Re: GTV6 rear smoke from axle

[Thomas Washburn <thomasw@domain.elided>]

BKarbocus@domain.elided wrote:

> Any ideas on smoke from rear of car after a 35 min run after 
> sitting for a while?  Car feels like rear brakes are slightly
> engaged when rolling slowly and has spongy pedal.  Just 
> acquired and looks like new or refurbed rear calipers.  Any
> ideas appreciated.  Bob

It's not unusual for the rear brake pad clearance to take up
after a brake job, resulting in dragging pads and a lot of
smoke.  I suspect that this is your problem.

You may need to bleed the brakes to get rid of the spongyness.
The thing to remember here is that the GTV-6 brake circuits
are left side / right side, not diagonal.

Check the rear brake pad/rotor clearance with a feeler gauge.  
It should be between 0.004" and 0.006" (0.10mm and 0.15mm).  
If the pads are too tight, you will need to adjust them.

The inner pad clearance is set with the hexagonal adjuster
that protrudes from the inner top edge of the caliper, facing
backwards.  The outer pad clearance is set with an allen-head
adjuster on the side of the caliper, facing the wheel.  The
outer adjuster is secured with a hex locknut and is covered 
with a plastic screw-on dust cover.

The trick with the outer adjuster is loosening/tightening the
locknut without turning the inner shaft.  I use a socket with
a bolt welded to the side (looks like a corncob pipe).  Using
the bolt as a lever, I can stick the socket into the adjuster 
recess and manipulate the locknut without obscuring the square-
drive opening at the end of the socket.  I poke an allen wrench 
through the square-drive opening to turn the adjuster itself.  
With the locknut slackened, the adjuster shaft should turn
freely. You could probably rig up a similar tool with a socket
and vise grips.  

There are little C-clips that prevent the locknut from turning
all the way off the end of the adjuster shaft.  If the locknut
won't loosen any more, you've run into the clip.

Do all this with the parking brake off and no tension in the
cable.  Afterwards, adjust the cable. Be sure to pump the brake
pedal repeatedly before first setting off.

The whole procedure takes a certain knack.  A good shop manual
should help you locate all the bits and pieces.  A competent
Alfa mechanic should be able to do the job in a 1/4 hour.
Of course, you've probably glazed the pads and maybe even
warped the rotors, but cross that bridge when you come to it!

- - Tom
thomasw@domain.elided

------------------------------