Author Topic: Project snowball - questions about parking brake and rear disc conversion  (Read 422 times)

twov8sandat4

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Good morning everyone,

I have owned my 74 Trans Am for 31 years.  For the most part, I kept it up and enjoyed driving the daylights out of it  :D.  A couple of years ago, I started noticing the car pulling to one side when I stepped on the brakes, and the pedal was feeling soft.  I figured one of the calipers were frozen, and took both out and rebuilt them.  I tried bleeding the brakes after install, but the left didn't bleed.  Looked like the hose was junk.  Since I always wanted to go discs all around, I picked up a used rear disc brake conversion kit from a friend who was building a pro touring Camaro with full on Wilwood brakes, and didn't want the generic rears.  I also ordered a full stainless steel line kit from Central Firebird with new booster and master cylinder.

When the car was ordered new in MA, the dealer must have applied rubberized undercoating.  All along the driver's side where the brake line runs had surface rust from trapping moisture.  Since the fuel vapor line runs in the same clip as the brake line, I got a set of stainless steel vapor line to replace the original.

So I have run into a couple of issues I'd need some help or guidance.

1.  Does anyone make a hard line for the rear axle to mate to the calipers?  The kit came with junk hoses and junkier bent parts store hard lines.  The Firebird Central kit lines do not match to the calipers, and I don't know if i can re-bend stainless.  Even if I could, the fittings in the line do not match the banjo bolt threads in the caliper.  I got a set of stainless braided lines to mate to parts store lines that go to the junction tee, but they look tacky.  If no hard lines are available, can I make stainless braided lines from the caliper to the tee?  Would that be too long for braided lines?

2.  Do you have to remove the parking brake cable in order to replace the front to rear brake and vapor lines?  If so, how do you do it?  Both lines run over a bracket that holds the cable with a c-clip, but I can't figure out what happens after you remove that clip.

3.  has anyone made the parking brake work with aftermarket calipers? how did you do it?  Do the stock drum brake cables work or do you have to replace them with something else?

Thanks for any help you guys can give me.

Little Miss G Racing

darrylta

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Welcome to the DAT World, ie Drop Another Thousand!
Darryl

JJ 109

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Made the brake lines out of Nicopp.

It’s very easy, hand bendable. Flares easily also. All the fittings are available.

You can talk to Inline tube for the entire lines or just the components to make them.

For parking brake, lot of options too.

Check out the Tesla ebrake. EBay has a ton of them cheap.
JJ
76 pro tour project
Twin Turbo LS1
Detroit

ryeguy2006a

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I approached mine the same way that JJ mentioned. NiCopp lines and hand bent them myself. I welded some tabs to the rear axle to secure the flex lines and it worked great. Not sure if your rear disk is OEM style or not, but I used LS1 rear brakes for my conversion and found that the universal emergency brake kit from Speedway was perfect for me.


1976 Trans Am LS1, 6 speed, C5 Brakes, LS1 rear 12" brakes, and much more...SOLD
My Build: http://transamcountry.com/community/index.php?topic=24465.0

New project: 1968 Camaro LS6, T56, Speedtech, Hotchkis, DSE, Z51 13.4" front brakes, LS1 rear disks, etc.
http://transamcountry.com/community/index.php?topic=74591.0

twov8sandat4

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Thanks for the quick replies guys.

I'll check out all the suggestions.

thanks again  :)
Little Miss G Racing


MNBob

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I used flexible stainless lines to hook to the rear calipers when I did the Blazer rear disks.  That way you can replace the pads without bleeding the system.

I also used the NiCopp to make the lines.  Very easy to bend to what you want.
1979 TATA Extreme TKO .64
Hedman elite; Pypes 2.5; Borla XS; MSD 6A; Performer intake; open scoop; Sniper QJ;  110 Amp Alt; 4 core radiator/Mark VIII fan; RobbMc mini starter; subframe connectors; solid body mounts; fiberglass rear springs; poly sway bar and link bushings; 81 master; D52’s; Blazer disks; 225/60 & 235/60 17's TrueContact's; relays for PW, PDL, lights; keyless entry

twov8sandat4

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I ended up using a spare set of flexible stainless lines for the rears and had my friend shorten the prebent stainless lines to make them work.  All the brake lines are now plumbed, and master cylinder bench bled and installed along with a new booster.

I am working on taking the parking brake out now.  I sprayed some PBBlaster on the bolts holding the cables to the frame next to the front leaf spring eyes.  The driver's side cable is too long since the caliper sits in front of the rear axle.  The passenger side might make it, as the caliper is behind the axle 

Thanks for all your help.
Little Miss G Racing

twov8sandat4

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The following should be a straightforward process, but for the life of me I can’t figure out what is going on.

As mentioned earlier, I replaced the entire braking system including booster, master cylinder, proportioning valve, and all the lines. The rears were converted to discs.  The booster/master cylinder/proportioning valve are the generic reproduction units (with the Delco stamp) that most vendors are selling.  They’re supposed to be for disc/disc setup.

