gear box swap

[luckyflush14]

lookin for some info guys and gals ive not long bourght a 1988 325i sport due to the fact that i crashed my 1990 4dr 325i se (twat) so my question is can i use the gear box from my moor door and swap it in to my sport because the problem is that they are both running dynoed at 210bhp but as the sport has close ratio box it aint got the legs like my 4dr and im a legs man yes the sports got the off the lights performance but come 3rd gear my 4dr will say good buy to most sports models you see i do a lot of motoway miles and the sport will run at 100 mph no props but it sits over 4000rpm but cams open so say good buy to the fuel were as my 4dr will sit at 100mph all day long at 3500rpm cams not open so i save loads of fuel so can i do a strait swap or is there any thing i need to do or know any help would be most greatfull many thanks and a happy new ......
scott..

[fowler]

sounds like a you need toi change diff ratio TBH as the tech 2 sport will have 3.91 and the more door can have any diff in 3.64 or 3.73 HTH

[hongkongfuey]

There is no way that you would be doing 100 at 3500 rpm

[Ross-E30MTECHII]

you can get a 2.93 for really long legs lol.

from what i know the gear boxes are all the same just different gear ratios inside, so should slot right in. quote me if im wrong.

[Curr946]

I would agree with Fowler here change the diff and leave the box.

plus im sure its only the lower gears that differ in the sport boxes im sure 5th is the same ratio unless your using a dogleg box.

[hongkongfuey]

The sport box has closer, 1,2,3 gears, 4 and 5 are the same