Date: Mon, 26 Nov 2001 23:19:57 -0800
Reply-To: Wayne Hagan <waynehagan@MAC.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Wayne Hagan <waynehagan@MAC.COM>
Subject: Re: knocking sound in tranny
In-Reply-To: <200111270314.fAR3E7A7027313@smtpin13.mac.com>
Content-type: text/plain; charset="ISO-8859-1"
Here is my long winded experience with Knocking sounds in my 91 Syncro
tranny.
Over the past year I noticed a rattling noise coming from the rear when I
was at idle and close to a wall. One of the critical diagnostic things was
that it only did it if I had the clutch disengaged, when I pushed in the
clutch petal it would go away. My local mechanic diagnosed it as a failed
main shaft bearing and said it would require a complete rebuild, around
$3000.00 parts and labor. The main shaft diagnosis seemed to make sense
seeing as clutch petal pressure would take the slop out of the tranny
bearing. I needed this van to move to NYC last summer and didn't have 3k
lying aroud so I searched the internet for advice and found Darel at AA
Transaxel willing to check it out for me (Seattle area). He has been doing
german transaxels for over 20 years and specializes in vans. He even had a
syncro tranny on the bench when I was there. After his inspection he guessed
it might be a reverse idler gear that was rattling and that crusing to NYC
should not be a problem. He found it hard to believe that my main bearing
would be going out with only 75K on the van. He recomended I change the oil
and check for any unusual amount of filings in the oil or on the plug magnet
just to make shure. This I did, and the oil and magnet were almost like new.
Well I made it to NYC fine but after a while I noticed when it warmed up
after a half an hour of driving a definate growl was coming from the tranny
when it was under load (accelerating). I had to return to Seattle in the
fall and I decided to take my chances on the road than dealing with an
unknown mechanic in Manhatten. By the time I left, the the tranny had the
grinding sound of my 1948 International truck. I made it to my fathers place
in Minnesota and dumped the oil for an inspection, I found myself looking at
what looked like golden pearlesent surup, few filings on the magnet though.
I called AA for recomendations at this point. He decided I must have a main
shart bearing problem after all, and that the suspended particles are
aluminum that is being milled off the housing because forth gear is trying
to bore a hole through the case. He thought I could still get home if I kept
my shifting to a minimum and that the worse case scenario was that I would
loose fourth and have to revert to third due to alignment issues.
After a rather nerve racking drive I did make it back and had him rebuild it
(Syncro, $1895.00 3yr warrenty) he was as puzzeled as I was why a van with
only 75K needed a rebuild, in his experience he didn't see syncro trannys
much until after 200K. (Unless you use the crawler gear for bump starting,
the 6:1 ratio will blow the gear out of the case!) Turns out on dissassembly
that one of bearing cartriges on the main shaft (I think) had a pin bearing
missing! It must have fallen out in assembly because it would have trashed
the others if it broke while running. Also he noticed lots of chips and
unusual damage throughout the tranny so he surmised it must have been
bouncing around in there before the first oil change at 45K to synthetic.As
an aside, this tranny had the upgraded 3rd 4th slider, a common breaking
point on van trannies causing shifting problems between 3rd and 4th.
One clunking noise that I worried about initially was a clanking-ring sound
that occured when ever I suddenly took the slop out of the drive train. This
turns out to be a normal sound on syncros, its the central drive shaft
amplifing the slop in the extensive drive train that syncros have. I guess
when on a dynamometer with all for weels at speed and no load, the drive
train alone makes all sorts of sloppy sounds.
If anyone is in need of van or any VW tranny work I would reccomend AA
Transaxel. http://aatransaxle.com/ His prices are competative and he ships
all over the country and more importantly he seems to enjoy his work. I had
my local shop do the R&R and he rebuilt it in 3 days. My van shifts better
now than when I bought it at 25K.
Wayne
> Subject: knocking sound in tranny
>
> <html><div style='background-color:'><DIV>I have a problem that seems to
> come from the tranny. If I put the van in first or second gear and push on the
> gas pedal real quick, a very bad knocking sound comes from the tranny ''
> Tok Tok, Tok''. Feels a bit like a chattering clutch but ten times
> worst. Can it be a cv joint, a loose engine mount, low tranny's
> oil or maybe a bad bearing in the transmission? Does anyone ever had a
> similar problem before? Please help.</DIV>
> <DIV> </DIV>
> <DIV>Mathieu </DIV>
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