The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 09-27-2007, 11:45 AM   #1
Custom 68
Registered User
 
Custom 68's Avatar
 
Join Date: Nov 2001
Location: Springfield, MO
Posts: 2,939
Cool Rear disk brake conversion WHY? any pros?

Not to start a fight or anything because I would like (I think) to convert to the rear disk but why? I mean on my 68 I converted to disk up front with a new prop valve. I have added an adjustable proportioning valve to the rear because they are so touchy. I had to do a panic stop or attempt to stop the other day and my rear locked up and sent me into a slide? I have since been adjusting the rear pressure to tone this down, I now feel I am relying soley on my front brakes to stop with very little pressure going to the rears.
so my question is 2 fold first do I have something setup wrong on my brakes? of course you dont know what all I have but it is power with a disk\drum proportioning valve and a conversion from GMC Pauls. and secondly, if my drum brakes will lock up (easily) what benifit is seen from the disk in rear?

Again I know there are vendors on here selling these so I am not slamming them I just am wondering is it more of a change because it sounds cool or is there benifits?
Thanks
Dave
__________________
Dave
1968 Custom Chevy with turbo charged 5.3 gen III 4l80e swap
1967-71 GMC 3/4 ton long step 4x4 (not sure what year exactly?)
"A good friend will bail you out of jail...but a true friend will be sitting next to you saying "that was frekin awesome".
"If it doesn't fit force it...If it breaks then it needed to be replaced anyway!"
Custom 68 is offline   Reply With Quote
Old 09-27-2007, 12:29 PM   #2
herb101
Used Register
 
herb101's Avatar
 
Join Date: May 2005
Location: Live Oak, TX
Posts: 379
Re: Rear disk brake conversion WHY? any pros?

For me, it's all about rotation mass and leverage. My Blazer is up in the air 6" and it's running on 35's. A rear disk conversion will offer more muscle to slow that extra spinning weight that's been added. I have already done a new booster (1-ton), new master cylinder (1-ton) and new calipers, new rotors, new braided lines, new pads and shoes, and new wheel cylinders, but even with all that, my breaks still need help.

On your situation, I think there is still an issue with bias. There should not be a dramatic difference in lock-up, but the rear should lock just slightly before the fronts.

Herb
herb101 is offline   Reply With Quote
Old 09-27-2007, 03:10 PM   #3
Longhorn Man
its all about the +6 inches
 
Longhorn Man's Avatar
 
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,690
Re: Rear disk brake conversion WHY? any pros?

if you havve a street driven 2 wheel drive 1/2 ton truck, that is unloaded, or hardly loaded most of the time, converting to discs would be a waste of time. They will do very little to help you stop and they weigh more.
Longhorn Man is offline   Reply With Quote
Old 09-27-2007, 03:18 PM   #4
jkade
Senior Member
 
jkade's Avatar
 
Join Date: Nov 2005
Location: AL
Posts: 2,517
Re: Rear disk brake conversion WHY? any pros?

Quote:
Originally Posted by Longhorn Man View Post
if you havve a street driven 2 wheel drive 1/2 ton truck, that is unloaded, or hardly loaded most of the time, converting to discs would be a waste of time. They will do very little to help you stop and they weigh more.
I will have to disagree with that. I have 72 front and implala disc on the rear of my 67 and it will stop on a dime and not lock up the rear tires. I am running 20's all the way around so that might have something to do with it but I think it is a great investment and you can put a kit together for less than $250 if you shop around.
jkade is offline   Reply With Quote
Old 09-27-2007, 04:19 PM   #5
Custom 68
Registered User
 
Custom 68's Avatar
 
Join Date: Nov 2001
Location: Springfield, MO
Posts: 2,939
Re: Rear disk brake conversion WHY? any pros?

Andy, that was kindof the direction I was pointing to also, my tires are 275/15/60 so they are not as heavy as say jkades 20s or herbs 35s so maybe that is where the difference is made?
I have fought or had concerns with my rear brakes for quite a while. I will keep digging but keep the coments coming!
thanks guys
Dave
__________________
Dave
1968 Custom Chevy with turbo charged 5.3 gen III 4l80e swap
1967-71 GMC 3/4 ton long step 4x4 (not sure what year exactly?)
"A good friend will bail you out of jail...but a true friend will be sitting next to you saying "that was frekin awesome".
"If it doesn't fit force it...If it breaks then it needed to be replaced anyway!"
Custom 68 is offline   Reply With Quote
Old 09-27-2007, 05:06 PM   #6
SactoJim
Registered User
 
SactoJim's Avatar
 
Join Date: Oct 2005
Location: Sacramento, CA
Posts: 1,970
Re: Rear disk brake conversion WHY? any pros?

I put rear discs on mine and to be honest, I'm not sure if they work better or not, but I'm sure they didn't hurt the way it stops.

Just take a look at the OEM's......I don't think there are too many new vehicles (including trucks) that don't have rear discs, which says something to me.

Sometimes some of the things we do to our trucks doesn't have to make sense and besides....rear discs are kinda cool!
__________________
72 Cheyenne SWB Fleet
Nut & bolt frame off in progress...99.9999%
- supercharged 383
- 4 wheel discs
- relocated fuel tank
-

My Build Thread
SactoJim is offline   Reply With Quote
Old 09-27-2007, 05:08 PM   #7
herb101
Used Register
 
herb101's Avatar
 
Join Date: May 2005
Location: Live Oak, TX
Posts: 379
Re: Rear disk brake conversion WHY? any pros?

