Might help if we knew WHICH M5 you were referring to. M5's were produced in E28, E34, E39, and E60 editions from 1985 through 2010 -- NONE of them were interchangeable between generations. Also, production date (or last 7 digits of your serial number) would be helpful. What's wrong with yours? Are you sure it's a tachometer issue and not an issue with the cluster or sensor(s)? Also, many speedometer shops can repair tachometers, often for less than the cost of replacing one outright.
Check at www.mye28.com in the Parts for Sale forum. If there's none there, I'd post a 'Wanted' message. OTOH, you might also check into our excellent Tech Forum and find a fix for it. I'm pretty sure the only difference between the M5 and the 535 tachs is the faceplate. You could probably swap plates on a good one and be done with it.
Are you this person? http://www.mye28.com/viewtopic.php?t=85096&highlight=tachometer If not, follow C.R.'s advice and get over there so we can pinpoint your problem. The most common cause of instrument malfunction is the SI board (motherboard.)
You're forgetting one small detail with the faceplate swap A key difference between later 5-series tachs and M5 tachs is that the M5 tachs substitute the vaccuum MPG gauge for an oil temperature gauge. That's going to involve a little more work if you want to retain that. Actually, many speedometer shops are capable of repairing these tachs. Particularly a place that's an authorized VDO specialist. VDO is the OEM maker of BMW gauges.
The US E28 M5 tach has no econo or oiltemp gauge on the tach at all, jsut a tach. Typically, the tach itself does not fail, rather a solder joint on the SI board or a trace on the SI board due to acid from the batteries leaking.
Not much. I've had E28 gauge panels apart. They're pretty much mix & match. You can swap the different gauges in as easily as BMW did. If you don't mind a little wallet rape ...
Thanks for the clarification I agree with the repair assessment. Especially in light of the fact that these tachometers may be NLA (No Longer Available) after being out of production for so long, and considering how rare E28 M5's are, even a used one may be tough to come by. Can't be worse than what a dealer would do to you, and assuming it would be expensive without checking would be kind of premature. A lot of these old style tachs resemble the inside of a wrist watch, and I bet its still cheaper than trying to acquire a new (if available) or used one. The parts swap with a non-M5 tach sounds promising -- IF you know what you're doing.
