Hi, I'm hoping for some advice about fixing my rear brakes. Despite replacing the rear callipers, and making sure the recall kit is fitted, I cannot get the parking brake to reliably work well enough for the annual safety tests. This has been going on every year for the last 17 years, and I've had enough.

I have a 85 iroc with J65 discs and would like to replace them with something that has a drum parking brake like the Baer 4302390B however these seem to require removing the axles and the Haynes manual suggests that touching the Borg-warner posi is a no-no. I don't particularly want to end up having to replace the whole axle. Is there an option that doesn't need the axles removed?

 

No rear conversion that I know of where you don't have to remove the axles. Besides, you'll have to remove the axles to get the old brakes off. Otherwise, you'll have to keep fighting your stock brakes.

I'm surprised it's a 9-bolt. Pontiacs received 9-bolts in 85, but I'd have thought Chevies got 10-bolts. But no matter, because there's nothing dangerous about removing 9-bolt axles.

If your car still has its 16" wheels, then you'll be limited to 12" rear brakes. And you'll have to replace the axle hardline on the driver's side, preferably with an 89-92 hardline, which is simple.

If it's a 10-bolt, then look for a 98-02 4thgen rear brake conversion, commonly referred to as LS1 brakes. Those have drum parking brakes. The conversion backing plates will probably have to be found used, but the calipers and brackets can be purchased as "new" remanufactured parts from auto parts stores. This will probably be the cheapest conversion, if you can find the parts. However, this conversion won't fit 9-bolts without some modifications to the backing plates.

For other conversions, 9 and 10 bolt, Big Brake Upgrade has a lot to choose from. He doesn't offer the LS1 rear conversion, but here's a link to his four Rear Brakes pages. There's a C5/C6 conversion which has a drum parking brake, and there are later conversions too, such as 5thgen, 6thgen and C7 conversions too. Not sure how many are as small as 12" though, other than standard C5/C6 rear brakes. Scroll through them and then get in touch with Scott. Scott IS Big Brake Upgrade. Very nice guy, very helpful.
Rear Brakes (bigbrakeupgrade.com)

There's also the 3rdgen "1LE"/4thgen LT1 rear conversions. The e-brake isn't drum, but it's much better than the old style from 82-88 rear brakes that you have.

 

You are of course correct, thank you! It isn't a borg-warner diff, and is actually a 10bolt posi. Got confused looking at the codes as its a borg-warner gearbox, and should have doubled checked by actually looking at it! d'oh
So no particular issue in removing the axles with a posi? Just been a while since I've worked on this car.

 

I've only ever done a 9-bolt. 10-bolt is different, but looks easier. There's a short video on youtube by 3rd Gen Guy, called GM 10 Bolt Axle Tear Down. He's a member here on TGO, and he shows how quick and easy it is to remove the axles.

His is a drum brake axle. Disc brakes should be less complicated to remove. Then axle removal begins at the 1:48 mark.

 

So for your confirmed 10-bolt, the most "natural" and direct bolt-on upgrade with a drum parking brake is the 98-02 "LS1" rear conversion. 12" rotors. Should bolt-on.

The backing plates with parking brake assemblies used to have to be found used/salvaged, but it looks like Hawk's now offers a brand new product. Looks like you would still have to get the parking brake shoes/parts, but you'd probably replace used ones with new anyway.
https://www.hawksmotorsports.com/199...acking-plates/

Several used sets on ebay, but they aren't much cheaper. 4thgens are plentiful in junkyards, so you might find some there for cheap.

And since you'll probably have to replace the driver's side axle hardline anyway, might as well go LS1 all the way and replace both sides with the 98-02 hardlines. Salvaged are, like, $5 each. New are about $40/set. Not bad. Their design is very nice.

Brackets for the hardline-to-soft line connections are also a nice design. You can definitely get those off of junkyard cars all day long. They wrap around the LCA bracket, have a provision for supporting the e-brake cables, and bring the hardlines to the front of the axle, for easy connections to the leading/fore/front-mounted LS1 calipers. I'm using this on my C6 rear conversion, which also has leading-mounted calipers, except I've lopped-off the wrap-around portion w/e-brake mounts and am just using the L-shaped portion on the outside of the LCA mount, due to my conversion already having e-brake mounts. Worth the swap, for an appropriate and clean installation. And the LS1 hardlines, which are designed for a 10-bolt, also fit my 9-bolt nicely.

Edited to change to this better picture.

If you do that, then you'd have to get the chassis-to-axle hose too, because 98-02 changed to inverted flare fittings in the T-block.
LS1 Rear T Braided line, single (flynbye.com)

Calipers and abutment brackets can be found used on ebay, or new remanufactured at auto parts stores. Or right here.
https://www.thirdgen.org/forums/engi...-brackets.html

A couple of short new soft/flex hoses to the calipers, some pads, e-brake cables, and you're all set. Homework done! I know, it just keeps adding up!

 

"And since you'll probably have to replace the driver's side axle hardline anyway, might as well go LS1 all the way and replace both sides with the 98-02 hardlines. Salvaged are, like, $5 each. New are about $40/set. Not bad. Their design is very nice."




I know this is a little old, but do you know where you can get the hardlines? Are they still available from the dealer? Any part numbers if so?


thx!

 

Inline Tube, Hawk's, Classic, probably any other vendor that handles 3rdgen parts, but probably not a GM Dealer. Inline Tube probably makes them for everyone, but that's just a guess.
Inline Tube | Preformed Lines, Brake Products, DIY & Restoration Parts

 

thanks! ill check these ouit!!