit for my Mk1 which has become available locally. I currently have a tired pre-A+ 1275 (12g1279 casting) from an ADO16 on a 22g1128 gearbox, so a 4 synchro remote change (I also think, but am not 100% sure, it's a SCCR gear set a-la Cooper S and Austin 1300GT), so this has the rubber crucifix couplings / cross type joints as per the original Mk1 setup.

 

The replacement I'm looking at buying is a very nicely spec'd pre-A+, originally a 1275GT lump which has had a lot of work and is basically my dream spec for a fast road car. The gearbox is an interesting late 1275GT "cross-over" type, which has been fully rebuilt with a X-pin diff and 3.44 final drive. All really nice stuff, however I'm presented with a bit of a dilemma trying to work out the best way that'd work to get this lump into my car, given the differences in the gearbox.

 

As I understand it, I'm going to have to go down one of a few different routes (please correct me if I'm wrong!):

1. Convert my car to later drive shafts to marry up to the pot joints on the new box, and fit the rod change mechanism with a conversion bracket to suit my round tunnel floor
2. Convert the gearbox to use the earlier rubber crucifix outputs rather than pot joints, to retain my existing driveshafts, and as above use a conversion bracket for the rod change mechanism
3. Split both engines and boxes apart and swap them over - so the nice new engine would sit on my old 22g1128 remote box, retaining the original remote shift mechanism & driveshafts

It feels like there are pros and cons to any of these approaches - so if anyone's had any experience with fitting a later 'box into an early car like this, I'd love to hear your opinion and any advice on the best way forward!

[imack]

Personally I'd mix and match.
I'd keep and overhaul the remote box but swap out the diff for the cross pin one from the rod box and fit the appropriate crownwheel and pinion. You can fit whatever output shafts you like to the diff to suit your driveshafts. I'd probably go with the rubber coupling yokes and use QL5000 joints. In my opinion the remote box in good condition has a much nicer gear change compared with the rod box, but it can be a lucky dip if it's multiple joints and bushings are worn out.
It also holds the engine rock solid without the need for additional stabilisers, something that's always issue on rod boxes, plus it has one less place to leak oil.

[Spider]

I think you've covered your options for fitting the new lump. It probably comes down to what you'd be happy with as a final outcome and also if you are doing the work yourself, what you feel comfortable doing.

 

Inboard joints are all pretty much good, though I would lean towards the Pot Joints and is a fairly simple conversion to swap out the drive shafts.

 

If you were to run the Rod Shift Gearbox, there's a few brackets about to fit the Shifter Housing in the early floor / tunnel, there's the Bracket that was factory fitted in the Australian Production (as we retained MKI floors up to the end of production in 1978) or I think Mini Spares have a bracket (?). There's also so quite good engine steadies that fit to the Thermostat Studs across to the bulkhead - all only spanner work to fit. 'Out of the box' the remote shifters do have abetter feel, but as Imack touched on, there's a lot of bushes in this set up that can wear, some are not so bad to replace, but those in the Remote Housing are quite a mission to align ream. Also, the Knuckle Joints on top of the Diff Housing wear and are NLA, they also work loose. I gotta say, in standard form, while the shift doesn't feel as nice and it may drip oil (but is fixable), I do prefer the Rod Shift Gearboxes as they are a much simpler mechanism with less to go wrong with them and just about anything that does wear or go wrong is external, where as with the Remote type, there's much that's internal that can (and sometimes does) come undone with them that's internal. There's also a few things that can be done with the Rod Shift to improve the feel of them to end up with a better shifter than the Remote.

[MiniCarJack]

Thanks both for your feedback and suggestions, I've done the deal on the new engine + box unit so that'll be in my possession soon - very exciting!!

 

I'm definitely leaning towards the first option at this stage, retaining the rod change and pot joints of the new box, especially if the shaft conversion is a simple affair - it's not something I've done before but it doesn't sound too tricky, especially compared to the other option of splitting the engine+box and swapping various bits over! The new engine comes with really nice adjustable billet engine steadies from DSN, including the extra one on the thermostat side, so I'm sure the engine will be held in rock solid without relying on the old remote shift housing.

[MiniCarJack]

I think you've covered your options for fitting the new lump. It probably comes down to what you'd be happy with as a final outcome and also if you are doing the work yourself, what you feel comfortable doing.

 

Inboard joints are all pretty much good, though I would lean towards the Pot Joints and is a fairly simple conversion to swap out the drive shafts.

