Flaminia final drive ratio

[peterblenk]

My 2.8 3b Coupe, which, according to La Lancia has a final drive ratio of 13/49 (3.77) needs 4,000 RPM to do 70mph (on the SatNav, not the speedo). That seems rather unrelaxed to me - especially for a "grand tourer"). It also means that at a top speed of 181kph (112mph), the rev counter would be reading 6,400rpm - surely an unsafe figure. Does anyone else see this as an issue, and if so, is there a solution? The highest final drive ratio listed is 13/45 (3.46), which is only 9% better than the one I have and would reduce the rpm at 70mph to a still high 3,680rpm.  Peter Blenk@aol.com

[lancianut666]

Tacho not right or tyres wrong size?

[Kevinlincs]

The Autocar road test from back in the day lists your car as having a 20.6mph per 1,000rpm in top gear so your 4,000rpm would work out as 82.4mph.
I agree that either the rev counter is wrong or more likely the tyres are undersized, what size are they?

[Spider2]

That is a 17.7% error when comparing RPM. IMO far too great to be caused by incorrect tyres. Got to be the speedo. I have a similar scale of error on an old Alfa. Hooking up an electronic rev counter to the coil will give you the answer.

[Kevinlincs]

It depends what size the car is running on, if it has been fitted with the wrong size wheels and tyres it is possible for it to make that amount of difference. But I would agree if it's close to the original design then it is too big a difference, but if it has been fitted say with some 15" wheels with some 65 profile tyres for instance then that's a big drop in rolling circumference over the OE tyres.
Attaching a digital rev counter up is a good call, the dash one is a mechanical cable driven one after all so it is possible that it's gone out of tolerance and could easily be reading 500 or so revs over at those speeds which working back assuming that he has the correct tyres and as he has already used a satnav for accurate speed reference then it should be 3,398rpm at 70mph.
Interested to know where the issue is, maybe a combination.
Tyres size wold help to know....

[lancialulu]

Of course the other reason is someone back in the day swapped the transmission (for a Berlina....). It happens a lot in Lancia land.

[chriswgawne]

Of course the other reason is someone back in the day swapped the transmission (for a Berlina....). It happens a lot in Lancia land.

On all Aurelias the final drive ratio is stamped on the underside of the transaxle casing fairly close to the riveted blue plate showing the model and build number.
Might be worth a look?
Chris

[Charles Frodsham]

Agree with the above regarding checking tyres and transmission. For general information, for high speed cruising, Thornley Kelham have an overdrive system.

[Jay]

The final drives ratios are model dependant, to my knowledge the 2.8 Super Sports has the highest and therefore are the fastest. Having a 2.5 3C GT, I have always felt the car could do with a 5th gear especially when cruising on the motorway. I read somewhere it was originally earmarked to have one, but the development costs were far too over budget, for it. To be fair, I have slowed down and now keep to 70mph, and try to use less motorways as the car feels so much nicer on A roads, plus wind noise is more of an issue than engine. 

[Mikenoangelo]

Overdrive sounds good but how do Thornley Kelham fit it one  to the Flaminia with it's rear mounted gearbox? I'd like to see a photo of the installation.

Mike Clark

[Charles Frodsham]

I think it’s at the front on the bell housing.

Personally, I agree about avoiding motorways and enjoying the car in the environment it was designed for.

[dannels]

+1 on wind noise Julian!

Cheers
Dave

[peterblenk]

The tyres on my car are the correct size - Pirelli Cinturato 175HR400. They might be a tad smaller than the Michelins in rolling circumference, but not enough to account for the error. Like you, I am suspecting the rev counter, as I was using the sat nav to determine the speed, so that should be correct (my speedo seems to over-read). I'll try testing with an electronic rev counter. Alternatively, or in addition, one could use 185 tyres, assuming they are not too wide for the rims, These might give a bit more rolling radius. Or one could substitute the CWP from a SuperSport, which is 13/45, or 3.46. Even if one could find this ratio, fitting it would be a nightmare. I believe that the listed one for my car is 13/49, or 3.76. I agree about the motorway, but this is a car meant for the trip to the south of France, and by the lovely B roads, on which one averages perhaps 30-40mph, the trip would take approximately forever. I find I have to use motorways even in pre-war cars.

[lancialulu]

The tyres on my car are the correct size - Pirelli Cinturato 175HR400. They might be a tad smaller than the Michelins in rolling circumference, but not enough to account for the error. Like you, I am suspecting the rev counter, as I was using the sat nav to determine the speed, so that should be correct (my speedo seems to over-read). I'll try testing with an electronic rev counter. Alternatively, or in addition, one could use 185 tyres, assuming they are not too wide for the rims, These might give a bit more rolling radius. Or one could substitute the CWP from a SuperSport, which is 13/45, or 3.46. Even if one could find this ratio, fitting it would be a nightmare. I believe that the listed one for my car is 13/49, or 3.76. I agree about the motorway, but this is a car meant for the trip to the south of France, and by the lovely B roads, on which one averages perhaps 30-40mph, the trip would take approximately forever. I find I have to use motorways even in pre-war cars.

Choosing the right d and n roads your average will be closer 50/60 mph !

[Dave Gee]

Regarding overdrives, from memory, Bill James successfully fitted a Triumph Stag overdrive to his Flaminia. It was sited on the back of the engine and he had to modify the prop shaft tunnel to take it. It also improved his mpg.

Dave Gee