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FAQ part 6/10

Section 13.5:	How do i decide on which brake fluid to use (track)?

A:	(by richard welty:welty@domain.elided)

most of the "special" fluids have fairly poor wet boiling points.
Ford Heavy Duty is roughly comparable to AP550; the dry boiling point
is roughly 550 degrees for both of them, and while i've never seen
a wet boiling point number for either of the two, they're both DOT-3
rated so it can't be all that good.

my recommendation:

start with Castrol LMA, readily available, good but not outstanding
dry boiling point (last i checked, about 450 degrees), good wet
boiling point, DOT-4.

if you can boil fresh Castrol LMA, then try ATE SL (this is OE
brake fluid on a lot of european cars; you'll see it at dealers
but will probably have to mail order it otherwise.)  DOT-4, dry boiling
point a touch over 500 degrees, good wet boiling point.

if you can cook ATE SL, then you need to look to AP550 or Ford Heavy
Duty; these are only DOT-3 because of a lower wet boiling point, but
both have dry boiling points of around 550 degrees.  the Ford fluid
was developed because of old men driving lincoln continentals around
town with one foot on the throttle and one foot on the brake, but
it happens to be a good racing fluid.

(Editor's Note: Another alternative recently available is ATE Super Blue.
I is DOT 4 and has a better dry point than ATE SL.)

if you're cooking Ford or AP550, then you need to change your braking
style, or perhaps your brake pads, or how your brakes are cooled.  there
are fluids such as AP600 that have even higher dry boiling points, but
they are supposed to be changed out for each race weekend and have
no DOT rating at all.  their wet boiling points are down in the dumper;
do not ever consider running them on the street.

as far as why one fluid is better than another, it's mostly a boiling
point issue:  if you're changing the fluid a lot, go for the high
dry boiling point.  if you're not changing the fluid a lot, go
for the high wet boiling point (remembering that brake fluid starts
out "dry" and ends up "wet" after enough time has passed.)  changing
the fluid "a lot" means several times a year for us track weenies;
the high heat of the track is tough on brakes and brake fluids.

as for the infamous Silicone fluids (usually confused with DOT-5 because
for a long time the only fluids that could meet the DOT-5 requirements
were Silicone based), they are a good choice for occasionally driven
restorations where the entire brake system has been rebuilt with
new rubber.   using them in a track-driven car is highly questionable,
as is using them in any car whose brake system has glycol-impregnated
rubber in it (that is, most any car on the road.)  there are supposed
to be glycol-based DOT-5 fluids around, but they are certainly not yet
common.  i would expect a glycol-based DOT-5 fluid to be a very
nice dual purpose street/track brake fluid.



==============================
Section 13.6:	Why is there break squealing/vibration?

A:	(by Roy Kao)

The problem of brake squealing seems common on all German cars, where
the use of more metal in the brake pads seems prevalent.  I have a
'93 VW Corrado and an '88 635CSi and we've had the brake rotors ground
a couple of times and the squeal comes back.  The service managers from
both VW and BMW say that the pads are the culprit and this cannot be
helped with newer factory pads.  Just in case you're wondering, my
friend's '91 MB 560SEL also has a brake squeal problem and the answer
has been the same.


<<<<<
Brake Vibration, E28, but applies to ohers
	(by Don Eilenberger:dje@domain.elided)

I think the one thing that becomes obvious from the mail on
E28 front ends is that vibrations (1) are fairly common
(2) may not be caused by one single item.. but may be
the result of marginal conditions of several components.

Here on the list over the past year - I have heard the following
to cure front end vibrations:

1. Thrust bushings
2. Tie-rods, center rod, etc..
3. Misc. bushings
4. Replace rotors
5. Upper strut bearings
6. Wheel balance
7. Tire squirm
8. etc..

My feeling is, that as ALL these components age - they work
together to ALLOW the vibrations. Good tight bushings may help
to damp possible vibrations that would be caused by very
slightly warped rotors.  Absolutely perfect rotors would
not try to induce vibrations that could be amplified by
worn bushings. etc.. etc..

It appears from following the postings for the past year -
that the same symptoms are often cured by different fixes.

As was mentioned, the E28 front end is very simple and
lightweight, and probably is prone to component induced
vibrations - and ALL the components must be in good condition
for it to work like BMW intended.

==============================
Section	13.7:	Eliminating brrake squeal

A: (eah@domain.elided:Eric Houston)

> you a light braker?  did you allow some time for the new pads and rotors to
> seat to each other?  did the squealing start immediately after installation of
> the new hardware?
>
> if the answers are y/y/n then you may want to try the
> run-it-up-to-80-and-stomp-on-the-brake method of removing any contaminants
> from the pad-rotor interface.  i have to do this on my e34 every so often to
> keep the brakes quiet (oem pads&rotors).  usually two or three 80-0 cycles
> will do the trick.  the objective is to generate a lot of braking force and
> heat to "purge" the interface, so go fast and brake hard -- you won't hurt
> anything, just try to do this away from other traffic and the local
> constabulary!
>
> good luck,
> steve roth
> srr2@domain.elided
>


<<<<< (by Jim Conforti:jec@domain.elided)

> let them cool for at least 1/2 mile between these stops
>  to avoid warping your rotors ..

