I am wondering if anyone has done this mod to their 9 bolt. If so was it difficult? What is involved in the swap? How do they work? I already have the aluminum PBR's but I want to upgrade.
Thanks.

 

I'm interested in the same thing except i have the j65 rears on a 9 bolt. I picked up a set of LS1 rears for 50 bucks at a swap meet and would love to have a rear emergency brake.

 

I did this. Used the directions from the tech article and used the brackets, caliper carriers and everything. Drilled holes in the caliper bracket to matchup up with the 9bolt axle plate. Worked real good.

The only change was to have a friend machine an aluminum ring to push the axle seals a bit further in when bolted down. The rear brake bracket is a bit thicker than the stock 9 bolt. Without the ring in place to push in the seal, the axle might have leaked.

No leaks so far and everything fit together nice. Made no mods to the proportioning valve in the change over. Haven't noticed any stops that caused the rear to lock up. That even counts 1 wet weather panic stop.

Pretty good!

I'm working on some other mods this winter and will set up the emergency brakes before spring, then hopefully start on LS1 front brakes.

 

so the only thing you did was to make the spacer to account for the increased thickness of the LS1 backing plate?? You did use the LS1 rears with the drum style parking brake in the rotor hat??

Did the rotor line up properly with the caliper or did you have to space the rotor?

I fell a little stupid if all i needed was a spacer!!

 

I did use the LS1 rotor for the drum ebrake. I did not need to shim the rotor for clearance.

 

i think you just made my year!! What are the chances that you have the specs for the spacers you made??

 

Well good news then.Do you have any pics?? Please post if you can. Thanks

 

Let me look around for the measured specs. To give you a head start the thickness was the thickness of the caliper bracket minus the lip off of the axle tube. The rest of the ring should be cut to fit within the bracket but not so small that it could slip into the axle tube.

Look at the pic and it should make sense. If I get the measurements, I'll post a followup.

 

Thank You Sir :hail:

 

so you keep the bearing retainer plate? you just redrilled the LS1 backing plate to bolt up and everything else goes back as it came out except for the spacer you added between the retainer plate and seal?

 

Correct, I redrilled the plate to the holes would match and the spacer is used only for pushing the seal inside the axle tube just as it would be if it were up against the plate.

 

any luck finding those dimensions??

 

To get the dimensions, I'd have to pull one of my axles back out. I was really hoping to avoid that.

I think if you go with my advice from the earlier post, you can't go wrong.

To give you a head start the thickness was the thickness of the caliper bracket minus the lip off of the axle tube. The rest of the ring should be cut to fit within the bracket but not so small that it could slip into the axle tube.

Remember the ring only needs to be big enough to hold that seal in place in the axle tube.

 

Thats cool. i really appreciate your help. I've been tripping over those brakes for over a year now and would love to get them working.

 

I just did this LS1 swap anto a factory poo disc 9 bolt myself and I may have a little helpful info. I do not have a mill so I had to figure out how to do this with hand tools and it worked great. Heres what I did.

To modify the bracket I had to chamfer the flange on the housing just a little on the corners to get the bracket to sit flush. I lined up the bracket by using the line of the axle flange and the line machined onto the backside of the bracket and this put the holes about as close as I could get them. Using a fine scribe I marked very carefully through the housing holes onto the backside of the plate. It would have been very difficult to drill out these new holes as they spilled over onto the existing holes by half dia or better so I used a small round file and filed them out perfectly. To finish the holes up nice once I had the elongated slots i used 3/8" brass bar stock and slid it through the holes where the bolts now need to go. Mig weld will not stick to the brass so I welded up the remaining space to eliminate any slop that elongating the holes has caused. Using the round file and a small grinder I cleaned the welds and finished up the bracket nice and clean.

To make the spacer for compressing the seal I used 1/4 inch plate steel and 20 gauge sheet metal. The 1/4 inch steel is actually slighly thinner than 1/4" by about .020" and the spacer required is about .025" larger than 1/4" and I wanted it to be as exact as possible so I made a shim from 20 gauge sheet metal which is .045" give or take a thousandth or two. The 1/4" plate and the 20 gauge or .045 sheet metal will give you the exact same compression as the factory set up when using the LS1 bracket.

First I used a 3" hole saw and drilled out two discs from the 1/4" plate.The "disc" that is left in the hole saw will fit perfectly inside the brake bracket. Then I drilled the center of the 1/4" "disc" out with a 2 3/4" hole saw and that gave enough room for the axle to slide through and compress the seal fully. Duplicate above process for the 20 gauge sheet metal and you will have two perfect fit shims.

