Figured I'd make this thread to document all of the modifications and maintenance on my car. I was inspired by mark4cam and his thread - https://www.corvetteforum.com/forums...ce-thread.html This is an excellent read and I will try to document my journey as well as he has.

First up, a little background on the car and me. I previously owned a 1992 ZF6 Black on Black coupe for a year which I sold just about 18 months ago. It was an awesome car to drive, and a solid gateway into the world of corvettes as that was the first one I had ever owned. It was in decent condition, but I didn't want to put any more money into it for any modifications as I knew I didnt want to keep it. I wasn't in love with the black (beautiful color, but terrible to maintain) and thought I wanted to move to a C3 at that point. Sold it, and went looking for a C3. Turns out, I quickly changed my mind after test driving my first 4-speed C3, a 1980. Still my favorite looking car of all time (specifically the 1980-1981), but it felt like a never meet your heroes moment. I grew up going to car shows with my dad as a kid and I always gravitated towards the corvettes, especially the c3. It was slow, did not feel sporty to drive in any way, and I preferred the way the c4 handled and shifted. I also got the chance to drive my friends base manual C5. It was fun to drive, but felt too refined and not as fun as the C4. So, after doing some more research, I went to looking for a 92-95 Dark Red Metallic ZF6. This took almost a year to find! I searched across the US on marketplace, craigslist, this forum, autotrader/cargurus, etc... just about every week. I did miss two cars on Bring A Trailer that seemed decent, but finally found what seemed the one on marketplace. I ended up driving 16 Hours from Augusta, GA to Iowa City, Iowa to pick it up. 1995 Dark Red Metallic with the Light Beige interior, ZF6, and only 47k miles. Took it back home on a uhaul trailer and now the fun begins.

The car itself is quite interesting. The first owner performed a good bit of modifications before passing away. His wife took possession of it and sold it to a dealership, and then changed hands once more before I bought it. Sadly, the documentation on the modifications was lost in the journey. It still has the original window sticker and build sticker, but all of the modifications seemed to be done correctly from what I could tell when inspecting it. It has TPIS Long Tube Headers, MSD 8.5mm spark plug wires, H pipe exhaust with flowmaster mufflers, vortex rammer air intake, and interestingly an LT1 intake painted red, and some form of an upgraded valve train with what appears to be older comp cam pro magnum roller rockers, and an aftermarket camshaft (potentially the LT4 conversion kit that was somewhat popular in the early 2000s when I believe this work was done). It still has the EGR Valve and secondary air system even with no cats - i intend to remove this along with the secondary air pump in the future, but I'll save that for when I get to it. The owner after buying it from the dealership put some C6 ZR1 Style bronze wheels on it. I'll be getting some 17x11 Silver A-Molds to replace these. Here's a list of things I intend to knock out, in no apparent order.

Updated 2/17/2026
1. Oil change
2. Transmission Fluid Change
3. Year Correct windshield wipers (current ones hit the hood)
4. ZFDoc Short throw shifter
5. Brake fluid change
6. New pads and rotors (probably going with Powerstop Z26)
7. Stainless steel brake lines
8. DRM Brake Bias Spring
9. Power steering fluid change
10. Clutch fluid change
11. Fix power antenna and re-install (removed from car, relay and motor work, but cable seems to be broken in motors)
12. Fix cruise control
13. LED Headlights to be more comfortable driving at night
14. 17x11 A-Molds with Michelin Pilot Sport AS4s (315/35 r17)
15. After Dark Speed Coil over conversion, as Fx3 System is currently disconnected from shocks
16. Miscellaneous After Dark Speed Suspension Upgrades
17. Dyno it!
18. Get it re-tinted. Tint is starting to bubble/peel
19. Re-seal rear diff (appears to have small leak around seal, gotta clean it to check) and side axle seals
20. Re-gear to 4.10
20. Re-seal valve covers (appear to be leaking onto engine block)
21. Passenger side knock sensor wire is frayed, just need to cut it, place a butt connector there, and heat shrink it
22. New center console cover, as the passenger side binds when opening
23. Secondary air sytem and EGR delete
24. Refresh exhaust (ceramic coating is peeling on headers, weld v-band clamps from headers to mid-pipe and mid-pipe to muffler section, polish/re-finish remaining pipes and mufflers)

My eventual goals are to build the car to run between a 12 and 12.5 on the drag strip, while retaining all of its drivability and the ability to take it to an autocross or street course if I ever desire. I would love to go to a drag and drive event, but that is a few years away. Oh, and be able to take it to a car show on the weekend, take the lady to get coffee or out on a scenic drive, and to work once in a while.

