Hi, just thought i would share some modifications that i have done with my gearbox, i have always thought that the coupe gears are quite long so thought i would try to lower them but i wanted to keep a long 6th gear for economy

JohnS very kindly gave me a broken 6 speed box he had which i have had rebuilt, i replaced the final drive with one from an alfa and the 6th gear from a lancia to give the following ratios

modified ratios standard ratios roughly

1st 5.1 mph per 1000rpm 1st 6 mph per 1000rpm
2nd 8.7 mph per 1000rpm 2nd 10.1 mph per 1000rpm
3rd 12.8mph per 1000rpm 3rd 14.7 mph per 1000rpm
4th 16.6mph per 1000rpm 4th 19.8 mph per 1000rpm
5th 21.0mph per 1000rpm 5th 24.7 mph per 1000rpm
6th 27.5mph per 1000rpm 6th 27.7 mph per 1000rpm

have to say it has improved the driveability no end

big thanks to JohnS for the gearbox, to trevor(nassa7) for his advice, johnnybravoturbo and dave at rusperalfa for building the gearbox and sorting out the problems with the inital build

Interesting, and well done for seeing it through! I must admit I've always liked the coop's gearing because it's so very long. A GT series turbo just adds to the sense of relentless urge

I'll work out your new ratios and run it through the calculator tomorrow and see what difference it would have made to the performance

p.s. You could have saved some money and fitted smaller wheels

Hi doug20vt,

Very kind of you to share your mods!
Improved driveability means your gears have closer ratios , so when you drop the cog down the car doesnt slow down as much but still pulls , is it correct?
I'm thinking of to do something like this when mine 5speeder goes.
How much did you pay for conversion?

be interesting to see what figures your calc comes up with trappy, think i would have had to use about 13inch wheels to get those ratios lol

anthrax, there is still a very similar drop in revs between the gears at set rpms compared with standard but with the gears being shorter acceleration is quicker

i would say it hasn't been a cheap mod as i was orignally running a 5 speed box so had to get a 6 speed which i was lucky to get for nothing

the garage then used the final drive from an alfa and in order to get the long 6th gear i had to buy the gear from a lancia thesis but to get the matching 6th gear i had to buy the entire shaft although i did get all new syncro's and gears when i bought that and then of course you have to add labour to all of that and you might as well replace the clutch when its out

nice work, will improve your acceleration

Well done Doug,
I am in agreement that the 6 speed box ratios need adjustment.
nice to see its how it should be finally

My advice is to everfill the gearbox by around .5-.9 of a litre.
Done it to a few now with no issues regarding oil leaks etc.

cheers John, it is fantastic to drive now, pleased i stuck with it, was reading the thread about your car, that must be something else to drive

Its a bloody headache matey.,
Not really driven it yet as its lost oil pressure on a new engine.Grrrrr.
And thats just the start of the issues.
I wouldnt mind about a few teething faults but it needs to be done for the 15th of June latest.

trying to find the standard ratios for the 5spd 'box, anyone know what the mph/rpm is in 5th?

They are in the first pages of the manual, where the general technical info is.
...and...could be done something similar with the late 5-speed for 20vt?
Cheers.

mph per 1000rpm on a standard 5 speed box is 25.18mph per 1000rpm assuming you are using standard 205/50/16 tyres

Yeah, but it feels the car have enough power on 5th to lower a bit the rpms, less noisy and thirsty on longer trips...and I usually do not drive faster than 120kmh.

thanks, that was what i was looking for

not tried it down the road yet to see how accurate the speedo is but either my rev counter reads wrong or my speedo does shows about 21mph per 1,000rpm at the moment. that is while sat on axle stands.
once it's on the road i can use my tom tom to see which is wrong, but i'm guessing it may be the rpm as the 145 had a 4cyl engine and now it has a 5pot

just to add to the possible descrepancies i have changed tyre size down to 205/45-16 due to clearance issues with the 205/50's.won't hurt the acceleration though as avtokrator says