Big Supes Posted February 7, 2016 Share Posted February 7, 2016 Hi guys, I'm in the process of choosing a gearbox for my manual conversion and I have decided to go down the BMW route. The two options I am considering are the e46 M3 6sp getrag and the 330d gearbox. Ideally, I want to get as close to the OE 6sp gearbox on the Supra, but before I commit to buy anything, I'd just like to run it by the gurus as I'm not too versed in ratios. 6 Speed (V160) / (V161) 3.827 / 3.724 2.360 / 2.246 1.685 / 1.541 1.312 / 1.205 1.000 / 1.000 0.793 / 0.818 3.280 / 3.192 3.266(all TT) Looking at the comparisons, I think the obvious choice would be the M3 6sp as the ratios are quite similar, but am I right in thinking the final drive ratio on the 330d would be geared too high, making it quite difficult to make power lower down the rev range? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 8, 2016 Share Posted February 8, 2016 Without a none standard diff ratio the diesel BMW gearbox will be like only having the lower 5 gears available in a Getrag six speed. Will be quite high revving at motorway speeds. Direct top gearboxes in modern cars need a very high ratio diff, as in the BMW. Or they are more for competition use. What is the recommended max torque for the M3 box? I doubt it will like turbo torque levels. These conversions sound cheap and great, but there are probably hidden dragons about. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 8, 2016 Share Posted February 8, 2016 Looking at the comparisons, I think the obvious choice would be the M3 6sp as the ratios are quite similar, but am I right in thinking the final drive ratio on the 330d would be geared too high, making it quite difficult to make power lower down the rev range? It would gear the Supra too *LOW* if you used the diesel box with any of the stock MKIV diff ratios. Quote Link to comment Share on other sites More sharing options...
ManwithSupra Posted February 8, 2016 Share Posted February 8, 2016 Keep in mind the rev drops as well.. Quote Link to comment Share on other sites More sharing options...
ManwithSupra Posted February 8, 2016 Share Posted February 8, 2016 (edited) this is based on a tyre with a rolling circumfrance of 2052mm (245/40R18) and a rev limit of 6800rpm If you used the M3 Gearbox with a 3.280 FDR This is what you would get Top Speed in 1 gear = 37.495 MPH changes into 2 gear at 4067 RPM dropping 2733 RPM Top Speed in 2 gear = 62.689 MPH changes into 3 gear at 4489 RPM dropping 2311 RPM Top Speed in 3 gear = 94.973 MPH changes into 4 gear at 5008 RPM dropping 1792 RPM Top Speed in 4 gear = 128.947 MPH changes into 5 gear at 5528 RPM dropping 1272 RPM Top Speed in 5 gear = 158.604 MPH changes into 6 gear at 5644 RPM dropping 1156 RPM Top Speed in 6 gear = 191.089 MPH If you used the M3 Gearbox with a 3.266 FDR Top Speed in 1 gear = 37.656 MPH changes into 2 gear at 4067 RPM dropping 2733 RPM Top Speed in 2 gear = 62.958 MPH changes into 3 gear at 4489 RPM dropping 2311 RPM Top Speed in 3 gear = 95.380 MPH changes into 4 gear at 5008 RPM dropping 1792 RPM Top Speed in 4 gear = 129.499 MPH changes into 5 gear at 5528 RPM dropping 1272 RPM Top Speed in 5 gear = 159.284 MPH changes into 6 gear at 5644 RPM dropping 1156 RPM Top Speed in 6 gear = 191.909 MPH If you used the 330/530d Gearbox with a 3.280 FDR Top Speed in 1 gear = 30.268 MPH changes into 2 gear at 3789 RPM dropping 3011 RPM Top Speed in 2 gear = 54.317 MPH changes into 3 gear at 4238 RPM dropping 2562 RPM Top Speed in 3 gear = 87.145 MPH changes into 4 gear at 4745 RPM dropping 2055 RPM Top Speed in 4 gear = 124.885 MPH changes into 5 gear at 5354 RPM dropping 1446 RPM Top Speed in 5 gear = 158.604 MPH If you used the 330/530d Gearbox with a 3.226 FDR Top Speed in 1 gear = 30.775 MPH changes into 2 gear at 3789 RPM dropping 3011 RPM Top Speed in 2 gear = 55.226 MPH changes into 3 gear at 4238 RPM dropping 2562 RPM Top Speed in 3 gear = 88.604 MPH changes into 4 gear at 4745 RPM dropping 2055 RPM Top Speed in 4 gear = 126.976 MPH changes into 5 gear at 5354 RPM dropping 1446 RPM Top Speed in 5 gear = 161.259 MPH Edited February 8, 2016 by ManwithSupra (see edit history) Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 8, 2016 Share Posted February 8, 2016 Has anyone got photos and dimensioned drawings of these diesel BMW `boxes please? Quote Link to comment Share on other sites More sharing options...