My mechanic friend bench bled the master cylinder for me, and he told me to keep the bleeder at the rear caliper open to help fill the new lines going to the rear to help with bleeding.  I have had the bleeder open for 4 days now, and the fluid level has not gone down any in the master cylinder. I also tried bleeding with the help of wifey, but again fluid was not moving.  There was a leak where the rear line connects to the proportioning valve that I fixed by tightening the fitting, so fluid is getting at least to that point.

Since I have never done a complete brake system, does it take a long time and patience to bleed a brand new system, or is there an issue I need to address?

Thanks for any help.
Little Miss G Racing

langss

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The following should be a straightforward process, but for the life of me I can’t figure out what is going on.

As mentioned earlier, I replaced the entire braking system including booster, master cylinder, proportioning valve, and all the lines. The rears were converted to discs.  The booster/master cylinder/proportioning valve are the generic reproduction units (with the Delco stamp) that most vendors are selling.  They’re supposed to be for disc/disc setup.

My mechanic friend bench bled the master cylinder for me, and he told me to keep the bleeder at the rear caliper open to help fill the new lines going to the rear to help with bleeding.  I have had the bleeder open for 4 days now, and the fluid level has not gone down any in the master cylinder. I also tried bleeding with the help of wifey, but again fluid was not moving.  There was a leak where the rear line connects to the proportioning valve that I fixed by tightening the fitting, so fluid is getting at least to that point.

Since I have never done a complete brake system, does it take a long time and patience to bleed a brand new system, or is there an issue I need to address?

Thanks for any help.
You could try a Mityvac https://www.harborfreight.com/mityvac-vacuum-pump-39522.html or one of the other systems that HF sells. I had a similar issue and used an older version to pull the fluid through the lines and caliper. It worked after several days of having assorted people help pumping the brake pedal. I never did find out what was the problem, but it fixed it for me. I hope this helps.

twov8sandat4

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You could try a Mityvac https://www.harborfreight.com/mityvac-vacuum-pump-39522.html or one of the other systems that HF sells. I had a similar issue and used an older version to pull the fluid through the lines and caliper. It worked after several days of having assorted people help pumping the brake pedal. I never did find out what was the problem, but it fixed it for me. I hope this helps.

That's a pretty good idea. I'll pick one up today and give it a shot.

Thanks  :smile:
Little Miss G Racing

twov8sandat4

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This is a venting post, so I apologize in advance...   :-)

So the working calipers I got as part of the used rear disc conversion setup were frozen solid.  I got the Mightyvac as suggested which worked great.  However, as much as I tried, neither rear caliper was bleeding or piston was moving.  I pent yesterday trying to chase down new calipers after figuring out those were 79-85 Eldorado units.  None of the chainstores had any here.  And to add insult to injury, the brand new lines going from the over the axle T to both wheels started leaking.  The brand new "rear disc conversion stainless lines" were actually for drum brakes, so i had to get the spare front flex hoses and hard lines to make them work....  where the flex meets the hard line on both sides now leak...  i think I am going to get stainless flex hoses from the axle T all the way to the calipers ( 24' left, 36" right.) Unless someone has a way to use brake line that will mate to the banjo fitting on the calipers.

Thanks.

Little Miss G Racing

langss

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This is a venting post, so I apologize in advance...   :-)

So the working calipers I got as part of the used rear disc conversion setup were frozen solid.  I got the Mightyvac as suggested which worked great.  However, as much as I tried, neither rear caliper was bleeding or piston was moving.  I pent yesterday trying to chase down new calipers after figuring out those were 79-85 Eldorado units.  None of the chainstores had any here.  And to add insult to injury, the brand new lines going from the over the axle T to both wheels started leaking.  The brand new "rear disc conversion stainless lines" were actually for drum brakes, so i had to get the spare front flex hoses and hard lines to make them work....  where the flex meets the hard line on both sides now leak...  i think I am going to get stainless flex hoses from the axle T all the way to the calipers ( 24' left, 36" right.) Unless someone has a way to use brake line that will mate to the banjo fitting on the calipers.

Thanks.
Sorry to hear of all the troubles...That as it turned out was the same problem I was having only I didn't know it at the time. That Mityvac sucked the fluid through that frozen caliper and after a little rubber mallet massage it worked just fine. I know there are conversion fittings and hoses made for the problem you are having, so someone will have the answer you need.

twov8sandat4

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Sorry to hear of all the troubles...That as it turned out was the same problem I was having only I didn't know it at the time. That Mityvac sucked the fluid through that frozen caliper and after a little rubber mallet massage it worked just fine. I know there are conversion fittings and hoses made for the problem you are having, so someone will have the answer you need.

Thanks. One of the caliper pistons moved, but the other is frozen solid.  Nothing was making it budge. I decided rather than mess with it, I got a pair of rebuilts from NAPA.  I also ordered a couple of stainless flex hoses from Summit to replace the contraption I have.

The “budget” disc conversion is not turning out to be one  :lol:.  At least this should work for the foreseeable future for me.

Thanks again.
Little Miss G Racing


 

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