Hey all, 78 L48, new to me.

Haven’t changed brakes, no clue when they were last done (on wait list to get done though, as I think it’s above my noob skill set).

Is all the black gunk just really old grease? Oil mixed? You can see I do have a very slow drip of transmission fluid, but checkout those ball joints, calipers, etc. Thick and even rubbery.

 

Looks like normal build-up of dirt on greasy and oily surfaces. The good thing is that the components underneath will be very well preserved. I believe it also shows decent lube servicing of the ball joints.

Your rubber trans lines look like they're swelled and softened, they should be changed at some point.

What are you planning for brake service? If it were mine, I'd start with a visual inspection of the pistons and boots where they contact the back of the pads. If leaking, then either new or rebuilt stainless steel sleeved calipers are in order. After that, new rubber lines from the frame, new pads, and flushing the system. Resist the advice to put on new rotors — Corvette C2/C3 rotors are stout and don't usually need to be replaced just because they're old.

 

Looks like the A arm bushings are starting to fall to bits too.

 

Yeah I noticed a lot of the bushings are cracked. Surprisingly they’re not completely gone but have seen better days. Probably original.

 

A guy could write a whole book on Corvette C2/C3 brakes. Let me clue you in on the highlights ...and if you take it to a shop you might want to be proactive that they know about C3 brakes. Or you could be in for a real ride...bc almost for sure a lot of uninitiated techs will be stymied ...and who knows what'll happen after that;

1) GM turned the rotors AFTER they (the rotors) were riveted to the front wheel hubs. Read that three times and remember it! What does that mean? it means in most cases the actual hub face isn't 'true' and the rotors were made 'true' by maching on Un-true hubs. Read that twice too. That means....if a shop goes to slap on new 'true' rotors onto untrue hubs...guess how true the new rotors will be? Not 'true' at all. And by true that means with a deflection of .003" max. When I put true rotors on my car's hubs (after drilling out and removing the old rotors)...the deflection with untrue hubs was .014. That will cause major problems if an unwitting tire tech does that (see next item).

2) When rotors have too much deflection, they "pump" air into the brake system and you loose brakes! LOL. It's a phenomenon that can occur. This was an early GM disc brake system they probably wish they could have done over. GM used Lip-type seals on the brake pistons and the pistons are SPRING loaded. Lip seals are like a jellyfish that pumps water and moves up/down in the water. And if you have a warped rotor, that's kind of what's going to happen, only it'll be pumping in air...b/c the pistons will be moving in/out real fast (and they're spring-loaded). And the pistons are aluminum...which is another issue I won't go into right now. But the key take-away is due to all those factors, your car needs really 'true' rotors or they can induce air into the brake system and you could (and many corvette owners have) lose brakes. Why did they lose brakes and almost get into an accident? Because someone put on new rotors and didn't check for and resolve excess run-out (on un-true rotors) which induced air into the brake system.

On all modern cars, the caliper O-rings are an actual square-cut o-ring (not lip-seals) which are mounted inside the actual BORE of the caliper body, not mounted on the actual piston (in most cases). And the pistons are usually SS, or chromed or phenolic (not aluminum) ...and not spring loaded. Therefore you don't get the jellyfish effect or air entrainment.

3) The calipers are 4-piston and split in half. There's an O-ring about 3/8" diameter which mates between the halves which allows brake fluid to go between the two halves. But over time they can develop corrosion at the o-ring point which can be a source of leaks. In your case, the oil looks pretty dry. It might be oil on the caliper from prior brake bleeding. Usually leaking calipers are very wet oily.

There's more, but the key things are 1) If your rotors are 'ok' and not warped, don't have the shop slap on new rotors like they often want to do. Otherwise they'll be scratching their heads why they can't get new rotors 'true' and you'll be in for a much bigger expense where you didn't need to be. And that's assuming they put a dial-indicator on the rotors, which a lot of shops don't do (but should). And you should request it. 2) Have the shop exchange the brake fluid with new. Keeping good quality fluid in the brake system, keeps moisture out and makes them last longer (less internal corrosion). It may be the case that a prior owner has already dealt with the rotors and either shimmed new ones 'true', or re-machined the hubs (true), or replaced the hubs with new (better) ones. That would be the best case. But if they haven't just know the basics.

