[SteveGB21]

I was wondering if a rear disc brake setup off an '86 Firebird will fit my '70 Lemans? Also, would I still be able to keep the 14" wheels, or would I need to upgrade to 15" wheels? If that is the case, I might as well, since the tires are in need of replacing.

[Captainofiron]

Originally Posted by SteveGB21

I was wondering if a rear disc brake setup off an '86 Firebird will fit my '70 Lemans? Also, would I still be able to keep the 14" wheels, or would I need to upgrade to 15" wheels? If that is the case, I might as well, since the tires are in need of replacing.

Im not sure if it will fit your rear end, when I was looking for the backing plates to use a 4th gen rear disk setup

if I remember right, the 4th gen rear setup is pretty close to the 1LE 3rd gen rear setup

I know for sure the 4th gen rear disk will not clear 14s, you need at least 15s (I think the rotor is around 11.8 or so in diameter)

Im pretty sure the the 3/4th gen rear axle flange pattern is the same essentially as the old 8.2 BOP axle flange

[Donovan]

Originally Posted by SteveGB21

I was wondering if a rear disc brake setup off an '86 Firebird will fit my '70 Lemans? Also, would I still be able to keep the 14" wheels, or would I need to upgrade to 15" wheels? If that is the case, I might as well, since the tires are in need of replacing.

Been awhile since I owned a set for this reason. I recall that there are actually 2 different styles of rear disk but that didn't come until 89? The set you have are about 10" rotors and are highly likely to fit inside a 14" rim.

You will need to figure out how to retain the axle with a custom plate or spacer since your diff is bolt in axles. The calipers are cast iron and the same design ratcheting e-brake setup on the 79-81 trans ams, but smaller.

For me this setup is too finicky and would not confer enough benefit over drums for all the work.

If you have a chevy rear diff it would be a bolt on and you'd need to figure out how to connect the e-brake cables.

For the effort I would put 15" rallys on the car and get a set of disks from an S10/Trailblazer. It's a much better design, lighter and easier to work on with a drum in hat e-brake. You still need a spacer.. There is a member talking about this in the suspension forum right now.

[SteveGB21]

I was wondering. So It would be best for me to look for the '88 and later for the 3rd Gen, as well as even one off a 4th Gen, right? What's good about a 4th Gen, I can ALWAYS go back to my '02 Firebird to reference it. Saw a '99 Firebird at that same U-Pull-It salvage yard. Thanks. This will help.

So 15's I would need to convert to, correct? Was planning on it, since my 14x7's are in need of new tires, as well as new studs for the axles and even converting to a posi-traction differential.

[Captainofiron]

Originally Posted by SteveGB21

I was wondering. So It would be best for me to look for the '88 and later for the 3rd Gen, as well as even one off a 4th Gen, right? What's good about a 4th Gen, I can ALWAYS go back to my '02 Firebird to reference it. Saw a '99 Firebird at that same U-Pull-It salvage yard. Thanks. This will help.

So 15's I would need to convert to, correct? Was planning on it, since my 14x7's are in need of new tires, as well as new studs for the axles and even converting to a posi-traction differential.

Actually the LS 4th gens have a different rear disk design than the LT

If I remember right the LS rear disks will not fit under 15 inch wheels, but the LT disks will.

The LT have a parking brake lever on the caliper, but the LS disks have the parking brake drum inside the rotor

Here is an LS setup


Here is the LT


Check out this link
http://www.carcraft.com/techarticles...kyard_builder/

[Overkillphil]

I prefer the LS type with the parking brake inside the hub of the rotor. I have a 2nd gen WS6 set up on my 72 Formula and the corkscrew setup in the rear calipers is not a great design. It's a pita to get right and never really grabs tight enough on a steep hill. I don't like putting the weight of the car on the trans either so I'd be interested in knowing what's involved in using an LS era rear disc setup on 2nd gen as well as 68-72 A-body's.(?)

[Captainofiron]

Originally Posted by Overkillphil

I prefer the LS type with the parking brake inside the hub of the rotor. I have a 2nd gen WS6 set up on my 72 Formula and the corkscrew setup in the rear calipers is not a great design. It's a pita to get right and never really grabs tight enough on a steep hill. I don't like putting the weight of the car on the trans either so I'd be interested in knowing what's involved in using an LS era rear disc setup on 2nd gen as well as 68-72 A-body's.(?)

basically all you have to do is find out of the 4th gen rear axle flange is the same as your axle and then find the caliper plates and then just walk in to the autoparts stores and buy the brake parts, from what I understand the cables you have can be either adapted or you can buy adapters

for what its worth the 4th gen rear axle flange is the same as my BOP 8.2

[SteveGB21]

Thanks. This helps much. Unfortunately, I did NOT see the 88 to 97 F-Body rear disc brakes (aluminum ribbed caliper). Only saw the earlier ones and the later ones. Will keep looking for the meantime. Thanks much.