So after three hard stops from 60 to 20 the squeek was almost gone
and the pedal action improved.  Without a doubt it is much better-
knowlege is power!  I rarely brake hard and that's all that they
needed



- - ---------------------------------------------------------------------------
Chapter 14.0: Transmission


- - ---------------------------------------------------------------------------
Chapter 15.0: AC, Heating, Coolants

Section 15.1:	What are the recommended coolants?

A:	(by Jim Conforti: jec@domain.elided)

From: 381-6007 ZK34/4T23 <"evms::plapine"@domain.elided>
        PASS

                Zerex           0.1 mg/cm^2/wk corrosion
                Award           0.2
                Pronto          0.2
                Trust           0.3
                Pah-Nol         0.4
                Texaco          0.4
                Recycled        0.6
                Prestone        0.7


        FAIL:

                Crown            8.4
                Shellzone       10.2
                Peak            11.9    <- this one's sold everywhere...
                Fleetline       12.6
                UniGard         12.8
                Beaver          13.5
                MacGuard        15.0
                Sure            19.7
                500XL           20.0

==============================
Section 15.2:	Heater Control Valve Problems

The control valve in the engine compartment fails open resulting in
continuous heat. The core can be changed out for ~$35.00. You can check the
working of the rheostat by putting a VOM across the leads that feed the
valve. As you go from full cold to full hot on the rheostat, the voltage
should go from steady 12 volts (valve closed) to oscillating every few
seconds when the actual temperature matches the rheostat temperature, to 0
volts in the full heat position (valve open).

If the voltage does not vary as described, the rheostat is at fault. Good
luck tearing into the console!. Odds are that it will function as
described, in which case the valve is at fault. 4 screws and one connector
(plus $35.000) and you should be fixed. The whole valve assembly is $125.00
so be careful that you get the core only.

===============================
Section 15.3:	Poor AC performance

	(by Rick Kjeldsen: kjeldsen@domain.elided)
Poor ac performance at low car speeds is often a symptom of a non-functional
auxilary cooling fan (it is supposed to come on slow when the AC is turned
on, pushing air over the condensor).  See section 12.3 for details.

===============================
Section 15.4:	New AC regulations

A:	(by Charles ?: CHMORRIS@domain.elided)

You can still buy R-12 until this October ('94), without a certification,
as long as you buy 20# or more in one container. Most auto parts stores
sell either a 20# or a 30# cylinder, at about $10 per lb.
  There are many posts on R-12 on the Mopar list, which I can probably
forward to this list if anyone's interested.
  The big problems with trying to use R-134a are: wrong expansion
valve, too small a condenser, different refrigerant oil. This last is
apparently the most serious. R-134a does not use the same type of oil
because it does not dissolve in the (R-12) mineral oil. unfortunately,
the rubber parts in your system (unless newer than about '89) are not
compatible with the new oil. This means changing every gasket, O-ring,
AND COMPRESSOR seal. I have also read that even traces of the old
R-12 will cause the new so-called P.A.G. oils to
break down and ruin your compressor (in a catalytic reaction much like
the alleged effect of R-12 on ozone).
  Bottom line seems to be: DON'T put 134 in a 12 system;
you CAN buy R-12, if willing to spend $200 at once.


	(by Richard Welty: welty@domain.elided)
and as John DeArmond. has pointed out (below, Ed.), there are other R-12
alternatives that may be cheaper and more effective than R-134a; they
were briefly banned during the Bush administration for non-technical reasons,
but in a fit of sanity the Clinton EPA has actually reversed that position.
i'd definitely NOT rush into a R-134a conversion at this time.


	(by jgd@domain.elided (John De Armond))

>  I've got an A/C system for a 2002 sitting in my garage that will probably
>  never get installed.  The reason is that I don't want to deal with the
>  R12 thing in the future.  According to a guy hear at work that knows a
>  great deal about refrigeration systems, the older style systems (up to the
>  mid '70s I think) have an expansion valve setup that won't work with the
>  new R134.

This not true.  R-134a works a bit better if the superheat is adjusted
via the hex screw inside the valve exit port but that isn't absolutely
necessary.  And if you do decide to change the valve, it is only about $20.
BFD.  Of vastly more concern for ANY system converted to 134a is the
incompatability of the PAG oil with even traces of old refrigerant.
Supposedly other types of oils that are compatable with traces of old
refrigerant are under development but the only ones shown to date,
the esters, are so sensitive to moisture that the moisture typically
present in the dryer will cause it to break down.  Plus it is a
lousy lubricant.  As of now, you MUST change everything that is porous
and has been in contact with the old refrigerant.  That includes the hoses,
the dryer, all O-rings and seals and the evaporator if it has any elastomer
seals.  And as a practical matter, a compressor replacement is in order
unless you want to take it completely apart to scrub the components and
replace the gaskets.

