The BMW UUC Digest
Volume 2 : Issue 74 : "text" Format
Messages in this Issue:
Re: Time for F rotors and pads - thinking Zimmerman (TMS)
Re: Time for F rotors and pads - thinking Zimmerman (TMS)
Re: 6-speeds for E36, was V12 & V8
Re: Leasing a BMW
M3 FS on eBay.....Need E34 parts too
Re: M Roadster Shocks
supercharger
Re: supercharger
Re: supercharger
Re: supercharger
GC rear shock mounts
Re: GC rear shock mounts
Cross drilled? (was: Time for F rotors and pads - thinking Zimmerman (TMS))
----------------------------------------------------------------------
Date: Tue, 9 Mar 2004 16:31:04 -0500
From: [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Subject: Re: Time for F rotors and pads - thinking Zimmerman (TMS)
Message-ID: <[EMAIL PROTECTED]>
Good comments...
My response...
1. The ATE Power Disc I had did a great job of reducing/eliminating
glazing/fading, versus the solid Balos on my other Ti. Which is why I was
inclined to get something else either slotted or drilled or both.
2. The Zimmerman's are cast molded with holes, not actually drilled
3. Pads are cheap - consider the type of driving I do, the average commute
I make, and the little autocross time my car sees. So I'm figuring on
getting a semi-metal or non-metal compound, going thru pads is easier than
going thru rotors for sake of a few extra feet in stopping distance.
4. My "Ti" has 325 brakes up front, so they do have more metal than
factory spec.
Phil
Brian Daley
<[EMAIL PROTECTED] To: [EMAIL PROTECTED]
m> cc:
Sent by: Subject: Re: [UUC] Time for F
rotors and pads - thinking Zimmerman (TMS)
[EMAIL PROTECTED]
cdigest.com
03/09/2004 03:35 PM
Please respond to
bmwuucdigest
Search the ARCHIVES:http://www.mail-archive.com/[EMAIL PROTECTED]
-----Original Message-----
>From: [EMAIL PROTECTED]
>
>I can only think of two advantages to drilled rotors:
>
>1. Cooling.
>2. Scraping the glaze off the pads before it transfers to the rotors.
I'd also add 3. Reduced rotating weight (the best kind to get rid of!) Of
course this is entirely irrelevant in a street application.
>
>Disadvantages:
>
>1. Unless you increase the size of the rotor, you have less metal to heat
>up. Braking converts motion to heat, so you don't want to reduce heat
>capacity.
Less metal to heat up, but more surface area to dissipate heat. Heat
capacity isn't really the critical factor - you don't want the rotors to
absorb heat, you want them to radiate heat. Reduced mass might have an
effect on the probability of warping though, not sure about that aspect.
Any engineers out there who know the math to calculate the net effect of
lost mass vs. increased surface area?
>2. Your pads will not last as long (the cheese grater effect).
I'd also add 3. Increased likelihood of cracking around the drilled holes
(although this seems to be largely a matter of religious belief on both
sides of the argument). If I recall correctly the big dollar "drilled"
rotors on Porsche GT2's etc. aren't actually drilled, the holes are cast
into the rotors. Any materials scientists out there who know about the
grain structure of cast iron and how drilling affects it?
Brian
'94 325ic (treated to new garden variety rotors and pads last weekend)
__________________________________________________________________________
In memory of Michel Potheau - friend, enthusiast, founder of the BMW CCA.
UUC Motorwerks - BMW Performance Fine-tuning and home of the Ultimate
Short Shifter - accept no substitutes!
908-874-9092 . http://www.uucmotorwerks.com
------------------------------
Date: Tue, 09 Mar 2004 15:20:47 -0800
From: "Bora Akyol (BMW)" <[EMAIL PROTECTED]>
To: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
Subject: Re: Time for F rotors and pads - thinking Zimmerman (TMS)
Message-ID: <[EMAIL PROTECTED]>
They are still bad.
I would stay with the Powerslots. They have a good reputation
and they last a long time.