 

If you were to run the Rod Shift Gearbox, there's a few brackets about to fit the Shifter Housing in the early floor / tunnel, there's the Bracket that was factory fitted in the Australian Production (as we retained MKI floors up to the end of production in 1978) or I think Mini Spares have a bracket (?). There's also so quite good engine steadies that fit to the Thermostat Studs across to the bulkhead - all only spanner work to fit. 'Out of the box' the remote shifters do have abetter feel, but as Imack touched on, there's a lot of bushes in this set up that can wear, some are not so bad to replace, but those in the Remote Housing are quite a mission to align ream. Also, the Knuckle Joints on top of the Diff Housing wear and are NLA, they also work loose. I gotta say, in standard form, while the shift doesn't feel as nice and it may drip oil (but is fixable), I do prefer the Rod Shift Gearboxes as they are a much simpler mechanism with less to go wrong with them and just about anything that does wear or go wrong is external, where as with the Remote type, there's much that's internal that can (and sometimes does) come undone with them that's internal. There's also a few things that can be done with the Rod Shift to improve the feel of them to end up with a better shifter than the Remote.

 

 

Ok so the engine + box will be dropped off to me on Saturday, and I'll start making preparations to get the old engine out and throw the new one (carefully!) in its place, including knocking up a temporary garage which should be fun.

 

I'll follow the usual procedure for taking the old engine out which I'm quite familiar with, but to convert to pot joint shafts which is my preferred way forward, I'm obviously going to have to take one or two extra steps for this.

 

I'm wondering, is it just a simple case of separating the old shaft from the outer CV, connecting the new shaft to it, then connecting that to the new inner joint when putting the new engine into place? And if so, is the separation process from the outer CV pretty easy given the engine won't be in the way for this? Hopefully these questions aren't too daft, I just want to make sure I know ahead of time what I need to do so I can have all the relevant tools, parts etc all in place for the swap   I do have a haynes manual but not sure it would cover removing the driveshaft in my particular scenario with the engine not in-situ, if that makes sense.

[GraemeC]

If it were me......

 

I would remove the brake calipers and tie them up out of the way (so you don't need to disconnect anything in the braking system).

Then remove the complete hub assemblies (top and bottom ball joint tapers and steering arm taper) complete with old drive shaft.

Remove outer CV gaiter.

Hold drive shaft vertically so hub is hanging down and with a good solid blow to the back of the CV (with a decent weight hammer) knock the hub assembly off the shaft (do this over something to cushion its landing - ie not directly onto concrete). 

Install new shafts to CV and replace gaiter.

Install new pot joints to gearbox (assuming they are new joint and will be complete).

Install engine.

Feeding driveshaft through the subframe. 

Put bottom hub ball joint taper into place and then with a 'good shove' locate driveshaft into pot joint.

Install top hub ball joint taper, steering arm and finally re-attach caliper.

[MiniCarJack]

If it were me......

 

I would remove the brake calipers and tie them up out of the way (so you don't need to disconnect anything in the braking system).

Then remove the complete hub assemblies (top and bottom ball joint tapers and steering arm taper) complete with old drive shaft.

Remove outer CV gaiter.

Hold drive shaft vertically so hub is hanging down and with a good solid blow to the back of the CV (with a decent weight hammer) knock the hub assembly off the shaft (do this over something to cushion its landing - ie not directly onto concrete). 

Install new shafts to CV and replace gaiter.

Install new pot joints to gearbox (assuming they are new joint and will be complete).

Install engine.

Feeding driveshaft through the subframe. 

Put bottom hub ball joint taper into place and then with a 'good shove' locate driveshaft into pot joint.

Install top hub ball joint taper, steering arm and finally re-attach caliper.

 

Thanks for this, sounds like a sensible plan of action - removing the hubs hadn't crossed my mind but it sounds like that could be the simplest way to go.

[Spider]

I'm wondering, is it just a simple case of separating the old shaft from the outer CV, connecting the new shaft to it, then connecting that to the new inner joint when putting the new engine into place? And if so, is the separation process from the outer CV pretty easy given the engine won't be in the way for this? Hopefully these questions aren't too daft, I just want to make sure I know ahead of time what I need to do so I can have all the relevant tools, parts etc all in place for the swap   I do have a haynes manual but not sure it would cover removing the driveshaft in my particular scenario with the engine not in-situ, if that makes sense.

 

 

 

This is how I have done them  v .

 

If it were me......

 

I would remove the brake calipers and tie them up out of the way (so you don't need to disconnect anything in the braking system).

Then remove the complete hub assemblies (top and bottom ball joint tapers and steering arm taper) complete with old drive shaft.

Remove outer CV gaiter.

Hold drive shaft vertically so hub is hanging down and with a good solid blow to the back of the CV (with a decent weight hammer) knock the hub assembly off the shaft (do this over something to cushion its landing - ie not directly onto concrete). 

Install new shafts to CV and replace gaiter.

Install new pot joints to gearbox (assuming they are new joint and will be complete).

Install engine.

Feeding driveshaft through the subframe. 

Put bottom hub ball joint taper into place and then with a 'good shove' locate driveshaft into pot joint.

Install top hub ball joint taper, steering arm and finally re-attach caliper.