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I recently aquired a somewhat neglected 1990 Corvette ZR-1, and as I get to know the car, a few questions arise.
First, the car has what I assume is non-stock front brakes / calipers. Can anyone identify these? They are marked Brembo on the back. A later model corvette retrofit?
The rear ones are however the rather sad looking, one piston, gray caliper. Can a set matching the retrofitted front brakes be aquired?
Second issue. Clutch fluid leakage. Previous owner said bad slave cylinder, so I ordered new master/slave. During removal of old slave, it became obvious that the fault was not slave, but clutch hyd. oil pipe rubbing on exhaust flange. The old slave seems to be the same Dorman slave I have now purchased. As you can se from the below photo, There are some issures positioning it in such a way that it does not touch anything. Now it clears exhaust by 2mm, but is not self-bled. If I turn it upside down, the vent screw will touch the chassis.
Third issue. The rims have gotten somewhat oxidized. Anyone have any experiance on how to refurbish the machined surface?
Not sure if it'll be worth the effort, so if anyone knows of a set 91-93 (93 preferred) ZR-1 wheels for sale, please let me know.
Fourth issue. Though I'm not entirely sure it's an issue yet. The previous owner never had the "full power" mode available during the four years he owned the car, due to a fault code (MAP hose had come loose = Good price for me). The secondaries has therefore not been in operation for over 4 years, and since it's winter here now, I havent really been able to test WOT driving all that much. The couple times I do believe I got into the realm of secondaries activation, it seemed to hesitate a bit, and not really give the nudge I was hoping for. This could ofcourse be imaginary, but is there anything I could check to ensure that the actuators are operational?
And a slightly poor teaser, as pictures are always nice.
The ZR1 registry will give you a wealth of knowledge in your issues...As far as the secondaries,they are operated by vacuum....Mark Haibeck is located in Chicago and Dempsey Anderson Evolution motor sports fredricksburgh VA are experts with the ZR1.....
My advice, change what you can get access to - oil 10w 30 Mobil one high mileage is good along with a Bosch filter..Spark plugs and air filter....The plenum will have to come off to get to the coils and wires....They are easy to change..Coils are held on by four screws and are easy to do....
Also how many miles on the car? Reason being if it's somewhat high the injectors were probably changed......The stock fuel injectors on those years are not ethanol tolerant and will fail..... Maybe you could ask the previous owner if he ever changed them or knew of anyone previously changing them.......A lot of ZR1 owners who have some mods on there car usually delete the secondary system anyway,so you are always running on the 16 injectors and don't have to worry about vacuum issues..
I'm located in Norway, so we're a bit lacking on local LT5 expertise.
The previous owner did nothing but oil-change, but then again, he never really used the car. He just lost a lot of bolts and sold the car to me.
The car's currently at approx. 70k miles, and the injectors were changed 2-3k miles ago.
Looking at the "quality" of work being done on this car, I doubt any of the previous owners would embark on such a thing, unless it's remarkably simple. I did however find a "secondary throttle test procedure" on ZR-1 registery, so I'll definately check it out.
Here's one of the previous owners marvelous mods. I'll probably have to contact Corsa in the near future.
I'm located in Norway, so we're a bit lacking on local LT5 expertise.
The previous owner did nothing but oil-change, but then again, he never really used the car. He just lost a lot of bolts and sold the car to me.
Norway? Hmm...Yeah that's a bit out of the way.....Yes check out zr1 registry..
If your going to replace the exhaust system and don't want to spend a ton of money I recommend OBX Headers and exhaust,I have that in my car...
The car's currently at approx. 70k miles, and the injectors were changed 2-3k miles ago.
Looking at the "quality" of work being done on this car, I doubt any of the previous owners would embark on such a thing, unless it's remarkably simple. I did however find a "secondary throttle test procedure" on ZR-1 registery, so I'll definately check it out.
Here's one of the previous owners marvelous mods. I'll probably have to contact Corsa in the near future.
Bubba loves ZR-1s. I'm having to undo some of Bubba's finest work myself. I had a local CL listed ZR that was in need of a new transmission. It's no longer listed.... I was thinking of getting it for my Christmas bonus to repair and flip or sell mine and keep it.
Must say it's remarkable how people can be so disrespectful of these cars. Surely it deserves a bit better than crap welded exhaust.
John, is that your ZR1? Looks real nice!
How's the drone on the OBX exhaust?
Yes in sixth gear there is a drone....Of course the faster you go in sixth gear it lessons..I'm not to sure but I think most do drone somewhat in sixth gear.....
The front brakes are adaptations of the Porsche 993 twin turbo car from about 1996.
A guy named Guido in Germany designed the mounting brackets for the caliper mount,
and the rotor hat is unigue to the ZR-1 application too. I had a set on my 91 when I roadraced it and they are somewhat better than stock. Unfortunately, the wheel sits out about 3/4" and the front suspension geometry is upset - scrub radius is no longer correct. The rotors and pads should still be available from Porsche and the aftermarket - I used Performance Friction and Porterfield pads ... good luck.
Much appreciated!
You're saying the conversion pushes the wheel further out? Interesting. I'll have to take a closer look.
Do you know if there's a similar conversion for the rears?
Yesterday brought a new issue as well. The rear studs seems to have been replaced with longer studs. Probably to accomodate spacers and such. Two of them are however now spinning in the hub. Anyone has any experiance in whether its the splines in the hub or the studs that fail first?
Much appreciated!
You're saying the conversion pushes the wheel further out? Interesting. I'll have to take a closer look.
Do you know if there's a similar conversion for the rears?
Yesterday brought a new issue as well. The rear studs seems to have been replaced with longer studs. Probably to accomodate spacers and such. Two of them are however now spinning in the hub. Anyone has any experiance in whether its the splines in the hub or the studs that fail first?
Guido did a rear upgrade too but it required an additional caliper for the parking brake. My experience is the ZR-1 has adequate stock rear brakes if you balance the front and rear pad compounds. It sounds like your vehicle had some aftermarket brakes on the rear too.
Re: studs - I've never seen what you describe - there are splines on the stud which cut into the hub and makes it a press-fit plus.
The car up there is zrc3john's facelift, unfortunately. Wouldn't mind the post 91 front bumper and wheels myself.
You're saying that the hub isn't initially splined, just the studs? In other words, replacing the studs might be adequate? I'll have to give it a try today.
Initially I wouldn't mind the stock rears, but having such screaming front calipers compared to the rear ones, it's kinda obvious that the front brakes are modified, wich might cause issues when it's due for periodic vehicle control. They don't like modified things.
Got the clutch pipe yesterday, and as expected, there is no way to install it in such a way it's self-bleeding. Is can be installed as depicted above, but it puts strain on the hose/pipe. Seems the 90 ZR1 might require the 91 clutch slave?
As you see, the bleed and hose connection are opposite one another on these, which would allow self bleeding installation.
The speedbleeder certainly looks interesting. One might wonder why such aren't standard on brakes etc.
gbrtng: Appreciate your input on the hub issue. Knocked out the old studs yesterday, and was able to pull inn the new ones with the lug nuts. Seems to be holding quite nicely.
Stud no.2 being pulled in (appologize the poor focus)
Studs replaced.
¨
Shouldn't the wear pattern be wider? Too small brake pads?
11-15-2016, 01:56 PM
Bought a 90 ZR-1 - a few questions
