1098 engine & gearbox in a 948 (1961) saloon. Good idea? Bad idea?

[pplatt]

I have found a nice 1961 2 door saloon for sale. It has the original 948cc engine and gearbox which appears not to have had any major work done in the recent past. It has the usual(?) issues - weak synchro on 2nd gear and possible clutch thrust bearing (and or excessive crankshaft end float). The latter showing itself as a significant drop in revs when flooring the clutch (gearbox in neutral).

The seller (a classic car specialist) has offered to swap the 948cc engine & gearbox for a 'good used' 1098 engine and 'box (at a cost of course) but keeping the current (original) diff.

In broad terms, is this kind of swap a good thing or would it be better to stick with the original engine and budget for an engine and/or gearbox overhaul at some point in the future?

Sorry if this question has already been asked somewhere in this forum. I had a quick look and couldn't find anything but I may have missed it!

[mobylette]

I suppose it really depends how much money the dealer wants to do the swap?

[geoberni]

You might find this discussion from 2013 informative: viewtopic.php?t=50506

[pplatt]

I suppose it really depends how much money the dealer wants to do the swap?

About £800 but that would include quite a few new parts (e.g. clutch, fuel pump, water pump, oil pump possibly) which all sounds sensible to me.

[pplatt]

You might find this discussion from 2013 informative: viewtopic.php?t=50506

That's a good read, thanks. I wonder if sticking with the original 948 diff would be a bad thing to do.

[geoberni]

You might find this discussion from 2013 informative: viewtopic.php?t=50506

That's a good read, thanks. I wonder if sticking with the original 948 diff would be a bad thing to do.

Don't ask me that one. I brought my car (SII) believing it to be fitted with a 948, the 803 gearbox rebuilt as a 948 but the 803 Diff.
Turns out the person fitting the engine didn't know what they had, so I've a 1098 engine, 948 G/B and 803 Diff.

[ManyMinors]

I am a fan of the 948cc engine but the later 1098cc engine along with its stronger gearbox does have some advantages. Will the seller allow you to keep the original 948 engine and gearbox if you have the 1098 unit fitted? If so, you'll perhaps have the best of both worlds - a decent driveable car for now and the option of getting the original unit rebuilt at some time in the future
The choice of differential depends rather on the driving you plan to do. You might find the car a little low geared with a 1098cc engine and the original 4.55:1 differential particularly if you are driving longer journeys on main roads but I wouldn't worry too much at this stage. To fit the 4.22:1 differential is slightly more than a simple nuts and bolts job because you'll almost certainly have to drill the axle casing to accommodate an oil filler plug. Not really difficult, but something to consider.

[mobylette]

I presume you would need to commit to the purchase before they would do the engine/gearbox swap? If so, you could well be disappointed to find a tired 1098 fitted that you were unable to reject. ”Good used” is not really a reliable description. And what has the fuel pump to do with it? I would buy as is if you are happy, and find a 1098 to rebuild at your leisure, plenty about.

[pplatt]

I presume you would need to commit to the purchase before they would do the engine/gearbox swap? If so, you could well be disappointed to find a tired 1098 fitted that you were unable to reject. ”Good used” is not really a reliable description. And what has the fuel pump to do with it? I would buy as is if you are happy, and find a 1098 to rebuild at your leisure, plenty about.

Good point. I'm hoping that I will have the opportunity to inspect and test drive the car following the transplant with the option to not buy if I'm not happy. I will confirm that before parting with any £££.

So it may be better to go with the 'good used' 948cc engine & box currently in the car? I've driven the car and it seems sweet (other than the issues mentioned in my original post) but I'm not a Minor expert so the 948cc engine is as much of a risk as the 1098cc engine & box.

Too many unknowns, too many choices!

[pplatt]

I am a fan of the 948cc engine but the later 1098cc engine along with its stronger gearbox does have some advantages. Will the seller allow you to keep the original 948 engine and gearbox if you have the 1098 unit fitted? If so, you'll perhaps have the best of both worlds - a decent driveable car for now and the option of getting the original unit rebuilt at some time in the future
The choice of differential depends rather on the driving you plan to do. You might find the car a little low geared with a 1098cc engine and the original 4.55:1 differential particularly if you are driving longer journeys on main roads but I wouldn't worry too much at this stage. To fit the 4.22:1 differential is slightly more than a simple nuts and bolts job because you'll almost certainly have to drill the axle casing to accommodate an oil filler plug. Not really difficult, but something to consider.

Keeping the 948 engine & box would possibly be an option (at a cost) but I don't really have anywhere to keep it! My garage is full of motorbikes!

Are 948cc engine & gearboxes 'rare' and or 'valuable'?

[ManyMinors]

Keeping the 948 engine & box would possibly be an option (at a cost) but I don't really have anywhere to keep it! My garage is full of motorbikes!

Are 948cc engine & gearboxes 'rare' and or 'valuable'?

No, they're worth very little - especially if they require a rebuild. I have Minor of similar age which was originally a 948. It has run with all 1098 running gear for more than 30 years and I have no plan to revert despite feeling that a good 948 car is a very smooth and useable car. The cost of properly rebuilding an engine and gearbox is high now and it is often a much cheaper and convenient option to fit a known good secondhand unit so that is what I chose to do.

[olonas]

Elsewhere in the Message Board there's a thread about my '62 Saloon. It was built with 948cc engine and gearbox. Sometime in it's previous life someone had a 1098cc engine and 'box fitted. It still has the original differential. Whoever did the works incorrectly used the original thinner engine backplate and a 948cc clutch.
The combination did function, but the clutch started making strange noises which were coming from the bell housing. Maybe the originalclutch assembly was re-used?
I decided to have a new correct (1098cc) clutch fitted along with the correct thicker backplate. I still have the 948cc friction disc. The clicking and other noise was probably coming from that. It wouldn't have been very long for this to fail if the noises had been ignored. The rivets securing the outer friction disc to the centre were loose and as a result the outer moves with the inner static.
Sorry to ramble on at a tangent.
If the engine and g/box are good then I would go for it. Just make sure it's done properly with the correct components. Make sure all the original stuff is avaialble to inspect.
Still having the original diff. isn't an issue - for me.

[myoldjalopy]

Of course, at a distance, it is hard to know how good the existing set-up in the car is (nor how good the 1098 units are). As the vendor has offered to swap over the engine and gearbox I would be asking him more about why he has suggested it and what the pros and cons are. You say the original engine is 'sweet' so it might be a case of 'the devil you know' here.

[pplatt]

Of course, at a distance, it is hard to know how good the existing set-up in the car is (nor how good the 1098 units are). As the vendor has offered to swap over the engine and gearbox I would be asking him more about why he has suggested it and what the pros and cons are. You say the original engine is 'sweet' so it might be a case of 'the devil you know' here.

I guess that's the issue in a nutshell - I don't really know either devil (other than having driven the car as it stands with the 948 engine and gearbox). It's a gamble either way. The only obvious benefit from sticking with the original engine is that I save £800 or so. On the other hand some of that money would be used to supply a new clutch etc. that would be fitted with the 1098 engine.

At least part of the reason for the offer of an engine swap was my hesitation towards buying the car due to the 'weak' 2nd gear synchro and possible issues being shown up by a significant drop in revs when the clutch is floored (in neutral). Both of which may, or may not, be indicative of problems. It may also be because an engine upgrade could make the car easier to sell perhaps.

Time to flip a coin?