6 speeds have essentially identical in-gear ratios the 5 speeds do. You're just adding an overdrive.
Echoing exactly what Braymond said..
As i've touched on in other posts, S52's just don't take well to short gearing. The concept big turbo guys use applies to you too - by running taller(lower ratio) rear end, you'll stay in boost longer and capitalize on the power band. Short gearing winds the gear out quicker, but in the case of a centri SC your mega power range is even smaller than a turbo to begin with so you are basically shifting yourself *OUT* of peak power. Not to mention creating unnecessary traction issues and negating the value of having a 6 speed. With your power and style of use you should be running a 3.46 max IMO.
Very very rough math: +size wheels will offset your ratio by one gear step give or take. So by running 18's with a 3.46 it would be like running 17's with a 3.38. 3.73 would behave like a 3.64, etc. Vice versa, 17's with a 3.46 would be like 18's with a 3.64, or in your case 3.91+18" is more like 17's with a 3.73.
Last edited by jvit27; 02-09-2017 at 07:50 PM.
'99 Estoril Blue + Dove Grey ///M3 coupe
'04 Jet Black + Cinnamon ///M3 coupe
Excellent points!
Thank you both for your help. Time to hunt down a 3.46 diff to replace the 3.91.
Jon
08' BMW M5 (Alpine white/Indy red) - Dinan/Brembo/Corsa/Forgestar/Vorsteiner/3M/Dinmann/SMG
98' BMW M3 (Dakar yellow/black) - Dinan/RMS/Vortech/Work/Denon/Brax/Helix/3M/Recaro/Stoptech/AST/6MT/3.91 LSD
BMW 325isA (gone but not forgotten)
ACS Type II front bumper-ACS Type II sport mirrors-ACS Type II roof spoiler-ACS Type I rear apron-ACS rear wing-ACS pedals/dead pedal-ACS wood gear knob-ACS wood trim-ACS badges-BBS RS II 18's-TMS chip-ECIS intake/cover-RMS exhaust-Dinan transmission chip-ERT crank pulley-ZKW/DDEII/Phillips 6000k Hids-Kenwood eXcelon head/CD changer-Alpine sound field processor-PPI Art amps-MBQ speakers-Infinity 10' sub-Alpine 8070 alarm-Chrome trunk lid-Chrome gauge rings-In Pro smoked corners-BMW OEM clear tails-M3 mouldings-M3 floor mats-M3 door sills-M3 Lux wood trim-M3 rear sway-X brace-Koni shocks-Bav Auto springs-JTD RSMs-Front/rear strut braces-E46 front grills-Kamei eyelids-Kamei cf door handles-tinted windows-German ECC plate
The size difference in the wheels does not always apply.
Ie running a 245/45/17 = 25.7" tall tire. Switch that to a 245/40/18 and your still running a 25.7" tall tire. So, all will be equal.
1996 332IS
Built 3.2
CES/Steed TS Precision 6466, spraying a "$π!℅" load of meth.
Technique Tuning 80# tune.
1/4 mile 10.84 @ 136.72
Your 1 and only stop for all your BMW performance needs
WWW.CESMOTORSPORT.COM
Last edited by Butters Stoch; 02-09-2017 at 11:26 PM.
1996 332IS
Built 3.2
CES/Steed TS Precision 6466, spraying a "$π!℅" load of meth.
Technique Tuning 80# tune.
1/4 mile 10.84 @ 136.72
Your 1 and only stop for all your BMW performance needs
WWW.CESMOTORSPORT.COM
Bumping this for a pertinent question.
Does anyone know the exact length that a 5-speed driveshaft has to be shortened to facilitate the 6-speed swap?
I was initially looking at picking up a used auto driveshaft, but I've got a six bolt input at the differential and recently replaced my driveshaft (last year).
After contacting a shop that willing to modify the length, it'll be about the same price as getting a used auto shaft. I feel its better in the long run since I'll have something that I know works and was recently re-manufactured.
US spec 5 speed CV style driveshaft is 1469mm long
Euro 6 speed driveshaft is 1367mm long. So it needs to be 102mm shorter, or 4.016 inches. And that all has to be in the front section. If you are using a 4 bolt U joint style driveshaft, the flange length on the diff is different. Those are 1492mm long, but the extra 23mm is either the different in flange height from the diff or is taken up with the slide joint. I'm not sure.
So I'm not a driveshaft expert, and those are just the numbers that I've found online. And the euro 6 speed driveshaft I have is in my car at the moment, so I'm not going to be able to measure for you. Sorry. The best bet is to just take your car to the DS shop and have them measure it to be sure.
Last edited by kevinwilly; 03-16-2017 at 09:02 AM.
i hated the way my e46 m3 shifted (gearbox and clutch).
does the zionsville 6 speed feel like the oem e36 m3 tranny?
Some say the ZF GS6-37 shifts better than the Getrag 420G.
By all accounts that I've heard from people that have done both, the ZF is much less notchy and easier to use.
I've got the 420G and a Rogue shifter, it isn't bad, but it's not as nice as the stock 310..
If I were t do it again, I'd go with the ZF...
No matter where you go, there you are...
called zionsville- nice guys. $3500 for their ZF with potential $200 core for trade in
Having daily driven a car with a 420G and now daily driving a car with the ZF 6 speed, the ZF gets my vote any day of the week...
Smoother, less notchy, but not at all "vague" - you know where all the gears are and its like the gearbox actually wants you to shift into them. The 420G is almost so notchy that it's like "are you sure neutral isn't ok?" any time you try to put it into a gear.
Going into my TENTH YEAR of providing high quality reproduction BMW fabrics!
PRICE CUT on ALL FABRICS
Offering the best prices on the best quality reproduction fabrics!
Sounds like a shifter issue or the particular trans in the car you drove. I have the euro six speed (Getrag) and gear selection is a precise. Maybe it's the Auto Solutions shifter I'm using. The only negative of the Getrag is, when cold I get the 'second gear crunch'. Once warm, that disappears.
04M3 TiAg 69k slick-top 3 pedal
99M3 Cosmos 61k S50B32 euro 6Spd
88M3 AW 43k miles Project FS
WTB: 3.5" Eurosport/Conforti CAI
I've driven quite a few 420G's, they were all like that. Its just that it requires more force to get it into gear than the ZF. Have you driven a ZF 6 speed? If you haven't, try to get behind the wheel of one, its silky smooth.
I don't miss the second gear crunch... my ZF syncros are worn, so I get some 2nd gear grindtime funtime in my ZF too. Best of both worlds
Going into my TENTH YEAR of providing high quality reproduction BMW fabrics!
PRICE CUT on ALL FABRICS
Offering the best prices on the best quality reproduction fabrics!
yeh and if i remember correctly using the sport mode the e46 m3 made shifting even worse
The Getrag in my 99 was not beat and had less than 60K on it... or I just got lucky.
04M3 TiAg 69k slick-top 3 pedal
99M3 Cosmos 61k S50B32 euro 6Spd
88M3 AW 43k miles Project FS
WTB: 3.5" Eurosport/Conforti CAI
Bookmarks