brake mounting
Thread Starter
Drifting
Joined: Feb 2006
Posts: 1,263
Likes: 0
From: CV ca
St. Jude Donor '11-'12-'13
brake mounting
Does anyone know why or is there an advantage to, rear brakes mounted to the front of the disk and the front mounted to the rear?
A friend is changing from drum to disk and asked me about mounting location.
Thanks,Bryan
A friend is changing from drum to disk and asked me about mounting location.
Thanks,Bryan
Le Mans Master
Joined: Jan 2002
Posts: 9,036
Likes: 13
From: Edmonton AB
Here is what Mr Ortiz has to say
subject but I am unable to pull up a link.
.
The Mark Ortiz Automotive
CHASSIS NEWSLETTER
April 2004
EFFECT OF CALIPER MOUNTING POSITION
"What effect on wheel loading does the positioning of the calipers in a
leading or trailing location have – i.e. mounted at 3 and 9 o’clock
positions? Does a trailing caliper add or subtract load on the front tires?
In a rear independent suspension, does a leading caliper add or
subtract wheel loading, and is it the same in a live axle situation?
The short answer is no. Caliper location has no effect whatsoever on
wheel loading. Having the caliper’s mass lower or higher does have a
very minute effect, because it affects the CG location a tiny bit, but
there is no difference between a 3 o’clock mounting position and a 9
o’clock position. "
There was an article in Racecar Engineering in 2003 that discussed the CHASSIS NEWSLETTER
April 2004
EFFECT OF CALIPER MOUNTING POSITION
"What effect on wheel loading does the positioning of the calipers in a
leading or trailing location have – i.e. mounted at 3 and 9 o’clock
positions? Does a trailing caliper add or subtract load on the front tires?
In a rear independent suspension, does a leading caliper add or
subtract wheel loading, and is it the same in a live axle situation?
The short answer is no. Caliper location has no effect whatsoever on
wheel loading. Having the caliper’s mass lower or higher does have a
very minute effect, because it affects the CG location a tiny bit, but
there is no difference between a 3 o’clock mounting position and a 9
o’clock position. "
subject but I am unable to pull up a link.
.
Le Mans Master
Joined: Jan 2002
Posts: 9,036
Likes: 13
From: Edmonton AB
There has been discussion about caliper clocking having an
effect on anti-dive and anti-lift characteristics.
This CircleTrack article has an overview of how anti-dive
is provided in a design and considerations as to when a-d
is desirable.
.
effect on anti-dive and anti-lift characteristics.
This CircleTrack article has an overview of how anti-dive
is provided in a design and considerations as to when a-d
is desirable.
.
Melting Slicks
Joined: Feb 2006
Posts: 2,753
Likes: 15
From: backwoods upstate ny
calipers that are rear mounted may induce ''chatter'' under certain braking conditions....front brake calipers may require location in less than optimum location (i.e. rear mount) due to steering component (esp tie rod ends) encroachment...anti-dive is not influenced by caliper location, except for erratic movement that may occur during brake chatter
btw, there is a stop sign, at the end of a steep decline near my home, that i avoid (use alternate route) whenever driving my chev van, due to extreme brake chatter which occurs there....no problem elsewhere... the suspension and brake systems are all in excellent condition...calipers are on the rear of the rotor
btw, there is a stop sign, at the end of a steep decline near my home, that i avoid (use alternate route) whenever driving my chev van, due to extreme brake chatter which occurs there....no problem elsewhere... the suspension and brake systems are all in excellent condition...calipers are on the rear of the rotor
Last edited by redrose; Oct 21, 2006 at 09:21 PM.
Le Mans Master
Joined: Jan 2002
Posts: 9,036
Likes: 13
From: Edmonton AB
Mr Ortiz touches on this
"Now, do we actually want maximum cancellation of the bearing loads by
the brakes? We might suppose so, but actually there is an argument for
not having maximum cancellation. The effective radius of the brake
(roughly the radius to the middle of the pad) is often less than half of
the tire effective radius. This means that the force at the caliper is
more than twice the rearward force at the tire contact patch, and it
may also exceed the vector sum of the vertical and horizontal forces at
the contact patch. Consequently, the caliper force may not only
reduce the bearing loads, but reverse them. If there is any free play
in the bearings, or deflection in the components, this load reversal
may result in a vibration or a small variation in the steer angle of
the wheel. So there is a case for building the components nice and strong,
and positioning the calipers so the bearing loads will not reverse."
