I've read through several threads on this but I cannot get the driver side cable fed through the rear firewall. I bought the cable from 914rubber. I've tried pulling it through with the old one with both ends taped together. I've tried shoving it through. I've tried kinking the cable a bit. Lots of lube on either end. It's getting stuck at the kink. Any other ideas? Maybe physically fasten the old and new cable together? I'm worried any fastener will be too big. I'm also worried I'm going to ruin this new cable.

I had a similar issue on the driver side. I put a Phillips head screwdriver in the tube and relaxed the bend just a bit. Worked.

I played with this a bit and the tube felt really firm. This is the one time I wish the car was a bit rustier.

I was able to get it. I did end up bending the firewall tube a small amount. I then threaded the old cable through to the cabin and heat sinked it to the old one. Pulled it through. The really fun part is the new cable on that side is too short. Luckily the old set up had a second small cable I saved to make the link work.

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nice idea to heat shrink them together, that did not give a whole lot extra thickness to the cable to pull through !