Bora
On 3/9/04 1:31 PM, "[EMAIL PROTECTED]"
<[EMAIL PROTECTED]> wrote:
> 2. The Zimmerman's are cast molded with holes, not actually drilled
------------------------------
Date: Tue, 09 Mar 2004 13:46:53 -0800
From: [EMAIL PROTECTED]
To: Andrew Thomas <[EMAIL PROTECTED]>
Cc: [EMAIL PROTECTED]
Subject: Re: 6-speeds for E36, was V12 & V8
Message-ID: <[EMAIL PROTECTED]>
re: E36 diff ratios and strengths:
How would a regular duty diff hold up over time to230+hp at the rear
wheels? Have others used the regular duty diffs in the //M3 with
satisfactory results or have there been durability issues? Were there
E36 318i that came with LSDs?
Barry
Andrew Thomas wrote:
>"re: E36 axle ratios:
>It appears to be the same kind of "regular strength" diff as the 3.38/3.45
>from the 318i, the 3.15 from the 325i, and so on.
>Andy T
>
>
------------------------------
Date: Tue, 9 Mar 2004 16:22:59 -0800
From: "RussC" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Subject: Re: Leasing a BMW
Message-ID: <[EMAIL PROTECTED]>
If the E32 750iL is any indication of future E65 resale value, watch out
below.....
RussC
>Date: Tue, 9 Mar 2004 15:29:12 -0500
>From: "Brett Anderson" <[EMAIL PROTECTED]>
>To: "UUC Digest" <[EMAIL PROTECTED]>
>Subject: Re: Leasing a BMW
>Message-ID: <[EMAIL PROTECTED]>
>
>
>I think Joel was referring to the 8 year old E65 7 series, which
>is going to
>be worthless.
>
>Brett Anderson
>KMS
>
>> -----Original Message-----
>>
>> Joel Gallun writes: I wonder what the economics of leasing are when the
>> residual values approach zero?
>>
>> According to Auto-Spies, BMW ranks #1 in leasing value due to their
>> resale superior value as well as their consumer oriented money factor.
>> I wonder where you got your data regarding residual values Joel.
>>
>> Cheers
>> Steve
------------------------------
Date: Tue, 09 Mar 2004 20:44:41 -0500
From: [EMAIL PROTECTED]
To: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>,
"[EMAIL PROTECTED]" <[EMAIL PROTECTED]>,
E36M3 <[EMAIL PROTECTED]>
Subject: M3 FS on eBay.....Need E34 parts too
Message-ID: <[EMAIL PROTECTED]>
Anyone in the market for a '95 M3, Red/Black, 5 speed,............please
pass it along to anyone interested. I also have my daughter's college ride
for sale too. '93 318iSA. Motivated seller, need $s to help pay for 2 kids
going to college ;-).
I need a driver's side front fender, doors, front and rear bumper for an
'89 E34 535i. It's white w/ tan interior. If anyone knows of a parts car,
salvage, etc., I'd appreciate the help.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=6131&item=2466167911&ssPageName=STRK:MEASE:IT
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=6131&item=2466169789&ssPageName=STRK:MEASE:IT
Thanks,
Evan
------------------------------
Date: 10 Mar 2004 12:02:30 +0200
From: Werner Gillmer <[EMAIL PROTECTED]>
To: Bob Hyre <[EMAIL PROTECTED]>
Cc: [EMAIL PROTECTED]
Subject: Re: M Roadster Shocks
Message-ID: <[EMAIL PROTECTED]>
Go for the H&R/Blisten combo, it's not tooooo hard for the street.
Sway's is probarly overboard if the car only get occasionally
autocrossed. Yes replace the shock mounts, their cheap and easy to
replace and it does really improve your ride if your's is worn. Even it
yours it not worn, I would replace them if I were you while all the
suspension is out anyway, safes from taking it out again in the future.
I replaced my shock mounts on my e36 323i and it really did improve the
ride, it's amazing that such a small thing's adds that much to the car.
