Change gearbox M45 to M47 in 340GL
 

Any help about information to what is need to change a gearbox of a MY83' 340 1.4 M45 (4 gears) to a M47 (5 gears) ?

It's a thing that improves car performance? or not efectiveness at all?

Thnaks

A very straightforward bolt in job , where did you get your M47R transaxle from , ideally you want it to have the same rear axle ratio as yours then 5th becomes a true extra gear . with the wrong rear axle ratio you might find 5th is the same as your original 4th in which case acceleration might be improved in the lower gears at the expense of fuel consumption .. so ,firstly what is your current final drive ratio ? volvo used quite a few different ratios over the years ..

I did mine 25 years ago on my 1980 343 and 2 years ago on my 1988 1.4 which has a 3.64:1 final drive ratio which is the same as a 1.7 engined 340 which has a 5 speed as standard .. It works well , cruising is very relaxed , you might have to change to 4th for a long incline , i'm getting 45 mpg out of my 343, but i have done other things as well to optimise the fuel consumption but the 5th gear certainly helps . any more you need to know just ask.

It'll just bolt in - I'd personally fit the 5 speed box from a later 1.4 car, which came with the 3.82:1 ratio, as I think it's well suited to the 1.4

I would go with whatever 340 gearbox you can find as they are getting rather hard to get hold of.

Hang on to your old 4 speed box or pass it onto someone who can use it

Yes very hard to find a Transaxle now , it took me over a year of searching to find one ...

your 1983 4 speed will have the 3.82:1 ratio which is fairly low geared ( more revs when driving , feels lively )

The only 5 speed units with the 3.82:1 ratio are from the Diesel or the pre 1983 cars , we did not have the 5 speed in uk until 1984 did we ?

So you will have to find a transaxle from a 1.7 engined 340 with a final drive of 3.64:1
this will result in less rpm for any given speed in all gears and give a tall 5th gear .

I have this in my 1980 343 ( B14 1E ) and 1988 343 ( B14 4E )

I find in the earlier car it has noticeably reduced torque from the engine .

whilst with the later car in which the engine was revised slightly it works fine as volvo used the 3.64:1 final drive in later 340's .
It would be worth fitting the later B14 4E Engine if you can find one cheap , it has twin exhaust down pipes, computer mapped ignition ( RENIX ) and no radiator fan this does make a noticeable difference in power and economy .

I have a perfect low mileage M45R ( 4 speed ) 3.64:1 transaxle if anyone wants one !

Later 340 1.4 5 speeds (after '85) used the 3:82 final drive, 1.7's were all 5 speed and were 3:64 along with 360 injections. 360 Carbs were either 3:27 or 3:36 (or 3:45, I'm not sure) in the UK, as far as I know. Thankfully, I'd say the later 340 1.4 transaxle is probably the most commonly available.

There's a good post here:
http://www.volvo300mania.com/uk/foru...php?f=6&t=8625

Thanks to all for your opinion & Help

My 340 it's a 83 Model and at moment I do not know the real relation of my transaxle, but I will confirm that.

I think I find one 340 in a scrapyeard from 84 with 5 gears, and if it had a good price for me change my M45 to M47 of those of scrapyeard.

sounds good ! but will not be easy to find one now , Don't hesitate if you see one with a 1.7 engine get that gearbox and propshaft for a spare . MIght as well get driveshafts too .

The 340 situation has settled down now , they have been out of production for 27 years , and were in production for 14 years before that . Some were prone to rust , they are long gone .. the rest seemed to stay in great shape and are owned by people , The scrappage scheme took a lot away too .
so not likely to be any in scrap yards , just keep an eye on e-bay you might get one every 6 months or so .