Author Topic: Changing rear end to disc brakes questions  (Read 2505 times)

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Offline 1977TASE

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Changing rear end to disc brakes questions
« on: March 13, 2007, 09:07:59 PM »
I bought another 1980 TA that was going to the scrap yard. It has 4 wheel disc I am thinking of installing on the 1977. Besides the brake lines, master cylinder, and booster is there any other items I should be concerned with? I'm also thinking of putting the 3.23's from the 77.
1977 TA SE W72 Hurst T-tops
1980 TA
1969 Cutlass S Convertible
1991 911 Carrera Cabriolet
Regular everyday boring cars for weekdays

Offline Rick

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Re: Changing rear end to disc brakes questions
« Reply #1 on: March 13, 2007, 10:18:15 PM »
The pedal and linkage is different for 4WD, from what I understand, so you'll want that as well.

Offline eroc022

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Re: Changing rear end to disc brakes questions
« Reply #2 on: March 14, 2007, 03:02:21 PM »
no pedal and linkage is still the same...but it looks like you have everything listed, only thing i dont know if you know about is gonna be the parking brake setup from the splitter back..
Eroc
Fixing the car that Restore A Muscle Car jacked up....

Offline Rick

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Re: Changing rear end to disc brakes questions
« Reply #3 on: March 14, 2007, 03:17:51 PM »
Are you sure they're the same?  I remember a discussion of that over on TAC -- seems like the holes in the pedal were different -- that was in the pre-crash stuff over there... :(

Offline eroc022

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Re: Changing rear end to disc brakes questions
« Reply #4 on: March 14, 2007, 03:19:45 PM »
what holes ? there is only a hole for the bolt to mount the pedal...and there is a stud pertruding out for the booster rod to connect to....
Eroc
Fixing the car that Restore A Muscle Car jacked up....

Offline Rick

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Re: Changing rear end to disc brakes questions
« Reply #5 on: March 14, 2007, 03:30:53 PM »
what holes ? there is only a hole for the bolt to mount the pedal...and there is a stud pertruding out for the booster rod to connect to....

The mounting location for the master cylinder push rod -- something about the distance from the pivot point being different for 4WD brake cars -- this is *memory* of something I've read -- I have front disks/rear drums on my car and the cars I've worked on, so this ain't first hand info.  I defer to Maltese Falcon and others who have done the rear drum to disk conversion, but I'm pretty certain they've mentioned differences.

Offline 1977TASE

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Re: Changing rear end to disc brakes questions
« Reply #6 on: March 14, 2007, 07:09:13 PM »
Thanks for the info. What do you have to do different from the splitter back?
1977 TA SE W72 Hurst T-tops
1980 TA
1969 Cutlass S Convertible
1991 911 Carrera Cabriolet
Regular everyday boring cars for weekdays

Offline eroc022

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Re: Changing rear end to disc brakes questions
« Reply #7 on: March 14, 2007, 07:13:45 PM »
Thanks for the info. What do you have to do different from the splitter back?

well the cables are different than a drum in legnths i believe
Eroc
Fixing the car that Restore A Muscle Car jacked up....

Offline logikfive

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Re: Changing rear end to disc brakes questions
« Reply #8 on: March 14, 2007, 09:15:36 PM »
what holes ? there is only a hole for the bolt to mount the pedal...and there is a stud pertruding out for the booster rod to connect to....

The mounting location for the master cylinder push rod -- something about the distance from the pivot point being different for 4WD brake cars -- this is *memory* of something I've read -- I have front disks/rear drums on my car and the cars I've worked on, so this ain't first hand info.  I defer to Maltese Falcon and others who have done the rear drum to disk conversion, but I'm pretty certain they've mentioned differences.

You are correct. The hole drilled in the pedal is in a different location for the 4WDB booster. I think you can still use the non 4WDB pedal if you chose to, but I would imagine the pedal feel would be better with the correct pedal.

'88 Conquest 2.6L/Turbo @22psi | '99 Durango 5.9L SLT Supercharged @8psi
'76 Trans Am 462ci | '78 Trans Am 455

Offline Rick

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Re: Changing rear end to disc brakes questions
« Reply #9 on: March 14, 2007, 10:06:19 PM »
You are correct. The hole drilled in the pedal is in a different location for the 4WDB booster. I think you can still use the non 4WDB pedal if you chose to, but I would imagine the pedal feel would be better with the correct pedal.

Ah!  Memory vindicated! :) :) :D

Offline eroc022

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Re: Changing rear end to disc brakes questions
« Reply #10 on: March 15, 2007, 09:55:15 PM »
ok sorry rick for doubting you....i just dont get what hole there is ?
Eroc
Fixing the car that Restore A Muscle Car jacked up....

Offline Rick

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Re: Changing rear end to disc brakes questions
« Reply #11 on: March 15, 2007, 10:51:21 PM »
It's below the pivot point -- one is lower than the other -- different positions for the two setups.  Over on TAC somebody (either Maltese Falcon or Joe Bays) had posted a side-by-side pic of the two.  Of course now that we NEED that pic it's gone in the crash... :( :( :(

Offline eroc022

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Re: Changing rear end to disc brakes questions
« Reply #12 on: March 15, 2007, 10:52:53 PM »
well ive got both so ill check it out....
Eroc
Fixing the car that Restore A Muscle Car jacked up....

Offline Grand73Am

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Re: Changing rear end to disc brakes questions
« Reply #13 on: March 16, 2007, 09:43:10 PM »
I also remember that the hole is in a different location on the pedal. I think the write-up was in the tips & tricks forum. I was hoping I had saved it somewhere, but I can't find it, so I guess I didn't.
And the rear parking brake cables are different for the rear discs.
Steve F.