Hey all,

So I was recently underneath the rear of my car to replace a fuel filter and found that it is dirty. D-I-R-T-Y, Dirty. All kinds of dirt that just flakes off congregating all over my tranny, CV boots, cooler lines, etc.

So, here're my questions:

1) I want to change my fluid (who knows when it was last changed) and was wondering if there's an easier way to do it other than the Clark's writeup? Not too big a deal; I was mainly just wondering.

2) Should I take a pressure sprayer to the rear of my car and have at it? Or will this open up the possibility of creating/opening a leak?

3) I'm drawing a blank -- how does one test the LSD to make sure it's still in working condition? As we all know, LSDs get old... Do I hold one tire and then have a friend (or try myself with my enormously long arms) try to rotate the other? I forget which way the other wheel will turn if I turn only one wheel...


Thanks guys!

 

I believe you're supposed to see trippy colors with LSD. :P

If you spin one wheel, the other's supposed to go the opposite direction.

Underside of my car's kinda dirty...and I need to do the fuel filter too. How'd you clamp off the fuel line from the tank?

 

Collin,

I just performed this task over the weekend which in all honesty wasnt that bad. I changed it for the reason that I also have a 1986 and wasnt sure when the PO performed the maintanence. The proactive part of me would rather be safe then sorry.

Nevertheless, I ran over to Home Depot and purchased some clear tubing (plumbing section) and a large funnel. I connected them both using a small hose clamp around the tubing. I removed the top 17mm nut, then the bottom. Then cut the tubing to the correct size where it could be routed over the left rear tire. Slowly I poured Redline 75W90NS gear fluid into the funnel and watched it go in. I purchased 3 quarts for the job and what made things easier was my air compressor. The fluid goes in slowwww, so using my blow line attachement and extra tubing, I helped the fluid enter the gearbox. The only precaution is NOT to depress the blow line attachement all the way down (full pressure) or else it will fall out of the fill hole.

or better yet...buy a siphon

 

Thanks guys for the info; I'll be doing that once I get a little bit of spare time...so in other words it probably won't happen until Christmas!

Hmmm...IIRC I checked to see what happens w/ my wheels and I don't think they spun in opposite directions. I"ll check again just to be sure. I'm assuming it's the clutch that's out in the assembly? Can one rebuild it?



And Darren, I simply used some needlenose vice grips and wrapped a towel around the hose so as not to puncture it with the VG teeth. Technically a pair of VG specially made for hose clamping would be ideal, but I didn't have that luxury. And, with the towel wrapped around the hose, it hung down past the filter and helped to absorb some of the gas that inevitably will spill out.

As for the other line (the one I'm assuming is from the tank down at the bottom), I didn't worry about it. It is metal and points upwards, so after removing the filter I soaked up what bit of gas leaked out and then went about concentrating on the other line, from which loaddsssss of gas is capable of spilling.

 

Oh yeah -- what about a pressure sprayer? Should i just use a normal hose with a "jet" attachment just to be safe?

 

Oh, it's the line headed towards the engine. Gotcha! I don't have ANY clamps, so I might have to see about getting some hose clamps. I don't feel like a fuel shower! I love the smell of gas...but not that much.

 

Watch out for that brown stuff but hey it's your trip so be my guest...

 

Not sure that the spinning opposite directions is completely accurate. do a search, but that won't necessarily give great insight as to what is the actual way. it matters if it is in gear or neutral too.

You could probably test it by putting one back tire on ice or on a rolling jack and see if you can drive at all.

 

If they spin in opposite directions it is an open diff.

 

That is the easiest, and you can do it from under the car as well. Attach a clear hose to the bottle of fluid, turn upside down, punch a hole in the bottom, hold your air gun against the bottle as you slowly squeeze....watch fluid shoot into transaxle. Takes about 15 seconds a bottle.

Local auto parts stores will also sell a little gear lube pump that works as well, only you have to pump it about 150 times to empty a single bottle of gear lube.

 

Cool I just did a search (stupid me) and found my answer re: question #2 in the 993 forum. Unfortunately, the fix for this involved changing a clutch pack, which is apparently easy to do on a 993.

Is there a replacement clutch pack for the 951 LSD? Is it relatively easy?

FWIW I don't think it's working well b/c when turning I can induce a small amount of inner wheel spin. I'll have to check for sure.

 

When jacked up in neutral, turn one tire and the other will spin in the same direction with LSD. To test how strong it still is, jack up one side of the car so that the other side is still firmly on the ground. With the car in neutral, try turning the rear wheel in the air. It should be pretty tough to turn - the more resistance the tighter your LSD is.

Replacing the clutch pack is really not something a shadetree mechanic can do, but it's not all that tough for a Porsche shop. The local Porsche shop here installs 930 friction plates when they rebuild an LSD which are more durable and stiffen it up even more.

 

There is a torque spec the factory gives for determining allowable slip for an LSD. The test is designed to be done with the LSD unit in a vise with a jig for the torque wrench to turn the output splines/shaft. However, as Skip mentions, you could put a torque wrench and the rear axle nut (with the one wheel off the ground) and see what it takes to turn the wheel. I will have to try that, and see if it matches the torque that I found using the disassembled/vise method.


Skip,

Steinel doing the 930 discs? Which LSD units are they doing this with, the non-Turbo S or the Turbo S LSDs? Any machining operations required, or are the discs a direct replacement?


Collin,

All the 944 series LSDs now supercede to the Turbo S LSD, so the only parts available are the Turbo S guts. So, when replacing the original friction discs with the Turbo S disc, its required you use the Turbo S pressure cups also (which are $150+ a piece - need 2). I priced it out last year, and its about $500 to rebuild a pre-Turbo S LSD. So maybe this 930 disc replacement is a viable option.

944 LSDs are not that prone to premature wear or failure (like certain 964 and 993 units are). How many miles are on your car? Was it raced? If youre under 150k, and the car was not raced (and I mean raced, not a few DE's), then it would be unusual for the LSD to be completely shot - unless the trans has never had the fluid changed, or run low; but then you will have significant wear problems with other bearings and components also.

 

Hey Jim - yes Steinels was who I was referring to. I guess I didn't ask if they treat the S and non-S differently although would have though he would have mentioned it. I was planning on pulling my tranny this winter and taking it up ther to have them refresh the LSD. Tranny shifts great with no synchro issues, but I had one Eric's 944 specialists check it out at the track and while the LSD is not shot, it is certainly looser than it should be. He just turned the wheel by hand to feel the resistance although it would be nice to have a torque spec to check it to. For reference I have 130k miles on it, and tracked fairly heavily for the past 7 years. Have ran Swepco in it since 106k miles when I bought it.

 

Guess this is a good separate question since we're talking trannys...how often do y'all change the tranny fluid?