Also, it might not hurt to have the shop ensure the brake hoses are good too (replace if necessary)

Corvette brakes work great when the fundamentals are followed. But when you take the car to be serviced, one would be well-advised to be their own pro-active advocate on Corvette Brakes cause a lot of mechanics nowadays probably don't know what the issues are and what the ramifications might be. So when it comes to vette brakes, be proactive and protect yourself. And enjoy your VETTE!!! Hope that helps!

 

Swaybar end broken? Hard to tell.

 

Excellent explanation!

I might add that if a rotor is removed it should be marked so that putting it back in the same wheel stud orientation will maintain that factory truing. @JC 78 Vette, if any of your rotors are still fastened to their hub with rivets, this is the original orientation from the factory. Only remove the rotor if absolutely necessary and index it to the wheel studs. (Unfortunately the rear rotors must be removed to service the parking brake shoes - if the shop does this, make sure it's returned to the same studs in the same holes.)

If a rotor without rivets exhibits excessive run-out, don't assume warping is the cause. Try "re-clocking" (placing the rotor on the hub in a one stud clockwise rotation) and remeasure. Do this until runout is minimized - up to 4 additional re-clockings. Corvette rotors are thick, heavy castings that generally don't warp like modern rotors tend to do.

If a rotor is truly warped or needs to be turned to get a good surface, locate a shop that will do an on-the-car rotor cutting. This will true the rotor to the hub/orientation in which it's done -- much like GM did with the hub assembly that Mark G explained.

Good luck with the shop and remember that you don't have to agree to their recommendations without asking here first.

 

Thanks for the detailed responses you guys, though I’ll have to admit I’ve read these post several times and am still not fully tracking

I will keep these in mind though if I do have someone look at the breaks. Part of me wants to try to tackle it myself and just research the heck out of it and hopefully only need to really change out the pads/lines but it may be to challenging….definitely intimidating for a noob like me. Also, brakes stop you…quite important!

I just think brakes, suspension are abit about my pay grade. I definitely would prefer to keep roters and calipers if they’re still good, not in a hurry to just start throwing parts at this thing. Brakes run fine…had instance after I got car that brake light came on and was tough to brake, but front master cylinder was quite low and since I topped off it’s been fine.

 

In my opinion, brake work is one of the next steps to learn after regular maintenance as far as difficulty goes. (Suspension is much more involved and physically taxing.) There are just a few components at each wheel and they're basically all the same from corner to corner. You just need minimal basic tools like socket wrench, a couple line wrenches, and a way to bleed the system (could be as simple as a plastic tube and gravity or pedal pushing). To rebuild a caliper only requires separating the halves, cleaning the passages, maybe polishing the bores, and putting a seal and boot on each piston.

It can be intimidating to take on, but once you understand the process, it's straightforward and quite doable. You'll know if you have any issues on your first couple test drives. Catastrophic failure would be incredibly rare - more likely would be a leaking seal or supply connection and difficulty getting a firm pedal.

Where in the US are you located? Someone may be close by to assist.

 

Couple other points on the brakes:

1) If at some point in the future the calipers DO leak. It's often that o-ring between the caliper halves. It's easy to unbolt (split) the halves....clean that O-ring seating surface of corrosion ...and put back together. Right now that might not be necessary...but consider it in the future.

2) If you just wanted to buy new calipers, O-Riley Auto is probably the best place to get replacements. Lifetime warranty, no shipping charges.

But for now try tightening those hoseclamps which seem to be leaking. You might have to cut the hose back a little and reposition the clamps.

Let's see a picture of the rest of the car.

 

I'm seeing original brake calipers...so all the comments above should be well taken...a first step!

Its been undercoated! You can see it on the coil springs and the A-arms, that textured appearance. I also see coolant leaks out of the radiator coolant lines.

All that caked on crud is dirst that has accumulated over fluid leaks and has the effect of preservation. But then its still a fluid leak...clean the crud...fix the leak!

 

Brakes are the perfect start! Really not hard at all! Get stuck and don't be scared! All the help you need will be on this forum!

 

So what I’m hearing is hope my rotors are still good!

