FWD fuse to disconnect driveshaft

K_Dub · #1 02-26-2010, 06:57 PM

Does putting in the FWD fuse stop the driveshaft from spinning? Or does it just spin with the tires without any power going through it? I've got the fuse in but still have the metal scraping sound up front that my mechanic told me is my driveshaft.

Trevor · #2 02-26-2010, 07:37 PM

Quote:

Originally Posted by K_Dub

Does putting in the FWD fuse stop the driveshaft from spinning? Or does it just spin with the tires without any power going through it? I've got the fuse in but still have the metal scraping sound up front that my mechanic told me is my driveshaft.

The shaft will still rotate driven via the wheels, as you have suspected. The switch fuse will only prevent drive from the engine and transmission, as a result of preventing the centre clutch from engaging.

svxfiles · #3 02-26-2010, 07:40 PM

Quote:

Originally Posted by K_Dub

Does putting in the FWD fuse stop the driveshaft from spinning? Or does it just spin with the tires without any power going through it? I've got the fuse in but still have the metal scraping sound up front that my mechanic told me is my driveshaft.

If you have an AWD car, and the driveshaft is connected and not broken, it will spin as a result of the rear wheels turning, regardless of the fuse.

A very common cause of the driveshaft scraping is a bent heat shield.
Why don't you remove the aluminum heat shield above the exhaust, and below the driveshaft?

K_Dub · #4 02-26-2010, 09:14 PM

Quote:

Originally Posted by svxfiles

If you have an AWD car, and the driveshaft is connected and not broken, it will spin as a result of the rear wheels turning, regardless of the fuse.

A very common cause of the driveshaft scraping is a bent heat shield.
Why don't you remove the aluminum heat shield above the exhaust, and below the driveshaft?

Yeah, I've figured a lot out since I posted this roadside. I hadn't really thought things through, nor tested, or looked underneath, so... Yeah.

Thanks for your input.

Seems like they just slapped my car back together when they saw that the driveshaft they ordered was too short. So the heat shield is scraping, which it wasn't when I dropped it off, and the same vibration as before kicks in at 20-30mph. I was just freaked when I got in and it was scraping so bad, so I pulled over, got out the iPhone, and hit up the best SVX mechanics in the world.

I love this forum.

svxfiles · #5 02-26-2010, 10:06 PM

Your post speaks of vibrations...
And of a wrong replacement driveshaft.
Can you take your original driveshaft to a driveshaft specialist and have him de-stake the U-joints and replace them?
U-joints are only $25-$30 or so each, the tough part is finding someone who can reassemble it without causing a vibration.
Tom

svxfiles · #6 02-26-2010, 10:08 PM

If you want, I can see about rebuilding one here..
Shipping should not be that much if I split it into two pieces that you can bolt back together.

K_Dub · #7 02-26-2010, 11:18 PM

Quote:

Originally Posted by svxfiles

Your post speaks of vibrations...
And of a wrong replacement driveshaft.
Can you take your original driveshaft to a driveshaft specialist and have him de-stake the U-joints and replace them?
U-joints are only $25-$30 or so each, the tough part is finding someone who can reassemble it without causing a vibration.
Tom

Sorry, I've got some of these details in a Parts Wanted thread, and other breadcrumbs scattered over the forum for the past few months. I'm making a mess of the internets, I know. Maybe I should start from the beginning while I've got your attention.

I've had a rough vibration between 20 and 30 mph for the past few months. While I was installing new swaybar bushings and rear-diff bushings I saw that my CV boot was torn on my passenger front axle, so I figured I'd finally found my problem. I took it to an independent Subaru shop (after being told by 3 shops that they didn't work on SVX's), and they replaced the whole axle and both boots about a month ago.

While it was A problem, the axle wasn't the cause of my vibrations. So I saved my pesos and brought my car back to them on Wednesday. They said that my driveshaft was causing the vibrations (which I'd come to suspect) and also that my passenger rear bearing was shot (also no surprise). They found a "used '94 SVX driveshaft" for $350 local, and I told them to hold off. Enter my "parts wanted" thread. I found another one at a nearby yard for $200, but then they called back and said it wasn't from an SVX after all. So I pulled the trigger on the $350 one only to find out today at 4pm that it was too short. They claimed that the two-piece redesign wouldn't fit my car and I need one from a '92 or '93. I'm not buying it. Turns out I was offered two overpriced Legacy driveshafts in just 24 hours.

So I left the garage as they're closing up for the weekend and my car is making a horrible scraping sound from the front end. I freaked out a bit. I called the shop, as they'd closed the gate behind me, and they said that it was just a little worse off than before and to "take it easy on the throttle."

I've been searching here since I crippled it home, and yeah it sounds like the heat shield to me. I've also been learning about durability issues with the early one piece driveshafts, so now I'm thinking that upgrading to a later two piece might be the best idea. Tomorrow I'm going to get under there and see if I can get that heat shield back where it was before so I don't have to listen to it, then I'll be tracking down parts to get shipped. I might very well take you up on your offer Tom.

Thanks for listening. That was therapeutic.

svxfiles · #8 02-27-2010, 07:35 AM

Quote:

Originally Posted by K_Dub

I've also been learning about durability issues with the early one piece driveshafts, so now I'm thinking that upgrading to a later two piece might be the best idea. Tomorrow I'm going to get under there and see if I can get that heat shield back where it was before so I don't have to listen to it, then I'll be tracking down parts to get shipped. I might very well take you up on your offer Tom.

Thanks for listening. That was therapeutic.

OK, thanks for explaining.

1)All SVXi had the same length driveshaft.

2)The term "one piece" refers to a two piece driveshaft, that does not unbolt in the middle BUT it still has two sections of driveshaft with a flex joint connecting the two pieces.

3)In all of the worn out SVX driveshafts that I have seen, all of them had either the front U-joint, or the rear U-joint bad and never yet the middle one.

Is your bad driveshaft one that can be unbolted in the middle?
Is the front, rear, or both U-joints notchy?