Old Guy completes front end re-build; New Question

[Al Gray]

I recently completed the front end rebuild on the 1992 525i that my son, Sean, drives. We replaced the upper thrust arms, right and left tie rods, center tie rod, idler arm, sway bar links and yes.... even the pitman arm. I did everything except the pitman arm. My mechanic aligned it and put the pitman arm in. Thank God it wasn't the steering box. The lower control arms were fine. They must have been replaced before I bought the car. The front end is just like brand new.

Now for my New Question: My son noticed that when the car is cold that the tach needle and speedometer needle bounce all over the place. I was poking around on the E34 website and noticed something about dashboard capacitors. The job involved removing the instrument cluster and soldering things. Has anyone had experience with this job? I don't mind taking the instrument cluster out but I don't like the idea of unsoldering and soldering circuit boards and electronc stuff for fear of screwing something up. Any comments or ideas?

Al Gray

[RallyD]

mine does the same thing, but only when cold and I first start driving in the morning. because it goes away after a few minutes, I just ignore it.

[632 Regal]

Al havent heard from you in a bit! When the guages bounce around it is usually a groung which could be anywhere as you know. If nothing else is acting funky maybe it is just the dash connections. The capasitors usually work or just dont work. Try the basic grounds first before pulling the cluster and using electrical conducting compounds.

Hope you had a happy thanks giving all!

[shogun]

No Sir, especially in winter time this comes up again when it is cold and when car is started up.
Al, buy the caps and bring it to a radio/TV repair shop and they can do it for you. Cost of the items is less than 10 $.
I also did it, although I am not a electric expert, but looks more complicated than it is actually.
Here a sample but during the past days we had a similar thread, this is a cluster from the E32 http://bmwe32.masscom.net/johan/dash...dash_caps.html
grey backplate = very old E32, from 1988 till early 1989, after that came different ones, so inside it might be a bit different.

[BMWDriver]

I had to replace a 1000µF 12V capacitor in the cluster. Best soldering job I've ever done. The trickiest part is opening the cluster itself. Removing it is also somewhat tedious.

The replacement capacitor came from the derelict tape deck I had in the e34. It had bad output on top of not playing tapes. That capacitor is actually smaller than the one it replaces. I might replace all capacitors eventually, but I don't see why right now. Most everything works fine. I had trouble with the fuel gauge which dropped to empty when about half full.

Bad cap:


Good cap:


Board before cap replacement job
(pretty much the same procedure as Shogun's link):

[BMWDriver]

While we're on the subject Shogun, why were higher voltage capacitors put in there instead? I can't say I fully understand capacitors and what they should do.

[tim eh?]

nice job

[shogun]

A capacitor is basically the same like a rechargable battery.

The maximum energy that can be stored safely in a capacitor is limited by the breakdown voltage of the capacitor, which is the breakdown field strength of the dielectric material times the dielectric thickness. Due to the scaling of capacitance and breakdown voltage with dielectric thickness, all capacitors made with a particular dielectric have approximately equal maximum energy density, to the extent that the dielectric dominates their volume

Details:
http://en.wikipedia.org/wiki/Capacitor

[Al Gray]

Al havent heard from you in a bit! When the guages bounce around it is usually a groung which could be anywhere as you know. If nothing else is acting funky maybe it is just the dash connections. The capasitors usually work or just dont work. Try the basic grounds first before pulling the cluster and using electrical conducting compounds.

Hope you had a happy thanks giving all!

Jeff,

I have been keeping busy. Completed the re-build of front suspension on the 1992 525i. I also purchased a beautiful 2001 740il in March of 2007. I recently had to replace the battery and the alternator (water cooled). It was a 2 1/2 hr job (remove fan shroud, fan, belts, tensioner pulley and a bunch of other stuff) but my youngest son, Kyle, who is a pretty good mechanic and car enthusiast helped me and everything works fine. The amazing thing is the cost. I had to buy the battery from the BMW dealer ($209) because it is a special battery and not available from after market. While there I priced the alternator (not new, Bosche rebuilt for $1100..gads!) I called BMA and they priced the alternator for me at $385 (I thought it was Bosche rebuilt by Patrick at BMA said it was a new one) I think shop time to put the alternator in was 5 hrs. By installing it myself I figure I saved at least $1200.