I then used some RTV silcone and "glued" the shim and 1/4" plate together completing the spacer... one for each side of course. I squeezed them inside of steel plates on the vise and left to dry overnight. I used a hydraulic press to remove the bearings and slide the spacers down and reinstalled the bearings. If you don'y have a press a local shop should be able to help you out here fairly low cost as its about a twenty minute job for both tops. Good luck

 

OOPS I must amend the hole saw size for the inside of the "disc" Its 2 1/8" NOT 2 3/4" Sorry bout any confusion there. Also when I posted that thread I had only done one side of the brakes completely and the second side was AWFUL difficult to remove the bearing from the axle. I had to heat the retainer up many times and try all sots of tools before I removed it. Just a tip to anyone who wants to try this a torch may be required.

 

Bringing this back from the dead here...

Does the spacer requirement mean that the axles stick out farther than stock? I'm just trying to figure out the reason behind installing a bearing spacer, and not having pulled my axles out yet, I'm up a creek without a paddle.

 

I have a question. I am getting ready to swap a 9 bolt into my '89 formula. The rearend I have is a 1LE, with the aluminum calipers. What is the benefit of swapping to LS1 rears? Aren't the ILE REAR brakes essentially the same thing?

 

No the LS1 backing plate is about a half inch thick and the stock 9 bolt backing plate is about a quarter inch thick so the housing is made for such specs. The nine bolt axles need bolt in retention so if you just fire on the plates there will be a quarter inch of slop allowing the axle to slide out of its home and resulting in all kinds of nastiness. The spacer is required to make up the difference and keep the axle bolted in tight.

Yes pretty much. Only real difference is appearance and arguably the e brake works better on the LS1's ( although a bugger to get installed on third gens ). Aside from that no difference really. I wouldn't swap LS1 rears if I had stock 12" aluminum PBR's.

 

Here are two 3D images of a spacer/retainer I designed and made for installing the LS1/PBR rear disc brakes onto a Dana 44 rearend. I have not yet verified if these will fit/interchange with the BW 9-bolt but I hope to check it on one soon. May have to change some dimensions but it shouldn't be a big deal. Spacers are made from tubular structual steel....can't recall the spec at the moment. The cut out is for installing without having to remove the bearing from the axle shaft. I suppose you could re-install the cut out section for more uniform support.





Mike

 

this may seem stupid but did you make the rear end any wider by adding the ls1 brakes and the spacer. I have 315 in the rear that are just fit right, I dont wont to mess them up at all.

 

Did you even read the last couple posts?
I took a picture of when I did mine... you can see the spacers (black) between the bearing seal and the plate. Works perfect.

 

so by using a 1/4 inch thicker backing plate wouldent that move the axle out 1/4 inch. i may mot be getting just run it by me agen

 

Have you pulled your rear wheel, caliper, and disc off? If not, do that, take your LS1 backing plate and compare it to the stock one. Look at the thickness and you will see why spacers are needed.

 

The brake backing plate has NOTHING to do with this. The bearings seat into the housing and this is what determines your track width. The backing plates hold your calipers thats it.

 

the spacers go behind the backing plate and sit inside the tube. They play no role in axle position. But they do contact the seal helping hold it in propper position.

 

Talk about raising the dead! I found this post 4 pages back. Here's my situation. Have a complete ls1 brake setup, and the BBT just dropped off a set of Formula 16" wheels. Car is a '85 Trans Am, with the Borg 9 bolt axle and drum brakes. I read up on everything I need to do to the 10 bolt axle, before I looked and discovered I had a Borg 9 bolt installed. From what I've read in this post, this mod looks easier than what is required for the 10 bolt. Way up near the top of this post, gcore45 mentioned a tech article dealing with this mod to this axle, but all I can find is the tech article to modify the 10 bolt axle, am I missing something? Everything looks pretty straightforward, my only questions at this point deal with the mounting of the line brackets.

 

When I posted that I was referring to the 10 bolt article which still applies except for using a spacer.

I used the ls1 brake line brackets and bought new brake lines to replace the hoses to make up for the difference in driver/passenger side length. To you non 9-bolt folks, the flexible brake lines aren't equal length on the 9 bolt. Passenger side is way shorter than driver.

 

So, what year car did you do this mod on? What brake lines did you buy? Did you have any problems with mismatched thread or line sizes?