On Tue, 2004-03-09 at 21:16, Bob Hyre wrote:
> Search the ARCHIVES:http://www.mail-archive.com/[EMAIL PROTECTED]
>
>
> All,
>
> One of the original rear shocks on the M Roadster has started to leak oil at
> 62k miles. I think that I will replace all 4 shocks with Bilstein HD's
> since the car only infrequently autocrosses. I am afraid that if I do H&R
> lowered springs, sport shocks and stiffer sway bars at the same time that I
> won't like the ride for the street. While I am in there, should I replace
> the upper rear shock mounts too? I haven't heard if the M Roadster is
> subject to this failure like M3's. Is there anything else that I should
> look at while I'm going?
>
> Thanks,
>
> Bob Hyre
> Houston, TX
> '98 M Roadster
> '00 540iAT
>
>
> __________________________________________________________________________
> In memory of Michel Potheau - friend, enthusiast, founder of the BMW CCA.
>
> UUC Motorwerks - BMW Performance Fine-tuning and home of the Ultimate
> Short Shifter - accept no substitutes!
> 908-874-9092 . http://www.uucmotorwerks.com
>
------------------------------
Date: 10 Mar 2004 13:44:43 +0200
From: Werner Gillmer <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Subject: supercharger
Message-ID: <[EMAIL PROTECTED]>
Is this possible? I think it is, needs a 2nd opinion and is it a good
idea to do?
You have a supercharger in your car, but it does not boost, only on full
throttle does it starts to boost, so everyday driving your gas mileage
stays the same. However if you want to go have fun, you have a activate
switch to activate the S/C and then you start boosting, so if you climb
in the car hit the activate switch and turn it on, then you have a
normal supercharger.
------------------------------
Date: Wed, 10 Mar 2004 10:00:25 -0500 (EST)
From: Mark Andy <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Subject: Re: supercharger
Message-ID: <[EMAIL PROTECTED]>
Howdy,
On 10 Mar 2004, Werner Gillmer wrote:
> You have a supercharger in your car, but it does not boost, only on full
> throttle does it starts to boost, so everyday driving your gas mileage
> stays the same. However if you want to go have fun, you have a activate
> switch to activate the S/C and then you start boosting, so if you climb
> in the car hit the activate switch and turn it on, then you have a
> normal supercharger.
Plus, if you're ever driving through a post nuclear wasteland, you can
save gas until you really need to catch that homicidal maniac on the
motorcycle ahead of you.
Mark
------------------------------
Date: Wed, 10 Mar 2004 11:18:46 -0500
From: UUC Admin <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Subject: Re: supercharger
Message-ID: <[EMAIL PROTECTED]>
Werner,
What you are attempting to accomplish is easily done with turbocharger and
an electronic boost controller, a rising rate fuel pressure regulator and
some decent tuning. This is common in the high tech Japanese imports
rolling around.
Although you don't completely eliminate boost, you can run very
conservative settings.
On my Toyota Supra Turbo, I ran a Greddy Electronic boost controller with a
remote control high/low boost switch on the steering wheel. This allowed me
3 horsepower levels at the push of a button:
1. Boost controller off - 8 to 10 psi of boost.
2. Boost controller on (low boost setting) 14 psi of boost
3. Boost controller on (high boost setting) 21 psi of boost
The reason for this setup was that I would get uncontrolled wheel spin in
first and second gear at 21psi, so I would launch at 14 psi through first
and second gears, switching to 21 psi for the remaining high gears. The off
setting was almost never used - just too boring. ;)
Please remember that any turbocharger or supercharger that is not spinning
will act as a restriction in the intake path. (The roots type supercharger
setup in Mad Max is a fantasy by the way, it won't work..)
However you might be able to do it with a centrifugal supercharger and some
sort of clutch that allowed the impellers to free spin when not engaged,
but I think it would be a lot more hassle than it is worth.
A turbocharger with the right supporting systems is likely what you are
looking for.
Best Regards,
At 01:44 PM 3/10/2004 +0200, you wrote:
>Search the ARCHIVES:http://www.mail-archive.com/[EMAIL PROTECTED]
>Is this possible? I think it is, needs a 2nd opinion and is it a goodidea
>to do?
