whats the best diff for speed and mpg?

[ericthered]

Thanks for that Chris, I'm off to an autojumble on Sunday so I'll fill the boot up on the Daf with 3.9 diffs! lol

[welshrat]

Hi, recently asked most of the questions you have asked in this post and have recently fitted a 3.7 diff, follow this link http://www.mmoc.org.uk/viewtopic.php?f=4&t=38738
for some good advice from members.

[linearaudio]

My 1098 traveller has the "BMC" 12g940 head mods and MG Metro cam. It is still undergeared on a 3.9 diff, but much more relaxed than on the 4.55 it originally had. As "BMC" stated- 70+ in 3rd is now attainable. 40+ in 2nd is even more fun since you can also pull away in 2nd!! Fuel economy has actually improved over the standard engine/drive train setup. The car is used hard, often with equivalent of 3 adults on board, and is running a very predictable 41mpg (up 3mpg since fitting a Metro radiator and electric fan). First gear is still on the low side though, and a bespoke close ratio set with a 3.7 diff would probably be on my wish list in fantasy land!

Eek- just noticed that if I hover over the "41mpg" text, it converts to litres/100km in a little info box! Impressive use of technology!!

[bmcecosse]

A 3.7 final drive will suit you even better ! 41mpg - impressive. Wish I could get that!

[linearaudio]

A 3.7 final drive will suit you even better ! 41mpg - impressive. Wish I could get that!

Then move to somewhere flat!!!
Sorry the 41mpg sounds so anorakish, but ever since I bought the car 3 1/2 years ago I have filled it tank-to-tank (couldn't dream of that with the wifes 15 gallon monster!), so it has become a bit of a ritual to check the consumption each time, and it has proved remarkably stable, tending to dip about 4mpg in winter to account for cold starts, though even that should improve with the skinny Metro rad!
The point I was getting at was to dispel any worries people may have that by "messing about" with the engine you will end up with a fuel drinker! By applying Leyland's cheap, well proven evolution of the Metro engine onto our humble Moggy, you can only win!!

[MarkyB]

Then move to somewhere flat!

And dump the spare cylinder head, starter and dynamo!

I like linearaudios method for checking consumption too, fitting the electric fan that I have in stock just moved up to the top of my to do list!

[bmcecosse]

So - a metro rad fits in easily ? How about a picture.

[IaininTenbury]

Hi Iain,

Thanks for that, now I can keep an eye out at autojumbles and pick one up for a tenner! LOL

Heres a link to my little Daf.........
http://daf33.piczo.com/?g=1&cr=2

Thanks and best regards,
Eric.

Nice Daf! Always like the light elegant styling on these little cars.
Pop a 3.9 on one side for me when you find a stash of 'em, cheers!

[youngcamper]

So - a metro rad fits in easily ? How about a picture.

My dad has a metro rad in his 1275 traveller, he doesn't rate it at all. still if your interested I could take some pictures

[MarkyB]

Maybe on a 1275 it's a bit marginal?
Does he have any temperature figures to back up his dislike?

[linearaudio]

My dad has a metro rad in his 1275 traveller, he doesn't rate it at all. still if your interested I could take some pictures

Yes, it would be interesting to know his reason for disliking it! Given that the 1098 in my traveller is a bit "breathed on" and probably putting out close to as much power as a standard 1275; and that even in the sweltering heat the temp gauge only sits at 85, as it did with the standard radiator, I wonder if his may be a bit silted (assuming it's the cooling capacity that is his gripe!).

[youngcamper]

we've had it boil over a couple of times and its commonly near too overheating. his engine is out of an Ital if that makes any difference.

[faversham999]

so what would be the best diff for a 948cc dose 80 downhill with the standard diff

[IaininTenbury]

I'd try a 4.22 1098cc diff. It'll calm things down a bit without loosing too much pull. and they're cheap and readily obtainable. If then thats still too low for your liking and circumstances look for a 3.9

[bmcecosse]

If the Metro rad worked ok with the 1275 Metro........I don't see why it wouldn't be fine with a 1275 Minor......

[LVY165]

I have a '58 four door saloon that i bought a few weeks ago.
A suicidal low suspension as been sorted but I am worried that 70mph on the clock is only showing at 55 on the sat nav.
It has a 1275 mg engine and gearbox which are really smooth but I suspect still has the original diff.
I think from what I have found about the '58 saloon it probably has a 4.55 diff and originally had a 948 engine.
What would anyone suggest the rear diff should be if only to get the clock to read more accurately?

[Chipper]

Either the standard 1098cc Minor's 4.22:1 diff, or a 3.9:1 from an MG Midget would be fine for a 1275cc MG Midget engine and 'box.

I have a 1970 Traveller fitted with a 1275cc MG Midget engine, and find it works pretty well with the standard Minor ribbed-case gearbox and 4.22:1 diff, though I did recently try a 3.9:1 Midget diff - it was quite noticeably higher geared, which is good on dual carriageways and motorways but does blunt the acceleration out of junctions and steep hill-climbing ability somewhat (I live on the outskirts of Canterbury, Kent, so lots of quite steep hills and twisty little country roads for the most part, where you need fairly low gearing), hence I went back to the 4.22:1 diff.

It will still cruise quite comfortably at around the 70-75mph mark on the motorway, and return nearly 40mpg average.

So, fit whichever you think is best for the sort of journeys you usually do.

[ampwhu]

I have a 948 engine in my 1955 car, with 948 internals in the gearbox. 4.2 diff at the back. car sits nicely on the motorway at 65mph.