glenn993

Hi all. I have 2 issues that I could appreciate feedback on. I'm looking at a 993 and am wondering how bad a couple issues are... The car is great execpt for these issues. It has about 70k miles.

First, I had it up on a rack during PPI and I spun the drivers side rear wheel. I was expecting the passenger rear wheel to spin the opposite direction, but it didn't spin at all. Same with the passenger rear wheel.

I'm 90% sure the car doesn't have LSD, if that matters.

Is this normal? Didn't seem normal. If not, what does it mean?

Secondly, on occasion, I heard a grinding noise when when slowing to a stop. It literally only happened when the car is just slowing the last few feet, maybe from 5 to 0 MPH. It sounds like it was coming from underneath the engine, perhaps the gearbox. It only happened a maybe 20% of the stops, I couldn't figure out any correlation between when it made the sound. I definately had no gear selected, clutch out when it happened. It was definately noticable inside the cabin, but I don't know if it could be heard outside. The noise persisted for maybe a second after the car had stopped, so I don't think it was the brakes.

Any opinions on what that's all about? And idea if these 2 issues are related?

Thanks!

nsully

I would start by checking the option code sticker under the hood and in the owner's manual. This way you can determine if you do have ABD/LSD.
The grinding is probably the rear spoiler closing. It automatically closes on stopping, and most, unless they have been repaired make a bunch of noise.
This can be remedied with a inexpensive DIY repair.
Good luck,
Neil

TMc993

I can't help with the differential question, but I'm wondering if the "grinding" you hear isn't the spoiler retracting.

The spoiler goes up at 50 mph and then retracts when you get down around 5mph. So, on those time you don't get above 50 mph, you wouldn't hear it and on the time you do get above 50 mph you would...

See if you can duplicate the sound by turning the ignition on, but not starting the car, and then raising and lowering the spoiler with the spoiler switch on the console.

Don't worry too much if it is noisy, the replacement is a relatively simple DIY and can be found here: http://p-car.com/diy/spoilerdrive/

Good luck,
Terry

Stealth 993

That sounds like a LSD. A open diff would spin in the opposite direction, if not it's blown & the car would not drive. That's a weird issue to be hung up on.

Other then the spoiler, is it under braking? There might be something stuck in the brake pads.

glenn993

Thanks for the great responses, I appreciate it. More information:

I've confirmed the car does not have option code 220 or 224. So no LSD/ABD.

Also I thought about the spoiler and tested it - definately not the culprit. It happened on runs that I didn't get > 50 MPH and it doesn't make noise operated manually.

Any other ideas?

THANKS!

cabrio993

Maybe low on steering fluid reservoir?

If the power steering pump runs low, you'll hear a grinding noise coming from the rear. It gets accentuated on turns or when slowing down as the pump can't get the fluid.

Also, If the noise happens when slowing down while braking, maybe something on the rear brakes?

993Maineiac

With 70K you should check the regular cluprits with the brakes bing first on the list then the suspension componants. If you don't have documentation I would change the brake fluid and check all the pads-very easy on a 993 just watch out for the wear sensors.

MarkD

If I understand correctly, you were having a PPI done.
Why didn't the shop doing the PPI answer these questions?
It will be very hard to diagnose this here since you don't (I assume) have easy access to the car.

glenn993

Good stuff, thanks.

Re the grinding:

@Markd: The grinding I discovered on a test drive after the PPI so the PPI didn't "miss" that one.
@cabrio993: Good call re: the steering fluid, I'll see if I can take a look this weekend. I do have pretty ready access to the car. Also, the grinding noise persisted for maybe a second after the car had fully stopped, so that should rule out the brakes or suspension components.

I'm not sure why, but gut instinct says it's the clutch or gearbox, both of which seem to perform flawlessly in every regard except for this grinding issue. Can anyone think of why a gearbox might make this sound?

Re the diff:
@Markd: The tech did see the rear wheel behavior but basically wasn't concerned about it, didn't even note it in the report.

@Stealth993 - Re: your comment about the diff: "That's a weird issue to be hung up on." Do you mean that's a weird issue for me to be humg up on, and that I shouldn't be hung up on it? Or do you mean that's it actuall is a weird issue and that it shouldn't be happening?

Re: both...

I'm not sure whether to be concerned about these issues or not and am looking for opinions on the potential problems and their solutions so I can calculate it in.

Thanks again for your input.

Paul902

[QUOTE=glenn993;5954390]

I've confirmed the car does not have option code 220 or 224. So no LSD/ABD.


Any other ideas?

QUOTE]

If the car is a C4S (or possibly C2S, not sure...) it will have LSD by default, with no indication on the option sticker.

glenn993

@Paul - it is a 1996 Targa.

ppressle

If you put it in gear, I bet the other wheel will spin in the opposite direction. In my experience, if it was a working limited slip both wheels would spin in the same direction.

Don't know about the noises. Agree with the comment about needing to be there.

Robin 993DX

Maybe the previous owner upgraded the transmission by adding LSD? and the most recent gear oil change was changed oil that does not contain friction modifier?

An easy way to tell is to turn the steering wheel all the way to either direction and back up. A binding LSD plate will be act up more on reverse.

chris walrod

+1 -- if the car is in neutral, the gbx is just free wheeling, no problem.

does this grinding noise only happen when first gear is selected, clutch in? In other words, if you come to a stop with the car in neutral, is the noise still there?

glenn993

So it sounds like the opposite wheel issue is expected when the car is neutral, which is good news.

Re: The grinding, the steering fluid checked out fine, so that's probably not the issue unfortunately.

@Chris - yes, the grinding sound definately happened in neutral with my foot off the clutch...