Big Supes Posted February 8, 2016 Author Share Posted February 8, 2016 That's a wealth of information guys, thanks very much. I think I can live with the ratios on the M3 box. I'm not too sure on the amount of torque it can handle, but I will make some enquiries. I recall it being able to handle more than enough 'power' for me, but as 'torque' is what kills them, yeah, it might be wise to find out. Quote Link to comment Share on other sites More sharing options...
tkddav3 Posted February 8, 2016 Share Posted February 8, 2016 There's a boosted e46 m3 that's fairly local to me running 500hp plus and that has no problems with the box as far as I know Quote Link to comment Share on other sites More sharing options...
Big Supes Posted February 8, 2016 Author Share Posted February 8, 2016 Apparently the most power/torque known to be running on the M3 getrag 6sp is 660bhp / 570fpt. It has taken some serious abuse and is holding up just fine. One of the guys who offers the conversion believes it can handle more, but personally, I won't be going any higher than 600bhp... if that. - - - Updated - - - There's a boosted e46 m3 that's fairly local to me running 500hp plus and that has no problems with the box as far as I know That's good to hear. Quote Link to comment Share on other sites More sharing options...
Big Supes Posted February 10, 2016 Author Share Posted February 10, 2016 Would you guys recommend swapping out my UK large case diff for a TT 6sp to help with getting the RPM down a bit? Auto differential ratio is 3.769 6spd differential ratio is 3.133. I am quoting figures from MKIV.com as I presume they are going on US cars. Quote Link to comment Share on other sites More sharing options...
j_jza80 Posted February 10, 2016 Share Posted February 10, 2016 Would you guys recommend swapping out my UK large case diff for a TT 6sp to help with getting the RPM down a bit? Auto differential ratio is 3.769 6spd differential ratio is 3.133. I am quoting figures from MKIV.com as I presume they are going on US cars. J-spec TT6 diff ratios are different to UK/EU/US TT6 ones And the latter ones are VERY hard to come by and generally very expensive. - - - Updated - - - Have you used the gear ratio calculator on the forum wheel/tyre size calculator? Quote Link to comment Share on other sites More sharing options...
Big Supes Posted February 10, 2016 Author Share Posted February 10, 2016 J-spec TT6 diff ratios are different to UK/EU/US TT6 ones And the latter ones are VERY hard to come by and generally very expensive. Put that one down to a slight brainfart, J. Have you used the gear ratio calculator on the forum wheel/tyre size calculator? I haven't. Is this on the site or a different website? Quote Link to comment Share on other sites More sharing options...
j_jza80 Posted February 10, 2016 Share Posted February 10, 2016 Everything you could ever need to know about gear ratios http://www.mkivsupra.net/vbb/showthread.php?225050-Supra-specific-gear-diff-ratio-and-tyre-size-calculator&highlight=calculator Quote Link to comment Share on other sites More sharing options...
Big Supes Posted February 10, 2016 Author Share Posted February 10, 2016 Awesome. You're a gent. Thanks mate. Quote Link to comment Share on other sites More sharing options...
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