Over about 20mph my speedometer is screaming like a wild banshee and unless I'm in hyperdrive and don't know it saying I'm going 120-150 mph. Disconnecting the cable (which I just replaced) makes it stop.

Are these speedos user serviceable or do I need to send to someone for repair?

Cable?

That is the service item. I'd be if it was the gauge itself...

Nope, replaced cable and still there.

Stop driving between 120 and 150 mph?

The speedo head isn't too hard to work on ,gears are availiable from several vendors or ebay.
However getting the bezel off can be a real mission,its not so much getting it off it's doing so without destroying it.
There is a guide on Pelican detailing the procedure,I have done 3 gauges now and it tests your skills.
Your only option is to get a good used one or farm it out to a shop to repair if you don't feel happy doing it yourself.

It's a porsche, it s'posed to go fast?!

holy frijoles, those little gears are expensive! there's a guy on ebay from Manassas, VA advertising rebuild/repair for $85. Anyone know who he is?

Contact timothy_nd28 on here as member. He provides a service of adding LED lighting to the gauges, but he is also very good at rebuilding the internals. I've used him and can't say enough good things about him...

if you hook your guage to the cable but not have speedo installed, but have cable less kinked, does speedo still make noise?

i found a kinked ( aka: too tight a radius ) cable can cause speedo noise. at least that is what i think. i have not installed a new cable to verify.

North Hollywood speedo

+1. Tim is a standup craftsman and a valuable member of 914world.

Paul

Emailed him, thanks