[DeTomaso] Brake Discs?
Tom Borcich
Tborcich at msn.com
Mon Dec 9 00:51:47 EST 2019
Thanks for the input Jack. That's my concern with going with a giant rotor and huge calipers, is it seems to be over kill. Maybe if I were running a wide body with bigger tires or racing slicks that are sticky as hell, I'd need more brake, but that's not the case.
Yes I expect to add a brake bias adjuster to the system. I had lots of fun with brake bias adjustments on the McLaren Can Am car I had, so I'm well familiar with that issue.
An interesting comparison, the McLaren ran 12" rotors front and rear with Girling 16-3-LA calipers. Not substantially bigger or more powerful than what the Pantera runs, but the weight of the McLaren was only 1400-1700 lbs depending on fuel load, and the contact patch of the tires was considerably bigger and stickier than the Pantera.
[cid:4e1cd12e-85d8-43e2-a64e-803258325cdb][cid:88be0f00-8f04-43a5-9cf2-8884718be1d3]
Best Regards,
Tom
________________________________
From: jderyke at aol.com <jderyke at aol.com>
Sent: Sunday, December 8, 2019 3:56 PM
To: Tborcich at msn.com <Tborcich at msn.com>; detomaso at server.detomasolist.com <detomaso at server.detomasolist.com>
Subject: Re: [DeTomaso] Brake Discs?
On larger OD rotors: they accomplish nothing unless the calipers are moved outward so they grip near the OD of larger diameter rotors and increase leverage. That means some sort of adapter mounting bracket must be used rather than a direct mount (e,g- stock). With minor OD changes in rotors (like 11-1/4" vs 11-1/2"), there is no change in the leverage stock-mount calipers can generate, so all that happens is a small increase in wt. The calipers must move outboard to gain extra leverage.
With minor changes in master cylinder bores or caliper piston sizes, there are equally minor changes in clamping pressures. Changes in pad composition may also gain some stopping power, sometimes at the expense of more disc or pad wear, especially if the discs & pads are not matched. Going from two pistons to four means a larger area brake pad can be used, resulting in less change in pad thickness wear and more durability. Same thing happens with 6 pistons in place of 4; this an increase in durability, not necessarily in stopping power. Changing to thicker rotors increases the resistance to brake fade by adding mass to absorb more heat but doesn't necessarily mean your car will stop quicker.
In about 1995 I mentioned that If, after removing the non-adjustable factory proportioning valve, tune up or discard the shuttle valve (that only turns on an indicator light), add good Aeroquip brake hoses that don't swell under hard braking, and adjust alignment, you test brakes and find that stock sized rotors & calipers can lock the front wheels. Improving the brakes at this point will only allow you to lock the wheels quicker and make the car more sensitive to braking. At this point, you need more tire in contact with the pavement to further reduce stopping distance.
If the rears lock first in your brake tests, you need a well adjusted manual proportioning valve IN THE REAR brake line to stop rear lock-up. This is highly unstable and the main cause of brake spins. Don't adjust the proportioning valve to a razor's edge of lock-up, either. Doing that will guarantee rear lock-up if the road surface changes- like a touch of moisture or dirt on public roads when you brake 'as hard as usual'. Blacktop & concrete are different as well. Give yourself a little leeway here.
Superlight ll Wilwoods may be out of production; mine have been on the front of our car since the early '90s. In the back I run ATS aluminum 2-piston calipers intended for the front of mid-'70s Porsche 911s, both with early Porsche 911 vented rotors. I don't use front rotor spacers; I fabricated aluminum front hubs sized to fit Porsche rotors directly (and lose more wt). Quella now sells bolt-on aluminum front hubs. An adjustable proportioning valve is necessary to balance these brakes. Wilwood's mechanical caliper & custom bracket is a legal e-brake. I use a Byars conversion GM dual-diaphragm power brake assembly- which may also be out of production. There are all Aeroquip dash-3 brake lines. With this rig either Judy or I can lock up 245-50 x 15" front tires in a hard stop.
-----Original Message-----
From: Tom Borcich <Tborcich at msn.com>
To: jderyke at aol.com <jderyke at aol.com>; detomaso at server.detomasolist.com <detomaso at server.detomasolist.com>
Sent: Sun, Dec 8, 2019 12:45 pm
Subject: Re: [DeTomaso] Brake Discs?
