Ix final drive ratios

[jute91]

Hi all!

I have reade nando's story and im wondering where i can purchase longer ratios for my ix? that 3.38 would be awesome!

[Kershaw]

you have to custom assemble the diffs yourself from other BMW diffs.

however, the early model euro IX has a 3.64. if you can settle for that, you can just buy the diffs.

[nando]

there is no 3.38 front ring and pinion that will fit in the 325ix front diff. E34 is close but it's basically too big to fit. they are type 168mm ring and pinions up front, the rear is a standard type 188mm but the carrier is ix-specific. the front ix carrier, near as I can tell, is the smallest type 168 BMW has used.

your best bet is a 3.64 from an early ix, as they are somewhat easy to find and the set will bolt right up.

the 3.38 is from an E34, and requires basically the oil pan, front CV shafts, a 24v motor and a way to adapt the ZF 310/320 transmission to the E30 transfercase. Then you have to have a matching 3.38 a custom built for the rear, since no 3.38 ever came with in VC diff. The ring and pinion will bolt right up to the rear 188mm case, it just needs to be set up properly (backlash etc).

[jute91]

but my biggest +++ in the final drive would be that i could get some sense to lenght of 1. gear and 70mph rpms... when driving 70mph it would be nice have rpms more around 2k than 3k... it would lower the fuel consumption :) im not building racer of this car... its just my hobby..

[downforce22]

here in america we have 3.91 and 4,1 consider your 3.73 to be a blessing as it is. I am at about 65 in top gear at 3000 rpm. You could put bigger wheels to help, like 235/40 /17.

[nando]

final drive ratios are down to individual taste. Personally, I think it's fairly pointless to do ~50mph in 1st gear. That's what driving an automatic E30 is like (slowwwwww).

it helps when you don't have a stock redline, but there's really nothing wrong with the 3.91 or 4.10. These cars are slow as it is. besides, later EU models got the 3.91 and 4.10 anyway.

205/40-17 tires are too small BTW. 215/40-17 is pretty much the same size as stock. definitely taller tires will help. even a 225/40 or 235 would work well if you want some extra "gear" without spending $$$ on a custom diff ratio.