BRAKEing Discovery 98+ rears on thirdgen
 

Toady I experimented with mounting 98 and up F-body rear brakes onto a thirdgen disc brake rearend. So far the adapter plates, rotors and calibers fit fine. The 98+ rear brakes have 12 inch rotors and huge PBR calipers. The only issue I see is re-doing the parking brakes. The 98+ rear brakes are unique since they have a parking brake that works like an old style drum brake. The drum being the inside hub of the rotor. I have yet to check for rim cleanernce and proportionoing valve match up. These brakes look great compared to the 82-88 crap disc brakes. I hope to have some picture very soon. As far as I know no one on this board has attempted this conversion yet. Okay recap I removed the 86 caliper backing plates and basically I bolted on 98+ brakes.
spelling check DISABLEEED

Check the clearance and please get back to us on this. I would like to go to disc brakes out back but I have figured it was worthless unless I could get GOOD brakes.

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, Jon (350 TBI!)
91 Red My website

So how did you deal with the whole thirdgen hub+rotor vs fourthgen hub-over-rotor problem?

And does anyone have good specs on these rotors and calipers? How do they compare with something like Baer's 82-92 rear Touring brakes?

Specs on Baer F-Body 82-92 Rear TOURING:
single piston PBR caliper
12.00 inch dia rotor
0.81 rotor width
rotors vented, slotted, drilled

As for rim clearance, I'd really like to know what size rims are required. Baer provides some templates... could you compare your setup to these (again, secifically the first template: 67-92 Touring Rear PBR1):

http://www.baer.com/template_lists/gm_f_body.shtm

Sorry to be so demanding. Thanks!

Michael - he's talking about the rear brakes. There is no hub on the rear.
Changing out the entire differential is a brezze, too, going 3rd gen to 4th, as it's a straight changeover.

very good to hear, I could lose crappy disc brakes and spacers all at once since I'm running 4th gen wheels.

Ok, so I'm ignorant... sorry I'm a new firebird owner (been wanting one for about 20 years, just took the plunge) and I have drums. I'd like to replace the brakes all 'round with fourthgen discs.

So, 3rd and 4th gen have the same type of discs in the rear, but different designs for the front?

Okay I'm back.
the problem is I can't get to the yard til the middle of next week.
I know that you probably will need 16 inch wheels. All my experiments are being conducted on rearends that are off the cars. I need take some measurments on everything. I wish I had a buddies car with a disk rear on it that way I could do a swap and check for hang ups. Here is the following observations:
1. The 4 holes on the backing plate(part of axle tube ends,3rd gen), bolt up directly to the 98+ backing plate. NOTE: the 98+ backing plate includes a brake lining that serves like brake shoes on drum brake(wish I had pictures).

2. The rotor opening slips over a thirdgen axle hub without any problems.

3. The caliper was mounted onto the backing plate(over the rotor), I was able to turn the rotor by hand with everything tightened down.
I did this at a friend's junkyard.
I found a bare 1986 disc rearend. I removed the caliper/backing plates. I then installed the posi from the 98+ reaend(to provide correct angles and lenght). I used a 28 spline axle(from a 91RS). All the 98+ components were bolted to the 86. I installed the axle, to include the C clips and cross pin. I wan't get a good chance for photos til next week. I think this will be a killer CHEAP upgrade.
Spell check DISABBLEED

Mike
Okay the 4th gen rear brakes 93-97 had a smaller size rotor. Also the used the standard method parking brake(i.e. cable tightens the pads into the rotor.

Awsome! Keep us posted, and post as many pics a possible.

So you guys are saying if I get the caliper mounting plates from a 98+ they will bolt to a thirdgen axle and let me use the 12" brakes.

Zac Spalding

I've got 98+ rear brake parts for sale here:

https://www.thirdgen.org/internal/cl...cfm?adid=10411


Check it out if you're interested.


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Mike L.

