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Crossmember Bars POLL



That whole post was very tongue in cheek. I don't normally test starters 
like that. At that point I was fairly sure it was bad. I had been under the 
car with a meter and verified that it was indeed getting more than 8 volts 
as the Bentley states. I was getting close to 13 from the battery and about 
10.5 from the starting circuit. It's a cheap ass meter accuracy isn't it's 
strong point. A simple light tells me voltage more accurately. Despite this, 
I have a fairly high confidence that it was getting more than 8v. Also I did 
the screwdriver/palm of the hand/ear trick on the housing and with my crude 
"stethescope" I could hear the bendix engaging. Since I believe in double 
checking everything, I pulled it out and did what I did. Last time I did 
this I had someone put a foot on it. I think deep down I just wanted to see 
the damn thing dance. 
 However that's a really good idea about the old tranny. I don't have any 
laying about, but I may go and get a dead one for this purpose. There's a 
place called Bap Geon in this area (think they go all the way up to New 
York) and they can get stuff for me ALOT cheaper, and 9 times out of 10 I 
don't have to wait (and even if i do I don't have to pay shipping) Even if I 
have to go to a junkyard... I am not going to pay $117. Hell if my knee 
wasn't jacked up I would push start that bastard--that's how cheap I am. LOL
Chris

 On 6/19/05, Peter <peter@thescirocco.com> wrote: 
> 
> $117 does seem kinda high...
> 
> You really shouldn't bench test VW starters like that, they need the trans
> to support the end of the spindle, so the windings don't get damaged.
> 
> I usually hold them, or bolt them, to a spare trans to test them. I 
> recently
> cut up an auto trans and made up a test jig, but a spare trans works just 
> as
> well.
> 
> 
> Peter
> http://thescirocco.com/
> 
> Please! Include the previous text in your reply...
> 
> -----Original Message-----
> From: scirocco-l-bounces+peter=thescirocco.com@scirocco.org
> [mailto:scirocco-l-bounces+peter=thescirocco.com@scirocco.org] On Behalf 
> Of
> Chris Bennett
> Sent: Saturday, June 18, 2005 8:50 PM
> To: Nate Lowe
> Cc: scirocco-l@scirocco.org
> Subject: Re: Crossmember Bars POLL
> 
> I got under the 85 with the 16v conversion today. The starter apparently 
> has
> died. (good charge on the battery, click click with the ignition) I 
> thought
> about trying to push start it but I have had two knee surgeries in the 
> last
> year and I don't push like I used to... I removed the starter and 
> performed
> the INFAMOUS "mexican jumping starter dance" (that would be a set of 
> jumper
> cables on the starter and a jumper...er I mean wire to test to see if the
> bendix works or not. I forgot to put my foot on it and scared the shit out
> of myself.) The bendix extends and it spins very weakly sometimes not at
> all. Jumper wire gets REALLY damn hot really damn quick. So I decided to 
> end
> amatuer hour and take it to a FLAPS. I walk in and dude asked me if that 
> was
> the turbo from my scirocco. I realized at that point that I was in deep
> shit. After discovering what it was he goes to the test bench and punches 
> in
> the the code and tells me that he can't test it. So I was like COME ON
> MAN!!! There's only four wires... So he hooks up the +12v and the two
> smaller wires, (ignition and something else--don't remember off the top of
> my head.) and tells the thing to go... As politely as possible I remind
> supergenius that it needs a ground. You know how dem dere "turbo's" act 
> when
> thays ain't properly grounded.
> So once grounded he hits the button and the bendix extends once again and
> then the machine tells us that it is a bad starter. So I still don't have 
> a
> warm fuzzy since this guy told me he couldn't test it and he didn't know
> what the hell it was, so I asked him to go and get a new one off the shelf
> and prove that the machine is doing what it's supposed to. Well he wasn't
> "allowed" to do that until I pay for it. So I was like fine, what's the
> damage?
> $117 plus a $60 core. I think I stared at him in disbelief for a good 12
> seconds. I am thinking: WHY THE FUCK WOULD YOU CHARGE ME A CORE WHEN I 
> HAVE
> THE DAMNED THING SITTING IN FRONT OF YOU?!? and then WHY THE FUCK WOULD I
> PAY THAT MUCH FOR A STARTER?!? I resisted the urge to shove the starter up
> his ass, thanked him with all the nice I could muster, and left. I don't
> have that kind of money anyway.
> Anyhow, here's the bottom line of this story. While I was under the car I
> took a real hard look at the cross member and I do not see any cracks.
> There's a lot of sludge and crap and I wiped it off the best I could but I
> still didn't see anything. I was looking from the bottom where the two 
> bolt
> for the fwd mount plate are, and didn't see anything. So for the time 
> being
> I am safe or is there somewhere else I should look?
> Chris
> 
> On 6/18/05, Nate Lowe <nlowe79@gmail.com> wrote:
> >
> > On 6/18/05, Allyn <amalventano1@tds.net> wrote:
> > > i knew that one was coming. the way this bar works is similar to
> > > that
> > bar
> > > you see the big-ass weight lifters using on tv. the guy lifts the
> > > bar
> > near
> > > the center, with massive weight at either end. these bars get used
> > > for
> > years
> > > and years. it may weaken and bend easier over time (yield strength /
> > > ultimate strength lowers as it is fatigued), but you never see one
> > > just snap. the failure mode in this case is to become more bendable,
> > > not to brittle fracture.
