Stock ‘89 but given this

Four wheel disc optioned (J65) IROC-Z's rear brakes were increased in size from 10.5 inch rotors to 11.65 inch rotors with PBR Australian built aluminum calipers and more reliable parking brake actuators. Front discs still had 10.5 inch rotors with Delco-Moraine single piston calipers.

have been considering upgrading just the front brakes to get a little more bite. This caught my eye in the classifieds not too far outta town
https://www.kijiji.ca/v-other-auto-p...ationFlag=true
so thought I’d ask the braintrust:

1) direct bolt on or some new base or spindles or whatever required?
2) probably require a rebuild? Too costly to bother given all the wilwood etc full kits for $4/500? Kinda wanted to stay in the era with some old stuff vs the new kits..
3) even if these are rusty junk, if they were gleaming new would the incremental improvement in stopping power be that noticeable?

Cheers
SR

Thanks sofa, great guidance. These arent the HDs b/c 12” not 13” rotors, correct?

Wow what a wealth of info. Thanks James.

Given
The C4 NON-HD brakes have thinner rotors, 0.81 inch, then the 1LE (1.1 inch) rotors. The C4 NON-HD caliper also has a smaller rotor opening to accommodate the thinner C4 rotor. The C4 HD 13 inch brakes have about the same thickness router as the 1LE but have a 1 inch larger diameter.

can I assume my rears are the 1.1 inch?

Also some interesting reading against these two types of C4 brakes here.
https://www.thirdgen.org/forums/hist...e-history.html

Thanks James. Given the rarity of solid thirdgen 1LE front brakes coming up regionally (shipping, currency and brokerage would murder any long distance deal) I’m still kinda considering this 12” nonHD conversion. Get some period double piston PDRs and a proper rotor, thickness notwithstanding, in the front- some more bite and visually pretty damn close to the rears. I note Ed at flynbye has brackets. Dude in the original ad got back back to me, said they worked perfectly when they came off the car to make way for an upgrade.

Ok two more questions for anyone still following this thread
1) would the surface rust on the one rotor be a fairly simple machining clean-up or a deal ender?
2) negotiate the steel flex lines outta the deal or would they fit on an f-body too?

Thanks gentlemen. Yeah I get the modification of my car’s front spindles and bracket purchase from Ed part but the hub bit is a little trickier.. Some other nonHD C4 front brake threads on here touch on the fact you can modify the 12” C4 rear rotor for use on the front but not the C4 front rotor, if I have that right.

With all the trouble (for non machinist 3G enthusiasts) you see pretty fast why most only go to the effort for the C4 HD 13” upgrade. Reviews from the vette folks are mixed, some claim the thicker 13” setup is way better others claim not a massive improvement. Against my 10.5” DM single piston fronts the dual piston 12” looks damn good to me. I think to avoid spending nearly as much as a basic brand new modern front brake kit I’d wanna use the rotor/hub in the guy’s sale if at all possible- or I’m basically buying the calipers, possibly needing a rebuild themselves, and pads! lol On the other hand Ed’s full 12” C4 front kit (new and turnkey) is $850 USD so could be worth it still.

skinny agreed new 12” rotors aren’t too bad (eg corvette depot up here) if necessary- more importantly you got a shop in Oshawa familiar with all this stuff?

Check out big brake upgrade.com. He makes all the brackets and machines the original rotors down to use as hubs. I installed his LS1 front kit (brackets, hubs,& ss hoses on my ‘86 and my friend’s ‘92. We both bought powder coated calipers from eBay, Callahan Brakes. 3 years and 3k miles on his, only 600 miles on mine, but zero issues.

Ah cool thanks Skinny. Hold off on buggin him please until I take these down. I’ve asked if he has the rear rotors available as the old C4 12” brakes threads seem to suggest these are preferable over the fronts.

ROC I’ve definitely perused bbu, very cool stuff. Way more money but this kinda thing is awesome
http://bigbrakeupgrade.com/product/l...te-conversion/

My vintage aim for an upgrade closer to ‘89 remains so I’m gonna ask if he can create a hub for the C4 12”- the menu has moved with the times past these it seems, lol, and flynbye is apparently a don’t-expect-em-anytime-soon kinda thing.

Bit of a PITA that for this particular upgrade operation I can’t have the hubs created out of the 10.5” stock DM fronts nor the very C4 rotors I’d be buying.

That’s seems to be the verdict. He himself is on half the 15+ year old threads that developed this concept. I figure since “winter is coming” if not in bbu’s wheelhouse I’ll ask Ed with an eye through to Feb/Mar if he can handle it.

Well I just now bought’em for a cool 100 northern pesos so I’ll be calling Ed tomorrow lol. My readings indicate a different kind of bracket is called for to get the front C4 rotors on thirdgen hubs.

BBU is not in the C4 brake business - I’ve PM’d alloy/machinist, the inventor of the front brackets solution, and if he’s not into the job will try Ed on the phone.

Well after a bit of phone tag got Ed of flynbye on the phone and he’s down for spindles brackets hubs studs all set up to go for these and able to make and send over the next couple weeks.. Super nice guy. Scott of BBU was very responsive and friendly as well but either way this route should shave off a few hundred bucks from Ed’s C4 12” full kit or Scott’s LS1 full kit. Before I even broached the job I was after Ed explained he had the C4 12” on his fronts for years and the difference was “night and day” over the DM 10.5” stock fronts, later moving to the C4 13” HD which he said was a not very noticeable improvement over the 12s. Obv great to hear and reaffirms my whole plan.

Skinny thanks for the offer on your guy (I used to go into Performance Improvements on the Queensway all the time) but with work and kids gonna have the whole deal as a simple simon to go on with some other suspension stuff this Fall.

So since thie deal came with some braided lines for the fronts that should hook up I’m now looking for some for just the rears. Russell 692370 seems to be the only game in town for ‘89 J65, but it’s all around. Summit’s got nada else and eBay is telling me StopTech Brake Lines Braided Stainless Steel Rear Chevy Pair 950-62501 fits ...any p/n recos?

Thanks gentlemen- Ed indeed does have a bunch of setups and confirmed added to the job.