Conversion is really a side issue because R-12 is going to be around for
a long time.  The Bush admin EPA was shilling for big industry as
represented by MACS and SAE.  The Clinton EPA is taking a much more
pragmatic approach (strangely enough), particularly after the industry
was caught lying about the ease of conversion and the reliability
of 134a systems.  They have already pushed back the deadline to stop
production of R-12 by a year and the feeling is it will be pushed back
further.  Plus there are alternatives.  R-406a, formerly known as
GHG-12, developed by George Goble (ghg@domain.elided) is an exact
drop-in for R-12.  Banned at industry request under the Bush admin,
it was re-examined under the Clinton administration and given approval
for everything except mobile use.  The exception is strictly a political
move in that the EPA doesn't want to admit all at once how bad it screwed
up so the mobile exclusion will go away within the year.  This blend
has over 4 years' testing in thousands of vehicles and works fine.
It even improves the cooling capacity of systems it is used in.  Meanwhile,
you can buy this blend from People's Welding in Indianapolis (try 800 info
for the number - I don't have it handy) and once you own it, you can
use it as you wish, including in your car.

Another alternative, OZ-12, was banned because MACS stirred up
media hysteria because it is flammable (mix of propane and isobutane).
A rational evaluation of the risks (a pound of this stuff right beside
a hundred lbs of gasoline) was never considered.  Reliable rumor
has it that OZ-12 is about to re-appear with a fire supression additive
that makes it non-flammable.  Like 406a, OZ-12 slightly improves the
performance of the system and is completely compatable with and can
be mixed with R-12.

Finally, if all else fails, you can mix your own refrigerant using
isobutane (NOT butane) camp stove fuel (22%) and propane (78%).
There is simply no way someone with a little ingenuity and motivation
will ever be without AC.  I assume that if you're clever enough to
install the system, you can use one of these alternatives.

Meanwhile the price of R-12 is down ( about $210 for a 30 lb can) and
can be bought by anyone until November so the easiest solution is to
grab a couple of jugs and stash it away.  If your system doesn't leak,
60 lbs will last a lifetime and if production ever does stop, that
money you invested in the stuff will turn out to be a wise one.

===============================
Section 15.5:	Blower Fan Problems

A:	(by Rick Kjeldsen: kjeldsen@domain.elided)

>   ...I found out
>   that neither the fan or the AC work at settings 1 to 3, but do work at
>   setting 4 (max fan speed). Nothing at all happens at 1 to 3.

Common problem.  BMW uses series resistors to reduce voltage to the
fan and produce the slower speeds.  You just lost the resistor board.
The AC doesn't work because it senses the airflow before it turns on.

The resistors are easy to fix, but somewhat hard to get to.  Look on
the top of the firewall from the engine compartement.  There is a
section about 18" long by 6" high right at the top which is removable
with a couple of screws.  You will probably have to take off a few
wires and tubes from the firewall as well.
After you remove that section you will see the top of the HVAC unit
sticking out of the passenger compartement.  Remove the plastic cover
(held on by a couple of straps if I remember right) to see the fan.
The fan motor is a horizontal cylinder with a squirl (sp?) cage fan at
either end.  The resistor board is slid into the HVAC case below the
fan.  It is a small board, about 1-2" square, with 3 bare wire
resistors on it.  You pull it out toward you, nothing to detach first,
it has plugs on the far side.  Either you lost one of the resistors,
or the contacts are dirty.  Check it with an ohm meter.  Installation
is the reverse of removal ;-)

<<<<< (uunet!cmd.com!sam (Sam Chien-shin Lin))

>  2) While I was driving yesterday, with the AC on, and the fan at the third
>  setting, the fan just stopped! When I tried other settings, I found out
>  that neither the fan or the AC work at settings 1 to 3, but do work at
>  setting 4 (max fan speed). Nothing at all happens at 1 to 3. This is too
>  weird. I checked the fuse box, thinking the fuse may have popped, but all
>  fuses were OK. I would think there is one fuse for all the fan speeds, but
>  I figured it was worth a shot. Anyone ever heard of this? I'm sure it's an
>  electrical fault somewhere, but where...?

my '85 325e was doing this lately.  there is a resistor pack mounted
near the blower.  the contacts on mine were corroded, so all i had to
do was pull it out, scrape the contacts, and plug it back in (too bad
i broke a few fins off my fan before i realized that you don't have to
take it out to get to the resistor.)

==============================
Section	15.6:	Cleaning the radiator

A: 	(by Jim Conforti:jec@domain.elided)

> So, finally decided to replace the radiator. Now the  temp gauge stays
> at 1/4 the scale on a 90 degree day at a highway speed. Previously it
> used to easily cross 3/4 mark and I have to run the heater to prevent
> it from going to RED mark.

  So you still have the old one ??

  Take it, dump out stale water/coolant ..

  Go to grocery store and buy 2 or 3 bottles of CLR ..

  (Calcium Lime Rust remover)

  Pour it into the radiator .. let it sit for at least 24 hours

  Pour out, rinse well .. done ..

  This stuff dissolves CaCO3 like magic, also MgCO3, etc ..

  it's the Carbonate minerals that do most of the clogging ...

  Also, a big help is to carefully pressure wash the outside, and
  straighten the "fins" ..

  PS: Professional pressure cleaning IS a waste of time/money

  PPS: This works *most* of the time ...