>
>You have a supercharger in your car, but it does not boost, only on full
>throttle does it starts to boost, so everyday driving your gas mileage
>stays the same. However if you want to go have fun, you have a activate
>switch to activate the S/C and then you start boosting, so if you climb in
>the car hit the activate switch and turn it on, then you have a normal
>supercharger.
Michael K Donohue
System Administrator
UUC Digest
http://www.uucdigest.com
------------------------------
Date: Wed, 10 Mar 2004 10:01:09 -0500 (GMT-05:00)
From: Brian Daley <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Subject: Re: supercharger
Message-ID: <[EMAIL PROTECTED]>
-----Original Message-----
>From: Werner Gillmer <[EMAIL PROTECTED]>
>
>Is this possible? I think it is, needs a 2nd opinion and is it a good
>idea to do?
>
>You have a supercharger in your car, but it does not boost, only on full
>throttle does it starts to boost, so everyday driving your gas mileage
>stays the same.
This is more or less how a centrifugal supercharger behaves. They don't make
significant boost before about 3000 RPM so just cruising around town they don't have
much effect, but when you floor it, hang on. As far as I know all the commercially
available supercharger kits for BMWs use centrifugal superchargers.
>However if you want to go have fun, you have a activate
>switch to activate the S/C and then you start boosting, so if you climb
>in the car hit the activate switch and turn it on, then you have a
>normal supercharger.
Sounds more like a turbo with electronically controlled wastegate. If you set the
wastegate low enough you basically get no boost. I think a while back there was a
centrifugal supercharger that was driven by an electric motor rather than a mechanical
crank-driven belt. Presumably that could be shut off as well, but I don't think
they're still around.
Brian
'94 325ic (naturally aspirated)
'94 Mustang Cobra (10 lbs. of centrifugal boost)
------------------------------
Date: Wed, 10 Mar 2004 10:14:37 -0500 (EST)
From: Mark Andy <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Subject: GC rear shock mounts
Message-ID: <[EMAIL PROTECTED]>
Howdy,
So I've not looked at the rear shock mounts in our '93 325is. Given other
stuff, I can't see how they won't need to be replaced... :-)
I'm looking at the ground control mount shown here:
http://www.ground-control.com/images/bmw/bmw-mount-race.jpg
Anyone have experience with how durable this thing is? I've heard
somewhat spotty reports of GC quality overall... This will be for a daily
driver that sees reasonably serious autox duty as well.
I'm not _too_ worried about ride quality on the street issues... Our other
cars include a '93 MR2 with Koni sports and recently included a '99 miata
with koni sports... We're used to a very firm ride (our softest riding
vehicle prior to the 325 was my '03 dually! :-). The car currently has
Bilsteins/H&R's and frankly feels like a big tub of lard.
I do wonder about noise though... Will these mounts result in banging,
squeeking, creaking, etc.?
And from what folks have said, the way these work is the nut gold nut
plate goes over the top of the shock tower and the black top shock mount
goes under the shock tower, right? Meaning that future shock removal can
be done from under the car?
What's the deal with the slotted shock mount holes?
Thanks!
Mark
------------------------------
Date: Wed, 10 Mar 2004 10:08:24 -0600
From: [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Cc: "Mark Andy" <[EMAIL PROTECTED]>
Subject: Re: GC rear shock mounts
Message-ID: <[EMAIL PROTECTED]>
"Mark Andy" <[EMAIL PROTECTED]> wrote:
>
> So I've not looked at the rear shock mounts in our '93 325is.
> Given other stuff, I can't see how they won't need to be
> replaced... :-)
>
> I'm looking at the ground control mount shown here:
> http://www.ground-control.com/images/bmw/bmw-mount-race.jpg
Those look like race RSMs.
GC also has street-oriented RSMs with polyurethane between the shock piston
and the mount bracket. I have the latter.
> Anyone have experience with how durable this thing is?
Rock solid.