The Weapon of Choice:
1987 IROC Z 5.7 TPI A4 3.27 Borg-Warner four wheel disc
Mods: 2300-2500 Stall Converter, Shift Kit(GM parts), TPI Specialties Stage 3 PROM, Modified Airbox w/ K&N's, homemade cold air, Relocated MAT sensor, Gutted MAF, 160* thermostat, MSD 6A, Accel 8mm Wires, bypassed TB coolant, Flowmaster 3 chamber single 3" in/out muffler, 3" MAC mandrel intermediate, custom dual !cat Y-pipe. airfoil, ported plenum. !smog, few others I forgot...???

**BOYCOTT LAPEER DRAGWAY**

Dont 98+ f bodies have ABS? is that not part of the discs?

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1983 Firebird
TH700R4 Auto
Small Block 400
LG4 ECM, Intake, Carb, Distributor, etc.
Soon to be non-computer.
Clarion Head Unit 45X4
2 Pioneer 400W 12" Subs
Third Gen Performance
"A four cylinder is half an engine."
"Ponies can run, but birds can fly..."

ABS is just a system that regulates the amount of pressure going to the brakes. It's a series of regulated valves that go between the MC and brakes themselves, and should have no affect on this sort of conversion.

What may potentially have an affect is the proportioning valve that regulates how much pressure goes to the front brakes vs the rear brakes. The stock proportioning valve is set up for our admittedly weak stock rear brakes. If you upgrade those to more powerful rear brakes, you will probably have to get an adjustable proportioning valve. Baer sells these, and they don't cost that much. The potential risk here is that you'll find yourself locking up the rear brakes LONG before you get the full benefit of the front brakes, because the stock valve is set up for the weaker rear stock brakes.

the abs sensor ring is inside the rear end so you don't have to worry about that

I'm back I have photos of the brakes. I have photos of them installed and just the components. Problem is that Photopoint changed their policies about free photo hosting. Once I get around that I'll have them posted.

so this means the 98+ swap is the real-deal? it all fits up and works proper, been test driven, and will be safe and straight forward?
i just got the rearend out tonight and will be rebuilding it tommorow. it would be great to do this swap too.
if this all works out it should be declared a monumental find for the thirdgeners, great work!!!

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-89 Trans Am
jet black w/ silver flake
suncoast ram-air hood
ASAI replica aerowing
centerline trigons
SLP headers, flowmaster.
Viper 550esp w/ rem start
Grant GT, all Kenwood.
BMR adj.phr, lca's, lca brackets, sfc's, jamex springs, PSC front end, kyb AGX struts,
tci starter, 3.73 gears,
Auburn posi

-96 Teal C4 Corvette

Update.
So far I have test fitted everything on a rear end that is not installed on a car.
This is not a done deal yet. this week I will get a rear end to the house, for more experiments.
I fitted the caliper and rotor assembly in a 16 inch rim and there is plenty of clearence. I also tried it with a 15inch 5 spoke RS rim and there was also some clearence.
once I get these photos posted I think everyone will have a better idea of the current progress.
I have both parking brake cables and the short cable that attaches to the parking brake lever. It seems pretty simple and I don't think there will be any dificulties with the parking brake set-up.

The first photo is the components of a 98+rear brake:backing/mounting plate, rotor and caliper.
http://photos.onebigvillage.com/pubimage.asp?id_=51502 or http://photos.onebigvillage.com/pubimage.asp?id_=51502

This one shows the brake components installed on a 1986 disc brake rearend, the posi is also installed to properly locate the axles.
http://photos.onebigvillage.com/pubimage.asp?id_=51504 or http://photos.onebigvillage.com/pubimage.asp?id_=51504
more to come.

Also try this link.
http://photos.onebigvillage.com/pubgallery.asp?id_=4452

What's the latest word on this swap? I'm looking forward to it eagerly... https://www.thirdgen.org/messgboard/biggrin.gif

Steve

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Steve's Trans Am Temple

Hope to get my hands on a 3rd gen disc brake rear end today or tomorrow. I will bolt everything on it(again). The bad news is that I will have to take a 2 month brake in my research, since the Army is sending me to a school. I need to find a better image hosting website. I don't think that I will be able to actually test the brakes installed on a car prior to departure. My current car had drum rear so I will have to either use a disc/disc prop valve or a aftermarket adjustable. When I got the 98+ rear brakes I also took all the brake lines(rubber and steel). I really think that a disc/disc prop valve will control these brakes without any problems. That's about it for the current progress.
P.S. Can someone post a pic of an 82-88 disc brake steup, prefer a side view with a car magazine next to it for size refrence.
Will keep you updated. Thanks

