I have a 95 SL1 that has a growling noise that starts at about 25mph and gets worse the faster you go. It only happens when going straight or turning left. I have replaced both half shafts, with no relief, now what?

That's a classic symptom of failing wheel bearings in either one or both wheels. Generally you will discover that its bad on the wheel opposite the direction you turn it due to the action of centrifugal force. It could be ball joints/tie rods as well, but I'd start with an inspection of the wheel bearings. If the growling noise is present even when moving straight ahead, and worse at lower speeds, then it's likely a brake issue. Get it to the shop. Unless you are a pretty darn good DIY mechanic, this is not a do-it-yourselfer!

This could be one of two things. We will first start with a wheel bearing. When you are driving, does the growling noise get louder as you go faster. Some times is will sound like you have a helicopter flying beside you depending on how bad the bearing is. The second thing that could be causing the growling noise is your transmission. There are also bearings inside your transmission that could be causing the noise. If you have a cvt transmission, you have a 120,000 mile warranty and can have it repaired at no cost to you. You will just have to go to a nissan dealership.

Is it a growl like a bearing? Have you tried rotating tires to see if any difference? Happens at all speeds? How far do you have to turn before it happens?

if it is a high pitched growl it is most likely a wheel bearing starting to go out.

Might want to check your brake pads

Have you checked the REAR whell bearings? Sometimes even when the noise appears to come from the front, the rear bearing can be the ones. Happende to me in my older Spirit R/T. By spinning the rear Wheel with an old impulsor motor in a Wheel balancing/alignment shop, the technician showed me that it wasn't a front drive problema, but rear bearings getting some moisture inside and going bad. It made a worse glowl when turning to one side. Amclaussen.

check the CV joints

sounds like a gearbox bearing ,,,this sounds like a growling noise usually when accelerating although as the problem gets worse it can happen constantly ,,, wheel bearings can growl too but will give a constant noise regardless of acceleration ,,, you need to see to this quickly as the more you drive you will cause more damage and cost to you ,,,,bearings will fix it in the early stages but if more damage is done you could have to pay for new gears and shafts which is expensive

possibly your ball joints, or a wheel bearing starting to go

Sounds like Your Power Steering Pump is on it's Death March. Replace it and your Problem will go away.