 

First order of business was some fluid changes. Went with Mobil 1 5W-30 and a Mobile 1 M1201A filter along with the Amsoil5W-30 Manual Synchromesh Transmission Fluid. I'll make it to the rest of the fluids in the near future

 

Next up, I decided to throw in the ZfDoc short throw shifter. I probability didn't need to do this modification first (and could've focused on fixing some other stuff) but wanted it when I had the other corvette, so I ordered this from Bill along with his beam plates. First hurdle in this installation was getting the exhaust off. I don't think the exhaust was messed with since it was originally installed, as the mid tubes had gotten very stuck to the long tube headers. I ended up having to cut some slits in the mid pipes in order to get them off. Here's some photos

 

After getting the exhaust off, the next issue I encountered was the shift **** retainer pin. Mine was extremely stuck. Some folks recommended prying with a screw driver on each side of the pin, but it ended up chipping the pin. I resorted to what ZF Doc recommended in his instructions. I locked a vice grip on the pin, with a pry bar in-between vice grip, stood up straddling the transmission tunnel with the top off, and pulled up as I hard as I could. Almost smacked my face when It came loose! The rest of the disassembly was pretty straightforward until i got to the drift pin. I'll try to remember to post some pictures of this process this weekend.

 

Beautiful car and you are ahead with the current mods. Your build plan is very similar to mine. I have already done most but not the shifter yet. Good luck with it and post your progress please.

 

Wow I love the paint, looking over your list and what has been done already to your C-4 starting my mind looking back at all the work that went into my 93 auto , This 93 has the same amount done to it but more, this one completely disassembled and repainted (ORG. color ) new rubber and lots fasteners lots ,3 years' worth , money lots ,new trans Diff. and on and on one more on ,Was it worth it well first got to be satisfied with the thing after ya spend all the money and do all the work ( you going to be doing it ) nobody around going to do it for ya and if they did BIG money that be crazy to do that ,I have owned lot's vets over the years new ones old ones I knew what I would have when I finished restoring this this 93 and I be HAPPY with it , fast yep .Good luck with your red C-4 ,going to be a cool ride ,Going to need lots of band aids ,LOL

 

Thank you! I'll do my best with updating my progress, I'm behind but will hope to catch up here shortly. I recognize your name from quite a few threads I've read through, its always nice to see someone familiar here.

 

Thanks radar! I was dead set on finding one in this color, and it took me far too long to find it! My favorite paint job of almost any car I've ever seen. I've got a 2015 Ford F-250 in a Bronze Fire Metallic that gives it a run for its money.
I appreciate it, it seems like I'll be doing just as much as you will have done. Short of a few items (machine work on the engine, potentially a transmission build from ZFDoc, and maybe the rear differential rebuild), I will be doing all of the work myself. I find it very satisfying to be able to work on this and my truck as much as I can myself.

 

To continue with the ZFDoc short throw install, I was last at the drift pin. It did not bulge with a hammer and a brass punch - and after about 30 minutes with no progress (after letting soe penetrating oil sit on it overnight), I resorted to drilling. I did use a starter punch to center mark it, however my drill was a bit large for the tight space and the bit got off center. Managed to get the pin out eventually though, here it is stuck partially drilled and here is it out.

 

Forgot to post these first! Here's some images showing the disassembly of the interior. Be careful with the lower shift boot that is glued in - I accidently ripped it trying to get it unstuck from the tunnel. Otherwise, all of this is pretty straightforward.

 

And here's the shifter out of the car. Also shown is the direct comparison between stock and the ZFDoc shifter. Make sure to account for all of the shims and washers. Of note, the cup spring washers are placed with the concave side facing each other - should look like this (). ZfDoc provides new grease to use during the reassembly process and also has plenty of spare parts availbile if needed. I purchased a new drift pin, retaining ring, and a new housing (you can see a crack in mine in the 3rd picture, upper left corner).

 

Love it Keep up the good work, love seeing the progress.........And DAMN, Dark Red Metallic looks incredible on the C4

 

Only issue I ran into re-installing was that the drift pin now did not want to go back in! my first few attempts it had enough left over for me to get a vise grip on it and pull it back out. I ended up rounding the top of the drift pin as well as doing my best to cold shrink it. I had also aligned it, at least to my eyes and with a 1/4 punch, as perfectly as I could. It went pretty much the entire way, but had about the same thickness as the snap ring sticking out below. With how tight this fit was, I said this was probably not going anywhere and would be fine as is. My brass punches were pretty deformed after this - there is no way that pin was going in any further.