Quote:
Originally Posted by SactoJim View Post
I put rear discs on mine and to be honest, I'm not sure if they work better or not, but I'm sure they didn't hurt the way it stops.

Just take a look at the OEM's......I don't think there are too many new vehicles (including trucks) that don't have rear discs, which says something to me.

Sometimes some of the things we do to our trucks doesn't have to make sense and besides....rear discs are kinda cool!
I think GM has actually stopped discs on the pick-up line (at least the heavier ones). {flamesuit on - I said THINK - lol}

Herb
herb101 is offline   Reply With Quote
Old 09-27-2007, 05:51 PM   #8
SactoJim
Registered User
 
SactoJim's Avatar
 
Join Date: Oct 2005
Location: Sacramento, CA
Posts: 1,970
Re: Rear disk brake conversion WHY? any pros?

Think you're right Herb. Don't recall seeing discs on heavier trucks.
__________________
72 Cheyenne SWB Fleet
Nut & bolt frame off in progress...99.9999%
- supercharged 383
- 4 wheel discs
- relocated fuel tank
-

My Build Thread
SactoJim is offline   Reply With Quote
Old 09-27-2007, 06:28 PM   #9
PanelDeland
I am a Referee of life.
 
PanelDeland's Avatar
 
Join Date: Jun 2000
Location: Greensboro N.C.
Posts: 13,992
Re: Rear disk brake conversion WHY? any pros?

I doubt there's much advantage to them since the rear is usually light unless it's a work truck.The main thing I see for going with them is if running big open style wheels.They just look cool.However if the drums are painted and match or contrast with the paint on the truck they look just as good to me and I consider it foolish to spend money on a "Hot Rod" that doesn't make it perform better.
__________________
The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion.
You can't fix stupid,not even with duct tape.
"My appearance is due to the fact that "GOD" does punish you for having too much fun!"
Barrett-Jackson has perfected alchemy,they make rust into gold!
"You can lead a horse to water but you can't saddle a duck"
"Cleverly disguised as a 'Responsible Adult'
"Sometimes your Knight in shining armor is just a retard in tinfoil"
PanelDeland is offline   Reply With Quote
Old 09-27-2007, 07:13 PM   #10
1fun71
Registered User
 
1fun71's Avatar
 
Join Date: Jan 2007
Location: Kansas
Posts: 119
Re: Rear disk brake conversion WHY? any pros?

I have a 07' GMC Sierra new body style GMT900 I believe is what they call the half ton now. It has drums on the rear.
1fun71 is offline   Reply With Quote
Old 09-27-2007, 09:14 PM   #11
Custom 68
Registered User
 
Custom 68's Avatar
 
Join Date: Nov 2001
Location: Springfield, MO
Posts: 2,939
Re: Rear disk brake conversion WHY? any pros?

Thanks guys, my Tahoe has rear disk but I do think they quit doing that also the newer stuff also has ABS so that may help some?. but regardless they are cool that is probably why I have been looking and asking
I will try to work on mine some more, I am just not happy with the way they stop I may remove the adjustaable valve maybe that is getting me?
thanks
Dave
__________________
Dave
1968 Custom Chevy with turbo charged 5.3 gen III 4l80e swap
1967-71 GMC 3/4 ton long step 4x4 (not sure what year exactly?)
"A good friend will bail you out of jail...but a true friend will be sitting next to you saying "that was frekin awesome".
"If it doesn't fit force it...If it breaks then it needed to be replaced anyway!"
Custom 68 is offline   Reply With Quote
Old 09-27-2007, 11:59 PM   #12
N2TRUX
Happy to be here
 
N2TRUX's Avatar
 
Join Date: Mar 2000
Location: Cypress, TX
Posts: 39,021
Re: Rear disk brake conversion WHY? any pros?

The reason GM quit putting discs on the rear of their 1/2 ton trucks is because they were too cheap to do it correctly. They put too small of a disc in the rear and had problems with warping rotors.

Having had multiple trucks with rear discs both converted and factory I can attest that rear disc is the way to go. It must be done correctly, with the right size rotor and caliper, but it offers a huge advantage over drum brakes.

The common misconception is that drum brakes work just fine because they can be made to lock up. That will only cause you to skid, and we all know that is counter productive to stopping.

If you use the proper components, and the proportioning valve is set with the correct bias rear discs will greatly improve your braking ability...
__________________
Follow me on Facebook and Instagram @N2trux.com

Articles-

"Jake" the 84 to 74 crewcab

"Elwood" the77_Remix

85 GMC Sierra "Scarlett"

"Refining Sierra"

Last edited by N2TRUX; 09-28-2007 at 12:00 AM.
N2TRUX is offline   Reply With Quote
Old 09-28-2007, 09:53 AM   #13
whatnow123
Registered User
 
whatnow123's Avatar
 
Join Date: Oct 2006
Location: Arizona
Posts: 835
Re: Rear disk brake conversion WHY? any pros?

I put rear disks on mine, I haven't driven it yet so I don't know if there was an improvment over drums, but I did it becuase of looks with my wheels.
Attached Images
 
__________________
67 Short Step, 355, 700R 4.11 posi rear, 4/6 drop Discs on all 4 corners.

Build thread:
http://67-72chevytrucks.com/vboard/s...d.php?t=219094
whatnow123 is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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

Forum Jump


All times are GMT -4. The time now is 01:54 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com