There are so many options for the driveshaft. You can also use the M3 E30 driveshaft, mainly because it has the bigger guibo. You always have the option to use a driveshaft from any of the E30 models described below.
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It is recommended that you simply install an existing ’87 325e or ’88 325 driveshaft from your donor car. If your car was an 87-92 325i with the smaller guibo, you must source one from a local junkyard. I have estimated this cost to be approximately $20. For details, see Figure 24. You can also refer to “transmission” section for more detail about guibo and driveshaft size.
’85, ‘86, ‘87 325e(s)
’88 325 “supereta”
No driveshaft from an “i” car shall be used.
To Install the driveshaft, follow these steps:
1 Ensure that the Guibo is installed on the Transmission output shaft and 3 bolts are tightened. Also, ensure that the spline sleeve is loose so that the driveshaft halves can slide on each other.
2 Install the rear differential side first
3 There are 4 studs that go right into the differential input shaft. This will lock the rear of the driveshaft in place easily. You don’t need to put the 17mm nuts on if you don’t want to. Just push it on.
4 Bend the driveshaft at the center bearing and slip the front end through the centering 3/8” pin which resides on the transmission.
5 Line up the holes on the guibo roughly.
6 Push the center of the driveshaft up into the tunnel and screw in the 2 13mm bolts, but do not tighten.
7 Preload the center bearing and tighten the 13mm bolts on the center bearing.
8 Now screw the input and output bolts/nuts.
Note that you CANNOT cut and weld the driveshafts. They require sophisticated welding and balancing machines that can only be sourced at a professional shop.
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Even though I had the correct driveshaft size from my 325 supereta, it was very unbalanced and I needed a new one regardless. I decided to go to www.wholesaleimportparts.com and bought a refurbished/rebalanced driveshaft for my ’88 bmw 325 supereta. The part number was 20680.
1. Click on the link and then go to “catalogs”.
2. Then click “driveshaft store”.
3. Look for BMW, choose “manual” and you’ll see 2 main choices for the E30:
After going through the website, you might want to call them up yourself, but make sure you buy a driveshaft that has the bigger guibo size. See below:
The bigger guibo (3.12”) fits perfectly. The part is $325 with an addl. $60 core deposit. Comes with a brand new center bearing installed already! Do not buy the smaller driveshaft size as the output shaft from the transmission will not fit. When you get the driveshaft, you just send back the old one in the same box, free shipping back… you get your $60 back within 2 weeks credited to your card. So here’s what I did: I used the driveshaft that they gave me and installed it. With my 2 ½ engine position, the driveshaft had plenty of spline contact, not to mention I still gave my center bearing that preload it needed as per the Bentley manual. See Figure 23 for more detail about the E30 driveshaft and the bolts that correspond to its removal/installation.
To be more accurate with the driveshaft flange differences, see dimension A in Figure 24. This dimension corresponds to the 3.12” or 2.6” as described. Dimension A should match or you can’t hook up the driveshaft.
I have not had any problems with the driveshaft since. It is perfectly balanced up to 145mph and can handle up to 300rwtq and probably more, even on a hot day when the tires are extra sticky.