> >
> > Interesting analogy, but I don't think it's completely applicable. I
> > don't know anything about those bars used in weightlifting, but I do
> > konw what you're talking about. The thing is, those bars can't last
> > forever, they will break if they are used too much. The same goes for
> > the crossmember bar (well, maybe not, if you crunch the numbers it
> > very well come out that the bar is never pushed passed the fatigue
> > limit). I will also add another quote from my textbook: "Fatigure
> > failure is brittlelike in nature even in normally ductile metals, in
> > that there is very little, if any, gross plastic deformation
> > associated with failure. The process occurs by the initiation and
> > propegation of cracks, and ordinarily the fracture surface is
> > perpendicular to the direction of an applied tensile stress." That
> > sounds like the cracks people are seeing in their crossmembers. I have
> > to admit that I have never seen one in person, but I have seen
> > pictures and those pictures seem to fit what I'm thinking..
> >
> > > > Do you think the crossmember is breaking due to being pushed past
> > > > it's yeild strength?
> > >
> > > yes, this is the exact reason. the metal in the cross member is
> > > somewhat hardened steel. my guess is that it is hardened enough such
> > > that the RTT
> > is
> > > near ambient temperatures. if you've ever seen the cracks we speak
> > > of,
> > they
> > > are jagged and sharp at the edges. basically brittle fracture.
> > > brittle fracture is 'sudden, catastrophic failure of a metal under
> > > tensile
> > stress
> > > with little to no plastic deformation (bending)'. it requires a
> > pre-existing
> > > flaw (small crack, nick in the metal, etc). when a crack propogates
> > > in
> > this
> > > mode, the only way to stop it from propogating is to stop drill it.
> > > its basically the same as a crack in glass. the stresses are
> > > amplified
> > greatly
> > > at the leading edge of the crack, so it spreads that much easier.
> >
> > You are right in that once a crack is formed it will spread much,
> > much, much easier (I can't emphsize enough how easy it is for a crack
> > to spread once it's there). Again, the problem with your reasoning
> > here is that you aren't considering fatigue, you are only considering
> > brittle fracture alone. Lastly, I don't know what you mean by RTT,
> > I've never seen that abbreviation before and I'd like to know what it
> > means. I don't think it will change my opnion on this though.
> > I also left my responce in here (noted by the double arrows (whatever
> > they're called) because I think it's necessary to understand the
> > conversation if you havn't been reading every post. Allyn's words are
> > noted by the single arrow.
> >
> > > > I don't, because if that was the case drilling holes would do no
> > > > good and the entire crossmember would break in half before you
> > > > even noticed the cracks. The crossmember is cracking due to
> > > > fatigue.
> > >
> > > easy stop to that argument is the fact that only the _newer_ (~>85)
> > cross
> > > members are the ones that are cracking. wouldnt you think that a
> > > similar designed piece in a 30 year old scirocco would have more
> > > fatigue than
> > that
> > > of a 15 year old one? mileage and horsepower dont seem to have much
> > > of
> > an
> > > impact on it either. from my words above - i think vw hardened this
> > steel a
> > > bit more or used a different mix that had a lower fracture toughness
> > > /
> > RTT.
> > > i also believe that the cracks don't occur unles some major shock
> > > type stresses are applied to the member (i.e. accident, bad side
> > > mounts,
> > etc).
> >
> > I think that there are a couple different things that contribute to
> > this point. First, I'd agree that there was most likely a change in
> > the material used for the crossmember sometime during the mid 80's.
> > You must also consider that a 30 year old scirocco didn't have the
> > horsepower of a 16v out of the box. I thought, from what I've read,
> > that most people with this problem had 16v versions (not swapped, but
> > real 16v's). I may be wrong on this, that's just the impression I got.
> > It would be intersting to see who had cracks, when they started, and
> > what had been done to the motor over the car's life. I'm still
> > inclined to believe the cracks are from fatigue though.
> >
> > > > Good, now I know how thick the plate is. It didn't look that thick
> > > > in the pictures. But if you look at the geometry of that plate,
> > > > the
> > >
> > > whoa there, dont quote me on it :) its either 1/4 or 3/16. im going
> > > on eyeball gauge only.
> >
> > Oh, I thought you had the exact measurement. I won't quote you on it
> > then ;). I'd lean toward the 3/16 if not 1/8, but that's just eyeball
> > from me too, and from pictures only at that. This is nothing to argue
> > about since the designer is on the list and can just tell us what it
> > is.
> >
> > > gotta run, party at my place :)
> > > p.s. no flamage here, just opinions, backed by some navy training.
> > > Al
> >
> > Have fun with your party. No flamage from me either. I openly admit
> > what I'm saying is opinion and can be proven wrong. I don't mind at
> > all if someone points out where my reasoning is flawed, it certainly
> > won't be the first time :) But what I would like to say is that my
> > main focus here is that the bar hasn't gone through any rigorous
> > testing so nobody can say for sure how much it helps (and testing can
> > be as simple as doing a few calculations to see what it will
> > withstand. Granted some assumptions will need to be made, but that's
> > engineering). That said, I'd suspect that any car without any existing
> > cracks would probably be fine with this bar, it's the cars who already
> > have cracks that I really question. That is because of the major loss
> > of toughness (engineering meaning of thoughness: resistance to
> > fracture) for those unfortunate cars that already have cracks.
> > Nate
> >
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> >
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