RE: Brake Master Cyl Dimensions

["Buchholz, Steven" <Steven.Buchholz@kla-tencor.com>]

> my BDTD is on my 86 5ktq.  There were two MC's that fitted my car (I used
> them both on the same servo) pn 443  611 021 size 23,81X19/17 and pn 447
> 611
> 021 size 25,40X18/18.  The second one, the wider diameter is for the
> wagon.
> I used the smaller diameter one first with no noticeable braking
> characteristics.  Then I found the larger diameter one and decided to
> change
> to it since that was what the book called for for the wagon.  Again, I
> didn't find any braking differences between one and the other.
> 
> 
> 
> >Wondering if anyone has replaced the brake mc (87 5k cstq) and noticed
> the
> >following, regarding the replacement unit.
> >
> 
> >Perhaps newer replacements are smaller that my original 12 year old part?
> >Anyone think I should be concerned?
> 
... here is my impression based on what I see on the fiche and know about my
'88 5kCSQA ...

When one looks at the fiche there are heavy duty suspension and brake
components called out as being for the wagon ... perhaps the most
interesting being vented rear brake rotors.  My Avant has none of these
parts.  What I believe to be the case is that the beffed up rear suspension
was an option on the Avant ... perhaps a towing option, not all cars had
them.  What may be going on here is that you've got a car with the option,
and it may have come with a brake M/C with a larger diameter ... I've never
actually tried to correlate this on the fiche.

One other thing that is true is that there was a change in the diameter of
the bore on the slave cylinder from 36 to 38mm ... but this affected both
the sedans and the Avants, so I don't suspect that they changed the master
bore diameter just for this.  

If you'd like I can pull out the fiche and see what it has to say about the
M/C versions.  I can also check to see if there was a towing package and, if
so, what the option code was so that you can check your build tag to see if
you have it.  Of course it might be easier to look at the rear rotors to see
if they're vented.  

HTH!
Steve Buchholz
San Jose, CA (USA)