Date: Mon, 16 Oct 2006 09:50:06 -0700
Reply-To: Larry Chase <roadguy@ROADHAUS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Larry Chase <roadguy@ROADHAUS.COM>
Subject: Busted alternator brackets - the mystery
Content-Type: text/plain; charset="us-ascii"
Volks,
TC ... In my case it's the alternator bracket that is breaking not the
alternator adjusting arm.
See Photo
http://www.roadhaus.com/images/alt_bracket/alt18.JPG
BTW .. A few other details.
- 8 broken brackets in 3 years (~50k miles)
- 1 broken alternator bracket stud
- 2 alternators
- 2 water pumps
- One engine / AVP rebuild installed just before the first broken bracket
problem
- alternator belts 6-8
I have always felt there must be some weird vibration causing the problem.
I've probably tried all the more common solutions ...
- Belt not too tight
- Belt not too loose
- Changed alternator
- Tried one of Frank C's alternator brackets with extra welds to strengthen
- Tighten lower alt bolt .. Was slightly loose to allow belt adjustment
Dennis and BennyBoy brought up some things I hadn't considered before.
- slightly offset/oscillating crankshaft pulley
- check the mounting surface on the case .. Is it flat
- use grade 12.9 hex bolts, hardened washers, loctite & a torque wrench at
32 ft/lbs.
Thinking back it's possible that one or more of the lower alternator bracket
bolts was slightly loose at the time of breakage.
good road,
good adventure,
good life,
larry chase
www.roadhaus.com
soon to be roadhaus.org
- - -
Date: Sun, 15 Oct 2006 10:28:45 -0700
From: TC <trclark@SHAW.CA>
Subject: Re: 85GL 1.9 Busted alternator mounting bracket stud ..2nd time in
2
years
Larry
It looks to me like you are braking the alternator adjusting bracket ? for
me it is the stud/bolt that go into the block hairs from the water jackets
:( on the lower bracket under that alt : realy not feeling good about right
angle drilling that stud out again ...
>Alternator Brace Photo
>http://www.roadhaus.com/images/alt_bracket/alt03.JPG
And the brace pic is bracing the adjusting bracket ...
so I guess it looks like i am gonna see if a local machine shop can come up
with some type of a brace maybe both top & bottom
- - -
Date: Sun, 15 Oct 2006 12:13:42 -0700
From: Jake de Villiers <crescentbeachguitar@GMAIL.COM>
Subject: Re: 85GL 1.9 Busted alternator mounting bracket stud ..2nd time in
2
years
Those are a little wacky guys.
I was wondering Larry if you had tried welding a short piece of 3/4" or 1"
steel strap at 90 degrees to the top side of the adjustment arm to stiffen
it. Of course it might then transfer the load to the other bracket and cause
a failure like TC's!
Just thinking.....
- - -
Date: Sun, 15 Oct 2006 17:22:52 -0400
From: Dennis Haynes <dhaynes@OPTONLINE.NET>
Subject: Alternator brackets! Why they break.
The Water Boxer Alternator Bracket is one of those parts that can cause a
lot of grief. The problem with replacement is that the cause is often not
determined and corrected. To make matters worse, failure usually breaks the
studs and the moving bracket destroys the mating surface on the case so a
proper fix is difficult.
Failure can be the result of mechanical fatigue or corrosion of either the
bracket or the mounting studs. Improper belt tension, (too loose) or a bad
rear bearing can create shock waves or vibrations that put the mounting to
the test. After rear bearing fails, the rotor can hit the stator windings
taking chunks out of both. Rebuilds often use these damaged components.
Many folks leave the bottom alternator bolt just loose enough to allow belt
adjustment. This is a no-no. Any vibration will cause some movement at this
joint and now you get a little velocity. The alternator now becomes a high
speed hammer. Keep in mind that little alternator is spinning at some 2.5
times the engine speed. Yes, that 4,500 rpm hill climb is spinning that
thing at almost 10,000 rpm and that belt you left loose trying save the
bearings is flapping all over putting all types of cyclic harmonic loads on
the mountings.
So the bracket finally gives out and we have the broken studs. We some
drill, prey, curse whatever and get them out. We restore the threads and get
new studs, nuts, and a bracket. Is the mounting surface on the case flat? It
needs to be. Get a big file before installing the studs. Where did you get
the studs? Most studs are property class 5, (grade 5.8)or lower. These are
OK for crushing that exhaust gasket, maybe. Not to be used here. You need to
Property Class 10, (grade 10.9) or better. The nuts and washers have to
match. These can be hard to come by. A set screw can be used as a stud. I
myself like to use grade 12.9 hex bolts, hardened washers, loctite and a
torque wrench. Think CV joints at 32 ft/lbs.
That bottom alternator bolt also needs to be tight. Both sides of the
alternator should be true and the hole should not be worn into an oval. If
you can adjust the belt, the bolt is too loose.
Looking at Larry's picture, I see thread impact marks and corrosion in the
mounting bolt holes. It came loose before it failed. I also see some wear
marks where the alternator sits. It was probably moving there also. There
may be a problem with the alternator but it looks like the fasteners failed
first (lost preload and loosened) and the hammering caused the final
failure. Additional supports or braces probably will not help this. Get rid
of excess vibrations and improve the fasteners and all will be good.
Dennis
- - -
ate: Sun, 15 Oct 2006 21:40:55 -0400
From: +++++++++++ <vw4x4@VERIZON.NET>
Subject: Re: 85GL 1.9 Busted alternator mounting bracket stud ..2nd time in
2
years
REplace the Alternator.... Its way out of balance.
- - -
rom: Benny boy [mailto:huotb@VIDEOTRON.CA]
Sent: Monday, October 16, 2006 6:56 AM
To: VANAGON@GERRY.VANAGON.COM; Larry Chase
Subject: Re: 85GL 1.9 Busted alternator mounting bracket stud ..2nd time in
2 years
Ho men!!! can you believe that you went from that engine condition:
http://www.benplace.com/roadhaus/100_0213.jpg
To totday's condition... dirty dirty dirty boy...
he he he
To all: Remember one thing, ALT oscillation is normal to a point, i found a
few reasons for those ALT bracket break! -old alternators (unbalance) -Wrong
lower ALT bolt holding the ALT (miss-align) -ALT fan unbalance (you may have
a rebuilt ALT but they use the same fan) -weak bracket(S) (normal wear)
-poor design -Old water pump -too tight or too loose V-Belt -slighly
offset/oscillating crankshaft pulley (pulley has been hit with a hammer and
the pulley groove is not perfect anymore) -Bad V-belt
Current draw! mmm.... i guess it's possible
Another thing, worse than the ALT bracket breaking.. that oscillation can
wear out the water pump quite fast!!! lately, i brand new pump went wrong
(leaking) after 1500miles, i tought it was a defective one... nop! that ALT
was the reason.
Larry idea is nice...
Ben
http://www.benplace.com/