cross drilled rotors on a 67 chevelle - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Suspension - Brakes - Steering
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 02-09-2007, 08:09 PM
Registered User
 
Join Date: Feb 2007
Location: port orchard wa
Posts: 4
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
cross drilled rotors on a 67 chevelle

I need crosss drilled & slotted rotors that will match front and rear on my 67 chevelle. Rear rotors are 1979 Cadilac sevelle, and front rotors are 1981 monte carlo. Does anyone know what company will make these rotors so they will match front and bvack??????? Thanks

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 02-09-2007, 08:11 PM
poncho62's Avatar
Out of the Loop Moderator
 
Last wiki edit: Streetbeasts links
Last journal entry: at car show
Last photo:
Join Date: Oct 2003
Location: Hanover, Ontario, Canada
Age: 62
Posts: 16,857
Wiki Edits: 5

Thanks: 20
Thanked 247 Times in 201 Posts
How are you mounting your calipers?..........just wondering.
__________________
Ontario Rodders

Budget RVs
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 02-09-2007, 08:14 PM
Registered User
 
Join Date: Feb 2007
Location: port orchard wa
Posts: 4
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I have rear bolt on caliper hangers for 12 bolt rear end from King Tek enginering.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 02-12-2007, 10:37 PM
Registered User
 
Join Date: May 2006
Location: Alderwood,Washington
Posts: 14
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by m.docken
I need crosss drilled & slotted rotors that will match front and rear on my 67 chevelle. Rear rotors are 1979 Cadilac sevelle, and front rotors are 1981 monte carlo. Does anyone know what company will make these rotors so they will match front and bvack??????? Thanks
this is a bad idea from several angles:

1. 1979 Seville rotors are 5 on 5 bolt pattern for starters. And they are 11-3/8" in diameter. Your 81 Monte rotors are 10-1/2", so you will easily lockup the rears due to grooss bias mismatch.

2. Crossdrilled are ridiculous for the street; they are guaranteed to crack from stress risers between the vanes.

www.scarebird.com
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 02-13-2007, 12:49 AM
Member
 
Last photo:
Join Date: Aug 2005
Location: Yackandandah.Australia.
Age: 52
Posts: 641
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Amen, here, most disc manufacturers reccomend slotted only for a high perf or race application. I've seen cracks out of the holes on standard AMG discs (M/B C32 and E55). Thank christ they no longer use them, some engineers should be cleaning toilets at the factory.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 02-13-2007, 09:44 AM
Registered User
 
Join Date: May 2006
Location: Alderwood,Washington
Posts: 14
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
It is pressure from marketing; the kids like to see the holes. I asked Brembo about this at SEMA, as they wrote the book (literally) about disc brake design. If you have solid rotors, it is not an issue as you can countersink the holes and remove the risers.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 02-14-2007, 12:29 AM
Member
 
Last photo:
Join Date: Aug 2005
Location: Yackandandah.Australia.
Age: 52
Posts: 641
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by Scarebird
It is pressure from marketing; the kids like to see the holes. I asked Brembo about this at SEMA, as they wrote the book (literally) about disc brake design. If you have solid rotors, it is not an issue as you can countersink the holes and remove the risers.
I always thought Girlock suplied the first commercial discs in the 50s. I'm guessing that Brembo market their products very well, just as mazda are famous for the rotary - an NSU (wankel) design.
I may still have a steel girlock disc off a mid 70s sports sedan Monaro in the shed. Like most of the running gear on this car it is alledged to be ex Le Mans GT40. It has holes drilled and heat cracks. Funny how people want 'high tech' but will accept BAD 'old tech' as long as it doesn't work and looks trick.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 02-14-2007, 10:10 AM
Registered User
 
Join Date: May 2006
Location: Alderwood,Washington
Posts: 14
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Ian, you are corect about Girlock, Lockheed was also a pioneer, though theirs was originally on aircraft.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 02-14-2007, 02:49 PM
xntrik's Avatar
Save a horse, Ride a Cowboy.
 