.
the brakes? We might suppose so, but actually there is an argument for
not having maximum cancellation. The effective radius of the brake
(roughly the radius to the middle of the pad) is often less than half of
the tire effective radius. This means that the force at the caliper is
more than twice the rearward force at the tire contact patch, and it
may also exceed the vector sum of the vertical and horizontal forces at
the contact patch. Consequently, the caliper force may not only
reduce the bearing loads, but reverse them. If there is any free play
in the bearings, or deflection in the components, this load reversal
may result in a vibration or a small variation in the steer angle of
the wheel. So there is a case for building the components nice and strong,
and positioning the calipers so the bearing loads will not reverse."
Large Impressive Member
Joined: Jul 2003
Posts: 65,811
Likes: 71
From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Originally Posted by Slalom4me
Having the caliper’s mass lower or higher does have a
very minute effect, because it affects the CG location a tiny bit
very minute effect, because it affects the CG location a tiny bit
Melting Slicks
Joined: Feb 2006
Posts: 2,753
Likes: 15
From: backwoods upstate ny
happily, mr. o's explanation is correct and in complete agreement with my post.
unhappily, unless one already understands the mechanisms at work here, mr. o's talk will require lengthy dissection for comprehension.
''if'' there is free play in the bearings ?????....if there is NO clearance, don't expect to drive the car...duh !!!!
''deflection'' in components ????....without rubber bushings in the suspension, road vibration will destroy the suspension entirely in a very short time, even if occupant comfort and noise transmission were acceptable....deflection and ''compliance'' must exist to some degree.
''positioning the calipers so the bearing loads will not reverse''--c'mon mr. o , just say it--don't put the calipers on the rear of the rotor
unhappily, unless one already understands the mechanisms at work here, mr. o's talk will require lengthy dissection for comprehension.
''if'' there is free play in the bearings ?????....if there is NO clearance, don't expect to drive the car...duh !!!!
''deflection'' in components ????....without rubber bushings in the suspension, road vibration will destroy the suspension entirely in a very short time, even if occupant comfort and noise transmission were acceptable....deflection and ''compliance'' must exist to some degree.
''positioning the calipers so the bearing loads will not reverse''--c'mon mr. o , just say it--don't put the calipers on the rear of the rotor
Last edited by redrose; Oct 22, 2006 at 11:18 AM.
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Melting Slicks
Joined: Feb 2006
Posts: 2,753
Likes: 15
From: backwoods upstate ny
Originally Posted by Corvette Kid
I'm having trouble understanding how unsprung weight affects CG.....
) and ''fat Albert'' is sitting on the top rung of the ladder...CG of you, the bike, and Al is a lot higher than if Al was riding on the handlebars.the CG change with the calipers top vs bottom is nowhere near as pronounced as Al climbing the ladder, but a small (prolly miniscule given the total mass of the average vehicle) change would occur....until some one designs a suspension with the ball joints in some other location (neat trick for whoever does), the calipers can't go top or bottom anyway
Le Mans Master
Joined: Jan 2002
Posts: 9,036
Likes: 13
From: Edmonton AB
My take on the remarks about play and deflection is that he means
if there is too much bearing play (I know he says 'any') and if the
brake mounting brackets lack adequate stiffness/rigidity.
In the former case, there may no vibration/chatter when the bearing
is new and within tolerance but with time & wear a problem could
develop. For the sake of happy customers and good J.D. Power
rankings it could be worth the time to compromise and retain some
bearing loading.
Ditto for the brackets. While a certain amount of material may
be adequate to keep the caliper attached, additional material
or time spent with Finite Element Analysis might be required to
dampen potential vibration. Again the trade-off.
Frankly, I think he is just hedging on the matter of location for the
sake of the purists. My sense is that he is saying put the caliper
wherever you fancy.
.
if there is too much bearing play (I know he says 'any') and if the
brake mounting brackets lack adequate stiffness/rigidity.
In the former case, there may no vibration/chatter when the bearing
is new and within tolerance but with time & wear a problem could
develop. For the sake of happy customers and good J.D. Power
rankings it could be worth the time to compromise and retain some
bearing loading.
Ditto for the brackets. While a certain amount of material may
be adequate to keep the caliper attached, additional material
or time spent with Finite Element Analysis might be required to
dampen potential vibration. Again the trade-off.
