Question.

[Kilroy]

Simply interested in your opinions.

For some time I have been of the opinion that the manual transmission version of the Morris Marina is more fuel efficient and makes better use of the available horsepower.

However - and despite it being a 2 litre engine - I have to state that my Auto Estate is;
a. quicker off the mark (by half a block..)
b. faster around town in overall consideration

So - do I build my 575 van as a manual or an auto.?

No argument - the manual is entirely preferable for touring, and enjoys better fuel mileage on the open road than the auto.
But - the auto not only pizzles the competition at the lights, but also allows much quicker changes of direction (forward/reverse/forward..), and is able to go about it's business with remarkable dexterity whilst the pilot is drinking coffee with the other hand.

Should my 575 workhorse be thus auto or manual.?

I am beginning to think I need one of each...

[MarinaCoupe]

So you need a touring car and a town car. One of each as you say.

What proportion of town versus country driving do you do? Go with which ever you do the most of.


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[Kilroy]

I am driving most of the day visiting clients, and carry a fair assortment of tools and parts with me, so the estate has been the workhorse for many years.
Now I am intending that the van should replace it - so it will spend most weekdays hooning about the city.

We did use the estate quite often for holidays/recreation as well - mostly because it was good for carrying toys.
Trouble is - the auto is a bit fussy at speed, and contributes to a fair bit more noise and a few hundred extra revs, which has a follow-on effect in lower fuel economy.

My real issue I suppose, is that although I shall have a good amount of power available (in Marina terms..), it is not possible to change gears as fast as one does in a modern, so it is harder to keep ahead of the hoi polloi without thrashing the coggery.
The auto allows full power without interruption - and with no ecu trying to second guess every situation - progress is immediate and brisk from the instant you press that little pedal.
I do enjoy that.

I need two vans...

[locost_bryan]

The old Borg Warner 3-speed "slush box" is far less efficient than the 4-speed manual, no question about that, but it is stronger, and the torque converter in the auto keeps the engine in the peak torque part of the power band (which explains it's ability to get up and boogie).

The manual gearbox is pushing it to handle much more power and torque than the standard TC throws at it (weak point of the GT6 too), and if you're going to be loading up the van, then the weight may require pumping more of your "race" engine's ample torque through the box more often, which sounds like the "big bang theory".

Since you're used to driving an auto Marina, you'll be using it mostly around town, you've fitter a "taller" car diff, you have a stash of auto bits, and you'll have more power than the manual can reliably handle (imho), then going the auto route sound's like a no-brainer.

It's a pity that none of the O-series engined cars or vans had a 4-speed auto (the Sherpa V8 had a ZF4HP22, like Ben fitted to his V8 Marina), that would have given you an "overdrive" for highway cruising. Mind you, the torque converter on the auto should let you get away with the taller 3.29 diff ratio (same as used on the 2-litre Ital auto and Dolomite autos).

[MarinaCoupe]

I think Bryan has the solution, change the auto estate diff ratio from 3.63:1 to 3.29:1. Given the torque you've got in the O series it shouldn't blunt the performance very much, but will improve economy on a run. It would improve the top end gear by just under 10%.

So did NZ get the 3.29:1 diff in any types of Triumphs, or is this hypothetical?

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[Kilroy]

I suppose the 1500 Spitfire might have had a 3.29 diff - but they are hardly thick on the ground.
I do know a Triumph service guy down here - will check him out in case he has anything laying around...

We seem to be leaning auto...

[MarinaCoupe]

It's also turned up in the early auto version of the 4 speed TR7s if that makes sense?

The diff will bolt straight across into the Marina axle.



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[locost_bryan]

It's also turned up in the early auto version of the 4 speed TR7s if that makes sense?

The diff will bolt straight across into the Marina axle.

Spooky, just been reading about TR7s. Be surprised if any auto TR7s made it down here, but I have seen auto Dolomites, so there could be a few 3.27 diffs around.

Would sooo like to pick up a cheap rusty TR7 from down country, just to get the 5-speed and back axle (but the wife would kill me if I started another project before finishing the TC and the house extensions ).

On a side note, the Rover SD1 2000 auto used the Borg Warner model 66 with a 3.9 diff and 175/70x14 tyres.

[MarinaCoupe]

SD1 different axle - same as TR7 5 speed axle.


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[MarinaCoupe]

Dolomite 1850 Auto axle is 3.27:1.




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[locost_bryan]

Dolomite 1850 Auto axle is 3.27:1.

That's the one I thought Kilroy might have most chance of finding down this way.