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If I recall correctly, the six speed box is half an inch longer, plus the ratios are different, so you need a matching diff for correct performance.

So;

Getrag 280/6 M5 gearbox
Matching Propshaft
Rear differential.



Some info on possible diff choices and resultant performance here at Rob Levinsons website.



Ivan.
 

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I thought the ratios were the same, with just an overdrive 6th gear being added for fuel 'efficiency'?
 

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The propshaft is shorter on the six-speeders too, so you'd need one of those (or to have yours shortened and balanced)
 

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Sounds like alot work and thought is needed for this conversion.
 

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Found this elsewhere...
"Under the skin however a six speed gearbox was fitted - fifth and sixth were roughly equivalent to the fourth and fifth in the old gearbox and the spread of ratios below were ideally suited to getting the most out of gear changing.

A higher drive (3.23:1) instead of (3.91:1) also made cruising more comfortable aiding remarkable fuel economy for a car of this performance.

I know I'm not the brightest thing on two legs, but if 5th & 6th were equivalent to 4 & 5th how does that improve fuel economy???

I've always longed for an overdrive type gear on long motorway way runs, the car seem to think 5th is 3rd and just keeps on accelerating......
 

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I was definitely interested in doing this, and as my 5 speed box is going to need a rebuild / replacement, it seems like an ideal time.

BUT - I haven't been able to find a 5 or 6 speed box (other than Paul from Infinicar's 6 speed he was selling with 3.8 lump from his tourer) yet, so am nearly considering just getting mine rebuilt. Anyone have any ideas where i might find a 6 speed or 5 speed box?
 

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The fifth speed gear in the six speed box, combined with the ratio of the matching diff from a six speed car, is equivalent to the fifth gear in a five speed box with the five speeders diff.

Completely different ratios but the end effect is the rear wheels turn at the same speed on both cars per engine rpm.



Top speed in a factory six speed car is obtained in fifth gear. The sixth gear was brought in for two reasons; as an overdrive to give a tiny bit more fuel economy (makes the brochure look better!) and to lower the rpm at motorway cruising speeds in europe, in order to reduce the noise.


The difficult thing is finding a donor car for these upgrade, not fitting the bits! Buying new from a dealer is gonna sting, the 6 speed gearknob is $60 alone! :)

Ivan.
 

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Mmm-Five said:
I thought the ratios were the same, with just an overdrive 6th gear being added for fuel 'efficiency'?
Read an article last week about the 6 speeders brought the 0-60 down to 5.4 from 5.9 :M5launch: and made the top speed 170mph :eek: i`ve done 168 so believable :noSMG: :noSMG: :noSMG:
 

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IvanDias said:
The difficult thing is finding a donor car for these upgrade, not fitting the bits! Buying new from a dealer is gonna sting, the 6 speed gearknob is $60 alone! :)

Ivan.
I rang a dealer today out of curiosity :-
new 6 speed box £3,500
new 5 speed box £2,500

didnt even ask if it includes vat
 

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grrrrrrr Rant time!

Although I've only driven examples of the 5-speed M5 a couple of times, fairly briefly, the box is nicer than the six-speed box to use. I've found that's a common trait on cars which have both 5 and 6 speed versions, from the Vauxhall Calibra to the Volkswagen Transporter.

I know I've written this before, and it's fairly likely no-one cares what I think, but although the 6th gear economy and lower motorway revs are welcomed, and although it can be improved with uprated shifter linkage bushes and better ATF (mine was an example with those improvements) it's a horrid agricultural gearbox, and even one in good condition is akin to stirring cornflakes with a ladle.

I once read a review of the Honda VTR1000 motorcycle. I owned one at the time. The author of the piece rightly commented that "Swapping cogs in the Honda 'box is akin to climbing a broken ladder". That's how the M5 6-box feels most of the time.

The six-speed boxes in the e39 M5 and M3 Evo are the same.

grrrrrrr

Rant over.
 

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Having read posts like this I was afraid the 6-speed would be a pig. It's not. It's actually pretty sweet. And that's talking about a gearbox with 260k km on it. The only pigs in the driveline are is the dual-mass flywheel and the guibo that's not up to it's job, so I'll be putting in my third guibo shortly.

AndyE said:
grrrrrrr Rant time!

Although I've only driven examples of the 5-speed M5 a couple of times, fairly briefly, the box is nicer than the six-speed box to use. I've found that's a common trait on cars which have both 5 and 6 speed versions, from the Vauxhall Calibra to the Volkswagen Transporter.
Rant over.
 

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Stevie said:
Having read posts like this I was afraid the 6-speed would be a pig. It's not. It's actually pretty sweet. And that's talking about a gearbox with 260k km on it. The only pigs in the driveline are is the dual-mass flywheel and the guibo that's not up to it's job, so I'll be putting in my third guibo shortly.
--------

how do you know the guibo needs replacing?
 

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Propshaft starts vibrating under heavy load at higher speeds. Heavy load is 4000rpm plus with foot down is 3rd or higher. You get this "rumble" through the whole car. And you can check it visualy for cracks and tears... I just ordered mine without looking at the current one, but if I do I'm sure it will be torn.

Jahangeer said:
--------

how do you know the guibo needs replacing?
 

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Hi Illijah

Looks like Paul/Infinicar/toxicfrog 'Is' selling his 6 speed box separately, take a look: http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=10374&item=4561552482&rd=1



illjah said:
I was definitely interested in doing this, and as my 5 speed box is going to need a rebuild / replacement, it seems like an ideal time.

BUT - I haven't been able to find a 5 or 6 speed box (other than Paul from Infinicar's 6 speed he was selling with 3.8 lump from his tourer) yet, so am nearly considering just getting mine rebuilt. Anyone have any ideas where i might find a 6 speed or 5 speed box?
 
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