I have had a set on my M3 for 4+ years.
In fact, over the last 4 months I have broken two 1" thick steel Koni SA
pistons that were attached to the GC RSMs! I'm not sure if that could be
viewed as a complement to GC RSMs (I strongly suspect that I got a
defective batch of Konis), but it should certainly tell you that RSMs are
fairly durable ;-)
> I've heard somewhat spotty reports of GC quality overall...
Hmmm, I haven't.
The worst thing I've heard about GC is that their BMW customer assistance
is minimalistic.
> This will be for a daily driver that sees reasonably serious
> autox duty as well.
>
> I'm not _too_ worried about ride quality on the street issues...
> [...] I do wonder about noise though... Will these mounts
> result in banging, squeeking, creaking, etc.?
Nope.
I've heard polyurethane bushings sometimes squeak in colder temperatures,
but haven't had much first hand experience since I live in Dallas, TX.
FWIW, my GC rear trailing arm reinforcements/spacers do squeak like crazy
:http://www.ground-control.com/images/bmw/e36-rear-lca1.jpg
> And from what folks have said, the way these work is the nut
> gold nut plate goes over the top of the shock tower and the
> black top shock mount goes under the shock tower, right?
> Meaning that future shock removal can be done from under the
> car?
Yep.
All future shock removal can be done from inside the wheel well.
The pics on this site should answer all your future questions:
http://www.the-welters.com/racing/gc-installation/
> What's the deal with the slotted shock mount holes?
Beats me.
The mounts I have do not have the slots. Mine look more like what's in the
following picture, but even those are not exactly what GC sold and I bought
a while back. I guess they had gone through a few model iterations over the
years.
<http://www.m3motorwerks.com/products/image.php?image=http://www.m3motorwerks.com/images/fullsize/GC-RSM.ST_fs.jpg&name=Ground+Control+Street+Rear+Shock+Mounts>
HTH,
alex f
------------------------------
Date: Wed, 10 Mar 2004 10:30:11 -0500
From: "chet.dawes" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Subject: Cross drilled? (was: Time for F rotors and pads - thinking Zimmerman (TMS))
Message-ID: <[EMAIL PROTECTED]>
Okay, I'll bite.
'Drilled' rotors:
Originally were developed when pads sucked and out-gassed like crazy to
help allow gasses to escape from the pad/rotor interface. Since pad
technology has improved drastically in the last 40 years, the need for
drilled rotors has become a marketing tool and a way for companies to
extract a few more bucks from consumers for the 'cool factor' of drilled
rotors. I have absolutely no problems with that aspect as long as
people are honest about why they do it.
Yes, Porsche's high end 'drilled' rotors actually have cast holes. The
reason is drilling into a cast iron surface creates stress risers and
due to the residual stress in the cast rotor will cause cracks after
sufficient heat cycling. That's also why drilled rotors have chamfered
holes (the good ones are NOT a 45 degree flat chamfer) and are usually
peened for additional strength at the hole to reduce this tendency.
The cooling effect of the drilled holes is minimal and probably offset
by the reduced heat capacity of the rotor due to the lost mass. The
airflow is perpendicular to the drilled holes and moves outward in the
radial direction from inertia and the pressure created by the fins on
the interior of the rotor not in/out of the drilled holes. If anything,
it could destroy the flow characteristics of the cooling passages and
allow air to escape (assume for a second it does travel in/out of the
holes) through a shorter path permitting less heat transfer to the air
from the rotor surface. The radiant heat transfer from the additional
surface area is the only 'real' added cooling. I believe even that is
minimal.
The reduced mass rotational inertia argument falls apart (within reason,
we're not talking huge changes here) when you recognize that heat
capacity is what you're after. The stock solid rotors on my 318ti have
nearly half the rotational inertia of the vented variety. However, all
else being equal (piston diameter, rotor diameter, pads, swept area,
etc) the car just plain will does not have the braking capacity and
therefore is slower because you'll boil the fluid and over-heat the pad.