I converted my '82 Z28 to the full 1LE brake package. 12" rotors at all 4 wheels (see the temp 1LE brake upgrade board). I experimented with many booster/ master cyl/ proportioning valve combinations. The one that worked the best, was the stock J50 (disc/drum) set up. I drive the car every day, and it still performs pefectly.
Thanx,ANDYZ28

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82Z 305 w/comp 270 magnum cam,Edelbrock Performer RPM,Holly 1850-4,serpentine belt drive.TH700R4 w/B&M holeshot 2000 converter,& megashifter.1LE front brakes, 9bolt 3.27 w/1LE rear brakes.Aluminum driveshaft,boxed rear susp.poly everything,IROC swaybar+wonderbar. 70mph@2200rpm ASE Master Tech plus L2
also recently obtained a
'69 chevelle SS396 w/Turbo 400,3.31 posi,11.0 to 1, headers,etc. Latest project car,'86 IROC stock 305TPI hit on left side,but not too bad

Thanks for the info about the prop valve.
I'm currently building a small website with my progress on it. Also I should have the 3rd gen disc rear end at the house this evening. Thanks

Any more news? I only have one operating rear caliper currently and before I drop money on another piece of crap I want to see if this swap works!

Steve

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Steve's Trans Am Temple

Sorry for the long wait.
Okay I started a small website that has my progress and many images. This page is under construction and I have alot more to add. Sorry up front about any banners or pop-ups.

http://88irocarmy.worldbreak.com

Okay I have the brakes mounted on a 86 rear-end in the garage. To make the story short. The rotor turns freely through the loaded caliper(everything tighten and installed,on jack stands). But my experiment has been put on hold til 10 Nov, due to school. Since everything has bolted on(backing plate, brake lines, rotors, etc). I feel that this will be a successful conversion.
GO SEE my website.

http://88irocarmy.worldbreak.com

Guess what? They also will work on my 15 inch turbo cast aluminum rims (82-84 RPO N89). I just took one of my rims to my local Pontiac dealer and had them try it on a 98 Trans Am they had up on a lift. I guess a dealer is good for something... https://www.thirdgen.org/messgboard/smile.gif

I must say it is a close fit, and I may have to grind down the calipers or rims just a tiny bit to make sure I always have enough clearance. I don't think I will have to though.

Thanks 88IROCARMY!

88IROCARMY - Looks suhweeeet! However, several of your pictures aren't showing up. Looks great though and I'll be on the lookout to do this swap myself!! https://www.thirdgen.org/messgboard/biggrin.gif

Steve

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Steve's Trans Am Temple

at the LS1 board, they think that the C5 and 98+ 4th gen rear brakes are the same, so it might be possible to have the rear C5 calipers on this brake system. (I think the only difference is the color and lettering)

I'm really looking forward to doing this upgrade!! Thanks 88IROCARMY

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85 Z28, 305 TPI A4
pretty stock with a few toys
15.2@91mph
http://photos.yahoo.com/j_hougnon

http://screamindeamin.cz28.com/images/jesse/

Re: BRAKEing Discovery 98+ rears on thirdgen
 

Alright, let me get this straight, all the disk brake hardware from the 98-UP Firebird rear disks will bolt on my 1984 disk brake rear Trans-Am? My calipers, brackets and pins are all worn out to the extent they are rattling in their mounts, so it's past due. I need all those components anyhow. And I'll actually have a working parking brake??

Nice.

I just wanted to double check that I wasn't reading a typo and you had ment the 98 and up rears would fit on the 4th generation birds..

Could you also clairify the fact you are using a newer posi rear carrier? That would be a bonus, the posi carriers are getting pretty hard to find for my vintage..