[MNBob]

I have a 2nd gen WS6 set up on my 72 Formula and the corkscrew setup in the rear calipers is not a great design. It's a pita to get right and never really grabs tight enough on a steep hill. I don't like putting the weight of the car on the trans

X2, I have to keep a wheel chock in the car so I can park on any type of incline. Does anybody know if the 4th gen lever style calipers are more effective?

[Donovan]

Originally Posted by MNBob

X2, I have to keep a wheel chock in the car so I can park on any type of incline. Does anybody know if the 4th gen lever style calipers are more effective?

Avoid this style all together. Use the trailblazer rear disks that fit in the same wheel.

[MNBob]

That's what I suspected, thanks for the input. Yes, I am planning the Trailblazer set up for an install this summer. Not only a functional parking brake, but a little bigger disks as well, always a good thing.

[SteveGB21]

But, I have seen the Trailblazer, Envoy, 02 Bravada, Rainer have a 6 lug bolt pattern. This would be the S10 chassis ones with 2WD, correct? Was also wondering about that conversion as well.

[MNBob]

Yes, the parts can come from an S10 and 3 or 4 other models. I think the 2 wheel drives have the 5 x 4.75 lug pattern.

There is a very detailed write up here:

S10-Blazer rear disc conversion

[Captainofiron]

Originally Posted by MNBob

X2, I have to keep a wheel chock in the car so I can park on any type of incline. Does anybody know if the 4th gen lever style calipers are more effective?

the 4th gen LT type arent bad, its very mountainous here and I have parked on some serious inclines and havent had problems

[Captainofiron]

Originally Posted by SteveGB21

But, I have seen the Trailblazer, Envoy, 02 Bravada, Rainer have a 6 lug bolt pattern. This would be the S10 chassis ones with 2WD, correct? Was also wondering about that conversion as well.

If I remember right, the rear axle in the 4th gen is the same axle used on the S10 and Astro vans

[SteveGB21]

Captain Of Iron,

I heard the early Astro/Safari vans have the 2WD Truck/B-Body 5 lug 5" bolt pattern. Then in 2001/2002, it changed to the 6 lug bolt pattern that the earlier 4WD models used (and then the 99 to present Silverado/Sierra trucks), up until 2005 when GM ceased production of their RWD/AWD minivans (more trucklike than carlike). The Blazer/Jimmy and S10/Sonoma that were 2WD did have the same 5 lug 4.75" bolt pattern.
So you live up the freeway from me (I-10)? Cool. There are some hills and even the mountains (same in El Paso, depending where you're at). Did notice some junkyards with older cars in Las Cruces. I do need to check there. Also have seen Alamogordo has some as well.

[MNBob]

There is a thread on using 98-02 rear brakes on 2nd Gen TA’s here:

Rear Disc brake conversion

One poster in the above says that he has done this rear conversion four times and it fits 15x8 snowflake and Turbo wheels.

Both the LS and the S10 Blazer systems are great upgrades with the hat parking brake system. However, if you want to use mostly new parts, I found the LS system is considerable cheaper.

[Captainofiron]

Originally Posted by SteveGB21

Captain Of Iron,

I heard the early Astro/Safari vans have the 2WD Truck/B-Body 5 lug 5" bolt pattern. Then in 2001/2002, it changed to the 6 lug bolt pattern that the earlier 4WD models used (and then the 99 to present Silverado/Sierra trucks), up until 2005 when GM ceased production of their RWD/AWD minivans (more trucklike than carlike). The Blazer/Jimmy and S10/Sonoma that were 2WD did have the same 5 lug 4.75" bolt pattern.
So you live up the freeway from me (I-10)? Cool. There are some hills and even the mountains (same in El Paso, depending where you're at). Did notice some junkyards with older cars in Las Cruces. I do need to check there. Also have seen Alamogordo has some as well.

Yea Im up here in Las Cruces.

It could be that the Astro vans are 5x5, Im not sure

[77HANDMEDOWN]

I have the ls rears and they will not fit my stock 15's but I have 17s so who cares. Supposedly the s10 do fit stock 15's if yo want to run 15s still.

My stock 10 bolt had a ton of axle play and would have had a ton of pad knock back had I not gotten a Detroit trutrack where I could "tune" the end play out of the axles.

[MNBob]

I have the ls rears and they will not fit my stock 15's but I have 17s so who cares.

What kind of 15 inch wheels did you have? The rally's?

17's are nice, but I want to keep the TATA look with the Turbo wheels.