That's why I have 328 calipers and vented rotors on the car! For a
motorcycle with nearly no limit to the rotor diameter, they use solid
rotors (very thin) with minimal swept area and reduce mass and therefore
inertia by cross drilling since the heat capacity is so far above what's
needed to stop something that weighs that little. Feel is more
important than capacity in that case.
Effectively your braking capacity is directly proportional to the added
heat capacity (mass) of the rotor. SO if you increase the mass by 25%,
your ability to absorb braking energy (transferred to heat) just went up
about 25%. Yes, the rotor has to absorb the energy/heat before it can
transfer it to the surrounding air! You don't want the rotor to hold
heat (that's why vented is so much better than solid of the same mass),
you want it to absorb and dissipate it as quickly as possible. Holding
heat in the rotor means transferring it to the pad/fluid/wheel bearing
etc. and obviously that's not the goal. Adding mass changes the rate of
temperature change (slower) in both directions heating and cooling (as
Gary indicated). However, increased mass means less temperature rise
for the same energy absorption, so the same braking maneuver that would
over-heat a lighter mass rotor would not with a higher mass rotor with
more capacity.
Obviously there is a trade off and you'd ideally size the rotor to the
mass of the vehicle and it's intended use (speed, tire grip, and braking
conditions) so you don't have more capacity than will be needed in the
worst case. That allows minimal rotational inertia with the greatest
energy absorbing capacity for the application. Too much of a good thing
applies since pads have a temperature dependency on their effectiveness.
In practice, drilled rotors have little or no benefit in my opinion. I
would not waste your money buying them drilled. If you want to scrape
away the pad glaze, buy your rotors slotted. Very little stress change
in the cast rotor since it does not go all the way through and a better
"cheese grater" effect, or pad bite than chamfered holes (more of a
cheese slicer I suppose). Look at high end road racing cars, most are
running slotted floating rotors these days as opposed to drilled rotors
for exactly those reasons.
Ultimately if you want to stop faster, it takes tires with more grip to
do so. If you want to brake harder more often, you need fade resistance
(heat capacity) and cross drilling does not help in that department.
Any *potential* cooling advantage is offset by lost swept area and heat
capacity.
Sorry for the long-winded response.
Chet Dawes
(you asked for an engineer's input....) :)
From: [EMAIL PROTECTED]
I can only think of two advantages to drilled rotors:
1. Cooling.
2. Scraping the glaze off the pads before it transfers to the rotors.
Disadvantages:
1. Unless you increase the size of the rotor, you have less metal to
heat
up. Braking converts motion to heat, so you don't want to reduce heat
capacity.
2. Your pads will not last as long (the cheese grater effect).
I'd stick with a good quality rotor (like Balo), choose better pads and,
if
your brakes are fading, switch to higher temp brake fluid and improve
cooling by ducting more air to the brakes.
Well, you asked.
Scott Miller
From: Brian Daley <[EMAIL PROTECTED]>
I'd also add 3. Reduced rotating weight (the best kind to get rid of!)
Of course this is entirely irrelevant in a street application.
Less metal to heat up, but more surface area to dissipate heat. Heat
capacity isn't really the critical factor - you don't want the rotors to
absorb heat, you want them to radiate heat. Reduced mass might have an
effect on the probability of warping though, not sure about that aspect.
Any engineers out there who know the math to calculate the net effect of
lost mass vs. increased surface area?
I'd also add 3. Increased likelihood of cracking around the drilled
holes (although this seems to be largely a matter of religious belief on
both sides of the argument). If I recall correctly the big dollar
"drilled" rotors on Porsche GT2's etc. aren't actually drilled, the
holes are cast into the rotors. Any materials scientists out there who
know about the grain structure of cast iron and how drilling affects it?
Brian
Added mass causes the rotor to heat and cool more
slowly. Added surface area increases convection. The
answer is it depends. With long stops and long
cooling periods in between the added mass may be
better. With many shorter stops, the added cooling
may be better. It also depends on if your brakes are
ducted properly to take advantage of the extra
cooling.
Gary [no answer today] Derian
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