Charles and Mike thanks for the detail on the rotors! That's awesome and ridiculously inexpensive for rotors. I will probably go with the slotted version! Damn! Under $60!
https://www.summitracing.com/parts/ceb-125-61053/overview/
https://www.apcautotech.com/part-detail/12561053
Jack, I like the idea of the Wilwood Superlite II dropping weight and possibly improved clamping force. Also, since I will be running Campy Clone wheels (which add unsprung weight) it would be nice to have a newer design and lighter caliper. This is what I found on the Superlite caliper, but could not find Superlite II. Not sure of its dimensions on it bolting up. There are 20 or more versions of this caliper.
https://www.summitracing.com/parts/wil-120-11132/overview/
For $14-$225 per caliper, it's a no brainer.
I'm surprised the OE calipers are that much heavier than the Wilwoods. I also thought that a steel rotor on an aluminum hat would also drop a few more pounds of unsprung weight, but will it make that much difference in performance for what I will be doing (street and some track time) and I have many other places to throw money, I will likely stick with the OE replacement and Centric option.
This brings up another question, running larger rotors with 17" & 18" wheels, so I have plenty of room inside the wheel for bigger rotors, for those that run an 11.75" vs. 12" vs. 13" rotors, how much of a difference do you notice with larger rotors and will that extra braking torque overpower the tires (front: 245/40-17 & rear: 285/40-18) I'm running?
Lastly, Wilkinson told me years ago he changes out the master cylinder to a different diameter from stock and it changes the braking system totally for the better. Has anyone done this?
Tom
________________________________
From: jderyke at aol.com <jderyke at aol.com>
Sent: Saturday, December 7, 2019 1:22 PM
To: tborcich at msn.com <tborcich at msn.com>; detomaso at server.detomasolist.com <detomaso at server.detomasolist.com>
Subject: Re: [DeTomaso] Brake Discs?
Besides the now-unavailable early Mustang rotors, certain models of Volvo used vented rotors that have been adapted to Euro Panteras with a machined spacer. If you mean "any", then you could use my adaption of '69-'80 Porsche 911 ventillated rotors with a 1" thick aluminum adapter. These are sold using Brembo discs by Pantera Parts Connection in Carson City NV, and are indeed a drop-in replacement for the stock solid ones while being 4 lbs/side lighter than the stockers. With more work (you must remove & strip each upright of its stock rotor & replace with the adapted vented assembly), the same vented Porsche rotors and a different aluminum adapter fits in the rear, too. All with stock Pantera calipers.
Going further down this road, Wilwood Superlite ll four-piston calipers are also a lightly-modified bolt-on replacement for the 12 lb(ea) stock Girling front calipers. The mod entails bolting 5-1/2 lb Wilwoods on using its top bolt boss, marking the steering arms for a new bolt hole that can be drilled & tapped to accept the stock caliper bolt. In isolated instances, the extra tapped bolt hole will come very close to falling thru the bottom of the stock steering arm. But since it's forged steel, adding a small weld blob to the arm, then filing it to look nice, easily fixes that. Some adaptions don't bother with the extra weld.
These two minor mods drop nearly 20 lbs of unsprung weight from your car, for better handling over bumpy real streets and highways, as well as providing better braking. And they're relatively cheap. Once you have the kit, stock 911 rotors are a forever-available replacement item. Note Wilwood offers caliper rebuild kits, but mine have been on our '72 L since the previous century without needing attention.
-----Original Message-----
From: Tom Borcich <tborcich at msn.com>
To: detomaso at server.detomasolist.com <detomaso at server.detomasolist.com>
Sent: Sat, Dec 7, 2019 10:08 am
Subject: [DeTomaso] Brake Discs?
Are there any replacement rotors for a 72L? I remember lots of talk
about the 66 Mustang V8 Rotors were a direct replacement, but the they
were changed in include the bearing carrier.
Looking at either replacements or going with a Wilwood kit with rotors.
Thanks in advance!
Best Regards,
Tom
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-------------- next part --------------
Thanks for the input Jack. That's my concern with going with a giant
rotor and huge calipers, is it seems to be over kill. Maybe if I were
running a wide body with bigger tires or racing slicks that are sticky
as hell, I'd need more brake, but that's not the case.
Yes I expect to add a brake bias adjuster to the system. I had lots of
fun with brake bias adjustments on the McLaren Can Am car I had, so I'm
well familiar with that issue.
