antil33t 90 Report post Posted June 15, 2010 (edited) Wasn't sure where to put this. But, this fella on trademe is stripping a few BMW's locally. I'm after a diff with a taller ratio, sick of the fuel economy. He has a 4:10 out out of an 86 318i which I guess is a PFL. I also guess it's a small casing. He has an E34 520i too (he never said anything about the diff) (would that fit??) No, it won't... Would the older 4:10 be fine, or should I look out for something else? Gear calculator reckons I should be around 2,500rpm @ 100kph, instead of the 2900-3000~ that I do now. Cheers. Edited June 15, 2010 by antil33t Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted June 15, 2010 (edited) What tyre size are you running and is your gearbox 1:1 in 5th or .8 : 1 ? BTW: What ratio diff are you running ATM ?? Edited June 15, 2010 by *Glenn* Quote Share this post Link to post Share on other sites
antil33t 90 Report post Posted June 15, 2010 4.45 Top Gear is 0.73 (it's auto) Tyres, 195/65/14 (stock weaves) I realise auto isn't exactly the best, but if I went manual the car would rev even higher in 5th. Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted June 15, 2010 (edited) Yes your present RPM @ 100kph is 2.900RPM A 3.64:1 would give you 2,300 rpm in top gear I have a medium case 3.64:1 open diff here in good working order...new side seals, new oil and I've had the back off to check it $250 if your interested. You would need a 3.15:1 or a 2.97:1 for manual if the gearbox was 1:1 The 3.64:1 would still be ok for a manual gearbox with a .8:1 output ratio Edited June 15, 2010 by *Glenn* Quote Share this post Link to post Share on other sites
pureboiracer 0 Report post Posted June 15, 2010 my 325 auto has a 3.6 and it is about right for what u want... and all model e30 diffs are interchangeable Quote Share this post Link to post Share on other sites
antil33t 90 Report post Posted June 16, 2010 Ahh, that's what I want to hear Oli. Cheers Glenn, Will keep that in mind Quote Share this post Link to post Share on other sites
