1987 325e diff swap

[Meyerse30]

Hey all. I was wondering what is the best ratio to swap in my 325e? It's an auto with the stock 2.93 open rear diff. Car has 107K. LSD would be the preferred unit. Just some opinions would be appreciated.
Thanks

[MR 325]

A 3.25 LSD is great for a manual Eta car. For an auto Eta something like a 3.46 might be even better.

[Meyerse30]

Thanks for the reply. A 3.46 is hard to find. I have a guy willing to sell me a 3.73 lsd. I'm thinking a nice ratio for the city, but not the hwy. Any thoughts... The car currently is a daily driver. Hoping to change that by spring

[MR 325]

Honestly an automatic Eta is more of a MPG machine than a performance car. Putting short gears in it won't do much besides lowering your fuel economy. I would either look for a 3.25/3.46 or leave it stock.

[Meyerse30]

I was thinking the same thing. There is currently a 3.46 Lsd for sale on eBay. Upgraded to 40% lock. But the price is high, with shipping $800. seems a little steep if you ask me.

[long tall eta]

a 3.73 will render your 1st gear almost useless. get a 3.25 and a chip

[Meyerse30]

I have a Turner chip that I recently installed. It made a difference in performance. I believe my fuel injectors need cleaning and or replacement as well. I found a guy an Hours drive with a 3.25 lsd. Hopefully picking it up after the holidays.

[long tall eta]

I have a Turner chip that I recently installed. It made a difference in performance. I believe my fuel injectors need cleaning and or replacement as well. I found a guy an Hours drive with a 3.25 lsd. Hopefully picking it up after the holidays.

make sure you're using premium fuel and the new diff will really wake her up. an upside to the 3.25 is that at 80 mph you'll still only be at 3000 rpm's.

[Meyerse30]

Awesome! yeah I always run premium fuel in my cars. Hopefully have the diff installed by the new year. 3000rpm @ 80 thats not bad.Thanks

[long tall eta]

Awesome! yeah I always run premium fuel in my cars. Hopefully have the diff installed by the new year. 3000rpm @ 80 thats not bad.Thanks

make sure the upper mounts are snugged up well. they can be a bitch and sometimes they seem tight but aren't.

[Meyerse30]

Thanks for the tips!. I really appreciate it.

[mrgraphics]

I put a 3.25 in my 86 along with a chip, and it's quite nice to drive around. Has pep, pulls out ok, and cruses nice at 70 mph and 2400 rpm. Mind you everything is in perfect condition, including rebuilt injectors.

Got my 3.25 lsd from pick-n-pull for under $100 off an 84 535. When I opened the diff up the oil was low and black. Just put new oil in and it works perfect. Those things are built like tanks.

[Meyerse30]

I just picked up a 3.25 lsd. Great condition. Need to swap rear cover and output flanges. Was in a 535is. Looking for someone to help swap it over. I'm going to replace the sway bar links and bushings while its jacked up.

[Halvo]

I have a very nice original condition 1986 325es with 140K miles, new injectors, SSSquid chip, Magnaflow exhaust. I did a ton of research on diff swaps, this thread included (thanks guys!). I did swap my steering rack to a Z3 steering rack and that has been my favorite upgrade. I had a friend tell me a diff swap was his favorite upgrade on his 325e, he called it "free horsepower". I use either premium 93 gas or more recently ethanol free 90 or 91 gas. I got a really nice refurebished 3.25 diff, had it installed by our local old beemer guru, and honestly I don't see that much of a difference. Gears are a little shorter, maybe it pulls ever so slightly harder when passing on the highway, but in no way shape or form was it worth the several thousand dollars it took to purchase, ship, and install it. I would leave it stock if I were doing it again. Just not enough difference to make it worth it. My $0.02 for anyone doing research and thinking it will be a big performance upgrade. It is subtle at best. Spend your money elsewhere. The Z3 steering rack on the other hand.... GO FOR IT!