After reading more about runabout, the above does make sense to me now. Here’s hoping rotors are fine and I can just focus on pads and or calipers. 46k miles on car. Lines definitely need to be done though w SS

 

Go into stainless lines with the caveat that they can be difficult to get a good seal at the connections due to their hardness and not conforming to the cone in the mating component. Regular carbon steel lines have lasted your car all this time, and will more than likely outlast your ownership.

 

The best thing to do is find a guy/shop who truly (I stress TRULY) ....understands and has experience with C3 brakes. Or print out my post above and make sure they read and understand it. Every mechanic you talk to at a shop is going to say, "Yeah...I know how to do brakes" ...but do they understand the real intricacies??

If not...just wait around till the shop gets the wheels off and pads pulled. Look to see if the original rotors are in place (they're riveted). Either way, have them put a dial indicator on the front rotors...and I would want to see with my own eye what the run-out is on each one. Record whatever number it is. Let us know. .003 or less is ok. Try to have a shop deal with them which has an on-car brake lathe as one poster pointed out.

The oil on the brake calipers might be from previous brake bleeding. They don't look very wet. Shops want to talk customers into anything they'll agree to. If they do need to replace them, OReilly Auto has LoneStar calipers with a lifetime warranty. I'd get those ....if I was doing it.

Don't count on a counter person to tell the guy doing the actual work what you do or don't want done. Messages like that are often forgotten about.

I'll just reiterate one more time...C3 brakes work great...when all the factors listed in the posts above are done properly. It's when techs just proceed as per they normally do, when ya run into trouble.

There should be some videos on C3 brakes...

 

C3 brakes are really great for their time. 4-piston, fixed caliper brakes went away after 1982, and didn't return to the Corvette until the C6 Z06. Modern cars that have them also have replaceable hub bearing assemblies. So the tricks required to get the brakes to work on a C3 are a bit of a lost art. @Mark G is spot-on that you need someone well versed in them. Or, you can easily teach yourself to do it using tips from the Forum. The key is near-zero runout on the rotors.

Here's a recent thread with a link to the correct way to do it.

https://www.corvetteforum.com/forums...r-run-out.html

 

To clarify, if I keep the rotors though (have to find min thickness and measure) I don’t have to worry about run out correct? Just determine if I need need calipers (or rebuild) and new pads. That’s my ideal scenario, only have 46k miles.

 

Maybe? You'll need to measure the thickness of the rotor, and you really should measure the runout, too. This is a great example of the tool costing less than a single diagnosis at a mechanic, and something you can use repeatedly.

I used a really cheap runout tool like this one, from Amazon, though they make nicer ones. It also worked to measure bellhousing runout for my TKX swap.

 

C3 rotors are really thick...like full-size truck rotors. I would worry much less about thickness and more about run-out. Excess run-out *is* the MAIN issue. (what happens if they swap in new rotors in place of old rotors...oftentimes). But maybe your car has revised 'true' hubs or the rotors are 'good', in which case all that has been written should be a non-issue. And that would be a releif. But don't rely on an uninitiated young 'tech' to discover it and take you down an expensive oddessey that you end up ultimately fixing yourself.

If you needed to, you could buy new 'true' hubs HERE. But only if you needed to. And that's just the front. And regardless. I would want to verify they are 'good' with a dial indicator on the outer hub-face for .000" run-out. And promptly send back for replacement any hub that has a little run-out. A little at the hub translates to a lot at the outer edge of the rotor.

You might consider go back and slowly re-reading everything that has been written so far. You seem to be missing the key details. Maybe watch a bunch of C2/C3 brake videos. We're just trying to help you avoid the pitfalls a lot of unwitting new C2/C3 owners fall into. Once you know what you have you may be able to rule things out...or know the best course of action to take.

Can you remove the front wheels one at a time and post a picture of the actual hub/rotor? Be careful where you put the jack at the rear...

.

 

I can do that and that will be my next step. I’ve been researching quite a bit and my hope is to do the following:
- remove tires and inspect each rotor. Goal is to keep existing. Pretty sure existing are original so I didn’t think I would need to worry about run out if I leave rotors in
- examine calipers to determine rebuild vs new
- change pads & lines

I’m actually thinking of doing it myself instead of a shop because even though I am inexperienced, I’ll be sure to take my time and be thorough