ebmiller88

iTrader: (7)

I'm debating on installing an 89 9 bolt or swaping to a 4th gen Z28 10 bolt in my 88 IROC. To guys who have done the swap or one similar, how do you like the braking performance of the 4th gen over the 3rd gen rear? Can you tell a difference? Doesn't the 4th gen rear have bigger 11 inch (?) rotors? Despite all the brake adjustment work, is it worth it?

Also, if anybody has any pictures of a 4th gen rear installed, I'd like to see them.

Also, will 89 calipers bolt onto my 88 rear? Both are 9 bolts. Thanks all.

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Ed Miller
Charlotte, NC
1991 RS, 305 TBI,
bone stock driver;
1988 IROC L98
TPIS Fast Pack, modified MAF, MSD 6A, Dynomax cat-back so far.

"Do you want to race or don't ya? I want to race." Dale Earnhardt

ebmiller88

iTrader: (7)

TTT.

Matt87GTA

I have no quantified evidence about braking distance and the like, but I think that my car stops better with the 4th gen rear brakes. I have done some other upgrades to my brakes as well (drilled slotted front rotors, braided SS lines, Carbon Brutestop pads) which also have improved braking performance so my GTA really hauls down now . I have a lot of compliments on the brake performance of my car.

I am not sure about the 88 versus 89 rear brakes. I can't remember when they changed to the aluminum caliper 11 inch rear brakes but if it was in 89, your 88 calipers won't be a direct bolt on. I think they didn't go to those bigger rears until 91 but I forget (someone will correct me).

Yes, a 4th gen rear will have the 11 inch rears that the 1LE cars and later 3rd gen cars had. If the rear axle comes out of an LS1 car (98 and newer), I think the brakes are even bigger. The tech article on this site on the swap is fairly well written. My GTA had rear disc so I didn't change my proportioning valve at first just to try it out, but the car performed so great that I am convinced that if you have 4 wheel disc already, then you do not need to change the proportioning valve. The only real pi$$er-off-er during the swap was getting the 4th gen brake cables to work with the 3rd gen bracketry. I posted on another topic about this procedure but it is hard to explain and you really need to get under there to see what needs to be done.

My rear came from a 97 so it had a dual rear brake channel system for the ABS that the 97 Z28 had. So this required me to adjust the right rear brake line and bend up a new left rear brake line to get them to work with the 3rd gen system. 96 and older 4th gens have a single channel rear brake system so I do not think this would be necessary.

See my website for a few pics of the rear axle installed. The pics are sort of big so I hope ya'll have a fast connection. Email me if you have any other questions.

Overall, with the gear ratio upgrade ad the brake upgrade, I am VERY happy with my 4th gen rear swap. I can't wait until I got enough cash for the spacers for the front and a set of 4th gen 17x9s .

Laterzzzzzz

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

Z28DJP1987

I have made the swap of 89 B-W 9 bolt with
11.655 discs and 2 piston PBR calipiers. All
you will need is the parking brake cables,
proportioning valve and some brake line fittings. The new disc rear works great and is improvement over the drums. I can not comment on 4th Gen rear except it is 2" wider
then the 3rd Gen, I would go with the 89.

PonyKillerZ

Im looking to replace my rear with a newer rear w/ 3.73 or 4.10 gears, i also want disc brakes..

what would be a good choice for my 1985 Z28?

how long did the switch take?

ebmiller88

iTrader: (7)

Thanks guys. I couldn't pass up the 89 disc rear so that's what I got. I'm more concerned with my brake issue than with gearing right now, which is another reason why I went with the 89. Plus, it came with all the brake lines, rotors, alum. calipers, e-brake cables, and even the sway bar, panhard rod, and LCAs. Not bad for a c-note.

The rear rotors are huge compared to my 88 rear, and it will be a direct fit. I may jump to a 4th gen rear later, but that will be down the road a while. I also have the parts for the 1LE front system and will be doing all the work this fall through next spring along with a suspension rebuild.

Matt, nice GTA and great site. The pics were also well done.

Pony, I have no good choices for you, but I would look into the 4th gen rear swap. It seems like a great improvement. I passed one up on Ebay last week that went for a whopping $76, had 3.42s and was complete!! Can't go wrong there for a street rear. Then swap gears if you need more.

Thanks again..

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Ed Miller
Charlotte, NC
1991 RS, 305 TBI,
bone stock driver;
1988 IROC L98
TPIS Fast Pack, modified MAF, MSD 6A, Dynomax cat-back so far.

"Do you want to race or don't ya? I want to race." Dale Earnhardt

Z28DJP1987

Good choice on the 89 9-bolt and a great price. You will like the Brakes.

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1987 Black Camaro IROC-Z (original owner) Replaced LB9 @ 86100 miles.
New 350 Crate engine
Balanced & blueprinted
World Prod SR 67cc Heads 9.6:1 C.R.
Cam: 454lift,216dur@50,110ls
TPI Induction(from 305)
22# Fuel Injectors,AFPR&Gage
SLP Intake runners
New GM 1988 chip
K&N filters & Air Foil
Hothkis STB
SLP 1 3/4 Headers
CATCO 3" Catalytic conv.
SLP 3" Cat Back Exhaust
700R4 Auto
SLP Torque Converter (2400 stall)
B-W 9 bolt rear 2:77 Possi. Four wheel disc brakes,245/45/ZR-17 Tires
17x8.5 ATI 5 Razze Wheels
Dyno results: 211 RWHP & 282 RWTQ.
264 HP & 352#/ft at flywheel with all emission controls installed. New Toy!