[R129 SL] Less brake dust/what kind of pads, etc.

[Derek Lee]

Here is a reply from another list I'm on that deals with the brake pad issue
(believe me, this guy is qualified to talk about it).  BTW, for reference,
"100" or "100 Series" refers to 100 Series Toyota Land Cruiser and Lexus
LX470 (current model), "80" or "80 Series" refers to previous model LC and
LX450 (1991-1997):


There has been much discussion of brake mods like vented brakes, metal pads,
100 pads and the like on this list and I've always been uneasy about it.  I
have an extensive background in vehicle design and have made a few comments
over the years on these threads of a cautionary nature.

Your situation is a perfect example of why brakes should not be altered
casually simply because the parts are available.  A vehicle's brake system
is one of the most rigorously researched, designed and assembled aspects of
its creation.  For some reason, the 80's brakes have gotten a bad name here
on the list and it has become part of LandCruiser lore.  Personally, I feel
the stock brakes are magnificent and highly effective and this lore is the
result of poor maintenance or other mods.  Mine stop the unladen vehicle
powerfully and with authority, and when I'm towing my boat there is no
question these large 4 wheel discs are up to the task - even during the
worst scenario I can imagine which happened last summer.  While towing on a
heavily crowned road a deer ran all the way across a field just to jump in
front of me.  I saw him coming for over 10 seconds and stayed on the gas
thinking there was no way he would catch us while my wife and I watched. He
suddenly picked up speed and practically threw himself in front of me -
literally running an eighth of a mile nearly parallel to the road to do so.
I hammered the brakes from 65 to 30 and everything not nailed down ended up
on the floor or against the seatbacks.  No drama.

In short, I feel an 80 series with stock pads, properly bled brakes,
antisieze on the pad locating pins, a properly adjusted LSPV valve and stock
tires is a vehicle that can stop with authority.

Putting larger surface area pads (100s) up front reduces the PSI you are
applying to the rotors.  Total force is the same, but PSI is critical in
converting forward vehicle motion into heat (that after all, is all that
brakes do).  The critical interface of pad and rotor was carefully taken
into consideration when Toyota designed the pads size, shape and material
composition.  Using a modified pad off another vehicle similar only by the
badge on its fender is ill advised.  Ditto purchasing aftermarket pads with
an unknown composition that was certainly not tailored to the LandCruiser
but simply spit out of a factory for every US vehicle.  Ditto putting
slotted or drilled rotors on it.

The conversion of forward motion into heat is a simple task, but the
efficiency of that task can be dramatically changed with relatively small
modifications.  I know I will catch some flak for this post as there are a
lot of people who've modified their 80 brakes.  And it is difficult to admit
that you've done something that may have decreased your vehicle's
performance under certain conditions, or ignore a challenge like mine to the
veracity of your modification.  Putting metal matrix racing pads that don't
stop well until they're warmed up on a street vehicle borders on insanity to
me, for instance!  Panic stops are called that for a reason - completely
unexpected.

Additionally, "My truck stops so much better now" and objective measured
reality may not coincide.  You might have said the same thing if you'd put
fresh stock pads on to replace the braking deficiency of the worn out pads
that caused you to make the change in the first place. And was this opinion
based on an untrained sample of one person's behind, or painstaking track
testing with high speed photography under the track surface, radio
transmitting temperature senders embedded in the rotors, and $100,000 worth
of computers and sensing equipment on board?  I've personally spent track
time on brake projects where different pad compositions being considered by
the manufacturer were tested and can tell you the odds of tossing a set of
randomly designed pads on a vehicle and improving its braking are
astronomically against you. You may achieve better hot braking for the first
20mph of deceleration, but the last 30mph will be 25% longer.  Or the
opposite.  Or they may be inordinately grabby when cold, but fade briefly
before coming back to full strength.  There are all kinds of brake
performance nuances that happen which drivers are completely unaware of.
Aftermarket pads may be intentionally "grabby" when first applied to give
the proud owner the "feeling" he's improved something.  In instrumented
testing, these brakes may fade midstop and produce a 7% longer stopping
distance.

My point here is that it is flawed thinking to assume that we can do a
better job with the brakes than Toyota did.  Absolutely flawed.

As to your case specifically JJG, I'll assume all is well with your braking
system.  If that's the case, then you've got pads on your truck that are not
generating the proper amount of friction, not transferring the heat thus
generated at the proper rate, the wrong size for the caliper piston's
designed pressure, contact the rotor before the nonlinear pressure in the
brake system reaches the peak pressure (too thick), or a combination of
these and a dozen other issues I won't go into.  Or, you could simply have
oil on the rotors - hit em with a can of brake cleaner.

This turned into a bit of a rant, but this topic has been a pet peeve of
mine for years and I guess I finally snapped today <grin>.  Seriously, brake
mods should not be conducted as casually as experimenting with a different
oil filter brand.  The brakes on your 80 are a complete system and minor
changes to any part can dramatically degrade its performance as a whole.
I'd be willing to bet a case of #6 that the best stopping 80 is one whose
system is in good working order with a set of stock pads on it.

