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I decided as a winter project to fit C4 seats into my C3, and as I have found differing opinions about this on various forums etc thought I would document this here.
Sourced a set of seats here in NZ at a reasonable price and had them shipped to me.
The reason I want to change the seats is the poor support the originals give especially when cornering which we do a lot of where I live. I'm worried that the "missus" is going to pull the door handle off one day whenever the cornering gets the least bit spirited. FWIW I have been in the passenger seat and its not much fun trying to "hang on".
After some preliminary measurements it looks like the most practical way to do this (and as mentioned in other posts by members) is to use the C3 tracks fitted to the C4 seats. This gets the seats down lower than it would be if you use the C4 tracks but means I am ditching the electric adjustment components that came with the C4 seats. Also, I noticed the C4 seats are considerably lighter than the C3 ones which is a plus
It appears that the front mounting holes in the C4 seat base will match up with the C3 tracks but not so the rear holes. I am considering making adapter plates to allow me to use the original holes in the floor pan to keep everything easily changed back to stock.
Last edited by Haggisbash; 05-23-2016 at 04:29 AM.
Reason: Updating
Test fit: The C3 seat is black leather under the cover, I am going to get the C4 seats dyed blue where they are now cream coloured. You can see in this pic how much higher the C4 seat is when fitted with its original tracks compared to the C3 seat.
I modded a set of C5 seats into my C3. Found a set of full power ones and had them recovered to my liking and they work great. But the full power part makes them sit up kind of high. But at 5-8, its not a problem for me or my 5-2 wife. See if you can find an upholstery shop that can add a logo for you. Makes a good mod in my opinion.
I like the logo idea, I will investigate this after the install. I have to get the car past inspection here with the "new" seats and if they are not happy I will have to get certification for the seats which could cot $700.00 gulp.
Following this thread as well, because I own a C4 and I like the styling of the seats. The 1974 bucket seats are really tough after a 100 miles or so! I'm going to study Patro46's pic and see how much higher the C4 seats are, than stock, because I'm almost 6' 2" and with a four speed, I'm worried that my left leg, might not have enough room for the clutch action. Any input on this, is appreciated! Thanks!
I hope to have the first seat mounted over the weekend, I will then post the measurements. At this stage it would appear the by using the C3 tracks on the C4 seats, the seat height will be close to the same.
I`m 6`3" and I installed fiero seats on fiero seat tracks, and I still fit! I could have bolted directly to floor for more room, but I really wanted to be able to adjust them.
The key is you have to get rid of the seat belt retractors under the seat so they will sit lower. I replaced seat belts with a set that is just like original with the shoulder retractable, but the lap belt is not, but is adjustable. I`m changing the interior color, so had to get new seatbelts anyway.
New brackets made to adapt from the C$ seats to the C3 tracks, I will get pics of these up when they are finished. C4 seat sits low enough for me, there is not much difference in height between the two seat bases.
I have installed the C4 passenger seat and took the car for a test drive today, full passenger approval on the seat and no hanging onto the grab handle in the corners
now:-)
The two 4mm steel adaptor plates pick up the original holes in the C4 seats and the C3 tracks so I could fit the two together without modifying either. This means it would be easy to convert back to the original seats if required. The 4mm thick steel is the minimum I would use because I countersunk the bolt holes, anything less in thickness and countersinking probably wouldn't work.
I used 8 x 20mm countersunk cap screws to bolt everything together at the back ( I couldn't get 7/16 ones locally) and 7/16 x 3/4 bolts at the front.
7/16 x
On the seat adjuster side you need to put a spacer between the track and the seat base or the track wont fit properly because where the adjuster fits onto the track there is a bump that stops the track sitting flush.
C3 tracks on C4 seat
Mounting holes in C4 seat, there were two sets of holes in the front of the seats I got, I don't know if this is std but the outer two holes at the front lined up perfectly for the C3 tracks and the floor holes.
Thanks for the great info and pics. I tried the Fiero seats in my '72, but wasn't a fan of the additional 2" of seat height. At 5'8" fitting in the car wasn't an issue, but the frame at the top of the window was in my vision a little more than I liked. The C4 seats look like a solid option thanks to your pics. I hope you get many miles out of them.
05-22-2016, 08:31 PM
C4 Seats into a '70 C3 project.