An interesting comparison, the McLaren ran 12" rotors front and rear
with Girling 16-3-LA calipers. Not substantially bigger or more
powerful than what the Pantera runs, but the weight of the McLaren was
only 1400-1700 lbs depending on fuel load, and the contact patch of the
tires was considerably bigger and stickier than the Pantera.
[cid:4e1cd12e-85d8-43e2-a64e-803258325cdb]
[cid:88be0f00-8f04-43a5-9cf2-8884718be1d3]
Best Regards,
Tom
__________________________________________________________________
From: jderyke at aol.com <jderyke at aol.com>
Sent: Sunday, December 8, 2019 3:56 PM
To: Tborcich at msn.com <Tborcich at msn.com>;
detomaso at server.detomasolist.com <detomaso at server.detomasolist.com>
Subject: Re: [DeTomaso] Brake Discs?
On larger OD rotors: they accomplish nothing unless the calipers are
moved outward so they grip near the OD of larger diameter rotors and
increase leverage. That means some sort of adapter mounting bracket
must be used rather than a direct mount (e,g- stock). With minor OD
changes in rotors (like 11-1/4" vs 11-1/2"), there is no change in the
leverage stock-mount calipers can generate, so all that happens is a
small increase in wt. The calipers must move outboard to gain extra
leverage.
With minor changes in master cylinder bores or caliper piston sizes,
there are equally minor changes in clamping pressures. Changes in pad
composition may also gain some stopping power, sometimes at the expense
of more disc or pad wear, especially if the discs & pads are not
matched. Going from two pistons to four means a larger area brake pad
can be used, resulting in less change in pad thickness wear and more
durability. Same thing happens with 6 pistons in place of 4; this an
increase in durability, not necessarily in stopping power. Changing to
thicker rotors increases the resistance to brake fade by adding mass to
absorb more heat but doesn't necessarily mean your car will stop
quicker.
In about 1995 I mentioned that If, after removing the non-adjustable
factory proportioning valve, tune up or discard the shuttle valve (that
only turns on an indicator light), add good Aeroquip brake hoses that
don't swell under hard braking, and adjust alignment, you test brakes
and find that stock sized rotors & calipers can lock the front wheels.
Improving the brakes at this point will only allow you to lock the
wheels quicker and make the car more sensitive to braking. At this
point, you need more tire in contact with the pavement to further
reduce stopping distance.
If the rears lock first in your brake tests, you need a well adjusted
manual proportioning valve IN THE REAR brake line to stop rear lock-up.
This is highly unstable and the main cause of brake spins. Don't adjust
the proportioning valve to a razor's edge of lock-up, either. Doing
that will guarantee rear lock-up if the road surface changes- like a
touch of moisture or dirt on public roads when you brake 'as hard as
usual'. Blacktop & concrete are different as well. Give yourself a
little leeway here.
Superlight ll Wilwoods may be out of production; mine have been on the
front of our car since the early '90s. In the back I run ATS aluminum
2-piston calipers intended for the front of mid-'70s Porsche 911s,
both with early Porsche 911 vented rotors. I don't use front rotor
spacers; I fabricated aluminum front hubs sized to fit Porsche rotors
directly (and lose more wt). Quella now sells bolt-on aluminum front
hubs. An adjustable proportioning valve is necessary to balance these
brakes. Wilwood's mechanical caliper & custom bracket is a legal
e-brake. I use a Byars conversion GM dual-diaphragm power brake
assembly- which may also be out of production. There are all Aeroquip
dash-3 brake lines. With this rig either Judy or I can lock up 245-50 x
15" front tires in a hard stop.
-----Original Message-----
From: Tom Borcich <Tborcich at msn.com>
To: jderyke at aol.com <jderyke at aol.com>; detomaso at server.detomasolist.com
<detomaso at server.detomasolist.com>
Sent: Sun, Dec 8, 2019 12:45 pm
Subject: Re: [DeTomaso] Brake Discs?
Charles and Mike thanks for the detail on the rotors! That's
awesome and ridiculously inexpensive for rotors. I will probably go
with the slotted version! Damn! Under $60!
[1]https://www.summitracing.com/parts/ceb-125-61053/overview/
[2]https://www.apcautotech.com/part-detail/12561053
Jack, I like the idea of the Wilwood Superlite II dropping weight and
possibly improved clamping force. Also, since I will be running Campy
Clone wheels (which add unsprung weight) it would be nice to have a
newer design and lighter caliper. This is what I found on the Superlite
caliper, but could not find Superlite II. Not sure of its dimensions on
it bolting up. There are 20 or more versions of this caliper.
