[W126 Coupe] Re: BRAKE DRAG

[Dick Spellman]

Hi Dan:

Not sure if you are describing the minor movement of the pads in their 
caliper holders when you put the car in reverse for a period of time 
like backing out the driveway but, this would be considered normal.  
I've had that same brief thunk from the brakes on many of the 126 B's.  
As for the brake drag there is a test you could easily perform.  Start 
with just the passenger front wheel and when the car is cold give it a 
spin by hand to get a feel for how much drag you have on this one 
wheel.  It should spin freely and stop after several revolutions.  Now 
take the car for a spin for 30 minutes or so of normal driving and 
repeat the above test.  Is the wheel harder to turn?  Does it spin the 
same number of rev's before coming to a stop?  If the wheel is in fact 
harder to turn after being heated up, I would suspect that the brake 
lines are in fact swelling inside creating added pressure on the caliper 
pistons.  Each caliper should also be checked for wearing the inner and 
outer pads/rotors evenly.  If this is not the case then you may need a 
rebuilt caliper or two.  Do you replenish the brake fluid every year or 
so to get the sludge and moisture out of the system?  Last question, 
have the front wheel bearings ever been checked for run out when 
servicing the brake rotors?  Have these wheel bearings been replaced 
recently by a shop?  This would be another point where if not properly 
adjusted you could see an increase in drag.

By the way, I have on different 126's replaced a frozen caliper, wheel 
bearings , the caliper rubber brake lines and so on where I have 
experienced all of these failures and done the diagnosis to repair only 
what was needed.  I think you can do the detective work and quickly 
isolate the problem you describe.

Last comment you are one lucky guy to have a euro 560.  Are you in the U.S?

Dick

Dan Gardner wrote:

> Ever since I have owned my SEC it has had a "thump" on the brake pedal 
> the first time they are used ,like leaving the garage and going down 
> the drive,it does not happen at any other time.
> Also there is a high amount of drag as the car will not roll on a 
> slight incline,whereas my 450SL will freely roll away down the same 
> stretch of road.
>
> After a trip of 30 mins all four wheels are warm to touch about the 
> same amount,is this a symptom of the ABS.
>
>    Any thoughts most welcome           Kind Regards  Dan Gardner   
> 560SEC EURO  1986  (220kw)
>
>