BMW part number 34 51 1 163 086 (34511163086) is the Rmfd hydro unit ASC (Automatic), a brakes part catalogued for the E32 (730i, 730iL, 750i), E31 (840i, 850Ci, 850CSi), E34 (530i, 540i). As of our last check (2026-10-08, bmwpartsdeal.com), BMW lists it as no longer available new (NLA). Also catalogued as 34510026458. 1 kit or reman option, 1 repair guide below.
Not available new from the US or the European dealer we checked. BMW Classic or another dealer may still locate one with your VIN.
No sourced aftermarket equivalent recorded yet. We only list brand numbers that a brand catalog or vendor page explicitly cross-references to this BMW number.
“Ships internationally” is shown only where we read it on the vendor’s own shipping page (checked 2026-09-28); otherwise check with the vendor. Import duties and taxes are the buyer’s responsibility. Amazon links carry our Associates tag, so we may earn a commission; other seller links are not affiliate links today.
Older numbers on the left, newest on the right. Numbers without a record open a lookup.
Listed directly for E32 and E31 and E34 in our data (see Fits). Models below are other listings of the same number.
Same BMW part number, but the source list is truncated or market-specific. More models may apply.
+2 more models not listed by the source.
No forum workaround recorded yet. If you know a thread, the hunt team wants to hear about it.
No DIY route recorded yet.
Write-ups and videos from owners, forums and specialists on removing and fitting this part. Summaries are ours; follow the link for the full steps, photos and torque values, and credit goes to the original author. Safety-critical part: have a qualified mechanic check the work.
ABS and ASC lights on a cold day are often a seized hydraulic-unit pump motor from lack of use. Timm frees it by running the pump from INPA, or without diagnostics by bridging the pump relay, before considering a replacement unit.
Tools mentioned: INPA (optional), insulated jumper for the relay
E34: Last listed $3396.06 on bmwpartsdeal (not orderable). SAFETY-CRITICAL (brakes/steering/fuel): have a qualified mechanic verify fitment and installation. E31: Last listed $3396.06 on bmwpartsdeal (not orderable). SAFETY-CRITICAL (brakes/steering/fuel/airbag): have a qualified mechanic verify fitment and installation. E32: Last listed $3396.06 on bmwpartsdeal (not orderable). SAFETY-CRITICAL (brakes/steering/fuel/airbag): have a qualified mechanic verify fitment and installation.
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