Disc brake rear from a 80 Trans Am some thoughts

[maldo]

I pulled a mint 80 disc brake rear some time ago for my 80 Camaro Z/28.

I am still up in the air of which brake system i am going with in the front)

I see tons of newer reaer disc brake convertions.. these days. wanted to know your opinon (wheather i should use the disc brake set from the T/A go with the newer stuff.

[Apogee]

Just my $0.02, but we started out selling kits based on the late 70's and early 80's Cadillac calipers (interchangeable with the 79-81 F-body stuff) and even in mint condition, they don't hold a candle to the C5/C6 based kits we currently offer with respect to performance and I imagine that's going to be the case with most of the other performance aftermarket kits available today as well. Aside from having an integrated parking brake mechanism and fitting inside of 15" wheels, they are not the greatest caliper design and tend to be finicky at best IMO.

That said, what level of performance do you want or need? How large of wheels are you planning on running? Do you have a brake budget, and if so, how big is it? These are all good questions to consider since no two people or builds are the same.

Tobin
KORE3

[10Seconds]

Dont forget the new Wilwood setup for the 2nd gens, its a Dynalite 6 piston front and 4 piston rear setup, I am getting ready to order it for my 78 trans am.

And forget the TA rear, junk it and get a 9-inch, its what I did. :)

[redfire69]

You'll need the 4 wheel disc proportioning valve for that setup to work...fyi only

[70bird]

The 79-81 rear discs work well for a street car and "spirited" street driving. Definitely better than drums. If your plan doesn't include racing on a track they will work nicely. Same for the 10 bolt, just depends on what you want the car to do, and your budget.
If it's what you have already, use them, it will be a marked improvement over the drums.

[Skip Fix]

So Tobin why do the C5 rears work better than the TA calipers? Don't they have ALOT smaller piston-or using a larger rotor to compensate? Both are single pistons and floaters. I'll agree they can be tempermental and not the best design. I would assume braking design is a combo of rotor size for leverage and surface area for cooling and applied torque from line psi on the piston Sq In.

A autocross buddy with a C4 always loved how my TA handled and brakes worked with them when he drove it. Knock on wood my calipers have been workign great for almost 20 years. I do think the silicone fluid has helped and never a spongy pedal either.

Mine has been pushing high 10s for awhile so the 10 bolt can handle plenty of power also.Upgrade with some 30 spline axles and you got a pretty stout one unless you are lauching with 10.5" slicks alot.

[ks71z28]

I have use my car for auto cross and track use for years with caddy 11" discs in the rear and 12 B-body in the front. I personally have NEVER touched the rear calipers in the 15 years they have been on the car. Up front I use a Wilwood GMiii aluminum replacement caliper, it is same just lighter. The pads you choose make the most difference on the track, i use Hawk HPS, they are noisy and dusty, but work great when hot. My car stops from 60 mph at 135', a base line car with a "stock" set up stopped at 150'. Tires seemed to be the biggest limiting factor. Just my 2c, save your money. I am upgrading my brakes in the near future, but because with slicks on the car I am running much faster, and I will be removing the bower booster also (for beter feel)

Keith

[Apogee]

My main complaint regarding the T/A calipers is the fact that the parking brake mechanism is integral to the proper functioning of the caliper itself, so if the parking brake has issues, then it can negatively impact caliper performance and function. Piston area of the T/A caliper is larger at about 51.5mm if I'm not mistaken, versus 45mm for the C5 calipers and 43mm for the C6 variety. The C5 rotor is only about an inch larger than the T/A rotor (12" versus 11.18"), or about 7%, so the T/A should generate more brake torque given the same pressures...but brake torque isn't everything as anything beyond lockup isn't gaining you anything.

Smaller pistons typically give better driver feedback and control as the system should be designed to provide the higher pressures required to achieve the desired brake torques. The larger the working range of pressure, the easier it is to modulate your brakes.

If you've got a "good" set of T/A calipers and can't justify upgrading the front brakes at the same time, I'd run the T/A's and then spend the money on the front when funds allow as that should net you the most braking performance for the least cost.

Tobin
KORE3

[maldo]

My main complaint regarding the T/A calipers is the fact that the parking brake mechanism is integral to the proper functioning of the caliper itself, so if the parking brake has issues, then it can negatively impact caliper performance and function. Piston area of the T/A caliper is larger at about 51.5mm if I'm not mistaken, versus 45mm for the C5 calipers and 43mm for the C6 variety. The C5 rotor is only about an inch larger than the T/A rotor (12" versus 11.18"), or about 7%, so the T/A should generate more brake torque given the same pressures...but brake torque isn't everything as anything beyond lockup isn't gaining you anything.

