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That didn’t sound good.
You know that sick feeling that you get in the bottom of your stomach when you realize that your car is having a major drivetrain failure? Yeah. It’s a one-two punch of “This is going to cost you a fortune” and “your wheels are about to lock up and everyone is going to die”.
My differential suffered a catastrophic failure recently while I was on my way to work. Now, I’ve been getting pretty adventuresome with my home mechanic routine lately. I recently figured out how to adjust my valve clearances, I changed out a water pump, an alternator, and even drilled a broken-off spark plug out of the cylinder head, but pulling the rear end out of the car was a bit intimidating to me. I called around, but it became evident that it was going to be tough to find someone who was interested in working on a 1973 BMW. I really don’t understand why shops are scared of them, as the 70′s BMW 2002 is about the simplest car to work on that you could imagine. So I realized that I would be the machanic again.
I visited the 2oo2faq message board to pick up a little advice. The BMW 2002 is major cult car. People love their 2002′s, and this board is full of active 2002 nuts. I found out that a differential failure in a 2002 is really viewed by the enthusiast as an almost welcome opportunity to upgrade. it turns out the rear-end from a 320i can easily be swapped into the 2002, and quite often is, in order to take advantage either the lower gear ratio, or the more prevailant limited slip differential that was optional on these cars. There are a bunch of ways to get the 320i diff to work in the 2002 using various combinations of CV joints, axles, and output flanges, or spacers. I did alot of research, and finally arrived at an understanding of what bits and pieces I needed. Now all I had to do was find the 320i limted slip diff.
I couldnt find a 320i LSD, so in the end I went with a 2002 diff, which saved me the trouble of adapting the 320i unit. I did manage to find one with the lower gear ratio however so although I wasn’t able to upgrade to limited slip, at least I still gained a little low-end torque. Next up: Installing a Weber 38/38 downdraft carb.
so….. where in the hail did you get a rear diff for your 2002? was it a new one? rebuild, or franken-steined from a donor? and how the heck did you switch it out and how long did it take?? what was the final cost vs time to do it? good work…. it would take me a few months to perform such a task! -vlad
Yo Vlad,
You bring up a good point about the time-spent versus money-saved issue. This is a complex calculation to make, as there are so many variables. What is ones time worth? Do you bill yourself at the rate that you make professionally? Is tinkering work or recreation? Where do the 2 intersect. Tough to say.
About the replacement differential. It is pull out from a wrecked car that was sitting in a pick-n-pull yard. There is no such thing as a rebuilt diff, due to lack of replacement parts. I just had to gamble. The one that I ended up putting in didnt look so great on the inside, but I had no way to preview it before I bought it. We’ll see how long it lasts.
“That didn’t sound good” sounds a little understated… Maybe “What the &*&U#*$* was that?” would have been more apporpriate when the differential failed.
Love your site, but you need more Automotive entries. That 73 2002 should provide lots of appropriate fodder. For example, how did you install that Becker Europa II?
Does Finkbuilt every do any website design on the side?
Thanks,
M.
Mark,
You’re right about the 2002. I ‘ve logged quite a few hours underneath that car that I could describe in detail. In fact 3 of my 10 posts relate to the BMW. i’m sure that ratio won’t go down as the site fills out. I do have some intersting non-BMW automotive articles in mind, I just have to find the time to write them.
steve
I miss my ’73 2002…
I still have pieces of my broken differential gears from the day that I decided to peel out in front of my girlfriend. I revved up the engine, dropped the clutch, and only lurched forward a little bit as I heard a big CLUNK noise, and then 2002 rolled backwards in first gear with the clutch out…
Bear in mind that the change in final drive ratio will affect your speedometer & odometer readings. Since you state that you put in a shorter rear end (actually a higher gear ratio — ie more inputrevs per output rev), you’ll be going slower (and not as far) as the readings indicate. The cure (if you didn’t already do it) is a different takeoff gear for the speedo — should bolt into the side of the transmission and probably is easy to change.
Go for the webers! I’ve got dcoe 40s weber sidedrafts on my old volvo 544 and they add some oomph and a satisfying sound when you hit the throttle.
What are the symptoms of a vehicle that has a limited slip differential that has gone bad and needs to be replaced?
Ha, i feel your pain Rossta, i have a nice 2005 318i black BMW, on my way to work i heard a clunking noice coming from the rear end when i pulled away from the lights, i thought, sh*t just get me to work car, but oooooo no !, it waited till i got to the worst set of traffic light in town, and as i tryed to pull away , a lound bang came from the back of my car, at first i thought i was getting hi jacked, but after a few minutes i realized it was worse,… the diff had gone to the big diff heaven in the sky, my car would not move even in gear, the engain reved freely, i thought “gee that sounded exspensive’”, i towed it to my friend who confimed my spider gears had smashed, i got a second hand diff and he fitted it, and i was R 4,000 lighter in my pocket, he told me BM`s are known for this problem, so BM stop using spider gears and start using elephant gears and maybe people could get to work.