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C4 Seats in a C3 Revisited


Well-known member
Jul 3, 2001
Auburndale, Florida
1969 Killer Shark
C4 Seats in a C3 revisited

This topic comes up often, so I thought I would share what I have learned with others considering the mod.

Thanks to John AKA Black Thunder I have had the awesome opportunity to install a set of 94 vette seats in my 69. There are some minor differences in the 94 seat from the 84-93, but the basic seat bucket and frame is the same.

To do it how I did it, you will need some good hacksaw blades, drill bits, 5/16" thread tap, a handfull of 5/16" bolts, and some raw stock 3/8" thick by 2" wide steel plate, and good dremel tool with bit.

First, I bolted the stock C3 tracks into the floor of the car. I then removed the lower cushion of the C4 seat and placed it in the car over the stock C3 track. I was able to use the factory C4 front bolt holes with a slight amount of dremel work to widen them by about 1/8".

I took it all back apart and then cut two 4" long pieces of the steel plate. I drilled and tapped the 5/16" threads and mounted it ontop of the rear seat track frame on both sides. What this did is raise the mount up, and give me a wider mount to bolt the seat frame to. In the front I made two small blocks from the same plate, drilled and tapped them, then ran a bolt up like a stud from the seat track.

Okay, I put the seat back on the tracks bolted on the floor, and lined up the front holes on the bolt studs sticking up into the stock C4 holes that I had dremeled out just a tad. I then marked the bolting plate in the rear through the stock C4 mounting holes.

I pulled it all back open, took the rear mount plates off and drilled out the marked hole. Another quick trip to the drill press and tapped out those holes with 5/16" threads. I had to custom cut the length of the bolts so they would not extend beyond the mounting plate and snag the track below.

Back to the car. I mounted the rear plates on the tracks, front spacer plates holding the bolts like studs, bolted the tracks to the floor, then sat the seat over the front studs, wiggled and lined up the rear mounts and ran bolts down through the seat frame into the mounting plate.

Ta DA!!!!!!!!

Oh, before that I had Nikki sit in the car (4'11" tall) and I sat in the car (5'7") to see that the seat would go where we needed it. On the passenger side I ended up mounting the 500 watt amp on the rear kick panel limiting the rear travel of the seat. I am not real happy with this, but it frees up the cubby, allows air to get to the amp, I can adjust the amp by pushing the passenger seat forward, and I will have some basic roll bars welded back there anyway.

Let me know if you guys want any more details on this swap.
Are there any aftermarket seats fro the C3 that dont involve dremels and hacksaws to get them in? :)
Yes, the Corbeau A4 from Corbeau. They are about $360 per in cloth and you can buy tracks for about $60 that are a direct fit. However, if you are more than a 36" waste, don't bother ordering them.
Sounds like adapting the seats to fit 69 tracks was a little involved. I will always wonder if the 94 tracks being on would only involve some fabricating at the rear as I had to do to get the 80 seats in my 68.
The rear mounting holes extend back further on the 80 tracks so I fabricated a plate with a forward extension to utilize the factory mount locations.
I knew you would get them to work, I had faith. Hope they look like you thought they would installed!
They really look great and seem to fit pretty well. Sounds like you took the best route on the newer C3 seats and tracks. Less mods and a perfect fit.

Here is one of the best parts of where I am at this point because of having the seats modded into place. Because I now have a seating arangement, glass, etc. I am finally ready to take it to the race shop and get the saftey/roll bars installed. In fact, I talked to the fellow today and he has scheduled it for Saturday morning. He may have it for two or three weeks.

He builds NASCAR, Winston Cup, and NHRA pro series bars for all kind of cars. I am not after that kind of strength, but I am sure he can adapt his know how with my vision of what I want.

Bottom line, I will have a secure metal structure behind the seats tied into the lock pillars and down under the seats with a pair of for mostly looks hoops behind the seats and a place for a four point seat belt to mount.

I have to get the car out of the garage for a few weeks anyway to make room for the engine swap in the 90. This freakin ZF six speed flywheel/clutch conversion is driving me nuts. I got a fantastic RAM brand clutch disc, new one piece flywheel, but now I am having trouble finding anybody that sells just a pressure plate. The local rebuild shop can't build the ZF pressure plate. New it is about $250.

Anyway, the 69 is going to get a little break until the 90 is together and my bank account has life again.
pair of for mostly looks hoops
Wow is that going to look sharp! Was thinking of that for Thunder after seeing it on the Porche (I think) Can't wait to see how it comes out!
Hope you find a flywheel....reasonable!
Ok I guess not,

I really like the C5 seats, I'll have to look around to see if this has been done yet.

I helped my brother install F4(93-02) seats in his F2(70-81), which track width was the same. So we just bolted(front bolts) on the tracks off the F2 on the F4 seats and did some fabbing for the rear bolts.
Ls1smlblck said:
Ok I guess not,

I really like the C5 seats, I'll have to look around to see if this has been done yet.


There is no doubt in my mind the C5 seats will work. Don't think I have not been eyeballing the ones in Nikki's car. I have also looked at them at swap meets and a local Corvette recycler. The problem is that the prices are really high still on those things. I am talking $500 to $1,500 for a pair of perfect C5 seats. Plus, the buyer will still have to fabricate and modify to get them in. I think when they become as plentiful as the C4 seats you will see more of them popping up in all kinds of cars.

One strange thing really is that the C5 seat is far less curvy and "race" looking than the C4. In fact, the C5 seat almost has more of the original look of a C3. I like the seats in Nikki's car, but they don't give me that F16 fighter jet feel that I have become so use to in the Vette.

The seats in the 90 make you feel like a test pilot just sitting in them. People complained an aweful lot about the trouble getting in and out of the C4 seat. Oh yes, the C4 seats I have put in the 69 are hard to get in and out of. However, the way I look at it, it is the time you spend behind the wheel that counts, not the micro seconds of any given day climbing in and out. Imagine how Bo and Luke Duke felt having to pour themselves in the General Lee for our personal home entertainment.
Wow, didn't realize that people are asking that much for them. Speaking of C4 what happened to the ZR1 that need some work?
I need to either have my seats redone, or get new ones. I have been looking at the Cerullo XR Sport Seats. I like these because they have two belt pass throughs on the upper portion of the seat, like my originals. Has anyone tried these seats? I plan to call them and discuss fit. You can check these out at www.cerullo.com
No more questions about the RED color

Thanks to John, aka Black Thunder, the C4 seats in my C3 are finally on the home stretch.

Just got them back from the interior shop with the fresh black covers. If I had a dime for every body that asked about why I had such bright red seats in the black car, I could have ..... well you know.

I got away with taking some grade A all thread and welding small studs directly to my seat tracks then drilled the seat pan my seats are 84-87 units though so might be a little different than yours
topless82vette said:

I got away with taking some grade A all thread and welding small studs directly to my seat tracks then drilled the seat pan my seats are 84-87 units though so might be a little different than yours

Yep, that would work too, except you had to drill new holes in the C4 lower pan. I was just trying to avoid any extra holes.

Did you put some shim material between the track and the seat to clear the forward/back adjuster lever area?

no shims, seats are flush against the tracks I have power seats on both sides.... did you get my private message with my address so I can get a money order off to you for the regulator springs
Yep, and I sent you one back :cool

I had some trouble with the reply feature for some reason. So, if you did not get it,

I need a couple of weeks to get the new springs in and make sure they are a 100% replacement. Then, I will ship the old ones to you.

Chris McDonald
565 William Ellery St.
Orange Park, FL 32073

(904) 723-2414
(904) 298-3017

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