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Discussion Starter #1
Hi all,
Not all that long ago i treated myself to a set of M parallels,throwing stars were a bit scabby,tyres all but knacked so i planned to upgrade wheels and the M parllels came along. The car now looks cool! I love them soooo much! Trouble is it really has ruined the acceleration/fun factor of the car compared to the 17's
I know some of this is down to the extra drag but the gearing must also be higher. How can i drop it back down again, another diff? if so,which one? or sourcing a 6 speed 'box and associated kit?
Thanx in advance!
 

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The overall size of the wheel should not have changed unless you are using something other than 245/40z18 tyres. There won't be much in the rotational masses either as what you gain on the wheel, you lose on the tyre.
 

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[. How can i drop it back down again, another diff? if so,which one? or sourcing a 6 speed 'box and associated kit?
Thanx in advance![/QUOTE]
Fit a 6 speed box as i did ,guaranteed to make a big difference,you'll have to change the prop too,leave the diff in and enjoy.
 

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Wane Ramsay said:
Fit a 6 speed box as i did ,guaranteed to make a big difference,you'll have to change the prop too,leave the diff in and enjoy.
I can vouch for that as I've got his 6spd box & diff!! And I am enjoying it!
 

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illjah said:
I can vouch for that as I've got his 6spd box & diff!! And I am enjoying it!
Glad to know that you're enjoying the box,how are you coping with the short shift?
I still have the new 6 speed gearbox if anyone else is thinking of going this route.
 

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Wane Ramsay said:
Glad to know that you're enjoying the box,how are you coping with the short shift?
Yeah its a massive improvement on what was in there, very little play, it is very notchy as you said, but feels firm and solid, and gear change is nice now. I used to have to change so tentatively from 2nd to 3rd in my old 5sp box.

And keeping the 3.91 diff is quite good fun, although I'm still considering possibly trying a 3.64 diff if I can get one in the long term - but I've got a lot of things I'm going to do first - like get that lovely new interior in!!! Its going in next week to get brake pipes re-done, few bushes and bits and pieces which will no doubt mount up to a pretty penny but hoping to be able to get the interior straight after that. I'll be in touch :cheers:
 

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Discussion Starter #7
Mmm-Five said:
The overall size of the wheel should not have changed unless you are using something other than 245/40z18 tyres. There won't be much in the rotational masses either as what you gain on the wheel, you lose on the tyre.
Hi, I am running 245/40x18 tyres but did notice during changing that stood next to the 255/40x17's there was a height difference, definately noticable with the first trip up the road that the car wasnt quite as lively. Am i right in thinking that the 6 speed has the same ratio in top as the 5 speed therefore making the lower gears closer together? which should help my cause? What should i be paying for a decent 6 speed 'box,prop,linkage and whatever else?
 

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Geach said:
Hi, I am running 245/40x18 tyres but did notice during changing that stood next to the 255/40x17's there was a height difference, definately noticable with the first trip up the road that the car wasnt quite as lively. Am i right in thinking that the 6 speed has the same ratio in top as the 5 speed therefore making the lower gears closer together? which should help my cause? What should i be paying for a decent 6 speed 'box,prop,linkage and whatever else?
If you use 6sp box with 3.23 diff (as supplied on M5's with the 6sp box) then gears 1-5 are essentially the same, but you have an extra 'over-drive' gear at the top for lower RPM cruising (or a theoretical top speed of 200mph!!). But if you use the 3.91 diff as what is in 5sp cars, then yes 6th gear is the same as 5th, and the lower gears are shorter, quicker and closer together.

This is exactly what I have just done, although I am considering getting a 3.61 diff from an 8 series to get a comprimise so i can have some lower rpm cruising . Rob Levinson's website has some info here:

http://www.robertlevinson.com/M5_Touring/upgrades/transmission.htm

I bought just the 6sp box and prop shaft, but was lucky to find a good donor car, and the box appears to be in good nick, the prop shaft was very new, and the box came with a SSK which was a bonus!

Have to say though, I'm very surprised (and dissappointed) to hear that just upgrading to the M-Parallels has caused such a noticeable deterimental effect - I love the M-Parallels, and was considering a possible upgrade in the very long term, as going from my 535i with 18" Alpinas, the 17" throwing stars just look too small for the car to my eyes cosmetically.
 

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Geach said:
Hi, I am running 245/40x18 tyres but did notice during changing that stood next to the 255/40x17's there was a height difference, definately noticable with the first trip up the road that the car wasnt quite as lively. Am i right in thinking that the 6 speed has the same ratio in top as the 5 speed therefore making the lower gears closer together? which should help my cause? What should i be paying for a decent 6 speed 'box,prop,linkage and whatever else?
Hi, i ran with M Parallels 235/40 /18 at the front and 265/35/18 at the rear without any problems, car felt very good,turn-in was excellent. I changed to a 6 speed box which made the car feel even better.
The going rate for a second hand 6 speed box is around the£1100/£1200 mark i think(if you can find a good one).I have a brand new 6 speed box which is up for sale.
 

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Wane Ramsay said:
I have a brand new 6 speed box which is up for sale.
I wish I was richer :crying:

but as I said the money I've saved on getting the s/h one, I can get the interior, have it fitted, and pay for all my bodywork niggles, and there doesn't seem anything wrong with the s/h one.

But I can't imagine how sweet it would be to have a spanking new box in there!!!
 

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Discussion Starter #11
Wane Ramsay said:
Hi, i ran with M Parallels 235/40 /18 at the front and 265/35/18 at the rear without any problems, car felt very good,turn-in was excellent. I changed to a 6 speed box which made the car feel even better.
The going rate for a second hand 6 speed box is around the£1100/£1200 mark i think(if you can find a good one).I have a brand new 6 speed box which is up for sale.
I wouldnt say its a problem but i do notice haveing to try 'harder to reach the same speeds on the same bits of road if that makes sense I ran the 18's and the 17's at a local RWYB and it really showed. I am not to worried about lower rpm high speed cruising as the nearest motorway is 110 miles away and round here I generally run out of road at 145+ . Anybody know what/if the difference in the rolling radius is between 245/40's and the 265/35's,not alot i should imagine?
 
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