1986 325e diff swap... What's best?

[86beast325e]

So I did some searching and even found a similar thread for an 87 325e but it was auto. I have a 5speed 1986 325e and my diff is noisy and dead. I replaced it with a 4.10 but it also has a whine and the seller is nice enough to take it back. The 4.10 has awesome response but at 80mph I am already hitting the top of my rpms. I like the 4.10 but was wondering if anyone had any advice.

[MR 325]

A 4.10 diff in an Eta is insane. A 3.25 ratio is what I'd recommend.

I actually have a 3.23 diff from a 1999 M Roadster that will work. PM me if interested.

[ruqknuf]

I put a 3.46 in, and was a massive upgrade for the 325E. It will turn the E into a fast revving street machine. It’s like going from a 4 door family sedan to a 2 door sports coupe. It’s a big difference. It was one of the first purchases I made to upgrade my eta.

[Wanganstyle]

I put a 3.46 in, and was a massive upgrade for the 325E. It will turn the E into a fast revving street machine. It’s like going from a 4 door family sedan to a 2 door sports coupe. It’s a big difference. It was one of the first purchases I made to upgrade my eta.

um no, it will make you blow through the rpm's quicker and one who is used to low power cars might be convinced that its faster.....but its NOT.

a 100% stock ETA engine (doesn't matter what is attached to it component wise) is happy in low and mid RPM ranges; it hates high rpm's.
keep the final drive stock.

I had a stock eta, and tried 3 different final drive ratios - stock BMW was best.

[HennaE30]

um no, it will make you blow through the rpm's quicker and one who is used to low power cars might be convinced that its faster.....but its NOT.



a 100% stock ETA engine (doesn't matter what is attached to it component wise) is happy in low and mid RPM ranges; it hates high rpm's.

keep the final drive stock.



I had a stock eta, and tried 3 different final drive ratios - stock BMW was best.

He said fast revving. And it does make it a fast revving engine.. I was stupid enough to put a 4.10 in mine.. Now I'm highly regretting it, but it does rev fast for sure.

I've heard 3.15 and 3.25, are some of the best ratios of your looking to give it some pep around town.. Whatever you do. DO NOT SWAP A 4.10 IN. Worst mistake I've ever made. Sure it was fun for the first day, but it's pretty much ruined my car

[BMMal]

I just got a 3.15 to swap into mine eta. Main reason was because I wanted something quicker than the 2.93 but still wanted to cruise on the highway without too many revs. Tires and all considered I should be sitting around 3100 rpm at 70 mph. Almost went with a 3.25 but I drive faster than 70 pretty frequently and I didn't want to destroy my fuel mileage too much.