Frankly, I think he is just hedging on the matter of location for the
sake of the purists. My sense is that he is saying put the caliper
wherever you fancy.
.
Melting Slicks
Joined: Feb 2006
Posts: 2,753
Likes: 15
From: backwoods upstate ny
Originally Posted by Slalom4me
At least they can't on outboard mounted calipers.
.
.
my bad...this thread started with a ''rear'' brake question, and my attention has drifted to the front, perhaps due to ''anti-dive'' (a function of front suspension layout) being injected...i multi-task poorly...however, the caliper location factors are the same front or rear
Le Mans Master
Joined: Jan 2002
Posts: 9,036
Likes: 13
From: Edmonton AB
Originally Posted by redrose
true....unfortunately large diameter rotors, ground clearance, and
halfshaft angle considerations render inboard brake mountings
impractical for anything other than static display.
halfshaft angle considerations render inboard brake mountings
impractical for anything other than static display.
Originally Posted by FF1wms
Does anyone know why or is there an advantage to rear brakes
mounted to the front of the disk and the front mounted to the rear?
mounted to the front of the disk and the front mounted to the rear?
Edit: Don't mean to cross the boundary over toward being
a smart alec. Just feeling a little sporty today ...
.
Last edited by Slalom4me; Oct 22, 2006 at 11:47 AM.
Melting Slicks
Joined: Feb 2006
Posts: 2,753
Likes: 15
From: backwoods upstate ny
Originally Posted by Slalom4me
And the Hummer H1.
.
.
not going racing in this weather, might as well toss some ideas around, isn't that what a ''forum'' is ??
Last edited by redrose; Oct 22, 2006 at 11:52 AM.
Le Mans Master
Joined: Jan 2002
Posts: 9,036
Likes: 13
From: Edmonton AB
I can't find pictures, but the brakes are mounted at the differentials.
You must be speaking about the old Hummers. For '06, they really
bumped up the braking capacity with new 12" rotors. Power is
up, too. Now the Duramax engine makes 300 hp and 520 lb-ft of
torque. Four Wheeler reports "Acceleration from 0 to 60 dropped by
18 percent, to 13.5 seconds."
Oh, gotta go. Time to get ready to watch the Michael Schumacher Swan Song.
.
You must be speaking about the old Hummers. For '06, they really
bumped up the braking capacity with new 12" rotors. Power is
up, too. Now the Duramax engine makes 300 hp and 520 lb-ft of
torque. Four Wheeler reports "Acceleration from 0 to 60 dropped by
18 percent, to 13.5 seconds."
Oh, gotta go. Time to get ready to watch the Michael Schumacher Swan Song.
.
Melting Slicks
Joined: Feb 2006
Posts: 2,753
Likes: 15
From: backwoods upstate ny
didn't know there was a ''new'' or ''old'' humbly...honestly, they are offensive to look at, i avert my vision....read 13 sec in your reply and then realized that was not 1/4 mile, only 0-60--imho that thing is a hazard to drive on the highway....must be dragging an anchor, doesn't need calipers ...curious abt what they have, tho, pics if you trip over em, tia
...curious abt what they have, tho, pics if you trip over em, tia
Tech Contributor
Joined: Jun 2004
Posts: 20,905
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Just my opinion, but here it goes.
On the front suspension of the C4 the steering rack tie rods are on the front side of the wheel. This potentially means that there is competition for space in the front half of the wheel, and hence more room to fix a caliper on the back half of the wheel. Additionally, putting the caliper behind the axle centerline helps in a very small way to move the C/G line towards the back axle.
Rear: With the two trailing forming a virtual swing arm, during suspension movement the back of the suspension (where the toe links are) will move a farther distance than the front area where the caliper is located. The slight ratio/leverage effect of the caliper location ahead of the axle centerline improves the tire/wheel response, versus the caliper weight being behind the axle centerline.
Just my $.02
On the front suspension of the C4 the steering rack tie rods are on the front side of the wheel. This potentially means that there is competition for space in the front half of the wheel, and hence more room to fix a caliper on the back half of the wheel. Additionally, putting the caliper behind the axle centerline helps in a very small way to move the C/G line towards the back axle.
Rear: With the two trailing forming a virtual swing arm, during suspension movement the back of the suspension (where the toe links are) will move a farther distance than the front area where the caliper is located. The slight ratio/leverage effect of the caliper location ahead of the axle centerline improves the tire/wheel response, versus the caliper weight being behind the axle centerline.
Just my $.02