Conference napalm::musclecars

    I have a vibration in my drivetrain. I have replaced just about
    everything. I have come to the conclusion that it has to be my
    driveshaft. I would like to have it checked for balance.
    
    I was told by a guy at a local speed shop that there is a place
    called W.D. Smith that does this type of work. He thought it was
    in Shrewsbury??
    
    Does anybody have and experience with this place or others?
    
    If you do could you please list the phone #'s and address'
    
    
     Thanks,
    
     Mark

W.D.Smith, on Route 20 in Shrewsbury, checked/balanced my driveshaft.  I called
the following day after dropping it off, and was able to speak to the mechanic
doing the balancing.  He said it was straight, tight, and balanced; and I 
should come down and pick it up.  I too was searching for some driveline
vibration.  

Anyhow, they didn't charge me!  The first pleasant experience I've ever had
with service work.  Give them a try.

Eric

    Thanks Eric, 
    
    I'll give them a try and let you know how I make out.
    
    p.s. did you ever find out what your vibration was?
    
    mh

     I have always had good luck with W.D Smith from u-joints to
    shortening drive shafts.
    
    Rich

The vibration turned out to be a worn out pinion bearing.  In particular, it was
the smaller front bearing that went south.  I beleive that wear caused a loss
of preload that allowed the driveshaft to vibrate in a runout-like condition.

Eric

But why?  I can understand that things break, and the driveshaft has a pretty
rough job, but why is the front of the driveshaft more likely to break then
the rear or middle.

A typical driveshaft loop is mounted around the front 1/4 of the driveshaft.  
Its purpose is to keep the driveshaft from either going through the floorpan, 
or dropping down.  Dropping down could pole-vault the rear of the car, and 
going through the floorpan would likely upset the driver.

However, the driveshaft loop wouldn't help if the breakage happened anywhere
but the front 1/4 of the driveshaft.  Is this *the* place a driveshaft breaks.

Anybody?

Eric

If it breaks further back there may not be the leverage to pole vault the car.
If it breaks in back, it's no big deal because it either drags on the ground
or falls out.

FYI, I just this week installed on on the Vega (neat place to hang the exhaust 
pipes when the headers are uncapped).  I used the Lakewood hoop kit and it took 
about an hour to install, includiong removing the seats to gain access to the 
floorpan.

Mark

I'm planning on doing that exact thing tonight.  Pulling the seats for access
and installing a Lakewood hoop designed to fit a late model Mustang.

Oh course, now I'll have to pull something else to offset the added weight. :-)
Sad but true. :-)

Eric

Eric, the Lakewood kit really does fit and bolts right in.  The only thing that
I had to do was buy longer bolts to attach it to the floorpan.

Hopefully the tomorrow the tech inspectors see the nice shiny hoop and don't 
nocice that my battery is not located in an NHRA approved location.  :-)

Mark_who_is_hoping_for_100mph_and_a_13_sec_ET_tomorrow

    Eric, the most likely failure point in the driveshaft is at the
    U-joints. Imagine the front one letting go at 100+ mph! Not only is
    there the danger of it pole vaulting the car, but it can also keep
    spinning until the car is stopped since it's now being driven by the
    rear wheels. Even if it doesn't dig in, this thrashing can take out the
    exhaust system, fuel lines, brake lines, and the emergency brake
    cables. It's a very ugly sight!
    
    Try driving an overpowered, lifted 4WD for a while and you'll learn
    more about U-joints and driveshafts than you ever wanted to know! In
    one particularly nasty Blazer that I owned, I replaced 13 U-joints in 1
    year! :-( That coupled with the annual ring gear shredding (ever do
    burnouts with 35x12 inch mud tires?) :-) were the primary motivating
    factors behind the drivetrain upgrades that now have a home under the
    ThunderTruck(tm).
    
    Harry
    

    
     Harry is right on the money. U-joints break very easily compared to
    the actual shaft. As some one who has broken both front and rear
    u-joints at RPMs over 6000, I can tell you that you can never to be too
    thankfull for the safety loops.
    
     When the rear joint failed, all that happened was the shaft sliding
    out of the trans and sliding across the track while getting bent into a
    banana shape. When the front joint broke, it snapped the trans yoke in
    half, blew a hole the size of my palm in the trans, broke two more
    mounting ears off the tranny, broke the bell housing in three places
    and put a serious tweek in the shaft itself. All of this inside of 4-5
    seconds between when I felt the first vibration and when I finally
    stopped the car. Even the loop itself was bent off center from the
    force of it all.
    
     So what's my point? Just make sure that your mounting is VERY secure
    if you ever intend on racing. Skimping on hardware here can give you
    more than just a busted u-joint if your loop is pulled out of the floor
    boards and thrown around underneath your car.
    
    Tony
    

    Thanks guys for the input.  The prospect of the driveshaft dropping has
    always bothered me; but I'm easily bothered and I wouldn't mind taking
    my practical experience secondhand in this case.  Lately, I'm using
    slicks and shifting up around 6400 rpms.  This is new stuff for me - I
    haven't yet been able to throw a decent shift in the dozen or so runs
    I've made.  I beleive the reason for the tentative shifting is fear.
    To put it in terms of Elapsed times, peace of mind could quite possibly
    be all I need to get my 12.99 timeslip :-).  
    
    Eric