After buttoning it back up, got to take it for a few drives. Not as many as I'd like, this past month has had some brutally cold weekends in GA. With the past two being filled with ice and snow! I absolutely love the feel of the shifter so far. While it does feel a slight bit notchier than stock, and requires more force to shift, the distance for each shift is so much shorter. In practicing for powershifting on the drag strip, I am very easily able to punch the clutch down to the firewall and shift to the next gear at the same time. Here is a section from ZfDocs website on this (https://www.zfdoc.com/techinfo.htm) Bottom of this website.

POWERSHIFT TECHNIQUE (hitting the mark) -

Optimize each shift-segment window-of-opportunity by full-cycling the clutch pedal completely to the floor.
Utilize the firewall mat for a springboard to literally bounce the clutch pedal back off of.
The clutch pedal to firewall mat strike point can easily be protected by laying down a few strips of 2" wide high quality electric tape.

How to practice your Shift Reaction Timing:

Out of vehicle -
While standing and balancing on your right leg, raise your left leg 7" up off the floor. Simultaneously tap the floor with the bottom of your shoe tip and snap your right hand fingers (ring/thumb) so as to make one combined noise between the two. Match'em 30 times in a row, and you're dialed in precision shifting.

In vehicle -
Position your seat close enough to the pedals so that depressing the clutch pedal
to the floor is achieved with between 50/50 to 60/40 percent combination of knee/ankle
joint deflection. Shift reaction time seems to tighten up (real nice) when approaching
the 50/50 percent end.
Shift lever movement should initiate to the next gear at the same time you expect to hear the "thunk" of the clutch pedal tapping the mat.

Warning - Shallow clutching is deadly to these transmissions when powershifting.


While I still have quite a few items to tackle before getting to the strip, I'd like to practice my shifting as much as possible. I also have a decent bit of work to do in general with driving a manual - while the first car I learned to drive on was a manual, but it was in southwest florida where even a slight incline is nonexistant. I only owned my previous zf-6 c4 corvette for just under a year, and then spent about 2 years without driving a manual. I definitely need to keep practicing my hill starts, as well as get comfortable with stop and go traffic, and begin getting faster off the line

 

An issue that does not affect driving is the antenna. Here you can see it removed from the car with the majority of the ribbon cable out - although I believe this is the most common issue where the ribbon cable has broke off in the gearset. I was able to confirm the relay and motor work by hooking up some test leads connected to a battery. To fix this, I need to drill out the plastic rivets holding the cover on, clean out the gearset, and replace the ribbon cable/antenna with a new one. I've seen someone on the forum talk about replacing the rivets with some small screws afterwards. Earlier years of the antenna assembly used screw to hold the cover on, so it is an easier fix. This is pretty low on the totem pole for me, but eventually I'd like to get to this. The more performance oriented modiofications take precedence.

 

Thanks Rush! I appreciate it!! Favorite color by far - once the weather warms up I'm hoping to grab some more scenic pictures to post on here.

 

Been working on my truck recently instead, but remembered to grab some pictures when I was in the garage over the weekend. Here's an engine bay shot showing the LT4 intake with a pretty cool customed machined plate with the corvette logo instead of where it normally says grand sport.


Also decided to peak at the heads to see if they were LT4 heads or not, as I only recently learned there should be an LT4 stamp visible through the oil fill. Well, there is not an LT4 stamp. However, it has ARP hardware visible and roller rockers. So definitely not stock LT1 heads. I tried to grab a picture of the rockers the best I could, but I do not have a borescope.




I really wish I had the documentation from the original owner who did these modifications, as I'd love to know exactly what was done. I might just take off the valve covers with the excuse to put new gaskets on to investigate further. Otherwise, car is running great. Weather is clearing up here in GA so hopefully I'll be able to take it out more. I'll try to take some videos the next time I take it out to post on here.

 

Those rockers look like the old Comp Cams Promags. Under the passenger side fuel rail cover is the intake casting number.

 

Great eye on that - they definitely look like those from the pictures I found on the internet. Intake casting number is 12552138. Darn - guess the orignal owner just painted it to look like an LT4! He even went so far as to put an LT4 plate on the cup holder lid