[3]https://www.summitracing.com/parts/wil-120-11132/overview/
For $14-$225 per caliper, it's a no brainer.
I'm surprised the OE calipers are that much heavier than the Wilwoods.
I also thought that a steel rotor on an aluminum hat would also drop a
few more pounds of unsprung weight, but will it make that much
difference in performance for what I will be doing (street and some
track time) and I have many other places to throw money, I will likely
stick with the OE replacement and Centric option.
This brings up another question, running larger rotors with 17" & 18"
wheels, so I have plenty of room inside the wheel for bigger rotors,
for those that run an 11.75" vs. 12" vs. 13" rotors, how much of a
difference do you notice with larger rotors and will that extra braking
torque overpower the tires (front: 245/40-17 & rear: 285/40-18) I'm
running?
Lastly, Wilkinson told me years ago he changes out the master cylinder
to a different diameter from stock and it changes the braking system
totally for the better. Has anyone done this?
Tom
__________________________________________________________________
From: jderyke at aol.com <jderyke at aol.com>
Sent: Saturday, December 7, 2019 1:22 PM
To: tborcich at msn.com <tborcich at msn.com>;
detomaso at server.detomasolist.com <detomaso at server.detomasolist.com>
Subject: Re: [DeTomaso] Brake Discs?
Besides the now-unavailable early Mustang rotors, certain models of
Volvo used vented rotors that have been adapted to Euro Panteras with a
machined spacer. If you mean "any", then you could use my adaption of
'69-'80 Porsche 911 ventillated rotors with a 1" thick aluminum
adapter. These are sold using Brembo discs by Pantera Parts Connection
in Carson City NV, and are indeed a drop-in replacement for the stock
solid ones while being 4 lbs/side lighter than the stockers. With more
work (you must remove & strip each upright of its stock rotor & replace
with the adapted vented assembly), the same vented Porsche rotors and a
different aluminum adapter fits in the rear, too. All with stock
Pantera calipers.
Going further down this road, Wilwood Superlite ll four-piston calipers
are also a lightly-modified bolt-on replacement for the 12 lb(ea) stock
Girling front calipers. The mod entails bolting 5-1/2 lb Wilwoods on
using its top bolt boss, marking the steering arms for a new bolt hole
that can be drilled & tapped to accept the stock caliper bolt. In
isolated instances, the extra tapped bolt hole will come very close to
falling thru the bottom of the stock steering arm. But since it's
forged steel, adding a small weld blob to the arm, then filing it to
look nice, easily fixes that. Some adaptions don't bother with the
extra weld.
These two minor mods drop nearly 20 lbs of unsprung weight from your
car, for better handling over bumpy real streets and highways, as well
as providing better braking. And they're relatively cheap. Once you
have the kit, stock 911 rotors are a forever-available replacement
item. Note Wilwood offers caliper rebuild kits, but mine have been on
our '72 L since the previous century without needing attention.
-----Original Message-----
From: Tom Borcich <tborcich at msn.com>
To: detomaso at server.detomasolist.com <detomaso at server.detomasolist.com>
Sent: Sat, Dec 7, 2019 10:08 am
Subject: [DeTomaso] Brake Discs?
Are there any replacement rotors for a 72L? I remember lots of talk
about the 66 Mustang V8 Rotors were a direct replacement, but the
they
were changed in include the bearing carrier.
Looking at either replacements or going with a Wilwood kit with
rotors.
Thanks in advance!
Best Regards,
Tom
_______________________________________________
Detomaso Email List is not managed by POCA
Posted emails must not exceed 1.5 Megabytes
DeTomaso mailing list
[4]DeTomaso at server.detomasolist.com
[5]http://server.detomasolist.com/mailman/listinfo/detomaso
To manage your subscription (change email address, unsubscribe, etc.)
use the links above.
Members who post to this list grant license to the list to forward any
message posted here to all past, current, or future members of the
list. They also grant the list owner permission to maintain an archive
or approve the archiving of list messages.
References
1. https://www.summitracing.com/parts/ceb-125-61053/overview/
2. https://www.apcautotech.com/part-detail/12561053
3. https://www.summitracing.com/parts/wil-120-11132/overview/
4. mailto:DeTomaso at server.detomasolist.com
5. http://server.detomasolist.com/mailman/listinfo/detomaso
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