scottharvey 60 Report post Posted October 16, 2012 How do i know which diff ratio i need. There is a cheap medium case 8 bolt on trademe 4.1 ratio. My e30 is a 88 it is a 320i with a m20b25 done by previous owner so dont know if gearbox was changed Quote Share this post Link to post Share on other sites
frkshow 0 Report post Posted October 22, 2012 How do i know which diff ratio i need. There is a cheap medium case 8 bolt on trademe 4.1 ratio. My e30 is a 88 it is a 320i with a m20b25 done by previous owner so dont know if gearbox was changed hae bro who did u buy your e30 off cause i think i built this one. if it is the dif is still the same auto diff. because i did a full manual conversion at the same tym i put the b25 in. Quote Share this post Link to post Share on other sites
BM WORLD 1265 Report post Posted October 22, 2012 (edited) small case 4 bolt diff looks like this http://www.trademe.co.nz/motors/car-parts-...n-525705860.htm medium case 6 bolt diff looks like this http://www.trademe.co.nz/motors/car-parts-...n-525416437.htm if it was a 320i it would normally have a small case 3.91 to 4.1 etc std 325i normally use a 3.64 medium case. but there are also variations on this of course. all depends on how many revs you want to be doing at say 100km/h in 5th gear try this http://members.dodo.com.au/~wawawa/revs.htm enter the gearbox type getrag 240 or 260. put wheel/tyre size in . then try some different ratios like 3.25 ,3.46 , 3.46 , 3.73, 3.91 4.1 , 4.45 etc ps. also e30 dont use 8 bolt large case diffs , thats what 5 ,6 , 7 & 8 series normall use V8's v12 ,M5 and big six engines like 3.5l 4L 4.4l 5L etc or e36 e46 M3 3.2L etc they look like this Edited October 22, 2012 by Brent HARTGE535i Quote Share this post Link to post Share on other sites
scottharvey 60 Report post Posted October 22, 2012 hae bro who did u buy your e30 off cause i think i built this one. if it is the dif is still the same auto diff. because i did a full manual conversion at the same tym i put the b25 in. Ive pmd u Quote Share this post Link to post Share on other sites
scottharvey 60 Report post Posted October 22, 2012 small case 4 bolt diff looks like this http://www.trademe.co.nz/motors/car-parts-...n-525705860.htm medium case 6 bolt diff looks like this http://www.trademe.co.nz/motors/car-parts-...n-525416437.htm if it was a 320i it would normally have a small case 3.91 to 4.1 etc std 325i normally use a 3.64 medium case. but there are also variations on this of course. all depends on how many revs you want to be doing at say 100km/h in 5th gear try this http://members.dodo.com.au/~wawawa/revs.htm enter the gearbox type getrag 240 or 260. put wheel/tyre size in . then try some different ratios like 3.25 ,3.46 , 3.46 , 3.73, 3.91 4.1 , 4.45 etc ps. also e30 dont use 8 bolt large case diffs , thats what 5 ,6 , 7 & 8 series normall use V8's v12 ,M5 and big six engines like 3.5l 4L 4.4l 5L etc or e36 e46 M3 3.2L etc they look like this Sweet mate i think i need to get my car actually not overheating first Quote Share this post Link to post Share on other sites
BM WORLD 1265 Report post Posted October 22, 2012 Sweet mate i think i need to get my car actually not overheating firstbring it around some time.have a workshop next door to my warehouse Quote Share this post Link to post Share on other sites
scottharvey 60 Report post Posted October 22, 2012 bring it around some time. have a workshop next door to my warehouse Ok sweet when can it drop it off?? Quote Share this post Link to post Share on other sites
