Aluminum Alternator Bushings - Opinions please...

[Fishhead]

Good idea or bad idea?

I see that there are some sellers on Feebay that sell aluminum alt bushings for other BMW models so I made up a set (my prototype on an E21 65 amp alt). In searches I have done on Feebay, I have noticed that some later alternators did not have the rubber bushes in the alternator at all.

My set is press fit in the alt and replaces the rubber bushings and metal spacer collar. I'll probably make a set for the adjuster end of the alt also.

Good idea or bad idea?

[c.d.iesel]

vibration insulation is yer friend .

[Mike Self]

for a reason--engine vibration elimination. You can buy urethane bushings that still eliminate vibration but don't turn into black goo in a few years.

Your aluminum bushings, while attractive will simply transfer engine vibes to the alternator. Go for urethane.

cheers

mike

[TobyB]

I'll third that-

I was never able to keep a stock alternator alive on the race car.

Something about that location really is a harmonic vibrator...

heh... heh....

t

[SteveJ]

The more solid you make it, the less resistance it has to vibration. Typically, vibration will just move on to the next weakest link to make itself known.

There is a reason that some things use insulators or suspension. You could replace the springs and shocks on a car with solid blocks of Delrin. The car would have NO body roll. It would not absorb any bumps or variations in the roadway. You'd have no fillings left in your teeth.

Use fresh rubber first. If that fails, move up to poly. One of those two will probably make things stable enough without thing tearing apart. The poly bushings seem to withstand oil contamination better.

[Fishhead]

Thnaks for your opinions..

I think I going to listen to them this time and just get the rubber bushes.

[1453aalapapa]

much stouter than the gooey rubber, and much better fitting than the urethane, and also better vibration protection than the urethane, are the teflon bushings that shops called the tii bushings. 12 31 1 268 447/449. #12 and #9 below:

http://www.bmwmobiletradition-online.com/bmw/showparts.do?model=3772&mospid=47156&btnr=12_0722&hg=12&fg=22&hl=12

these are supplied by bosch. i used to sell them by the hundreds back in the day. shops hate the urethane because they dont fit well.

[bob02]

While having a flexable bushing may reduce vibration, why did BMW eliminate them and use a solid mount on the E30 alternator? They both use near identical mounting brackets, and having the E30 alternator in my 2002 for a number of years,i can tell you there are no ill effects.

Further, the newer alternators have internal regulators(that could be sensitve to vibrations?) and solid bushings and seem to last a very long time.

i can't imagine you'd hurt anything by using the ones you made. Plus, you made them, so that part's cool also.

bob

[jgerry2002]

While having a flexable bushing may reduce vibration, why did BMW eliminate them and use a solid mount on the E30 alternator?

Wasn't the solid mount alternators for the M20s/M30s?

[Fishhead]

Here what got me thinking it was feasible.

http://www.ebay.com/itm/270806830643?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

The aluminum bushes in the auction are listed as fitting the m10, m20 and m30.

Heres 2 listings for a m20 alternator that are solid mounted.

http://cgi.ebay.com/ebaymotors/_W0QQcmdZViewItemQQ_trksidZp3984Q2em1423Q2el2649QQitemZ380365103498QQsspagenameZSTRKQ3aMEWAXQ3aIT

http://cgi.ebay.com/ebaymotors/_W0QQcmdZViewItemQQ_trksidZp3984Q2em1423Q2el2649QQitemZ220680139805QQsspagenameZSTRKQ3aMEWAXQ3aIT

Instead of making the spacers out of aluminum,I have some Delrin that they could be made out of instead that would be very simular to the Teflon that is mentioned above.

[aa/fd]

I think you will find Teflon has no memory and is not as good a solution as Delrin or Nylotron.

Oil and gas vapors are hard on certain rubbers natural and synthetic and are most likely the reason for "goo issue".

Viton would work but I am not sure how it handles the work loading. Neoprene is another option.

I find my 85 amp Bosch unit with solid mounting has worked fine for 18,000 miles on my Tii

[layers]

Hi Fishead--

I agree with Mike & others:

for a reason--engine vibration elimination. You can buy urethane bushings that still eliminate vibration but don't turn into black goo in a few years.

Your aluminum bushings, while attractive, will simply transfer engine vibes to the alternator. Go for urethane.

cheers

mike

I have had excellent performance from urethane alternator bushings, even if they seemed stiff pressing them into the bushing holes.

I used a TEP alternator for a while (it works fine and is for sale...). The problem is that TEP's electrical shop rebuilt a higher output VW alternator, machining the mount so it fits directly on the 2002 main mount bolt (solid mount). But the aluminum housing rubs against the steel mount, wearing the aluminum case so it wobbles quite a bit in use. A careful shim could make it work properly again, but I returned to a 320i alternator and bushings to solve the solid mount problem.

Larry

[TobyB]

Wasn't the solid mount alternators for the M20s/M30s?

the vibration modes for a 120 degree straight six are quite different

from those of a 180 degree ('flat plane') four!

heh

t

[Fishhead]

I made a set of solid aluminum mounts for the alternator and they have about 500 miles on them.

So far so good.. My old rubber mounts were shot(falling apart) so anything would be better than the way it was.

I'll see if they last or if they self-distruct from the vibration.