Smaller pistons typically give better driver feedback and control as the system should be designed to provide the higher pressures required to achieve the desired brake torques. The larger the working range of pressure, the easier it is to modulate your brakes.

If you've got a "good" set of T/A calipers and can't justify upgrading the front brakes at the same time, I'd run the T/A's and then spend the money on the front when funds allow as that should net you the most braking performance for the least cost.

Tobin
KORE3

Thank Guys for the input ... i am on a tight budjet and working with parts i already have in m stock pile.... as for the quote above (yes i remember years ago i had propblom with the rear calipers on my 80 t/a and had to replace on caliber becasue the parking park was frozen (could not twist the piston back in) .......

Is there any alternative to calibers that can be used on my (t/a axle set up) that bolt on with out any mods ?

[Skip Fix]

yep metric front calipes from around a 81 mid size. No E brake but same bolt pattern. The hose will need some tweaking as it is in a slightly different spot on the caliper.
Wilwood has aluminum Metrics I am going to use on the drag car just to not worry about the issues Tobin brought up but keep the brackets and rotors I had extra from the TA.

"but brake torque isn't everything as anything beyond lockup isn't gaining you anything.

Smaller pistons typically give better driver feedback and control as the system should be designed to provide the higher pressures required to achieve the desired brake torques. The larger the working range of pressure, the easier it is to modulate your brakes."

Good points, why the whole package from MC diameter, pedal ratio, booster assist amount, piston size &#, rotor diameter, and tire diameter all play a factor. The factory engineers have alot of variables they work through for a system, although the ones who did my 97 Chevy truck screwed up! Hardly any pressure to the rear drums in those things, 170K miles on the factory shoes!

[71FormulaRA3]

'98 and up S10/S15 rear disc brakes work great. Works without axle housing mods and has a built in E-brake too.
http://www.highperformancepontiac.com/tech/hppp_0606_pontiac_rear_disc_brakes/index.html
and here http://www.nastyz28.com/forum/showthread.php?t=109454&highlight=disc+brake

I bought the parts for mine from a salvage yard for $150.

[WS6]

personally, I hate my rear discs on my 79TA and it came from the factory this way. I have never been able to get the brakes to be worth a damn in years. I say ditch it for something more simple. The rear end itself is very strong and will handle almost anything you can throw at it. Maybe you can keep the rear end and get an after market setup for it

[maldo]

I agree that the rear disc calibers for those years can be a pain in the butt...
I already have the rear out of the car (it in perfect conditon calibers work and all) but would like to upgrade the calibers if possible before i install the rear .... I am trying to make this a painless as possible

Which calibers are a direct bolt on if any and if i need different baking plates to make a newer set of calibers work (part numbers etc .. year make model of a car i can pull from etc )
I want it where i can go down to my local parts store if i need parts or if i need replacment stuff in the future
Its nice to have the aftermarket stuff but sometimes it a pain to get parts right away if you need it.
any one out there has pictures for my car with the disc bake set up already done (i would like to have as much deatail as possible.. i see allot of stuff but no part numbers etc) sorry dont mean to be a pain :banghead:

[CarlC]

Tobin,

What about the F/R piston area ratio? Those early calipers usually have a pretty large area vs. the later model OE and AFT parts.

[Skip Fix]

81 Malibu front right calipers are a swap or Wilwood metric calipers are direct bolt on. Neither has an E brake if needed.

[maldo]

81 Malibu front right calipers are a swap or Wilwood metric calipers are direct bolt on. Neither has an E brake if needed.


ok cool so these will bolt on to my backing plates without a problem right?

[Skip Fix]

They have on a set I have!

[maldo]

They have on a set I have!

do you have pictures of your set up?

[Skip Fix]

I can snap some of the metric Wilwoods on it this weekend.

[Skip Fix]

OK here are two views of the Metric Wilwoods. The brake lines wil need to be modified. Possibly a short flex line. One other issue I just noted is the caliper bolts that it slides on are 0.030 smaller than the outside holes. They do not use a rubber O ring to take up slack like the factory ones do so the caliper can rock slightly. I'll have to call Wilwood and see if that is an issue but I can rock it by hand.

As you can also see the float is already got the bolt head into the caliper. The factory rear calipers look a little more centered. But I did have new taper bearing ends welded on the 12 bolt.

[DAK]

They do not use a rubber O ring to take up slack like the factory ones do so the caliper can rock slightly. I'll have to call Wilwood and see if that is an issue but I can rock it by hand.


I bought a caliper o-ring set from the local parts store and I used a dremel with a ball bit to cut grooves for the o-rings.

https://static1.pt-content.com/images/noimg.gif

[maldo]

bump

[Tpichevy]

Did you end up keeping the rear TA disk setup? If so are you happy with it