Steve

Wow! What an old message, one of the first about LS-1 brake swap.
Well your disc rear should work with the 98 up pieces. The pictures show that the system is retained by the four bolts on the axle flange (check pics on website).
You can use your posi/diff, for my experimnet I had a newer 28 spline diff for which I had to get 28 spline axles.
Believe it or not, I still have not assembled or installed the converted rear, I jut got back from Iraq. However, search this site there are many members that have done this conversion

Wow, you mean I can get rid of my drums!? Awesome!

Although, I see that you did all the fitting on a disc rear car... I have an 88 with a drum rear, will it work? Also, I see above some discussion on the proporsioning valve, what's the verdict? Can I use the stock disk/drum one?

Thanks, I don't really have any rear brakes right now, and it would be great to do some good back there!!!

98 Rear discs on a 9 Bolt?
 

Found the postings here about up-grading a 3rd. Gen. rear discs to 4th Gen ( 98 & up larger Discs) rear discs onto a 10 bolt rear. My question here is has anyone tried this change-over on a 9-Bolt? I know that the 9-bolt discs and calipers are the same but the backing plates and housing are different. What modifications are necessary to do this swap - or should one head in a different direction (different than the 98 & up swap parts). thanks

I asked the same question right above you pretty much... I guess no-one knows!

The outer axle bearing caps on a 9-bolt will not fit back on internally under the LS1 stlye drum parkingbrake assembly on the rear disc setup. I believe they can be used on a 9-bolt without the e-brake internals (so no e-brake at all)

Heres a shot of my Wilwood LS1 assembly on my 10-bolt- but you can see how the 9-bolt c-clip eliminator axle caps would not fit inside the e-brake assembly. If the internals of the drum e-brake were to be removed, it would fit. But its not wise to run a street car without an e-brake.

98 e-brake on a 9-bolt
 

It is obvious that the 9-bolt rear assembly will not accept the 4th. Gen. Larger brakes because of the drum e-brakle set-up. Also true that it is not a great idea to run without a e-brake set-up. So it's on to search the aftermarket for other ideas, thanks.

So why not just go with the 12" LT1/1LE PBR style then? First off, they'll give you all the rear brake you should need out back on a street car. Second, it would be a total bolt on with no modding necessary as all parts are available. You can go with just GM parts or even look to Baer for a rear kit if your budget allows.


Ed

Big Brakes
 

I have found an 89 1LE with the big brakes (11.65" X .783" Rotors) and the rear brakes are no problem - straight switch over to my 84 with the 88IROC 9-Bolt rear. On the front ones, because my 84Z is stock in the front, does one need to swap the spindles and all....or just from the backing mounts and outwards? Thanks.

You'll need 9 bolt backing plates to make the rears work, and for the fronts, you'll need to either mod your currect spindles or grab the 1LE spindles off the car...I'd grab the spindles and all if I were you.


Ed

Heres a couple pix of my swap, first is the stock 88 iroc disk brakes, and the second is 1997 Z28 disk brakes, BIG diffence!

11.5" rotors

http://img.photobucket.com/albums/v2...ikes383103.jpg

http://img.photobucket.com/albums/v2...ikes383092.jpg

Why are you comparing the front and rear brakes? Just curious...

Ed

like he said

Bigger Brakes
 

I have solved my problem on the rear brakes with 89 1LE set-up, from the backing plates all the way out to the 11.5 rotors and aluminum calipers. The complete set-up fit my 9bolt standard with 10.5 disks to start with…so far so good.
On the 97 Z28...were all of the 97 Z28 11.5 rotors? Or is it in the 97 Z28 1LE option that had the 11.5” rotors? In either case if I find them from the spindles out, complete set-up, will these spindles fit my 84 Z28 OEM front. I have also noticed that Spohn has a very nice set up to up-grade my front brakes ( dual piston calipers and 12“ rotors), but I would rather save money if I can find good used parts, then just add new Rotors, pads, bearings and a rebuild kit or two. I have the next few months to search for parts, when I know what to search for. Thanks for all, Ed.

All disc rear brakes from '89-97 were 12" (~11.5" or so) PBR style.

The 4th gen front suspension is totally different from your '84 so no it won't bolt up. YOu can however install the 4th gen brakes with a few modding to what you already have. Read the LS1 thread in the FAQ section. Also look into C4 and C5 brake setups.


Ed