Last photo:
Join Date: Jul 2005
Location: Arkansas
Posts: 5,131
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Quote:
Originally Posted by Scarebird
this is a bad idea from several angles:

1. 1979 Seville rotors are 5 on 5 bolt pattern for starters. And they are 11-3/8" in diameter. Your 81 Monte rotors are 10-1/2", so you will easily lockup the rears due to grooss bias mismatch.

www.scarebird.com

What about rear wheel proportioning valves? I thought that was their purpose.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 02-14-2007, 05:58 PM
Registered User
 
Join Date: May 2006
Location: Alderwood,Washington
Posts: 14
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by xntrik
What about rear wheel proportioning valves? I thought that was their purpose.
no. their job is to limit pressure AFTER a certain point is reached. when you stamp on the brake hard they kick in, but during normal stops, they allow full pressure to the rears, allowing the rears to help stop the car.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 02-14-2007, 06:08 PM
Member
 
Last wiki edit: Ford axle ratio codes
Last journal entry: Rear Suspension
Last photo:
Join Date: Aug 2005
Location: Prattsville
Posts: 6,352
Wiki Edits: 31

Thanks: 2
Thanked 53 Times in 49 Posts
Quote:
Originally Posted by Scarebird
no. their job is to limit pressure AFTER a certain point is reached. when you stamp on the brake hard they kick in, but during normal stops, they allow full pressure to the rears, allowing the rears to help stop the car.
right, and not only that. most disc/disc applications do not use them. they are used because of the self energizing ( duo servo ) drum brakes, they don't need as much brake preassure, once they rotate over ( self energize )
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 02-23-2007, 02:06 PM
Lurker...
 
Last photo:
Join Date: Feb 2006
Location: Hamilton, NJ
Age: 44
Posts: 25
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by Scarebird
this is a bad idea from several angles:

1. 1979 Seville rotors are 5 on 5 bolt pattern for starters. And they are 11-3/8" in diameter. Your 81 Monte rotors are 10-1/2", so you will easily lockup the rears due to grooss bias mismatch.

2. Crossdrilled are ridiculous for the street; they are guaranteed to crack from stress risers between the vanes.

www.scarebird.com
He probably has WS6 Trans Am rotors (5x4.75). Similar setup.

Holes = cracks - slotted or solid is the way to go. Modern pads do not outgas like pads of the olds days.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 02-23-2007, 05:11 PM
Registered User
 
Last wiki edit: Wheelbase database Last photo:
Join Date: Jan 2007
Location: Virginia
Posts: 3,519
Wiki Edits: 1

Thanks: 6
Thanked 146 Times in 133 Posts
Quote:
Originally Posted by Scarebird
no. their job is to limit pressure AFTER a certain point is reached. when you stamp on the brake hard they kick in, but during normal stops, they allow full pressure to the rears, allowing the rears to help stop the car.
Maybe I'm misunderstanding what you're trying to say, but as I read it, that is confusing. Tilton has graphs showing the output pressure curves of their proportioning valves in their installation instructions here:

http://www.tiltonracing.com/pdfs/29.pdf

The output pressure will ramp up at the same rate as input pressure up to a preset pressure (usually a very low pressure) then at a certain point the ramp rate changes and output pressure becomes proportional to the input pressure but lower (hence the term PROPORTIONING valve). The peak output pressure is also always less than the peak input pressure. I think the confusion is in your statement that "during normal stops, they allow full pressure to the rears". I think what you mean is that under light braking, the pressures are the same, but under light braking you won't be locking up the rears anyway.

On factory units this proportioning is not adjustable, but the whole purpose of aftermarket adjustable units is to allow you to change the output to input ratio. Under NO condition does the rear brake see the full input pressure that the front sees when using a proportioning valve unless you back it off to the point that it's disabled.

Proportioning valves are used in disc/disc systems all the time to account for front/rear weight distribution. The factories leave them out when possible to save cost. Pickup trucks use load-sensing proportioning valves to change the front/rear bias depending on whether the truck is full or empty.

There's nothing magic about a proportioning valve. It does not change how it operates due to the rate of pressure rise. It is essentially a pressure regulator, but rather than limiting the output pressure to a fixed PSI, it is designed to reduce the output pressure to a percentage of the input pressure. Yes, you CAN use a proportioning valve to prevent premature lockup if you have bigger rotors on the back than the front. The only issue is that you're potentially wasting money installing those bigger rear rotors if you're just going to reduce their effectiveness by dropping the line pressure.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 02-23-2007, 07:26 PM
Registered User
 
Join Date: May 2006
Location: Alderwood,Washington
Posts: 14
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
well put. ..................
Reply With Quote Quick reply to this message

Recent Suspension - Brakes - Steering posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
67 chevelle 12 bolt fit in 70 chevelle? 70chevelle327 Transmission - Rearend 11 09-11-2006 07:52 AM
Cross Drilled Crank 35WINDOW Engine 3 02-14-2006 02:21 PM
Meaning of the iron cross? FASTCHEVY Hotrodders' Lounge 15 03-05-2004 11:01 PM
Can I make my own cross drilled rotors? jacobm99 Suspension - Brakes - Steering 4 03-01-2004 07:44 PM
Ford granada cross drilled rotors FAIRLANE DUDE Suspension - Brakes - Steering 3 03-08-2003 03:59 PM


All times are GMT -6. The time now is 06:12 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.