DougM

>
> I changed the rear brakes yesterday and further adjusted my proportioning
> valve.  I went with 80 series Metal Masters in the rear.  About a month
ago
> I went with Toyota 100 series pads in the front.
>
> Anyway, I wanted to test the lockup of the brakes so I disabled the ABS
with
> a very quick on/off of my center diff lock switch.  I did not have any
> gravel roads available and I really wanted to test on dry good pavement,
so
> I went to my nearest parking lot.  My 80 would not lock up it's brakes for
> anything! I tried about 6 times, slamming on the brakes with plenty of
force
> from about 30 mph.  The brakes would not lock!  Every time the rig just
came
> to stop with no drama and no pulsing of the ABS.
>
> This means that
> A) I have something else wrong with my braking system or
> B) the 80's series brakes are really not good enough for the weight of the
> rig and the traction provided by the stock 275/70 Michelin LTX's.
>
> I feel any braking system should have enough clamping force to lock up the
> brakes on dry pavement when no ABS is not used.  If the braking system
> cannot do this then there is room for improvement.  When the braking
system
> can lock up the tires you are now limited by traction.
>
> Can some experts (or not) comment on this.  Is the 80 series brakes truly
> not up to the task?  Can anyone lock up their brakes on dry pavement, with
> good traction and abs disabled?
>
> TIA,
> John
> 97 fzj80

_____________________________________________
Derek Lee
`90 R129 500SL (fairly stock)
`94 FZJ80 Land Cruiser (extremely modified)
`97 FZJ80 Land Cruiser Collectors Ed. (stock)
Elk Grove, CA, USA


> -----Original Message-----
> From: r129list-admin@mbcoupes.com [mailto:r129list-admin@mbcoupes.com]On
> Behalf Of Tom Reynolds
> Sent: Saturday, August 02, 2003 10:44 AM
> To: r129list@mbcoupes.com
> Subject: [R129 SL] Less brake dust/what kind of pads, etc.
>
>
> Two more, one long, one short and succinct from a master Mercedes
> mechanic.
>  This should about be the end of the thread from me, by the way, as I was
> just wondering what kind of pads I should use next time they need
> replacing, and I think I have some pretty good ideas now.
>
> Regards,
> Tom Reynolds
> Hereford, AZ
>
> >Date: Sat, 2 Aug 2003 11:41:55 EDT
> >From: SGR100@aol.com
> >Subject: [MB] Re:Brake pads - Metal Master experience
> >
> >Gary,
> >
> >Your post to the list Re: Metal Masters is almost identical to
> the post I
> >made several years ago when I first got our 400E and tossed the
> high dusting
> >Textar pads for the Metal Master's I'd used on my Porsches and
> Volkswagens
> for years. The resident list expert and co-list owner Stu Ritter,
> offered his
> >contrary opinion based on years of servicing customer's Mercedes and
> flatly slammed MM pads as too hard, taking too long to warm up with poor
> braking performance and a host of other complaints. I didn't buy this
> because of my previous experience with these pads, so I installed and ran
> these long wearing pads for almost 4 years on our 1992 400E and continued
> to run them on my 944T street car while I graduated to Pagid orange
> competition pads on my Porsche racecar (absolutely NO comparison to any
> street pad both in braking performance and noise).
> >
> >Fast forward to April of 2003. We come by this awesome deal on a loaded
> 2002 Camry for my wife and decide to off her 400E for something newer for
> me to drive. Without comparing this car to a Mercedes (how can you?), I
> have to say that the brakes on the Camry are very good, contrary to past
> models of this car. Great pedal feel, excellent fade resistance with very
> large pads and over 12" in diameter rotors on the front. At full song
> (125MPH) the car stops almost as well as my Porsches!
> >
> >My wife and I swap cars for a day and she gets back into the
> 400E (used to
> be
> >her daily driver) and promptly calls me to report that the brakes
> are...well...she used stronger words, but they "...don't stop well". In
> fact she says they barely stop the car! Meanwhile I'm in the Camry
> wondering why this car stops so much better than the 'Benz.
> >
> >I quickly realize that the high pedal pressure and poor low to medium
> >temperature performance of the Metal Master's have her convinced that the
> brakes are bad! I agree with her after we trade cars back and I promptly
> replace the pads with Textar OEM style pads and quickly realize how poorly
> the MM pads work in normal everyday situations, like panic stops and
> aggressive commuter driving. I think because we had MM's on both our cars
> in the beginning, we were used to the high effort, long stopping distances
> that are normal with the Metal Masters. The exact poor performance Stu
> (Ritter) commented on when I posted my postitive comments on MM pads a few
> years back.
> >
> >So, I'd STRONGLY urge folks to NOT run the Metal Master pads on anything
> that requires good braking performance at all temperatures with
> normal pedal
> >pressures. The additional dust is worth the improved performance of the
> OEM Textar or Jurid pads. I won't run Metal Master's on anything now.
> >
> >My experienced .002
> >
> >Steve Russ
> >
>
> and the last comment;
>
> >Steve, you had the unique experience of being able to compare pad A and
> pad B.  Most owners never get to do that. They have their brake pads and
> that's it. There is little human memory for retardation rates and pedal
> fee. >Now, once you've been a professional and have driven thousands of
> nothing but Mercedes, you really know what the brake pedal should feel
> like. As I've stated before, give me 50 feet and I'll tell you if they are
> MetalMasters or not. Those pads just don't stop the car until
> they get warm
> and when you need brakes the most they are ice cold. They also chew up
> brake rotors in my >experience. They leave lots of ridges on the
> rotor face
> while Textar
> leave a nice smooth clean braking surface.
>
> >Stu
> >(who also adds)  >Simply put, Metal Masters are the worst brake pad I've
> ever experienced.
> >Period.